AT1008-NOL

UNIT I: Crumple zone

Mercedes-Benz "Fintail", an early example of a car with crumple zones

The crumple zone on the front of these cars absorbed the impact of a head-on collision

Activated rear crumple zone

A crash test illustrates how a crumple zone absorbs energy from a crash. The crumple zone of an automobile is a structural feature designed to compress during an accident to absorb energy from the impact. Typically, crumple zones are located in the front part of the vehicle, in order to absorb the impact of a head-on collision, though they may be found on other parts of the vehicle as well. ome racing cars use aluminium or composite honeycomb to form an !impact attenuator! for this purpose. An early example of the crumple zone concept was used by the Mercedes-Benz engineer B"la Bar"nyi on the #$%$ Mercedes-Benz "Fintail".This innovation was first patented by MercedesBenz in the early #$%&s.

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Function 'rumple zones wor( by managing crash energy, absorbing it within the outer sections of the vehicle, rather than being directly transmitted to the occupants, while also preventing intrusion into or deformation of the passenger cabin. This better protects car occupants against in)ury. This is achieved by controlled wea(ening of sacrificial outer parts of the car, while strengthening and increasing the rigidity of the inner part of the body of the car, ma(ing the passenger cabin into a !safety cell!, by using more reinforcing beams and higher strength steels. *olvo introduced the side crumple zone, with the introduction of the +, - ide +mpact ,rotection ystem. in the early #$$&s. The purpose of crumple zones is to slow down the collision and to absorb energy. +t is li(e the difference between slamming someone into a wall headfirst -fracturing their s(ull. and shoulderfirst -bruising their flesh slightly. is that the arm, being softer, has tens of times longer to slow its speed, yielding a little at a time, than the hard s(ull, which isn!t in contact with the wall until it has to deal with extremely high pressures. eatbelts restrain the passenger so they don!t fly through the windshield, and are in the correct position for the airbag and also spread the loading of impact on the body. eat belts also absorb energy by being designed to stretch during an impact, so that there is less speed differential between the passenger!s body and their vehicle interior. +n short/ A passenger whose body is decelerated more slowly due to the crumple zone -and other devices. over a longer time, survives much more often than a passenger whose body indirectly impacts a hard, undamaged metal car body which has come to a halt nearly instantaneously. The final impact after a passenger!s body hits the car interior, airbag or seat belts, is that of the internal organs hitting the ribcage or s(ull. The force of this impact is the mechanism through which car crashes cause disabling or life threatening in)ury. The se0uence of energy dissipating and speed reducing technologies - crumple zone - seat belt - airbags - padded interior, are designed to wor( together as a system, to reduce the force of this final impact. A common misconception about crumple zones is that they reduce safety by allowing the vehicle!s body to collapse, crushing the occupants. +n fact, crumple zones are typically located in front and behind of the main body -though side impact absorption systems are starting to be introduced., of the car -which forms a rigid !safety cell!., compacting within the space of the engine compartment or boot1trun(. The mar(ed improvement over the past two decades in high speed crash test results and real-life accidents also belies any such fears. Modern vehicles using what are commonly termed !crumple zones! provide far superior protection for their occupants in severe tests than older models, or 2*s that use a separate chassis frame and have no crumple zones. The 3&&4 ,ininfarina Nido 5xperimental afety *ehicle locates crumple zones inside the urvival 'ell. Those interior crumple zones decelerate a sled-mounted survival cell.

+t was an inventor Bela Barenyi who pioneered the idea that passengers were safer in a vehicle that was designed to easily absorb the energy from an impact and (eep that energy away from the people inside the cabin. Barenyi devised a system of placing the car!s components in a certain configuration that (ept the (inetic energy in the event of a crash away from a bubble protecting the car!s occupants. Mercedes obtained a patent from Barenyi!s invention way bac( in #$%3 and the technology was first introduced into production cars in #$%$ in the Mercedes-Benz 33&, 33& and 33& 5 models. 6or example, Barenyi arranged the steering column and other heavy components so that they would not form bloc(s that would heighten the impact on the cabin. The system was designed to have the car!s body crumple around the cabin, absorbing the worst of the (inetic shoc( of impact. 7esign changes affected the inside of the cabin as well, with the dashboard and controls all made with soft-edges and made to yield easily in a crash. Those Mercedes models were also some of the first to introduce over-the-shoulder seat-belts. The inventor1engineer Barenyi is credited with about 3,%&& patents, more than half as many as the more famous inventor, Thomas 5dison.

Composite Sandwich Panel Manufacturing Concepts for a Lightweight Vehicle Chassis
INT !"UCTI!N Much of the rationale behind this pro)ect has been explored in the wor( of 8ovins and others 9#:. They suggested that the circumstances in which the automobile industry may well find itself within the near future calls for a rapid reassessment of vehicle manufacturing. 5nvironmental pressures are demanding a radical step change in technology and procedures, rather than the traditional incremental refinements to existing design and manufacturing philosophy. This paper does not see( to provide an answer to that complex challenge, but merely to present an alternative manufacturing concept which could be adopted to meet at least some of the points raised by that research. andwich panel constructions using metallic and polymeric honeycombs and foams have been used for many years in the competition and high performance sectors of the automotive industry, and there is considerable (nowledge and confidence in their static, dynamic and crashworthiness properties 93:. ;owever, it should be noted that with regard to vehicle structures, sandwich panels have only been used to produce extremely limited numbers of product and have been essentially hand-wor(ed. This consumes large and expensive periods of time in order to maintain the re0uired accuracy. <hilst handmade products have a certain appeal, the 0uality and repeatability of process and standards cannot be achieved by these methods within mass production.

+n this paper we are exploring the potential of lightweight composites for chassis structures. ;owever, we have ta(en a different approach to manufacture, in an attempt to circumvent the difficulties associated with wet resins, consolidation pressure and cure cycle control. This is achieved by machining, folding and bonding finished flat stoc( material, using standard '=' e0uipment. At first sight, this strategy sacrifices one of the principal advantages of polymer composites, namely the ability to mould complex geometries in one operation. >n the other hand, the assembly of structures from flat sheet as described here has a number of advantages/ ← ← ← ← =o tooling is re0uired. 5xisting technology '=' e0uipment may be used. Material 0uality is assured by the supplier, not the manufacturer. 7irect integration between 'A7 drawing, 65A and 'AM is straightforward.

These advantages have obvious implications for capital and production costs. #$ M%T& I%LS The potential advantages of polymer composites for automotive parts -high specific strength and stiffness, corrosion resistance. are well (nown. 6urther benefits are available from the use of sandwich construction, in which a relatively stiff, strong s(in is bonded either side of a much thic(er, lightweight core. andwich panels have been widely used for structural applications in the marine, aerospace and performance automotive industries for several decades 9?:. 8ightweight core materials have included balsa, polymer foams and metallic, paper or polymer honeycombs. These have been used in various combinations with s(ins of carbon, glass and1or aramid fibrereinforced polymer, as well as aluminium. The principle of sandwich construction is that bending loads are carried by the s(ins, while the core transmits shear load. They enable large gains in structural efficiency, since the thic(ness -and hence flexural rigidity. of panels can be increased without significant weight penalty. ome representative properties of sandwich panels are given in Table #.

Thic(ness Bending stiffness per <eight per unit area of -mm. unit width -=m31m. sandwich beam -(g1m3. 6-board #?.@ 3B.4 %3.? #?.$ 3B.B %3.& #,#&& 4,%&& 3&,%&& ?,%&& #?,%&& %3,%&& ?.&A 4.3# @.%4 4.B@ %.@? @.A4

M-board

<eight per unit area of monolithic Al. with same bending stiffness -(g1m3. #% 3% 4# 3? ?B %B

Table 1. Comparison of beam stiffness of ‘F-board’ (GRP skinned aluminium one!"omb#$ ‘%board’ (aluminium skinned aluminium one!"omb# and monolit i" aluminium. &ata "ourtes!

'e("el Composites. <hile the design of sandwich panels for stiffness is relatively straightforward, design for strength is more complex. This is because sandwich structures exhibit a range of failure modes, depending on materials, geometry and loading. The most problematic are usually debonding of the s(ins and core shear failure. The energy absorbing characteristics of composites in general and sandwich structures in particular have been the sub)ect of extensive investigation by a number of industries 93, 4, %:. +n all cases the use of such materials enhances the crashworthiness of the structure. The prototype described in ection 4 used CD, s(in1aluminium honeycomb 6-Board, donated to the pro)ect by ;excel 'omposites. This was used solely as a readily available material, and no attempt has yet been made to optimise the panel, either for performance or manufacture. +n high performance car construction, most sandwich panel elements are vacuum bag1autoclave moulded on a contact tool, usually in several stages -e.g. first s(inE core to s(in bondE second s(in.. Although this permits complex shapes to be produced on low cost tooling, it is necessarily a time consuming and labour intensive process. A high degree of cleanliness and sophisticated process control are re0uired, and inspection is notoriously difficult. ;owever, sandwich panels are also available as flat sheet, stoc( material. ;excel 'omposites, for example, supply a range of honeycomb cored sheets of varying specifications which is widely used for building cladding, aircraft flooring, luggage bins and bul(heads. The use of a stoc( material is attractive, since primary material 0uality and specification becomes the responsibility of the supplier, not the manufacturer. '$ "&SI(N %N" M%NU)%CTU IN( P% %M&T& S The current and established philosophy of mass vehicle production uses cheap material, i.e. steel, and expensive press tooling. The method relies on a large output over a long period, utilising the tooling to its absolute maximum in order to achieve profits and recoup the initial enormous investment. Typically, a steel componentFs costs are divided #%G for the steel itself and A%G for shaping and finishing 9B:. There is much excellent research being carried out to improve the performance of steel and aluminium for vehicle production 9@, A:, but all such research revolves around the use of existing tooling methods. The ma)ority of manufacturers and designers recognise the inherent advantages, and indeed the re0uirements, to reduce overall vehicle weight, whilst improving crashworthiness and strength. Desearch into utilising composites in vehicle construction have been underta(en by most of the ma)or manufacturers. <hat emerges is that all of these efforts are aimed at ma(ing new materials fit existing manufacturing methods. +t has been said that composites are not Hblac( steelH and that a component that loo(s the same in composite as it did in metal is incorrectly designed. Dather one must use appropriate materials with appropriate methods. This pro)ect does not see( to introduce new materials and try to ma(e them fit into existing processes, but rather see(s to investigate the feasibility of redefining the manufacturing concept. This involves the opposite of the current Icheap material1expensive toolingF philosophyE namely Iexpensive material1cheap toolingF.

Monoco0ue construction has proven itself the most cost-effective way of producing vehicles when using pressed steel methods. ;owever, this method does not necessarily produce the strongest, stiffest or most efficient vehicles. Many highly regarded low volume vehicle manufacturers, such as 8otus and T*D use a chassis1body method which allows each area of the vehicle to use the most appropriate materials to perform specific tas(s. This pro)ect has begun by ta(ing the concept of chassis1body construction one step further. The form of the chassis is expanded so that it forms a structural endos(eleton which provides stiffness, strength and the vast ma)ority of passenger protection. +f a stoc(, flat material had sufficient properties to be used without expensive, complex tooling and forming to construct such a structural endos(eleton, other areas of the vehicle could use materials more suited to their particular functions. everal techni0ues are well established for the shaping and assembly of structural components from flat sandwich panel 9$:. ome of these are illustrated in 6ig. #. ,anels may be bent to re0uired angles by removing a defined strip of material from the inner s(in, then folding and adhesively bonding the )oint. imilarly, panels can be )oined at right angles.

Fi)ure 1. *ome +ointin) met ods for sand,i" panels. (Courtes! 'e("el Composites# 6or additional strength, reinforcing material can be added at the s(in )oints. +t is emphasised at this point that the process of shaping a panel re0uires no tooling, and assembly can often be arranged so that parts are self-)igging. Although panels can be machined with hand tools, a ma)or attraction of these techni0ues is the potential they offer for computer control and automation. +n this pro)ect we have used a general industrial '=' router1cutterE as described in ection 4, adhesives were applied manually, but this too could be readily automated. *$ +UNIC% , C-%SSIS . P !!) !) C!NC&PT The student pro)ect underta(en in #$$%1B at the 2niversity of ,lymouth aimed at a preliminary proof of concept. +t was felt that the best way to achieve this was to design a vehicle endos(eleton -6ig. 3. on standard 'A7 software, and then to use the data directly with a '=' router to produce the re0uired panels. These panels would then be bonded and some existing suspension and

drivetrain components would be fitted to the resulting chassis. The 2ni'ar design was reasonably non-specific, other than it should be of average dimensions and capable of transporting six adults. 7ue mainly to suspension aspects, a 'itroen 3'* was chosen as the component donor vehicle. The chassis was therefore designed to incorporate the leading and trailing arm suspension, but the drivetrain was reversed and mounted centrally, still driving the front wheels. This allows very simple mounting of the drivetrain and provides good dynamics as well as a more efficient use of the structure as it negated the re0uirement to cantilever the engine out of the front of the car. There was then also the added attraction of having the largest single mass underneath the vehicle occupants rather than in front of them, providing centre of gravity, safety and crashworthiness advantages. 5xpected loads for the chassis were calculated at 33 (= and then doubled to provide a safety factor. Thus the maximum force transmitted to the chassis by the suspension would be around four and half times the mass of the vehicle, which e0uates to a force of about 4& (= experienced in a longitudinal direction when the vehicle traverses a bump. To transfer these loads to the honeycomb panels, a ##& mm diameter steel ferrule was manufactured through which the suspension arms would pivot. These were tested to %& (= with stress propagation as predicted and without compromising the board or the ferrule. Mountings for the dampers were manufactured and successfully tested for similar loads. The chassis was based on a beam design which provided simplicity with efficient use of the material and a structure which was continuous along the vehicle length, offering stiffness and a degree of front and rear impact resistance.

Fi)ure -. .& "omputer model of t e /niCar " assis "on"ept The chassis was designed to be assembled using the cut-and-fold methods outlined in ection ?,

and after some #1%th scale model-ma(ing using corrugated card, the sandwich panel components were drawn using Auto'A7. These drawings were then used by a local engineering company with a '=' router to machine the panels. The twin longitudinal beams were bonded first and then suspension components fitted to the panels. The panels were then bonded and the remaining components fitted. Bonding was achieved throughout the structure with Dedux 43& adhesive applied with a special application gun. +nitial testing of the torsional rigidity of the chassis as a structure was performed. The chassis was restrained at three corners and then loaded at the fourth corner to induce torsion. 7igital angle meters were used to measure angular displacements and dial gauges used to measure vertical and horizontal displacement. The angular displacement was validated using dial gauge displacement readings and their geometric relationships. 6or a weight of 4A (g, the 2ni'ar chassis achieved a torsional rigidity of %$&& =m1deg and a bending rigidity of B&$% =m1mm. Table 3 shows values for current state of the art -IDeferenceF., 2ltra 8ight teel Auto Bodies -28 AB., aluminium extrusion construction -8otus 5lise. and flat sandwich panel construction 9A:. IDeferenceF and I28 ABF are monoco0ue, whilst the other two are chassis1body constructions. Deference 3@# 43.%% ###B 28 AB 3&% $3.$B $B3 8otus 5lise BA #4@.&B n1a 2ni'ar 4A #33.$3 %B&

Mass -(g. pecific torsional rigidity -=m1deg.1(g 'ost -2 J.

Table -. Relati0e torsional ri)idities (data for ‘Referen"e’$ /1*23’ and 1otus from 456#. These initial results are very encouraging, and suggest that the overall concept warrants further investigation. /$ M%NU)%CTU IN( C!NC&PTS The proposed manufacturing system is only possible now because of the advances in material 0uality, and computer systems, controls, software and machinery. Before the advent of cheap, high powered computing facilities, suitable accuracy, repeatability, 0uality and cost effectiveness were difficult to achieve. +n line with general industry process, the design begins on 'A7 software on the des(top. As the main structural endos(eleton is manufactured from flat panels, the drawing process and stress calculation are far simpler than with current monoco0ue construction. The panel data is fed to lofting software and then to a '=' router1cutter where the panels are cut directly. At prototype stage the chassis can then be assembled and bonded by hand. This is only possible if the panels are cut by the computer, directly from the drawings.

As the ma)ority of crash protection is achieved solely by the endos(eleton, preliminary crash testing can be performed before manufacturing body panels. >verall dynamics and handling can also undergo preliminary assessment. 'omponents can be test fittedE stylists can wor( on full size vehiclesE fatigue testing, crashworthiness and so forth can then be tested. Modifications to panel weight, material specifications, a particular )oint or component interface is simply made on the computer and generated at the manufacturing level. All of this essential preliminary development wor( can be underta(en without any model-specific tooling.

7etailed 'A7

+n series production the whole manufacturing1assembly process is automated, but utilises simple folding and adhesive bonding robots, which are again, non-product specific. +n this case methods and materials for body panels are no longer constrained by being part of the monoco0ue. imple panels made from a whole range of materials from plastic to aluminium and lightweight steels can now be utilised, depending on the vehicleFs performance re0uirements, its function and intended mar(et. )U T-& "&V&L!PM&NTS ;aving successfully proven that the manufacturing concept is feasible in basic engineering terms,

wor( is currently in progress on chassis design and analysis. Although flat panel structures are relatively simple to model for 65A, it is necessary to 0uantify the mechanical properties of the bonded )oints, and to represent these in the model efficiently. A longer-term goal is to further integrate the ?7 'A7 design with stress analysis, thus enabling materials and structural optimisation prior to manufacture. +n the current situation of limited resources, the following aspects are recognised as being of considerable importance, but must await further funding/ ← election of sandwich panel component materials -s(ins and core. for ease and consistency of manufacture, performance and recycling. ← >ptimisation of adhesive for cure cycle and long term properties. ← 'rashworthiness testing. ← Dobot handling and positioning of panels. ← ,roduction plant layout, process monitoring and 0uality systems. ← 7esign and attachment of body panels. ← >perational considerations -e.g. thermal, acoustic and dynamic characteristics.. 6unding and in-(ind support is actively being sought from various bodies -e.g. materials suppliers, manufacturers and potential customers. to carry the pro)ect forward.

UNIT #:

%utomo0ile safet1 is the study and practice of vehicle design, construction, and e0uipment to minimise the occurrence and conse0uences of automobile accidents. -Doad traffic safety more broadly includes roadway design.. +mprovements in roadway and automobile design have steadily reduced in)ury and death rates in all first world countries. =evertheless, auto collisions are the leading cause of in)ury-related deaths, an estimated total of #.3 million in 3&&4, or 3%G of the total from all causes. Active and passive safety The terms HactiveH and HpassiveH are simple but important terms in the world of automotive safety. HActive safetyH is used to refer to technology assisting in the avoidance of a crash and Hpassive safetyH to components of the vehicle -primarily airbags, seatbelts and the physical structure of the vehicle. that help to protect occupants during a crash . Crash avoidance 'rash avoidance systems and devices help the driver K and, increasingly, help the vehicle itself K to avoid a collision. This category includes/
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The vehicle!s headlamps, reflectors, and other lights and signals The vehicle!s mirrors The vehicle!s bra(es, steering, and suspension systems

7river assistance A subset of crash avoidance is dri0er assistan"e systems, which help the driver to detect ordinarily-hidden obstacles and to control the vehicle. 7river assistance systems include/
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+nfrared night vision systems to increase seeing distance beyond headlamp range Adaptive highbeam assist which automatically and continuously adapts the headlamp range to the distance of vehicles ahead or which are oncoming Adaptive headlamps swivels headlamps around corners Automatic high beams which automatically adapts the headlamp range to the distance of vehicles ahead or which are oncoming Deverse bac(up sensors which alert drivers to difficult-to-see ob)ects in their path when reversing Bac(up camera Adaptive cruise control which maintains a safe distance from the vehicle in front 8ane departure warning systems to alert the driver of an unintended departure from the intended lane of travel Tire pressure monitoring systems or 7eflation 7etection ystems Traction control systems which restore traction if driven wheels begin to spin 5lectronic tability 'ontrol, which intervenes to avert an impending loss of control Anti-loc( bra(ing systems 5lectronic bra(eforce distribution systems

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5mergency bra(e assist systems 'ornering Bra(e 'ontrol systems ,recrash system Automated par(ing system

Crashworthiness

6errari 64?& steering wheel with airbag 'rashworthy systems and devices prevent or reduce the severity of in)uries when a crash is imminent or actually happening. Much research is carried out using anthropomorphic crash test dummies.
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eatbelts limit the forward motion of an occupant, stretch to slow down the occupant!s deceleration in a crash, and prevent occupants being e)ected from the vehicle. Airbags inflate to cushion the impact of a vehicle occupant with various parts of the vehicle!s interior. 8aminated windshields remain in one piece when impacted, preventing penetration of unbelted occupants! heads and maintaining a minimal but ade0uate transparency for control of the car immediately following a collision. Tempered glass side and rear windows brea( into granules with minimally sharp edges, rather than splintering into )agged fragments as ordinary glass does. 'rumple zones absorb and dissipate the force of a collision, displacing and diverting it away from the passenger compartment and reducing the impact force on the vehicle occupants. *ehicles will include a front, rear and maybe side crumple zones -li(e *olvo +, . too. ide impact protection beams. 'ollapsible universally )ointed steering columns, -with the steering system mounted behind the front axle - not in the front crumple zone., reduce the ris( and severity of driver impalement on the column in a frontal crash. ,edestrian protection systems. ,adding of the instrument panel and other interior parts of the vehicle li(ely to be struc( by the occupants during a crash.

Post-crash survivability ,ost-crash survivability devices and systems help minimise the chances that vehicle occupants who survive a crash will be in)ured or (illed by secondary effects of the collision, such as fire.

5xamples include technical standards for vehicle fuel system integrity and fire resistance and retardance of vehicle interior materials.Advanced Automatic 'ollision =otification systems will alert authorities automatically after an accident has occurred. 6iat in the #$$&s 6iat ,unto introduced an automatic engine compartment fire extinguisher system. Pedestrian safety

#$@4 Mini 'lubman 5xperimental afety *ehicle featuring a Hpedestrian-friendlyH front end. ince at least the early #$@&s, attention has also been given to vehicle design regarding the safety of pedestrians in car-pedestrian collisions. ,roposals in 5urope would re0uire cars sold there to have a minimum1maximum hood -bonnet. height. 6rom 3&&B the use of "bull bars", a fashion on 4x4s and 2*s, became illegal. Conspicuity A wedish study found that pin( cars are involved in the fewest accidents, with blac( cars being most often involved in crashes -8and transport =L 3&&%.. +n Auc(land =ew Lealand, a study found that there was a significantly lower rate of serious in)ury in silver carsE with higher rates in brown, blac(, and green cars. -6urness et al., 3&&?. The *ehicle 'olor tudy, conducted by Monash 2niversity Accident Desearch 'entre -M2AD'. and published in 3&&@, analysed A%%,3%A accidents occurring between #$A@ and 3&&4 in the Australian states of *ictoria and <estern Australia that resulted in in)ury or in a vehicle being towed away. The study analysed ris( by light condition. +t found that in daylight blac( cars were #3G more li(ely than white to be involved in an accident, followed by grey cars at ##G, silver cars at #&G, and red and blue cars at @G, with no other colors found to be significantly more or less ris(y than white. At dawn or dus( the ris( ratio for blac( cars )umped to 4@G more li(ely than white, and that for silver cars to #%G. +n the hours of dar(ness only red and silver cars were found to be significantly more ris(y than white, by #&G and AG respectively. 7aytime running lamp that have been standard on wedish cars since the #$@&s, are soon to be mandatory across the entire 52. History Automobile safety may have become an issue almost from the beginning of mechanised road vehicle development. The second steam-powered H6ardierH -artillery tractor., created by =icolasMoseph 'ugnot in #@@#, is reported by some to have crashed into a wall during its demonstration run. ;owever according to Ceorges Ageon, the earliest mention of this occurrence dates from #A&# and it does not feature in contemporary accounts.

>ne of the earliest recorded automobile fatalities was Mary <ard, on August ?#, #AB$ in ,arsonstown, +reland. +n the #$?&s, plastic surgeon 'laire 8. traith and physician '. M. tric(land advocated the use of seat belts and padded dashboards. tric(land founded the Automobile afety 8eague of America.9A: +n #$?4, CM performed the first barrier crash test +n #$43, ;ugh 7e ;aven published the classic %e" ani"al anal!sis of sur0i0al in falls from ei) ts of fift! to one undred and fift! feet. +n #$4$ AAB incorporated aircraft safety thin(ing into automobiles ma(ing the aab $3 the first production AAB car with a safety cage, and the American Tuc(er was built with the world!s first padded dashboard. +n #$%B, 6ord tried unsuccessfully to interest Americans in purchasing safer cars with their 8ifeguard safety pac(age. -+ts attempt nevertheless earns 6ord %otor Trend!s H'ar of the NearH award for #$%B. +n #$%A, the 2nited =ations established the <orld 6orum for ;armonization of *ehicle Degulations, an international standards body advancing auto safety. Many of the most life saving safety innovations, li(e seat belts and roll cage construction were brought to mar(et under its auspices. That same year, *olvo engineer =ils Bohlin invented and patented the three-point lap and shoulder seat belt, which became standard e0uipment on all *olvo cars in #$%$. >ver the next several decades, three-point safety belts were gradually mandated in all vehicles by regulators throughout the industrialised world. +n #$BB, the 2. . established the 2nited tates 7epartment of Transportation -7>T. with automobile safety one of its purposes. The =ational Transportation afety Board -=T B. was created as an independent organization on April #, #$B@, but was reliant on the 7>T for administration and funding. ;owever, in #$@% the organization was made completely independent by the +ndependent afety Board Act*olvo developed the first rear-facing child seat in #$B4 and introduced its own booster seat in #$@A

'onsumer information label for a vehicle with at least one 2 ='A, star rating +n #$@$, =;T A began crash-testing popular cars and publishing the results, to inform consumers and encourage manufacturers to improve the safety of their vehicles. +nitially, the 2 ='A, crash tests examined compliance with the occupant-protection provisions of 6M* 3&A. >ver the subse0uent years, this =;T A program was gradually expanded in scope. +n #$$@, the 5uropean =ew 'ar Assessment ,rogramme -5uro ='A,. was established to test new vehicles! safety performance and publish the results for vehicle shoppers! information. The =;T A crash tests are presently operated and published as the 2. . branch of the international ='A, programme. +n #$A4, =ew Nor( tate passed the first 2 law re0uiring seat belt use in passenger cars. eat belt laws have since been adopted by all %& states,9 and =;T A estimates increased seat belt use as a result save #&,&&& per year in the 2 A.

+n #$AB, the central ?rd bra(e light was mandated in =orth America. >ver the next #% years, most of the world!s other )urisdictions mandated the ?rd bra(e lamp as well. +n #$$%, the ++; begins frontal offset crash tests +n #$$@, 5uro='A, is founded. +n 3&&?, the ++; begins conducting side impact crash tests. +n 3&&4, =;T A released new tests designed to test the rollover ris( of new cars and 2*s. >nly the Mazda DO-A got a %-star rating. +n 3&&$, 'itroPn become the first manufacturer to feature H nowmotionH, an +ntelligent Anti (id system developed in con)unction with Bosch, which gives drivers a level of control in extreme ice or snow conditions similar to a 4x4 Safety trends 7espite technological advances, about 4&,&&& people die every year in the 2. Although the fatality rates per vehicle registered and per vehicle distance travelled have steadily decreased since the advent of significant vehicle and driver regulation, the raw number of fatalities generally increases as a function of rising population and more vehicles on the road. ;owever, sharp rises in the price of fuel and related driver behavioural changes are reducing 3&&@-A highway fatalities in the 2. . to below the #$B# fatality count. +nternational comparison +n #$$B, the 2. . had about 3 deaths per #&,&&& motor vehicles, compared to #.$ in Cermany, 3.B in 6rance, and #.% in the 2Q. +n #$$A, there were ?,43# fatal accidents in the 2Q, the fewest since #$3B The sizable traffic safety lead en)oyed by the 2 A since the #$B&s had narrowed significantly by 3&&3, with the 2 improvement percentages lagging in #Bth place behind those of Australia, Austria, 'anada, 7enmar(, 6inland, Cermany, Creat Britain, +celand, Mapan, 8uxembourg, the =etherlands, =ew Lealand, =orway, weden, and witzerland in terms of deaths per thousand vehicles, while in terms of deaths per #&& million vehicle miles travelled, the 2 A had dropped from first place to tenth place.934: Covernment-collected data, such as that from the 2. . 6atality Analysis Deporting ystem, show other countries achieving safety performance improvements over time greater than those achieved in the 2. . 2nited tates Creat Britain 'anada Australia 1787 Fatalities %#,&$? B,?%3 %,AB? ?,%&A -99- Fatalities 43,A#% ?,4?# 3,$?B #,@#% Per"ent C an)e -#B.3G -4B.&G -4$.$G -%#.#G

Desearch on the trends in use of heavy vehicles indicate that a significant difference between the 2. . and other countries is the relatively high prevalence of pic(up truc(s and 2*s in the 2. . A 3&&? study by the 2. . Transportation Desearch Board found that 2*s and pic(up truc(s are significantly less safe than passenger cars, that imported-brand vehicles tend to be safer than American-brand vehicles, and that the size and weight of a vehicle has a significantly smaller effect on safety than the 0uality of the vehicle!s engineering. The level of large commercial truc( traffic has substantially increased since the #$B&s, while highway capacity has not (ept pace with the increase in large commercial truc( traffic on 2. . highways. ;owever, other factors exert significant influenceE 'anada has lower roadway death and in)ury rates despite a vehicle mix comparable to that of the 2. . =evertheless, the widespread use of truc(-based vehicles as passenger carriers is correlated with roadway deaths and in)uries not only directly by dint of vehicular safety performance per se, but also indirectly through the relatively low fuel costs that facilitate the use of such vehicles in =orth AmericaE motor vehicle fatalities decline as fuel prices increase. =;T A has issued relatively few regulations since the mid #$A&sE most of the vehicle-based reduction in vehicle fatality rates in the 2. . during the last third of the 3&th 'entury were gained by the initial =;T A safety standards issued from #$BA to #$A4 and subse0uent voluntary changes in vehicle design and construction by vehicle manufacturers. 93$: Pregnant women <hen pregnant, women should continue to use seatbelts and airbags properly. A 2niversity of Michigan study found that "unrestrained or improperl! restrained pre)nant ,omen are :.8 times more likel! to a0e an ad0erse fetal out"ome t an properl! restrained pre)nant ,omen".9?&: +f seatbelts are not long enough, extensions are available from the car manufacturer or an aftermar(et supplier. Infants and children 'hildren present significant challenges in engineering and producing safe vehicles, because most children are significantly smaller and lighter than most adults. afety devices and systems designed and optimised to protect adults K particularly calibration-sensitive devices li(e airbags and active seat belts K can be ineffective or hazardous to children. +n recognition of this, many medical professionals and )urisdictions recommend or re0uire that children under a particular age, height, and1or weighride in a child seat and1or in the bac( seat, as applicable. +n weden, for instance, a child or an adult shorter than #4& cm is legally forbidden to ride in a place with an active airbag in front of it. 'hild safety loc(s and driver-controlled power window loc(out controls prevent children from opening doors and windows from inside the vehicle. +nfants left in cars *ery young children can perish from heat or cold if left unattended in a par(ed car, whether deliberately or through absentmindedness. +n Mune 3&&$, a # year old girl was accidentally forgotten in a car in 7enmar( on an extremely hot day and died from heat exhaustion.

Teenage drivers +n the 2Q, a full driving licence can be had at age #@, and most areas in the 2nited tates will issue a full driver!s license at the age of #B, and all within a range between #4 and #A. +n addition to being relatively inexperienced, teen drivers are also cognitively immature, compared to other drivers. This combination leads to a relatively high crash rate among this demographic. +n some areas, new drivers! vehicles must bear a warning sign to alert other drivers that the vehicle is being driven by an inexperienced and learning driver, giving them opportunity to be more cautious and to encourage other drivers to give novices more leeway. ome countries, such as Australia, the 2nited tates, 'anada and =ew Lealand, have graduated levels of driver!s licence, with special rules. +n +taly, the maximum speed and power of vehicles driven by new drivers is restricted. Lane departure warning s1stem

Doadway with lane mar(ings +n road-transport terminology, a lane departure warning s1stem is a mechanism designed to warn a driver when the vehicle begins to move out of its lane -unless a turn signal is on in that direction. on freeways and arterial roads. These systems are designed to minimize accidents by addressing the main causes of collisions/ driving error, distraction and drowsiness. +n 3&&$ the =;T A began studying whether to mandate lane departure warning systems and frontal collision warning systems on automobiles. There are two main types of systems/
• •

systems which warn the driver if the vehicle is leaving its lane. -visual, audible, and1or vibration warnings. systems which warn the driver and if no action is ta(en automatically ta(e steps to ensure the vehicle stays in its lane.

The first production lane departure warning system in 5urope was developed by the 2nited tates!s +teris company for Mercedes Actros commercial truc(s. The system debuted in 3&&& and is now available on most truc(s sold in 5urope. +n 3&&3, the +teris system became available on 6reightliner Truc(s! truc(s in =orth America. +n all of these systems, the driver is warned of unintentional lane departures by an audible rumble strip sound generated on the side of the vehicle drifting out of the lane. +f a turn signal is used, no warnings are generated.

%ir0ag

The driver and passenger front airbags, after having been deployed, in a ,eugeot ?&B car. An air0ag is a vehicle safety device. +t is an occupant restraint consisting of a flexible envelope designed to inflate rapidly in an automobile collision, to prevent vehicle occupants from stri(ing interior ob)ects such as the steering wheel or window.
•

Terminology Because no action by the vehicle occupant is re0uired to activate or use the airbag, it is considered a passi0e safety device. This is in contrast to seat belts, which are considered a"ti0e safety devices because the vehicle occupant must act to enable them.9#:93:9?:94:9%: Terminological confusion can arise from the fact that passive safety devices and systems K those re0uiring no input or action by the vehicle occupant K can themselves operate in an active mannerE an airbag is one such device. *ehicle safety professionals are generally careful in their use of language to avoid this sort of confusion, though advertising principles sometimes prevent such syntactic caution in the consumer mar(eting of safety features. *arious manufacturers have over time used different terms for airbags. Ceneral Motors! first bags, in the #$@&s, were mar(eted as the 2ir Cus ion Restraint *!stem. 'ommon terms in =orth America include *upplemental Restraint *!stem (*R*# and *upplemental ;nflatable Restraint (*;R#E these terms reflect the airbag system!s nominal role as a supplement to active restraints, i.e., seat belts. History

#$@% Buic( 5lectra with A'D

+n #$$4, 6ord of 5urope made airbags standard e0uipment in all the cars they built Invention An American inventor, Mohn <. ;etric(, a retired industrial engineer, designed the original safety cushion for automotive use in #$%3 at his (itchen table. ;is patent lasted only #@ years - long before mainstream automotive usage. ,opular cience May, #$BAR1refS while the +talian 5aton-8ivia company offered a variant with localized air cushions.9B: Allen Q. Breed is an inventor, entrepreneur, and pioneer in one of the most significant advances in automotive safety of recent times, the air bag. After earning a B. . in Mechanical 5ngineering from =orthwestern 2niversity in the years following <orld <ar ++, Breed first wor(ed in product design for D'A. After rising to a managerial post there, and directing a )oint venture with Cruen <atch 'ompany, he founded his first company, <altham 5ngineering, in #$%@. +n #$B#, Breed founded another company, Breed 'orp., in order to develop safety and arming devices under contract to the 2 military. 8i(e Macob Dabinow, Breed later applied to a broader realm the expertise in fuzes and timing and sensor technology that he gained from military wor(. pecifically, Breed envisioned a beneficent application for sensor-triggers and controlled explosions, in the realm of automobile safety. Breed invented his first sensor and safety system in #$BA/ this was the world!s first electromechanical automotive air bag system of its (ind. 5ven then, the air bag was not, in theory, entirely new to the automotive industryE but it too( some time to gain broad acceptance. Breed was still well ahead of the game when, in #$A@, he founded Breed Automotive -now Breed Technologies, +nc.. to refine and mar(et his safety systems. The principles on which air bags operate are fairly well (nown. The (eys to their success are reliable crash sensors -which detect an impact either violent or in combination with drastic deceleration., instantaneous triggering and deployment of the cushion, and the prevention of Hsecondary in)uriesH---i.e., in)uries from the passenger!s contact with the air bag.

Air bags have not proved completely successful in meeting this last challengeE but already in #$$#, Breed co-patented an air bag that vents air as it inflates, reducing the ris( of secondary in)uries by reducing the inflated bag!s rigidity. This -T%,&@#,#B#. is )ust one of over two dozen auto safety inventions that Breed has co-patented over the years. Today, Breed continues to oversee the improvement of auto safety mechanics and design, including the successful introduction of sideimpact air bags. Meanwhile, Breed!s company has expanded its scope to include seat belt, steering and other automotive safety technology. >nce located in 8a(eland, 6lorida, Breed Technologies is now (nown as Qey afety ystems, +nc. with head0uarters in 7etroit, Mich. +t does research, manufacturing and consulting wor( worldwide, and its products are now used in over 4&& models of cars. Breed himself has earned a number of honors for his wor(. +n #$$A, he was included in the 5rnst U Noung 5ntrepreneur of the Near %&&E in #$$B, he was inducted into the Tampa Bay Business ;all of 6ameE in #$$%, he was elected =ational 5ntrepreneur of the Near. And besides being admirable for his business success, Allen Breed, li(e <illiam Bolander, who won the inaugural 8emelsonM+T ,rize for his inventions in automotive safety, has applied his innovative instincts to a truly good cause. Breed 'orporation mar(eted this innovation first in #$B@ to 'hrysler. A similar HAuto-'eptorH crash-restraint, developed by 5aton, Nale U Towne +nc. for 6ord was soon offered as an automatic safety system in the 2 A,9#:R1refS As an alternative to seatbelts Airbags for passenger cars were introduced in the 2nited tates in the mid-#$@&s, when seat belt usage rates in the country were 0uite low. Airbags were mar(eted as a convenient alternative to seat belts, while offering similar levels of protection to unbelted occupants in a head-on collision.
9"itation needed:

6ord built an experimental fleet of cars with airbags in #$@#, followed by Ceneral Motors in #$@? on 'hevrolet vehicles. The early fleet of experimental CM vehicles e0uipped with airbags experienced seven fatalities, one of which was later suspected to have been caused by the airbag.9@: +n #$@4, CM made the A'D or HAir 'ushion Destraint ystemH available as a regular production option -D,> code AD?. in some full-size Buic(, 'adillac and >ldsmobile models. The CM cars from the #$@&s e0uipped with A'D have a driver side airbag, a driver side (nee restraint -which consists of a padded lower dashboard. and a passenger side airbag. The passenger side airbag, protects both front passengers and unli(e most newer ones, it integrates a (nee cushion, a torso cushion and it also has dual stage deployment which varies depending on the force of the impact. The cars e0uipped with A'D have lap belts for all seating positions but they do not have shoulder belts. These were already mandatory e0uipment in the 2nited tated on closed cars without airbags for the driver and outer front passenger seating positions. The automotive industry!s first passenger side (nee airbag -not separate. was already used on the #$@&s Ceneral Motors cars, it was integrated in the passenger airbag that had a (nee cushion and a torso cushion.9"itation needed:

The development of airbags coincided with an international interest in automobile safety legislation. ome safety experts advocated a performance-based occupant protection standard rather than a standard mandating a particular technical solution, which could rapidly become outdated and might not be a cost-effective approach. As countries successively mandated seat belt restraints, there was less emphasis placed on other designs for several decades.9B: Manufacturers emphasise that an airbag is not, and can not be an alternative to seatbelts. They emphasise that they are only supplemental to a seatbelt. ;ence the commonly used term H upplemental Destraint ystemH or D . +t is vitally important that drivers and passengers are aware of this. +n the ma)ority of cases of death caused by air bags, seat belts were not worn.9"itation
needed:

As a supplemental restraint

)rontal air0ag
The auto industry and research and regulatory communities have moved away from their initial view of the airbag as a seat belt replacement, and the bags are now nominally designated as Supplemental estraint S1stem 2S S3 or Supplemental Inflata0le estraints. +n #$A&, Mercedes-Benz introduced the airbag in Cermany. as an option on its high-end -'lass -<#3B.. +n the Mercedes system, the sensors would tighten the seat belts, and then deploy the airbag on impact. This integrated the seat belts and airbag into a restraint system, rather than the airbag being considered an alternative to the seat belt. +n #$A@, the ,orsche $44 turbo became the first car in the world to have driver and passenger airbags as standard e0uipment. The ,orsche $44 and $44 had this as an available option. The same year also saw the first airbag in a Mapanese car, the ;onda 8egend9A:. Airbags became common in the #$A&s, with 'hrysler and 6ord introducing them in the mid-#$A&sE it was 'hrysler that made them standard e0uipment across its entire line in #$$& -except for truc(s until #$$%..9"itation needed: Audi was relatively late to offer airbag systems on a broader scaleE until the #$$4 model year, for example, the A&1$&, by far Audi!s !bread-and-butter! model, as well as the #&&13&&, did not have airbags in their standard versions. +nstead, the Cerman automa(er until then relied solely on its proprietary procon-ten restraint system. +n 5urope, airbags were almost entirely absent from family cars until the early #$$&s, except for aab, who made them standard on the $&& Turbo in #$A$ and on all models in #$$&. The first 5uropean 6ord to feature an airbag was the facelifted 5scort MQ%b in #$$3E within a year, the entire 6ord range had at least one airbag as standard. By the mid #$$&s, 5uropean mar(et leaders such as *auxhall1>pel, Dover, ,eugeot, Denault and 6iat had included airbags as at least optional e0uipment across their model ranges. By the end of the decade, it was very rare to find a mass mar(et car without an airbag, and some late #$$&s products, such as the *ol(swagen Colf M(4 also featured side airbags. The ,eugeot ?&B was a classical example of how commonplace airbags became on mass mar(et cars during the #$$&s. >n its launch in early #$$? most of the range did

not even have driver airbags as an option. By #$$$ however, side airbags were available on several variants. 7uring the 3&&&s side airbags were commonplace on even budget cars, such as the smallerengined versions of the 6ord 6iesta and ,eugeot 3&B, and curtain airbags were also becoming regular features on mass mar(et cars. The Toyota Avensis, launched in #$$A, was the first mass mar(et car to be sold in 5urope with a total of nine airbags. Although in some countries, such as Dussia, airbags are still not standard e0uipment on all cars, such as those from 8ada. *ariable force deployment front airbags were developed to help minimize in)ury from the airbag itself.

Shaped airbags
The 'itroPn '4 provides the first HshapedH driver airbag, made possible by this car!s unusual fixed hub steering wheel.9$:

Side air0ag

ide airbag inflated permanently for display purposes

A deployed curtain airbag in a 6ord Mondeo There are essentially two types of side airbags commonly used today, the side torso airbag and the side curtain airbag.

Side torso airbag
ide-impact airbags or side torso airbags are a category of airbag usually located in the seat, and inflate between the seat occupant and the door. These airbags are designed to reduce the ris( of in)ury to the pelvic and lower abdomen regions. ome vehicles are now being e0uipped with different types of designs, to help reduce in)ury and e)ection from the vehicle in rollover crashes.

The wedish company Autoliv AB, was granted a patent on side airbags, and they were first offered as an option in #$$4 on the #$$% model year *olvo A%&, and as standard e0uipment on all *olvo cars made after #$$%.

[edit] Side tubular or curtain airbag
+n late #$$@ the #$$A model year BM< @-series and 5?$ %-series were fitted with a tubular shaped head side airbags, the H;ead ,rotection ystem -;, .H as standard e0uipment. This is an industry!s first in offering head protection in side impact collisions.9#&: This airbag also maintained inflation for up to seven seconds for rollover protection. ;owever, this tubular shaped airbag design has been 0uic(ly replaced by an inflatable !curtain! airbag for superior protection. +n May #$$A Toyota began offering the first side curtain airbag deploying from the roof on the ,rogr"s.9##: +n #$$A the *olvo A& was first given curtain airbags to protect both front and rear passengers. They were then made standard e0uipment on all new *olvo cars from #$$A and while initially seat-mounted later versions deployed from the roof. Doll-sensing side curtain airbags found on vehicles more prone to rollovers such as 2*!s and pic(ups will deploy when a rollover is detected instead of )ust when an actual collision ta(es place. >ften there is a switch to disable the feature in case the driver wants to ta(e the vehicle offroad. 'urtain airbags have been said to reduce brain in)ury or fatalities by up to 4%G in a side impact with an 2*. These airbags come in various forms -e.g., tubular, curtain, door-mounted. depending on the needs of the application.9#3: Many recent 2*s and M,*s have a long inflatable curtain airbag that protects all ? rows of seats.

4nee air0ag
The first driver!s side and separate (nee airbag was used in the #$$B model Qia portage vehicle and has been standard e0uipment since then. The airbag is located beneath the steering.9#?: The Toyota Avensis became the first vehicle sold in 5urope e0uipped with a driverFs (nee airbag.9#4:9#%: The 5uro='A, reported on the 3&&? Avensis, HThere has been much effort to protect the driverFs (nees and legs and a (nee airbag wor(ed well.H9#B: ince then certain models have also included front passenger (nee airbags.

ear curtain air0ag
+n 3&&A, the Toyota iV launched featuring the first production rear curtain shield airbag to protect the rear occupants! heads in the event of a rear end impact.9#@:

ear center air0ag
+n 3&&$, Toyota developed the first production rear-seat center airbag designed to reduce the severity of secondary in)uries to rear passengers in a side collision. This system deploys from the rear center console first appearing in on the redesigned 'rown Ma)esta.9#A:

Seat 0elt air0ag
+n 3&&$, the -class 5 6 safety concept car showcased seatbelt airbags. They will be included standard on the production 8exus 86A in late 3&#&, and the 3&## 6ord 5xplorer will offer rear seatbelt airbags as an option. n motorcycles *arious types of airbags were tested on motorcycles by the 2Q Transport Desearch 8aboratory in the mid #$@&s. +n 3&&B ;onda introduced the first production motorcycle airbag safety system on its Cold <ing motorcycle. ;onda claims that sensors in the front for(s can detect a severe frontal collision and decide when to deploy the airbag, absorbing some of the forward energy of the rider and reducing the velocity at which the rider may be thrown from the motorcycle.9#$: Airbag suits have also been developed for use by Motorcycle Crand ,rix riders. They are connected to the motorcycle by a cable and deploy when the cable becomes detached from its mounting clip, inflating to protect the bac(.93&: How airbags wor!

An A'2 from a Ceo torm. The design is conceptually simpleE a central HAirbag control unitH93#: -A'2. -a specific type of 5'2. monitors a number of related sensors within the vehicle, including accelerometers, impact sensors, side -door. pressure sensors933:, wheel speed sensors, gyroscopes, bra(e pressure sensors, and seat occupancy sensors. <hen the re0uisite !threshold! has been reached or exceeded, the airbag control unit will trigger the ignition of a gas generator propellant to rapidly inflate a nylon fabric bag. As the vehicle occupant collides with and s0ueezes the bag, the gas escapes in a controlled manner through small vent holes. The airbag!s volume and the size of the vents in the bag are tailored to each vehicle type, to spread out the deceleration of -and thus force experienced by. the occupant over time and over the occupant!s body, compared to a seat belt alone. The signals from the various sensors are fed into the Airbag control unit, which determines from them the angle of impact, the severity, or force of the crash, along with other variables. 7epending on the result of these calculations, the A'2 may also deploy various additional restraint devices, such as seat belt pre-tensioners, and1or airbags -including frontal bags for driver and front passenger, along with seat-mounted side bags, and HcurtainH airbags which cover the side glass.. 5ach restraint device is typically activated with one or more pyrotechnic devices, commonly called an initiator or electric match. The electric match, which consists of an electrical conductor wrapped in a combustible material, activates with a current pulse between # to ? amperes in less than 3 milliseconds. <hen the conductor becomes hot enough, it ignites the combustible material, which initiates the gas generator. +n a seat belt pre-tensioner, this hot gas is used to drive a piston

that pulls the slac( out of the seat belt. +n an airbag, the initiator is used to ignite solid propellant inside the airbag inflator. The burning propellant generates inert gas which rapidly inflates the airbag in approximately 3& to ?& milliseconds. An airbag must inflate 0uic(ly in order to be fully inflated by the time the forward-traveling occupant reaches its outer surface. Typically, the decision to deploy an airbag in a frontal crash is made within #% to ?& milliseconds after the onset of the crash, and both the driver and passenger airbags are fully inflated within approximately B&A& milliseconds after the first moment of vehicle contact. +f an airbag deploys too late or too slowly, the ris( of occupant in)ury from contact with the inflating airbag may increase. ince more distance typically exists between the passenger and the instrument panel, the passenger airbag is larger and re0uires more gas to fill it. 6ront airbags normally do not protect the occupants during side, rear, or rollover accidents.93?: ince airbags deploy only once and deflate 0uic(ly after the initial impact, they will not be beneficial during a subse0uent collision. afety belts help reduce the ris( of in)ury in many types of crashes. They help to properly position occupants to maximize the airbag!s benefits and they help restrain occupants during the initial and any following collisions. +n vehicles e0uipped with a rollover sensing system, accelerometers and gyroscopes are used to sense the onset of a rollover event. +f a rollover event is determined to be imminent, side-curtain airbags are deployed to help protect the occupant from contact with the side of the vehicle interior, and also to help prevent occupant e)ection as the vehicle rolls over. Triggering conditions Airbags are designed to deploy in frontal and near-frontal collisions more severe than a threshold defined by the regulations governing vehicle construction in whatever particular mar(et the vehicle is intended for. 2. . regulations re0uire deployment in crashes at least e0uivalent in deceleration to a 3? (m1h-#4 mph. barrier collision, or similarly, stri(ing a par(ed car of similar size across the full front of each vehicle at about twice the speed. +nternational regulations are performance based, rather than technology-based, so airbag deployment threshold is a function of overall vehicle design. 2nli(e crash tests into barriers, real-world crashes typically occur at angles other than directly into the front of the vehicle, and the crash forces usually are not evenly distributed across the front of the vehicle. 'onse0uently, the relative speed between a stri(ing and struc( vehicle re0uired to deploy the airbag in a real-world crash can be much higher than an e0uivalent barrier crash. Because airbag sensors measure deceleration, vehicle speed and damage are not good indicators of whether an airbag should have deployed. Airbags can deploy due to the vehicle!s undercarriage stri(ing a low ob)ect protruding above the roadway due to the resulting deceleration. The airbag sensor is a M5M accelerometer, which is a small integrated circuit with integrated micro mechanical elements. The microscopic mechanical element moves in response to rapid deceleration, and this motion causes a change in capacitance, which is detected by the electronics on the chip that then sends a signal to fire the airbag. The most common M5M accelerometer in use is the A7O8-%& by Analog 7evices, but there are other M5M manufacturers as well. +nitial attempts using mercury switches did not wor( well. Before M5M , the primary system used to deploy airbags was called a HrolamiteH. A rolamite is a mechanical device, consisting of a roller

suspended within a tensioned band. As a result of the particular geometry and material properties used, the roller is free to translate with little friction or hysteresis. This device was developed at andia =ational 8aboratories. The rolamite, and similar macro-mechanical devices were used in airbags until the mid-#$$&s when they were universally replaced with M5M . =early all airbags are designed to automatically deploy in the event of a vehicle fire when temperatures reach #%&-3&& W' -?&&-4&& W6..934: This safety feature, often termed auto-ignition, helps to ensure that such temperatures do not cause an explosion of the entire airbag module. Today, airbag triggering algorithms are becoming much more complex. They try to reduce unnecessary deployments -for example, at low speed, no shoc(s should trigger the airbag, to help reduce damage to the car interior in conditions where the seat belt would be an ade0uate safety device., and to adapt the deployment speed to the crash conditions. The algorithms are considered valuable intellectual property. 5xperimental algorithms may ta(e into account such factors as the weight of the occupant, the seat location, seatbelt use, and even attempt to determine if a baby seat is present.

Inflation
<hen the frontal airbags are to deploy, a signal is sent to the inflator unit within the airbag control unit. An igniter starts a rapid chemical reaction generating primarily nitrogen gas -=3. to fill the airbag ma(ing it deploy through the module cover. ome airbag technologies use compressed nitrogen or argon gas with a pyrotechnic operated valve -Hhybrid gas generatorH., while other technologies use various energetic propellants. ,ropellants containing the highly toxic sodium azide -=a=?. were common in early inflator designs. ;owever, propellants containing sodium azide were widely phased out during the #$$&s in pursuit of more efficient, less expensive and less toxic alternatives.9"itation needed: The azide-containing pyrotechnic gas generators contain a substantial amount of the propellant. The driver-side airbag would contain a canister containing about %& grams of sodium azide. The passenger side container holds about 3&& grams of sodium azide.93%: The incomplete combustion of the charge due to rapid cooling leads to production of carbon monoxide -'>. and nitrogen-++. oxide as reaction by-products.93B: The alternative propellants may incorporate, for example, a combination of nitroguanidine, phasestabilized ammonium nitrate -=;4=>?. or other nonmetallic oxidizer, and a nitrogen-rich fuel different than azide -eg. tetrazoles, triazoles, and their salts.. The burn rate modifiers in the mixture may be an al(aline metal nitrate -=>?-. or nitrite -=>3-., dicyanamide or its salts, sodium borohydride -=aB;4., etc. The coolants and slag formers may be eg. clay, silica, alumina, glass, etc.93@: >ther alternatives are eg. nitrocellulose based propellants -which have high gas yield but bad storage stability, and their oxygen balance re0uires secondary oxidation of the reaction products to avoid buildup of carbon monoxide., or high-oxygen nitrogen-free organic compounds with inorganic oxidizers -e.g., di or tricarboxylic acids with chlorates -'l>?-. or perchlorates -;'l>4. and eventually metallic oxidesE the nitrogen-free formulation avoids formation of toxic nitrogen oxides..

6rom the onset of the crash, the entire deployment and inflation process is about &.&4 seconds K faster than the blin( of an eye -about &.3 seconds.. Because vehicles change speed so 0uic(ly in a crash, airbags must inflate rapidly to reduce the ris( of the occupant hitting the vehicle!s interior.

Variable-force deployment
Advanced airbag technologies are being developed to tailor airbag deployment to the severity of the crash, the size and posture of the vehicle occupant, belt usage, and how close that person is to the actual airbag. Many of these systems use multi-stage inflators that deploy less forcefully in stages in moderate crashes than in very severe crashes. >ccupant sensing devices let the airbag control unit (now if someone is occupying a seat ad)acent to an airbag, the mass1weight of the person, whether a seat belt or child restraint is being used, and whether the person is forward in the seat and close to the airbag. Based on this information and crash severity information, the airbag is deployed at either a high force level, a less forceful level, or not at all. Adaptive airbag systems may utilize multi-stage airbags to ad)ust the pressure within the airbag. The greater the pressure within the airbag, the more force the airbag will exert on the occupants as they come in contact with it. These ad)ustments allow the system to deploy the airbag with a moderate force for most collisionsE reserving the maximum force airbag only for the severest of collisions. Additional sensors to determine the location, weight or relative size of the occupants may also be used. +nformation regarding the occupants and the severity of the crash are used by the airbag control unit, to determine whether airbags should be suppressed or deployed, and if so, at various output levels.

,ost-deployment view of a 5AT +biza airbag

Post.deplo1ment
>nce an airbag deploys, deflation begins immediately as the gas escapes through vent-s. in the fabric -or, as it!s sometimes called, the cushion. and cools. 7eployment is fre0uently accompanied by the release of dust-li(e particles, and gases in the vehicle!s interior -called effluent.. Most of this dust consists of cornstarch, french chal(, or talcum powder, which are used to lubricate the airbag during deployment. =ewer designs produce effluent primarily consisting of harmless talcum powder1cornstarch and nitrogen gas. +n older designs using an azide-based propellant -usually =a=?., varying amounts of sodium hydroxide nearly always are initially present. +n small amounts this chemical can cause minor irritation to the eyes and1or open woundsE however, with exposure to air, it 0uic(ly turns into sodium bicarbonate -ba(ing soda.. ;owever, this transformation is not #&&G complete, and invariably leaves residual amounts of hydroxide ion from =a>;. 7epending

on the type of airbag system, potassium chloride -often used as a table salt substitute. may also be present. 6or most people, the only effect the dust may produce is some minor irritation of the throat and eyes. Cenerally, minor irritations only occur when the occupant remains in the vehicle for many minutes with the windows closed and no ventilation. ;owever, some people with asthma may develop an asthmatic attac( from inhaling the dust. "egulatory specifications #nited States >n ## Muly #$A4, the 2. . government amended 6ederal Motor *ehicle afety tandard 3&A -6M* 3&A. to re0uire cars produced after # April #$A$ to be e0uipped with a passive restraint for the driver. An airbag or an automatic seat belt would meet the re0uirements of the standard. Airbag introduction was stimulated by the 2. . =ational ;ighway Traffic afety Administration. 93A: ;owever, airbags were not mandatory on light truc(s until #$$%.9"itation needed: +n #$$A, 6M* 3&A was amended to re0uire dual front airbags, and de-powered, or secondgeneration airbags were also mandated. This was due to the in)uries caused by first-generation airbags, though 6M* 3&A continues to re0uire that bags be engineered and calibrated to be able to HsaveH the life of an unbelted %&th-percentile size and weight HmaleH crash test dummy. utside the #$S$A$ Most countries9, o<: outside =orth America adhere to internationalized 5uropean 5'5 vehicle and e0uipment regulations rather than the 2. . 6ederal Motor *ehicle afety tandards. 5'5 airbags are generally smaller and inflate less forcefully than 2. . airbags, because the 5'5 specifications are based around belted crash test dummies. +n the 2nited Qingdom, and most other developed countries there is no direct legal re0uirement for new cars to feature airbags. +nstead, the 5uro ='A, vehicle safety rating encourages manufacturers to ta(e a comprehensive approach to occupant safetyE a good rating can only be achieved by combining airbags with other safety features.93$: Thus almost all new cars now come with at least two airbags as standard. %aintenance The examples and perspective in this section ma1 not represent a worldwide 5iew of the su06ect. ,lease improve this article and discuss the issue on the tal( page. (*eptember -995# +nadvertent airbag deployment while the vehicle is being serviced can result in severe in)ury, and an improperly installed or defective airbag unit may not operate or perform as intended. ome countries impose restrictions on the sale, transport, handling, and service of airbags and system components. +n Cermany, airbags are regulated as harmful explosivesE only mechanics with special training are allowed to service airbag systems. 2nder Cerman 6ederal 8aw, used but intact airbags are to be detonated under secure conditions, must not be passed on to third parties in any way, and no untrained person is permitted to handle airbags. ,urchase is restricted to buying a new replacement unit for immediate installation by the seller!s 0ualified personnel.9"itation needed:

ome automa(ers -such as Mercedes-Benz. call for the replacement of undeployed airbags after a certain period of time to ensure their reliability in an accident. >ne example is the #$$3 %&& which has an expiry date stic(er attached to the door pillar. In&uries and fatalities This section ma1 re7uire cleanup to meet 8i9ipedia:s 7ualit1 standards$ ,lease improve this section if you can. (%a! -995# Airbags can in)ure or (ill vehicle occupants. To provide crash protection for occupants not wearing seat belts, 2. . airbag designs trigger much more forcefully than airbags designed to the international 5'5 standards used in most other countries. Decent airbag controllers can recognize if a belt is used, and alter the bag deployment parameters accordingly.9?&: +n)uries such as abrasion of the s(in, hearing damage from the extremely loud #B%-#@% dB deployment explosion, head in)uries, eye damage, and bro(en nose, fingers, hands or arms can occur as the airbag deploys.9"itation needed: Most vehicle airbags are inflated using hot gas generated by a chemical process. 2sing hot gas allows the re0uired pressure to be obtained with a smaller mass of gas than would be the case using lower temperatures. ;owever, the hot gas can pose a ris( of thermal burns if it comes in contact with the s(in during deployment and occupant interaction. Burns are most common to the arms, face and chest. These burns are often deep dermal or seconddegree burns that ta(e longer to heal and ris( scarring.9"itation needed: +n #$$&, the first automotive fatality attributed to an airbag was reported,9?#: with deaths pea(ing in #$$@ at %? in the 2nited tates.9"itation needed: TD< produced the first gas-inflated airbag in #$$4, with sensors and low-inflation-force bags becoming common soon afterwards. 7ual-depth -also (nown as dual-stage. airbags appeared on passenger cars in #$$A. By 3&&%, deaths related to airbags had declined, with no adult deaths and two child deaths attributed to airbags that year. +n)uries remain fairly common in accidents with an airbag deployment. erious in)uries are less common, but severe or fatal in)uries can occur to vehicle occupants very near an airbag or in direct contact when it deploys. uch in)uries may be sustained by unconscious drivers slumped over the steering wheel, unrestrained or improperly restrained occupants who slide forward in the seat during pre-crash bra(ing, and properly belted drivers sitting very close to the steering wheel. The increasing use of airbags may actually ma(e rescue wor( for firefighters, emergency medical service and police officers more dangerous,9"itation needed: because of the ris( of deployment while the emergency responder is assisting or extracting vehicle occupants. +mprovements in sensing and gas generator technology have allowed the development of third generation airbag systems that can ad)ust their deployment parameters to size, weight, position and restraint status of the occupant. These improvements have demonstrated a reduced in)ury ris( factor for small adults and children who had an increased ris( of in)ury with first generation airbag systems.9?3:

Air bag fatality statistics 6rom #$$& to 3&&A, the 2. . =ational ;ighway Traffic afety Administration identified #@% fatalities caused by air bags. Most of these -#&4. have been children, while the rest are adults. About ?.? million air bag deployments have occurred and the agency estimates more than B,?@@ lives saved and countless in)uries prevented.9?#: A rear-facing infant restraint put in the front seat of a vehicle places an infant!s head close to the airbag, which can cause severe head in)uries, or death if the airbag deploys. ome modern cars include a switch to disable the front passenger airbag -although not in Australia, where rear-facing child seats are prohibited in the front where an airbag is fitted., in case a child-supporting seat is used there. +n vehicles with side airbags, it is dangerous for occupants to lean against the windows, doors, and pillars, or to place ob)ects between themselves and the side of the vehicle. Articles hung from a vehicle!s clothes hanger hoo(s can be hazardous if the vehicle!s side curtain airbags deploy.9??:

'ar 7eformation
+ntroduction
Crash and catastrophe analysis has been a rather seldom discussed field of traditional engineering in the past. In recent time, both the research and theoretical analyses have become the part of the everyday planning work [1][2][ ]. !he most interesting point in crash analysis is that even though the crash situations are random probability variables, the deterministic view plays an important role in them. !he stochastic view, statistical analysis, and fre"uency testing all concern past accidents. Crash situations, which occur the most fre"uently #e.g. the characteristic features of the crash partner, the direction of the impact, the before$crash speed, etc.% are chosen from these statistics and are used as initial parameters of crash tests. !hese tests are "uite e&pensive, thus only some hundred tests per factory are reali'ed annually, which is not a sufficient amount for accident safety. (or the construction of optimal car$body structures, more crash$tests were needed. !herefore, real$life tests are supplemented by computer$based simulations, which increases the number of analy'ed cases to 1$2 thousands. !he computer$based simulations ) like the tests ) are limited to precisely defined deterministic cases. !he statistics are used for the strategy planning of the analysis. !he above mentioned e&ample clearly shows that the stochastic view doesn*t e&clude the deterministic methods [+][,]. Crash analysis is very helpful for e&perts of road vehicle accidents, as well, since their work re"uires simulations and data, which are as close to the reality as possible. -y developing the applied methods and algorithms we can make the simulations more precise and so contribute towards the determination of the factors causing the accident. !hrough the analysis of traffic accidents we can obtain information concerning the vehicle which can be of help in modifying the structure.parameters to improve its future safety. !he energy absorbed by the deformed car body is one of the most important factors effecting the accidents thus it plays a very important role in car crash tests and accident analysis. !here is an ever$increasing need for more correct techni"ues, which need less computational time and can more widely be used. !hus, new modeling and calculating methods are highly welcome in deformation analysis.

/ith the help of the methods introduced in this paper we can construct a system, which is capable to determine the energy absorbed by the car$body deformation using only digital photos taken from the crashed car, as inputs. !he proposed techni"ue is based on the combination of new methods of digital image processing and intelligent techni"ues and as a result the system fulfills the above mentioned re"uirements0 the necessary computational time is decreased #furthermore, it can adapt to the temporal circumstances coping with the available time%, it produces more correct results, it can be used more effectively, and the obtainable information offers a way for wider usage. 1ew methods of computer based digital image processing #see e.g. [2]% offer a possibility to analy'e and evaluate visual information gained from the environment in such a way that we can obtain the information easily by which the security systems of a vehicle can be shaped in order to make the passenger security more and more effective and also the reconstruction of car accidents becomes reali'able. Intelligent computing methods #like fu''y and neural network #11% based techni"ues% are of great help in this. -ased on them we can construct systems capable to determine the energy absorbed by the car$body deformation using digital pictures as inputs. (urthermore, the system can be more effective than the traditional algorithmic computing systems and is very advantageous in obtaining the necessary information. !he paper is organi'ed as follows0 In 3ection II. the determination of the absorbed energy is discussed. 3ection III. is devoted to the details of the digital photo based 4 modeling of the crashed car body, while 3ection I5. presents the determination of the direction of the impact together with the amount of absorbed energy. 3ection 5. shows an e&ample to illustrate the effectiveness of the presented methods. Conclusions are summari'ed in 3ection 5I.

7eformation 5nergy 5stimation from 7igital ,ictures
6ecent methods of car crash analysis analy'e the e&tent of the deformation from the top view of the car body however in some cases the deformation can not be seen from the top view at all. !his problem could be eliminated by constructing the spatial model of the deformed car$ body elements. It means that during the local accident analysis pictures are taken of the damaged car body from different points of view. -ased upon these photos we can construct the spatial model of the deformed car body by using recent methods of digital image processing #see e.g. [2]$[7]% combined with intelligent techni"ues. In the followings a new intelligent 4 modeling and deformation analysis method will be introduced. 8odern computers can efficiently analy'e digital photos. In contrast of the analog photos, digital ones are constructed of pi&els #in other words, it is defined only by certain points of the plane%. In addition, the brightness or color of these pi&els does not change continuously and only certain predefined colors may occur. 9ach point has its brightness$code, so a digital picture can be viewed as nothing else then a matri& with as many lines as the picture has and within a line with as many elements #columns% as many picture points a line has. !hus, the well$developed methods of matri& algebra and mathematical analysis can be applied to the analysis [7]. 8ethods for 4 reconstruction from point or line correspondences in a se"uence of images have achieved a high level of sophistication with impressive results [1:], [11]. In our proposition the evaluation of the car$body deformation is done in two steps. (irst, the 4 shape of the deformed car$body is created with the help of digital pictures taken from

different camera positions. ;s the second step, the 4 car$body model is processed by an intelligent computing system. !he system needs only the above mentioned digital pictures, as inputs, while as outputs, we get the direction of the impact and the deformation energy absorbed by the car$body elements from which the direction and the speed of the crash can be determined. !he system works automatically, i.e. it does not need any e&ternal #human% intervention during the calculations. !he processing time of this method is much less than the processing time of the past methods, i.e. it can supply the outputs already at the accident plotting time. !his property is very advantageous in supporting the work of road accident e&perts.

?7 'ar-Body Model 5stimation 2sing a e0uence of 7igital +mages
!he topic of building 4 models from images is a relatively new research area in computer vision and, especially when the ob<ects are irregular, not finished at all. In the field of computer vision, the main work is done at one hand on the automati'ation of the reconstruction while on the other on the implementation of an intelligent human$like system, which is capable to e&tract relevant information from image data and not by all means on building a detailed and accurate 4 model like usually in photogrammetry is. (or this purpose, i.e. to get the 4 model of the deformed car body, to limit.delimit the ob<ects in the picture from each other is of vital importance [12]. ;s the first step, the pictures, used in the 4$ob<ect reconstruction are preprocessed. ;s a result of the preprocessing procedure the noise is eliminated. (or this purpose we apply intelligent fu''y filters [2], [=]. ;fter noise$filtering, the edges $ob<ect boundaries ) are detected with the help of a fu''y based edge detector [>] and the corners #vertices% are also determined by a new method which combines classical and fu''y techni"ues #for details see [1 ]%. !he ne&t step is the determination of the 4 coordinates of the car$body edge points. (irst the verte& correspondences are determined which is followed by the determination of the edge correspondences. !his latter can be based on the comparison of a well$defined small region around the analy'ed image point with the corresponding regions around each of the candidate image points in the other image. (or this purpose we need several images taken from different camera positions. If the angle between the camera positions is relatively small then after the evaluation of the pro<ection matrices of the images the corresponding points can be calculated automatically with high reliability in each image. !he problem to overcome is that a point determines not another point but a line #the so called epipolar line% in the other images, so the searching procedure can be reduced to 14 #along a line%. (irst, we assign the edge points of the epipolar line, i.e. those points which belong to an edge of the image, then the fu''y measure of the differences of the environment of the points are minimi'ed. !he ne&t step is the determination of the perspective pro<ection matri& for each image. It can be calculated with the help of si& given # 4? 24% point correspondences [1+]. ;fter this we can calculate the 4 position of the image points and in the knowledge of the 4 coordinates and the correspondences of the significant points the spatial model of the car body can easily be built [1+].

5stimation of the +mpact-7irection and the Absorbed 5nergy
!he block diagram of the intelligent system is illustrated by (ig. 1. !he spatial model of the

deformed car$body is created with the help of the module @Image ArocessingB #see (ig. 1%. !he inputs of this module are digital pictures of the deformed car$body taken from different camera positions and as a result #output of the module% we obtain the 4 deformed car$body model. ;fter constructing the 4 model of the deformed car body we have to determine the volume of the detoriated car body which means the comparison of the deformed and the undamaged 4 car$bodies. !his calculation is performed by the module named @comparison of modelsB #see (ig. 1% and as result, we obtain the volumetric difference between the two models. !he spatial model of the deformed car$body serves as input of the module named e&pert system, as well. !his module produces the direction of the impact. (or the

4igital photostaken fromdifferentcamera positions

(igure 1. -lock$structure of the system

determination of this direction we use the so called @energy$centersB of the undamaged and deformed car bodies and the direction is estimated from the direction of movement of the energy$center. #4uring the deformation the different 4 cells of the car$body absorb a certain amount of energy. !he energy$center can be determined by weighting the cells by the corresponding energy values.% (rom the volumetric difference and from the direction of impact an intelligent, hierarchical fu''y$neural network based system evaluates the energy absorbed by the deformation and the e"uivalent energy e"uivalent speed #993%. (or the training of this part of the system simulation data can be used. !he relation among the direction of impact, volumetric change, and the deformation energy is illustrated by (ig 2. !his surface is symmetric #to the longitudinal a&es of the vehicle% so it is enough to deal with its half part. !he mapping is appro&imated by a hierarchical fu''y$11 system #subsystem @(u''y$1eural 1etworkB in (ig. 1%. !he surface is divided into domains, which can @easilyB be modeled. 9ach domain is modeled separately by a small 11. -ecause of the uncertainties in the transitions among the domain, a fu''y system is applied for the determination of the fired domain#s%. !he mapping in (ig. 2 needs only to be divided into two domains according to the impact direction #see (ig. %, thus in this very simple case the fu''y rulebase @aboveB the 11 system contains only two rules #!he input fu''y sets are shown in (ig. +.%0 I( the direction I3 41 !C91 use 111I( the direction I3 42 !C91 use 112

(igure 2. 6elation among the direction of impact, volumetric change, and the deformation energy based on simulation data # based on the test data of 8ercedes 27:% (igure . 3egmentation of the surface in (igure 2.

Cere we would like to remark two things0 1. In general the mapping is more comple& and it can be advantageous to define more domains using both inputs to keep the comple&ity of the used 11s low. 2. !he module responsible for the determination of the absorbed energy applies a pre$ classification step according to a hierarchical decision$tree #(ig. ,%, because for choosing the correct set of neural networks we have to pre$determine the category and the type of the analy'ed vehicle and the main character of the crash #frontal impact, side impact, rear impact%. 3ide impact means that neither the front nor the rear of the vehicle is touched. (or appro&imating domains 41 and 42 we applied simple feed$forward backpropagation 11s with one hidden layer and three hidden neurons. !he 11s are used to determine the deformation*s energy and 993. 4uring the tuning #teaching period% of the system, the determined 993 values were compared to known test results and the parameters of the e&pert system were modified to minimi'e the D83 error #the error surface can be followed in (ig. 2%.
1

Impact 4irection [deg]

(igure +. 8embership functions defined on the universe of impact direction
5ehicle

Car Dight duty !ruck

!ype 1 !ype 2 . . .!ype n

(rontal Impact 111

3ide Impact 112

6ear impact 11

(igure ,. Cierarchical structure of the pre$classification in the 993 determination

6igure B. 5rror surface of mapping in 6ig. ? approximated by the hierarchical fuzzy == system

5xample
In this 3ection the operation of the introduced intelligent crash analysis system is illustrated on a crashed car. !he parameters of the car are as follows0

#a% #b% (igure >. #a% Eriginal photo of the crashed car #;udi% corrupted by noise, #b% (u''y filtered image of the photo in (ig >a

#a% #b% (igure =. #a% Image of the photo in (ig. >b after fu''y based edge detection, #b% Image of the photo in (ig. >b after fu''y based corner detection

#a% #b% (igure 7. #a% Eriginal photo of the crashed car #;udi% corrupted by noise #viewpoint 2%, #b% (u''y filtered image of the photo in (ig. 7a

#a% #b%

5ehicle.8ass of the vehicle0 ;udi 1::.1 2, kg 5olumetric change.;bsorbed deformation energy #evaluated%0 :.22 m .1>172: Foule 6eal.evaluated direction of impact0 :.2 4egree !he real 993 of the vehicle0 ,, km.h !he calculated 993 of the vehicle0 ,= km.h !he photos taken from two different camera positions are processed in (igs. >, = and 7, 1:. (ig. >a shows the original photo of the crashed car corrupted by noise. In (ig. >b the fu''y filtered image while in (ig. =a the image after fu''y based edge detection can be followed. In (ig. =b the assigned vertices are shown. (igs. 7, 1: illustrate a different camera position of the car. (or the determination of the deformation energy the hierarchical 11 system taught by the test data of a 8ercedes 27: were used. !his caused only a tolerable amount of error because the two cars belong to the same class within the category @normal carB.

UNIT ':
Seat 0elt

A t ree-point seat belt. A seat 0elt, sometimes called a safet1 0elt, is a safety harness designed to secure the occupant of a vehicle against harmful movement that may result from a collision or a sudden stop. As part of an overall automobile passive safety system, seat belts are intended to reduce in)uries by stopping the wearer from hitting hard interior elements of the vehicle, or other passengers -the so-called second impact., are in the correct position for the airbag to deploy and prevent the passenger from being thrown from the vehicle. eat belts also absorb energy by being designed to stretch during an impact, so that there is less speed differential between the passenger!s body and their vehicle interior, and also to spread the loading of impact on the passengers body. The final, so-called !third impact! after a passenger!s body hits the car interior, airbag or seat belts, is that of the internal organs hitting the ribcage or s(ull. The force of this impact is the mechanism through which car crashes cause disabling or life threatening in)ury. The se0uence of energy dissipating and speed reducing technologies - crumple zone - seat belt - airbags - padded interior, are designed to wor( together as a system, to reduce the force of this final impact.

•

Types of seat belts

8ap seat belt -or Ht,o pointsH. in an aircraft

T ree points seatbelt in a car. The three points belt is the standard seat belt for road cars.

Fi0e points harness in a racing car. 'ap Ad)ustable strap that goes over the waist. 2sed fre0uently in older cars, now uncommon except in some rear middle seats. ,assengers aircraft seats also use lap seat belts to prevent in)uries. Sash Ad)ustable strap that goes over the shoulder. 2sed mainly in the #$B&s, but of limited benefit because it is very easy to slip out of in a collision.

Three-point imilar to the lap and shoulder, but one single continuous length of webbing. Both three-point and lap-and-sash belts help spread out the energy of the moving body in a collision over the chest, pelvis, and shoulders. *olvo introduced the first production three-point belt in #$%$.9#: The first car with three point belt was a *olvo ,* %44 that was delivered to a dealer in Qristianstad on August #?, #$%$. The three point belt was developed by =ils Bohlin who earlier had wor(ed on e)ection seats at aab.93: 2ntil the #$A&s, three-point belts were commonly available only in the front seats of carsE the bac( seats had only lap belts or diagonal belts. 5vidence of the potential for lap belts to cause separation of the lumbar vertebrae and the sometimes associated paralysis, or Hseat belt syndromeH, has led to a revision of passenger safety regulations in nearly all developed countries re0uiring that all seats in a vehicle be e0uipped with three-point belts. ince eptember #, 3&&@, all new cars sold in the 2. . re0uire a lap and shoulder belt in the center rear.9?: Besides regulatory changes, Hseat belt syndromeH has led to tremendous liability for vehicle manufacturers. >ne 8os Angeles case resulted in a J4% million )ury verdict against 6ord Motor 'ompanyE the resulting J?& million )udgment -after deductions for another defendant who settled prior to trial. was affirmed on appeal in 3&&B.94:

'arness (elt-in-Seat )(IS* The B+ is a three-point where the shoulder belt attachment is to the bac(rest, not to the b pillar.9%: The first car using this system in the 2nited tates was the #$$& Mercedes-Benz 8.9B: ome cars li(e the Denault *el atis use this system for the front seats. This system allegedly is safer in case of rollover, especially with 4XA years old children,9@: though other sources dispute this claim.9A: +,perimental production car safety belts • Criss-"ross 5xperimental safety belt presented in the *olvo ''. +t forms a cross-brace across the chest.9$:

• • •

.=- Point *eatbelt/ 5xperimental safety belt from Autoliv similar to the criss-cross. The ?Y3 improves protection against rollovers and side impacts.9#&: Four point "belt and suspenders"/ An experimental design from 6ord where the HsuspendersH are attached to the bac(rest, not to the frame of the car.9##: ;nflatable *afet! 3elts/ An airbag is included within the belt for the rear seat belts.9##:

Five-point harnesses These restraints are safer but more restrictive than most other seat belt types. They are typically found in child safety seats and in racing cars. The lap portion is connected to a belt between the legs and there are two shoulder belts, ma(ing a total of five points of attachment to the seat. - trictly spea(ing, harnesses are never to be fastened to the seatKthey should be fastened to the frame1sub-frame of the automobile.. Si,-point harnesses These harnesses are similar to a five-point harness but include an extra belt between the legs, which is seen by some to be a wea(er point than the other parts. These belts are used mainly in racing. +n =A 'AD, the six-point harness became popular after the death of 7ale 5arnhardt. 5arnhardt was wearing a five-point harness when he suffered his fatal crash. As it was first thought that his belt had bro(en, some teams ordered a six-point harness in response.9#3: Seven-point harnesses )-./* Aerobatic aircraft fre0uently use a combination harness consisting of a five-point harness with a redundant lap-belt attached to a different part of the airframe. <hile providing redundancy for negative-g maneuvers -which lift the pilot out of the seat., they also re0uire the pilot to un-latch two harnesses if it is necessary to parachute from a failed aircraft. History eat belts were invented by Ceorge 'ayley in the late #A&&s, though 5dward M. 'laghorn was granted the first patent -2. . ,atent ?#3,&A%, on 6ebruary #&, #AA% for a safety belt..9#?: American car manufacturers =ash -in #$4$. and 6ord -in #$%%. offered seatbelts as options, while wedish aab first introduced seat belts as standard in #$%A.9#4: After the aab CT @%& was introduced at the =ew Nor( motor show in #$%A with safety belts fitted as standard, the practice became commonplace.9#%: The first three point seat belt -the so-called C;R-Gris,old restraint. was patented in #$%# by the Americans Doger <. Criswold and ;ugh 7e ;aven9#B:, and developed to its modern form by =ils Bohlin for wedish manufacturer *olvo - who introduced it in #$%$ as standard e0uipment. Bohlin was granted 2. . ,atent ?,&4?,B3% for the device.9#4: +n #$@&, the state of *ictoria, Australia, passed the first law worldwide ma(ing seat belt wearing compulsory for drivers and front-seat passengers.9#@:

Technologies

eat Belt uncovered +nertial Deel Most seat belts are e0uipped with loc(ing mechanisms -or inertia reels. that tighten the belt when pulled fast -e.g. by the 0uic( force of a passenger!s body during a crash. but do not tighten when pulled slowly. This is implemented with a centrifugal clutch, which engages as the reel spins 0uic(ly. Alternatively, this function may be secured by a weighted pendulum or ball bearing/ when these are deflected by deceleration or roll-over they loc( into pawls on the reel. Types of inertia reel type seatbelts/ =8D -no loc(ing retractor./ 'ommonly used in recoiling lap belts 58D * -emergency loc(ing retractor - vehicle sensitive./ ingle sensitive mechanism, composed of a loc(ing mechanism activated in an emergency by deceleration or rollover of the vehicle. Thus, the seatbelt is sensitive to the vehicle!s motion. 58D *< -emergency loc(ing retractor - vehicle and webbing sensitive./ 7ual sensitive means a seatbelt retractor that, during normal driving conditions, allows freedom of movement by the wearer of the seatbelt by means of length-ad)usting components that automatically ad)ust the strap to the wearer, with a loc(ing mechanism that is activated by two or more of the following/
• • •

deceleration or rollover of the vehicle, acceleration of the strap -webbing. from the retractor, or other means of activation.

A recent study by Mc'oy U 'hou -3&&@. from the 6ord Motor 'ompany - afety Test Methodology, ,-3#3?. demonstrated that the standard inertia reel seatbelt does not stop the head from ma(ing contact with the interior of the roof on a standard rollover test in their dynamic Dollover 'omponent test ystem -D>' .. 5ven with modern pre-tensioning devices the head contacts the interior of the roof and the nec( suffers !visible! compression.

Pretensioners and webclamps eatbelts in many newer vehicles are also e0uipped with HpretensionersH and1or H<ebclampsH.
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,retensioners preemptively tighten the belt to prevent the occupant from )er(ing forward in a crash. Mercedes-Benz first introduced pretensioners on the #$A# -'lass. +n the event of a crash, a pretensioner will tighten the belt almost instantaneously. This reduces the motion of the occupant in a violent crash. 8i(e airbags, pretensioners are triggered by sensors in the car!s body, and most pretensioners use explosively expanding gas to drive a piston that retracts the belt. ,retensioners also lower the ris( of HsubmariningH, which is when a passenger slides forward under a loosely worn seat belt. An alternative approach being loo(ed at by ma)or car companies is the 'C-8oc( technology whereby the occupant is held in position via the lap belt in order to prevent the passenger from coming out of position in the event of a crash. <ebclamps clamp the webbing in the event of an accident and limit the distance the webbing can spool out -caused by the unused webbing tightening on the central drum of the mechanism. these belts also often incorporate an energy management loop -Hrip stitchingH. which is when the lower part of the webbing is looped and stitched with a special stitching. The function of this is to HripH at a predetermined load, which reduces the load transmitted through the belt to the occupant, reducing in)uries to the occupant.

Inflatable Seatbelts The +nflatabelt eatbelt utilities tubular inflatable bladders that are contained within a outer cover. <hen a crash occurs gas is introduced into the bladder causing the inflation of the bladder to increase the area of the restraint contacting the occupant and also shortening the length of the restraint to tighten the belt around the occupant improving the protection. The inflatable sections may b shoulder only or 8ap and houlder. The system supports the head during the crash better than a web only belt. +t also provides side impact protection. The inflatable eatbelt was first invented by 7onald 8ewis and tested at the Automotive ,roducts 7ivision of Allied 'hemical 'orp. Automatic seat belts Main article/ Automatic seat belt ome vehicles have shoulder belts that automatically move forward to secure the passenger when the vehicle is started. A separate lap belt is usually included, and the lap belt must be fastened manually. Automatic seat belts have fallen out of favor recently, since the airbag became mandatory in many countries. #se of seat belts by child occupants Main article/ +nfant car seat As with adult drivers and passengers, the advent of seat belts was accompanied by calls for their use by child occupants, including legislation re0uiring such use. +t has been claimed that children in adult restraints suffer lower in)ury ris( than unrestrained children.

The 2Q extended compulsory seatbelt wearing to child passengers under the age of #4 in #$A$. +t was observed that this measure was accompanied by a #&G in"rease in fatalities and a #3G in"rease in in)uries among the target population.9#A: +n crashes, small children who wear adult seatbelts can suffer Hseat-belt syndromeH in)uries including severed intestines, ruptured diaphragms and spinal damage. There is also research suggesting that children in inappropriate restraints are at significantly increased ris( of head in)ury,9#$: one of the authors of this research has been 0uoted as claiming that HThe early graduation of (ids into adult lap and shoulder belts is a leading cause of child-occupant in)uries and deaths.H93&: As a result of such findings, many )urisdictions now advocate or re0uire child passengers to use specially designed child restraints. uch systems include separate child-sized seats with their own restraints and booster cushions for children using adult restraints. +n some )urisdictions children below a certain size are forbidden to travel in front car seats.9"itation needed: In rear seats +n #$%% -as a #$%B pac(age. 6ord offered lap only seat belts in the rear seats as an option within the 1ife)uard safety pac(age. +n #$B@ *olvo started to install lap belts in the rear seats. +n #$@3 *olvo upgraded the rear seat belts to a three point belt.93#: +n crashes, unbelted rear passengers increase the ris( of belted front seat occupants! death by nearly five times.933:93?: "eminder chime and light

+n =orth America, cars sold since the early #$@&s have included an audiovisual reminder system consisting of a light on the dashboard and a buzzer or chime reminding the driver and passengers to fasten their belts. >riginally, these lights were accompanied by a warning buzzer whenever the transmission was in any position except par( if either the driver was not buc(led up or, as determined by a pressure sensor in the passenger!s seat, if there was a passenger there not buc(led up. ;owever, this was considered by many to be a ma)or annoyance, as the light would be on and the buzzer would sound continuously if front-seat passengers were not buc(led up. Therefore, people who did not wish to buc(le up would defeat this system by fastening the seatbelts with the seat empty and leaving them that way. By the mid-#$@&s, auto manufacturers modified the system so that a warning buzzer would sound for several seconds before turning off -with the warning light., regardless of whether the car was started. ;owever, if the driver was buc(led up, the light would appear, but with no buzzer. =ew cars sold in the 2nited tates in #$@4 and the first part of the #$@% model year were sold with a special Hignition interloc(H, whereby the driver could not start the car until the seat belt was fastenedE however, this system was short-lived. Today, the belt warning light may stay on for several minutes after the car is started if the driver!s seat belt is not fastened.

+n 5urope and some other parts of the world, most modern cars include a seat-belt reminder light for the driver and some also include a reminder for the passenger, when present, activated by a pressure sensor under the passenger seat. A wedish study showed that of the cars with seat belt reminder A of #& drivers not using the seat belts were driving an Audi.934: ome cars will intermittently flash the reminder light and sound the chime until the driver -and sometimes the front passenger, if present. fasten their seatbelts, and they sometimes even loc( the speed to #& (m1h or less.

UNIT *
Collision a5oidance s1stem:

UNIT /:

Tire.pressure monitoring s1stem A Tire.pressure monitoring s1stem -TPMS. is an electronic system designed to monitor the air pressure inside all the pneumatic tires on automobiles, aeroplane undercarriage, straddle-lift carriers, for(lifts and other vehicles. The system is also sometimes referred to as a tire-pressure indication system -T,+ .. These systems report real-time tire-pressure information to the driver of the vehicle, either via a gauge, a pictogram display, or a simple low-pressure warning light.
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Types 0irect 7irect-sensor T,M es employ physical pressure sensors inside each tire and a means of processing and sending that information from inside the tire to the vehicle!s instrument cluster. These systems can identify simultaneous under-inflation in all four tires in any combination. 7irect-sensor T,M are specifically designed to cope with ambient and road-to-tire friction-based temperature changes, both of which heat up the tire, and increasing its pressure.9"itation needed: The alarm-activation threshold pressures are usually set according to the manufacturers recommended Hcold placard inflation pressuresH. +n order to transfer data from a rotating wheel, a direct-sensor system may use a radio-fre0uency -D6. communication channel or an electromagnetic coupling means to overcome the tire1chassis rotational boundary. The pressure sensor devices used in direct-sensor T,M may be either battery-powered or batteryless. Battery-powered, D6-based T,M present some issues and challenges/
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Batteries are chemical systems with lifetimes that perform very poorly in extreme temperature environments typical of =orth America and 5uropean climates and1or in aerospace applications -The chemistry of batteries used in automotive T,M applications must be able to perform over the range -4& o' to Y#3% o' and for aerospace applications over the range -%& o' to Y#@& o'..9"itation needed: D6 transmission power must be (ept low in order to conserve battery life and also to conform to various countries! regulations and standards for short-range radio communications. -7espite this limitation, D6 technology is being used in more than 3& million vehicles since its mandatory introduction in the 2 mar(et started in 3&&@..9"itation
needed:

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T,M Batteries are normally designed to last for @ to #& years and not the entire life of the vehicle -#?yrs. or 3&&.&&& (ms. ;owever, vehicle manufactures only cover T,M battery replacement within the warranty period of the vehicle, which is usually less than the vehicle!s life. o, after several flat tire occurrences batteries eventually become exhausted and must be changed at the vehicle owner!s cost.9"itation needed: ensors fitted at the bac(-end of valve stems and are prone to damaged during tire mounting and dismounting procedures at the tire fitters. Banded sensors attached rim dropwell circumferences are prone to damage the tire!s bead during tire fitting operations.
9"itation needed:

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Battery-powered direct systems typically use large sensors which are mounted either on valve-stem ends or banded to wheel rims. +n either case they affect a wheel!s balance. The sensors total mass -excluding the valve. is in average #%g or #%&gm for banded sensors. Both contribute to ad)ustments for the normal balancing procedure of wheels.9"itation needed: The total cost of ownership for battery powered direct-sensor T,M is much higher than for HbatterylessH direct sensor and HindirectH systems. +n addition, battery powered D6 systems may be adversely affected by a tire!s ferrous or carbon blac( content, thus limiting the choice that consumers may have for replacement tyres.9"itation needed:

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Battery-less direct-sensor systems, however, overcome these limitations and have the additional advantage of being maintenance-free.H.9#: *isiTyre is the first true Batteryless 7irect sensor T,M technology available for the passenger vehicle mar(et.9"itation needed: Indirect +ndirect T,M do not use physical pressure sensors. +ndirect T,M measure the HapparentH air pressure, by monitoring individual wheel rotational speeds, and other signals available outside the tire itself. Most indirect T,M use the fact that an under-inflated tire has a slightly smaller diameter than a correctly inflated tire and therefore has to rotate at a higher angular velocity to cover the same distance as a correctly inflated tire. =ewer developments of indirect T,M can also detect simultaneous under-inflation in up to all four tires using vibration analysis of individual wheels or analysis of load shift effects during acceleration and1or cornering, which can be realized in software using advanced signal processing techni0ues. ;owever, the vibration analysis techni0ue re0uires the use of additional suspension sensors which result in increased complexity and cost of the overall system as long as vertical chassis movements are concerned. That is why most current advanced indirect systems use the spectral content of the wheel speed sensor signals so no additional sensors are needed and the computations can also be carried out by usual processors for example in usual AB or 5 ' control units.9"itation needed: +ndirect T,M are realized in software in combination with wheel-speed sensors for anti-loc( bra(ing systems, and electronic stability control systems. A disadvantage of indirect T,M is that the driver must calibrate the system by pushing a reset button on the dashboard or through the onboard computer and if this is performed when any tire is in an under inflated condition then the system will not report correctly.9"itation needed:

History The first passenger vehicle to adopt tire-pressure monitoring -T,M. was the ,orsche $%$ in #$AB, using a hollow spo(e wheel system developed by , Q.9"itation needed: Ma)or T,M manufacturers are B5D2 f#systems 'ontinental AC, chrader 5lectronics, Advantage ,ressure,ro 88',93: 8ionax +nc.,9?: temco!s BatD6,94: marTire ystems, hanghai Baolong +ndustries, <i-Cauge wireless T,M , 9;angsheng 5lectronics 'orp:; A5, iemens *7>, Beru AC, TD< Automotive, 5T* 'orporation ,8 -*isiTyre.,9%: ,acific +ndustries, chrader-Bridgeport,9B: 5nTire olutions 88', =+DA 7ynamics AB -Tire ,ressure +ndicator., Transense Technologies, +V-mobil Cmb; -D7Q ., 9@: A,D+ s.r.o., and T5 5ngineering.9A: 7ue to vehicle safety and maintenance economy, T,M appeared more widely in 5urope as an optional feature for top range luxury passenger vehicles, li(e the Audi AA, Mercedes-Benz -'lass and the BM< @ eries. +n #$$$ the , A ,eugeot 'itroPn decided to adopt T,M as a standard feature on the ,eugeot B&@. The following year -3&&&., Denault launched the 8aguna ++, the first high volume mid-size passenger vehicle in the world to be e0uipped with T,M as a standard feature.9"itation needed: The 6irestone recall in the 2nited tates in the late #$$&s which was attributed to more than #&& deaths from rollovers following a tire tread-separation, pushed the 'linton administration to publish the TD5A7 Act. This act mandates the use of a suitable T,M technology in order to alert drivers of a severe under-inflation condition of their tires. This act affects all light motor vehicles -under #&,&&& pounds. sold after eptember #, 3&&@.9"itation needed: ,hase-in started in >ctober 3&&% at 3&G, and reached #&&G for models produced after eptember 3&&@. <hile in the 2. ., T,M legislation grew from safety-related motives, 5uropean 2nion -52. and 6ar 5ast legislators are loo(ing at T,M as a way of reducing '>₂emissions, and are presently considering compulsory tire-pressure monitoring systems from this environmental stance.9"itation needed: Degardless of 2. . and 52 legislation, the introduction by several tire manufacturers of run flat tires ma(es it mandatory for car manufacturers to fit a system where the drivers are made aware the run-flat has been damaged. The run-flats are designed to be used at no more than A& (m1h -%& mph. for no more than a distance of A& (m, and this is why it is mandatory that runflats are monitored by T,M . They have received a mixed reception from the public due to their impact on comfort with a harder ride.9"itation needed: 8astly, the most recent advance with T,M technology is the introduction of battery-less directsensor systems which re0uire zero maintenance and are very reliable. *isiTyre is the first of this new class of battery-less T,M which allows pressure on demand readings immediately from ignition and unli(e radio-fre0uency T,M systems is also transparent to all tire construction types.
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Audi is the first car ma(er to attempt the launch of the Audi AB model year 3&&$ in the 2 with an indirect T,M to comply with the 2 T,M legislation. ince its introduction =;T A has tested the system, however an official report of conformity with a ,A 16A+8 assessment is yet to be released. There are many reservations on whether or not this system complies with the regulation, by admission of Audi themselves in the vehicle!s owners manual there are several scenarios in

which proper performance of the indirect T,M system is not guaranteed -li(e sporty driving or winter conditions and many others., however Audi is confident that the car is able to pass the regulation test procedure. 2nfortunately for Audi the test procedure, as stated on the document itself, is not enough to guarantee compliancy with the regulation, but this is up to =;T A to assess.9"itation needed: 0irect TP%S technology +n the early days of development T,M s were implemented using radio fre0uency technology, to avoid expensive and rather complicated rotating contact wiring, together with an electronic control unit fitted inside the vehicle, which provides the necessary processing functionality to interpret pressure data coming from battery-powered sensor transmitters within tire cavities. The system delivers alerts and warnings to the driver.9"itation needed: 'ompanies li(e chrader 5lectronics designed first-generation T,M s using battery-powered radio transmitters, with sensors mounted on a standard tire valve, and a chassis mounted radio fre0uency receiver, whose functions can also be integrated in other radio-fre0uency units mounted on the vehicle, such as remote (eyless-entry receivers, and body control units.9"itation needed: Typical D6 T,M systems employ four or five battery-powered transmitter-sensors,9$: one D6 receiver -either stand-alone or integrated in other vehicle electronics., and some other satellite hardware which can perform the function of identifying the tire position involved in the inflation anomaly. 5ach tire-pressure sensor can periodically trigger a transmission of pressure status, or be polled continuously on demand. The most technologically challenging part of the system is the conservation of battery power used by the D6 transmitter-sensor. Most D6 based T,M sensors on the mar(et today use a battery, a silicon-based pressure sensor, and an D6 oscillator -either A<or ,88Xbased.. Automa(ers re0uire a battery lifespan of between seven and ten years, so T,M system designers use power saving techni0ues to extend the battery life. The heart of the sensor is a silicon application-specific integrated circuit -A +'. chip, which can manage critical power saving algorithms and other functions of the sensor. ;owever, there remains the fundamental problem that all batteries eventually become exhausted with the result that the consumer is faced with flat battery problems as well as flat tire problem. The battery represents safety and replacement cost issues for the consumer. *ehicle manufacturers are also concerned about costly warranty claims and litigation that may result if in)ury and loss of property occur as a conse0uence of D6 based T,M battery failures.9$: +n the 2. ., there are approximately #B million new passenger vehicles manufactured annually, which must ultimately comply with the legislative re0uirements of the TD5A7 Act, and be fitted with T,M . +f each vehicle has four or five wheels fitted with battery-powered D6 T,M wheel modules there could be more than B% million batteries introduced annually into the environment. 7isposal of the batteries in such a widespread consumer application is a significant environmental concern and adds to the total carbon footprint addition of automobile production.9"itation needed: To overcome the battery issues a new generation of battery-less T,M is being developed by two companies using 0uite different technologies. Transense is promoting a A<-based technology. *isiTyre is using an electromagnetic close-coupling technology to effectively eliminate the sensor

battery and ma(e the T,M maintenance free. *isiTyre battery-less T,M also eliminates the need for any H8earn ToolsH to register new sensor positions after wheel rotation and wor(shop procedures. Transense has licenced its technology to several automotive companies but it is not yet commercially available for >5M -original e0uipment manufacturer. passenger vehicles.9"itation needed: >ther developments with T,M include research into the use of energy harvesting devices which may lead to future types of battery-less T,M .9"itation needed: The tire unit is a concentration of challenges for today engineers/ M5M technology, wireless data transmission, semiconductor, mechanical engineering. Among all these challenges wireless data transmission is one of the most critical part of the architecture/ engineers have to cope with the target of transmitting data from tire to the ;M+ in the dash board and tire rotation, multipath propagation, rubber attenuation, structure of tire including wiring in sidewalls, chassis attenuation and Hwhite noiseH due to environment are some of the unsolved issues in T,M . >ther critical factor is connected to what is called Hauto-locationH which is the way to detect exact position of the deflated tire/ front, rear, left or rightE several are the concepts used to get rid of it/ in some architecture the location of tires is solved using what is commonly (nown as the 8ow 6re0uency -86. that wor(s at #3% Q;zE other approaches are typically based on accelerometers to detected right and left side and discriminating front or rear axle via elaborated software in the receiver interface and comparing, in very simple words, the emitted D6 level generated by each one of the transmitters.9"itation needed: >ther approaches are connected to the use of 4 small receivers installed in the nearby of the tire, let!s say somewhere in the hub, which collect the data of each tire separately/ those receivers, in technical slang called HdeafH, are engineered to perform the tas(s of receiving data only from the closest transmitter. The data are delivered via B2 to the central receiver and than displayed in the dash board.9"itation needed: The (illing factor for T,M based on battery designs is the energy budget management/ the low energy is what usually contributes to HdestroyingH the ability of producing a good D6 lin( margin budget, which is re0uired to delivering data from the tire to the dash board with a reasonable and reliable level of redundancy.9"itation needed: T,M engineers are struggling to find the best rate between current consumption and D6 lin( margin budget/ rubber attenuation, phisical effect of rotation, Henvironmental pollutionH -white noise. and the Hauto-locationH feature are typically part of the challenge.9"itation needed: At the end of that there!s the economical aspects that drammatically influence strategies/ microcontrollers! DAM and 68A ; memories, silicon based technologies, M5M , accelerometers, wireless transmitter, including auto-location and rubber attenuation, contribute to increase overall cost of system architecture.9"itation needed: Todays engineers have to generate a low cost and energy efficient T,M tire units bearing in mind that a good architecture for monitoring pressure in tire must have9"itation needed:/ a. at least Y#BdBm pea( emitted power, corresponding to -#?dBm1#&Q;z power density to stay in the limits determined by normatives. b. 5nergy efficient strategy/ to comply with #& years expected life time the current consumption must be of less than %&& nA. ome of the systems are engineered with 3 or ? axis accelerometers

to shut down system when in stand-by mode -sleep mode. but with conse0uent impact on the economical budget. c. low weight and high robustness. d. +ntegration for an easy installation and good logistic practicings. e. Auto-location feature without complicate and expensive strategies based on accelerometers and1or 86 -accelerometers and 86 contribute on reducing energy efficiency and usually have negative economical impact on the target price of the wheel unit.. The ,O as proven concept to reduce energy consumption and mechanical dimensions of T,M tire unit/ To cope with all these challenges T5 5ngineering, a company based in the north of +taly, has introduced a new concept of energy efficient wireless sensor device based on a technology called ,O - hort ,ulse Technology.. The new concept has been first introduced in a new class of >5Moriented T,M tire stem whose concept is basically the integration of a simple hybrid ceramic circuit inside the body of a standard tire stem, as opposed to traditional T,M which have an electronic ,'B located in a dedicated plastic box, )ust beneath the tire stem itself.9"itation needed: - 9#&: Advantages of this solution are obviously connected to the use of an + >-T 0ualified tire stem, as normally used in the automotive mar(et, allowing huge cost savings and enabling standardization of remote direct T,M . 7ue to extremely reduced power consumption, measured to be about three orders of magnitude less than standard technologies, this new application allows use of reduced size battery cells X in fact, a #3.% mm diameter standard cell can now replace the 3& mm cell normally used. T5 says that, being able to HsurviveH fed by the very small energy harvesters devices are able to generate, this new technology approaches the highly desirable HBattery-lessH operating conditionE >ther benefits are/ reduced overall weight, mechanical robustness, cost reduction, and extended temperature range --4&W Y#3%W'.. T5 concept introduces a new methodology which sees in-stem electronics rather than Hattached-to-the-stemH technology/ the high grade of integration has been achieved through a substantial reduction of components with benefits in terms of costs savings and enhanced mechanical robustness. The ,M#@ -a new (ind of tire stem. has demonstrated to be able to improve supply chain performances with regards of production planning and logistics. The similarity of ,M#@ tire stem to traditional mechanical valves normally available on the mar(et, well support >5M!s planning of ris(s reduction due to non-conformal mounting processes, after-mar(et and after-sales strategies. The procedure of installing a ,M#@-based T,M wheel unit clearly avoids weird procedures used to couple tire!s bid with rims when mounting standard HbutterfliedH T,M .9"itation needed: - The ,M#@ tire stem has been recently demonstrated during the +*th international +ntelligent Tire Technology conference in <iesbaden ->ctober 3&&A..9"itation needed: %ar!ets 'ight-duty vehicles Tire-pressure sensors in the light-duty vehicle -3B,&&& pounds or less. mar(et are usually based purely on cost and installed by the >5M. +n the 2 HThe Tread ActH applies to these vehicles. +n the 5uropean 2nion and 'hina, T,M legislation is also being prepared.

Heavy-duty vehicles 6or heavy-duty vehicles -class @-A, gross vehicle weight 9C*<: greater than 3B,&&& pounds., most of the above-mentioned systems don!t wor( well, re0uiring the development of other systems. The main issues on a large vehicle are/
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8ac( of standardization. Tires are often purchased in bul( and moved between tractors over time, so a given T,M system can only wor( with compatible sensors in the tires, creating logistic problems. D6 systems for these units must also wor( over much longer ranges, which may force repeater systems to be installed on the tractor or trailer.

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+t is expected that battery lives on these systems should be in the %-@ year range since the cost of brea(ing down a tire can be so much more expensive. The 7epartment of Transportation!s maximum-loading re0uirements force trailer manufacturers to spread loads over multiple axles giving rise to trailers typically with A-#3 tires, but high as $B tires on specialty haulers. Tire carcasses can have lifetimes of up to A years through multiple retreading processes. This has given rise to a specialized industry that focuses solely on the issues found in the truc(ing industry. 'entral inflation systems originally claimed to eliminated the need for pressure-monitoring systems. - ome ma)or inflation systems are Meritor , +, ;endric(son international and *agia used mostly in outh America.. ;owever, they have not yielded a complete solution since they do not solve all the issues -i.e., no support for the steer axle., and they bring new issues with maintenance of the rotary couplings in the hub caps. 6urthermore, inflation systems can sometimes shorten the life of tires by covering slow lea(s caused by embedded ob)ects, which drivers would otherwise remove after inspecting the problem tire. +n order for a tire-pressure sensor to be completely effective it must have several capabilities to allow for the various maintenance personnel groups to use them. 6irst, each driver is re0uired to do a pre-trip inspection so it is nice if the tire-pressure monitor has some indicator that can be read without tools )ust by loo(ing at the wheel. econd, it usually should have the capability to cover dual sets of tires in some fashion. +t is also nice if the fill points can be centralized so that airing can be done easily without reaching through the small hand holes in the rims. Thirdly, they need to have some wireless communication system that has a reasonably long range and a long battery life. +t is important that sensor regularly communicates as an H+!m aliveH condition, since having a dead sensor can be worse than having a no sensor at all if everyone thin(s the monitoring is being ta(en care of automatically. +n-cab tire-pressure monitoring can still be valuable for the tractor1trailer combinations but these systems must have the capability to adapt to changing of tires and trailers without operator intervention. +t is important to find ones with long ranges since repeater systems can add tremendously to the cost. These systems alert the driver to the hazardous blowout condition, however, even these new systems still may not help larger fleets deal with slow lea(ing tires,

because the driver may ignore a slow lea(ing tire and not tell fleet maintenance personnel about the issue until it is too late. This has given rise in recent years to monitoring solutions that trac( the tire condition and send bac( alerts to fleet maintenance personnel that allow for them to schedule maintenance on the slow lea(ing tire on an exception basis instead of having to chec( each tire manually. Many fleets today admit that tire-pressure chec(ing is a ma)or problem in enforcement. Most have policies in place re0uiring the regular chec( of every tire, however, the practice is not terribly effective because of the sheer scope of the issue and the fact that it is hard to get a complete record of all tire chec(ing. Today the best systems consist of automated data collection systems. ome of these use gate readers that automate the collection of tire data bac( to a databases or to web portals that allow maintenance operators to see the entire fleet at a glance. 6or long haul fleets that may not see their vehicles for long periods of time, a centralized reading system may not wor( but there are emerging systems that aggregate the tire-pressure sensor data bac( to the asset trac(ing systems so that alerts can be sent bac( to the main office when an issue arises. 6or small fleets, handheld devices exist that allow for the person chec(ing tires to simply wal( around vehicles and collect the data for downloading to a central database allowing for enforcement and trending to be done without errors. ome of the automotive manufacturers have attempted to broaden their scope into the heavy duty mar(ets but a few manufacturers have focused solely on this mar(et, li(e temco!s BatD694: and <abco. Setting up the system The T,M has to be installed and tested in the vehicle manufacturing environment. The process is generally as follows. The T,M sensors are attached to the wheel during the wheel and tire assembly process. The wheels are then attached to the vehicle. This is the first point at which the T,M can be clearly associated with the vehicle. +n the case of battery-powered D6 systems, it is on this final car assembly line that D6 antennas are used to extract the uni0ue +7s of the T,M . These +7s, and their associated wheel position on the car are downloaded to the vehicle 5ngine Management 2nit. This enables warnings to be associated with wheel position. imilarly, the franchised car dealer wor(shop needs to have portable tools available to extract the wheel sensor +7, and in the case of battery-powered T,M , reprogram the car!s 5'2 as would be re0uired for wheel sensor module replacement when a battery fails. ervice to the vehicle tires may also re0uire replacement of a T,M sensor due to valve core corrosion, a bro(en band, or other issues. <hen a T,M sensor is replaced, it is important to understand your vehicle. 5very manufacturer has a different method to reprogram the vehicle. ome vehicles simply reprogram themselves while you drive. >thers re0uire the user to perform an action, such as turning the (ey and pressing a pedal, or using the (ey-fob to trigger a re-learn mode. =ot all vehicles may be placed into a relearn modeK some re0uire an extra interface to the vehicles >B7++1'A=-B2 to spea( with the vehicle 5'2, B'M or other device. *ehicles with this interface re0uire the user to return to the dealership for a tire rotation.

7irect-sensor battery-less T,M s, such as the *isiTyre system, are zero-maintenance systems that do not re0uire any recalibration or specialist >B7 port H8earn ToolsH after tire replacement or tire rotation. Performance A T,M helps to improve vehicle safety, and aids drivers in maintaining their vehicle tire pressures. ,roperly maintained tires help with vehicle safety, performance and economy. +n the 2 , the =ational ;ighway Traffic afety Administration -=;T A. has estimated that every year, %?? fatalities are caused by tire defects in road accidents9"itation needed:. Adding T,M to all vehicles could avoid #3& of the %?? yearly victims and spare as many as A,4&& in)uries every year9"itation needed: . The 6rench "curit" DoutiZre -a road safety organization. estimates that $G of all road accidents involving fatalities are attributable to tire under-inflation9"itation needed:, and the Cerman 75QDA estimated that 4#G of accidents with physical in)uries are lin(ed to tire problems.9"itation needed: >n the maintenance side, it is important to realize that fuel efficiency, and tire wear are severely affected by under-inflation. +n the 2 =;T A data relates that tires lea( air naturally and over a year a typical new tire can lose between 3& and B& (ilopascals -(,a.. +f we also consider that over 4&G of vehicle owners in 5urope and =orth America chec( their tires less than once a year,9"itation needed: it is conceivable that 4&G or more of vehicles currently in use in those areas are running with underinflated tires. >f course, modern features such as pressure sensing systems encourage the average vehicle owner to feel less responsible for the maintenance and safety of their automobile. Many simply ta(e it for granted that the system is accurate, and fail to pay attention to elementary things such as the air pressure in their tires. ,eople are increasingly ignorant of the mechanical systems of their vehicles, which can be very dangerous as a person may not notice impending catastrophe such as loss of engine oil or transmission fluid, or even -you guessed it. low tire pressure in time to prevent the results. There is one school of thought that perhaps there should be an increased emphasis on basic mechanical familiarity for owners and operators of motor vehicles, in addition to the systems li(e T,M . >f course, the complexity of the modern car ma(es anything but the most basic of maininence unrealistic for most people, but the best way to ma(e sure that a nations automobiles are running on full tires is to have drivers themselves chec(. There is still a very large number of older vehicles on the road without tirepressure monitering systems, and ta(ing responsibility for ones own actions is never a bad thing, and neither is having at least a degree of self-sufficiency. The 5uropean 2nion reports that an average under-inflation of 4& (,a produces an increase of fuel consumption of 3G and a decrease of tire life of 3%G. The 52 concludes conclude that tire underinflation today is responsible for over 3& million liters of unnecessary burned fuel, dumping over 3 million tonnes of '>3 in the atmosphere, and 3&& million tires prematurely wasted in the world. 6or these safety and environmental reasons, the 2. . 6ederal government has mandated the use of T,M , and other countries should follow closely. The T,M mandated by the 2. . law must warn the driver when a tire is under-inflated by as much as 3%G.9##: ;owever, since the recommended tire pressures for most vehicles are more than #B& (,a -3? psi., a deflation of 4& (,a would be within the 3%G allowance and would not trigger the T,M warning mandated by 2. . law.

Therefore, the mandated T,M is mainly designed for safety and is unli(ely to deliver the above benefits. 7rivers are still advised to manually chec( their tire pressure often to maintain optimal performance. +n the case of battery-powered T,M , at some point in the vehicle!s lifetime, every battery will ultimately become exhausted and there will be an HunsafeH window where the system is unavailable. Battery lifetime is adversely affected by sub-zero temperature extremes which occur in certain areas of 5urope and =orth America. ;ence, vehicle manufacturers are showing a great interest in the next generation of battery-less T,M systems being developed by Transense Technologies, and 5T* with its *isiTyre system. Cenerally spea(ing, direct tire-pressure monitoring systems may offer the following features/
• • • • • • •

Measure -and may display. tire air pressure, with an accuracy able to detect under-inflation conditions of less than 3%G of the recommended cold inflation pressure Measure and display tire air temperature -optional. 8ocate tire involved in pressure defect -optional. Deact to fast and slow lea(s -less than % s. for early warning 7o not re0uire initialization or zero button, i.e., self-learning -optional. 'an monitor spare-tire pressure9%: 'an monitor tire pressure when stationary -direct T,M only.