Optimal TriggeridngOf An Airbag

Abstract

An airbag upon collision of automobiles must finish expanding at the time when the occupant arrives at the surface of tlie expanded airbag from the normal position and it must receive the body softly. Either an early or late expansion reduces the effect. Determination of the optimal timing for triggering the airbag is quite important. But i t is a difficult job, due to the time delay in the bag filling with gas after the collision. This paper will focuse on the airbag technology concemed with finding the optimal trigger timing and will present a new and straightforward algorithm to determine this timing by introducing the concept of the prediction. The algorithm first predicts how an occupant will move in a time corresponding to a delay time and then using this predicted information the airbag will trigger so as to compensate this delay in its operation. The algorithm determines the timing only from the acceleration measured by one sensor set i n the automobile and is composed of the following four basic processing blocks; Kalman filtering lo estimate the acceleration of the occupant and jerk from the noisy measured acceleration. Filtering to estimate the velocity and displacement of the occupant. Prediction of the velocity and displacement of the occupant after collision. Judgement to trigger the airbag from the above estimated and predicted variables by using neural networks. Simulations of the various conditions were carried out and the results demonstrated the validily of tlie algorithm.