Airbags are a standard feature in most new vehicles today. A large number of vehicles already have different airbags: front airbags, side airbags, head airbags and knee airbags for driver and front-seat passenger. All of these systems use a number of acceleration sensors located at different positions on the vehicle bodywork. The deceleration occurring after an impact is detected by the systems, evaluated and if necessary the decision taken to trigger the individual airbags. A self-diagnosis system monitors the operativeness of the systems before and during journeys. If malfunctions are recognized the system is deactivated, a message saved in the fault memory and the driver notified by an indicator light which comes on. Although modern airbag systems undoubtedly improve the protection potential for vehicle occupants considerably in interaction with the belt, very little is known about the effects of ageing on the reliability of these systems since airbags are not usually used during the life of a vehicle. The "International Motor Vehicle Inspection Committee" (CITA) thus commissioned the "Institut für Kraftfahrwesen Aachen" (ika) to investigate the operativeness of older airbag systems. In the context of this research project the extent to which the deployment threshold is reliably recognized by the electronics in older systems will be examined. The electronic components of the systems will be checked to allow a statement to be made on the deployment threshold of the different systems. For this purpose, the sensor system, wiring harness and control unit are mounted on a test sled in the crash test facilities at the ika. Tests will be also carried out at different impact speeds and decelerations. These tests should determine whether the deceleration threshold to trigger the airbag is recognized correctly. Furthermore, the airbag modules of the individual systems will be triggered and their correct inflation checked. Before the actual tests can be carried out, the various systems will be analysed and if necessary the electric characteristic of those components which are not connected (e.g. seat-belt tensioners) simulated so that numerous crash tests can be performed with the systems independent of the vehicle environment. The tests results show the mode of operation of the airbag systems, from which the reliability of the systems can be derived. A literature enquiry into the development, mode of operation and components of the airbag system precedes the study. (Author/publisher)
Abstract