Identification and control of a vehicle restraint system

To minimize occupant injuries, passive in-vehicle safety systems like the safety belt and the airbag restrain the occupant during a crash. This paper presents a design approach for a feedback controller for the belt force to reduce the maximum chest acceleration as a measure for the risk of occupant injuries. Only frontal crashes are considered. The available, experimentally validated numerical crash model is too complex to be used as a controller design model. Therefore, approximate linear models for the transfer from belt force to chest acceleration are derived by analysing the effect of stepwise perturbations of the belt force on the chest acceleration. Using these linear models, loop shaping is applied to arrive at a controller that satisfies a set of a priori defined criteria. The controller is implemented in and evaluated with the complex crash model, showing that a reduction of approximately 60 per cent in the adopted injury measure can be achieved. Furthermore, it is shown that this approach can be applied in different situations.