Optimal Vehicle Motion Control to Mitigate Secondary Crashes After an Initial Impact

Abstract

Typical drivers are not ready to react to unexpected collisions from other vehicles. The initial impact can startle the driver who then fails to maintain control. Since a loss of control leads to intense skidding and undesirable lateral motions, more severe subsequent events are likely to occur. To reduce the severity of possible subsequent (secondary) crashes, this paper considers both vehicle heading angle and lateral deviation from the original driving path. The research concept here is different from today’s electronic stability control systems in that it activates the differential braking even when the magnitude of yaw rate or vehicle slip angle is very high. In addition, the lateral displacement and yaw angle with respect to the road are part of the control objective. The Linear Time Varying Model Predictive Control (LTV-MPC) method is used, with the key tire nonlinearities captured through linearization. We consider tire force constraints based on the combined-slip tire model and their dependence on vehicle motion. The computed high-level (virtual) control signals are realized through a control allocation problem which maps vehicle motion commands to tire braking forces considering constraints. Numerical simulation and analysis results are presented to demonstrate the effectiveness of the control algorithm.