Vehicle Stability Control After Impact

Nowadays,vehicles have become a necessary means of transportation for people,but they bring convenience to people and may also cause dangers.Traffic accidents occur frequently.Therefore,vehicle collision safety has always been the focus of research in the field of active and passive safety.After collision,the vehicle may produce a yaw motion and deviate from the trajectory,and the driver may not respond in time or make an excessive operation,which will aggravate the vehicle's instability and cause secondary collisions or multiple collisions.In order to improve the safety of vehicles after collision and avoid more serious casualties caused by secondary collisions,this paper designs a controller of vehicles after collision under the model predictive control framework,which can adjust the stability of the vehicle and the trajectory after collision.,thereby reducing the possibility of subsequent collisions.In order to obtain the collision force during the collision process,a collision force calculation model is built according to the concepts of Newton's second law,conservation of momentum and recovery coefficient of the collision field,and the accuracy of the collision force calculation model is verified by joint simulation with CarSim.The collision force solved by the state before the collision of two vehicles meets the accuracy requirements.A linear vehicle collision model for controller is built,and the accuracy and precision of the model are verified under collision conditions.The results show that the accuracy meets the requirements of controller design.After a vehicle collision,two main issues need to be considered.One is to restore its driving stability;the other is to control its driving trajectory,and the control of the trajectory needs to be established on the premise of stable driving of the vehicle.Therefore,this paper proposes a control strategy for switching between the stability controller and the trajectory controller,the stability controller first controls the stability of the vehicle after the collision through differential braking and active steering.After the vehicle returns to stability,the trajectory controller control the vehicle to return to the original lane or the near lane through active front wheel steering.Based on the model predictive control algorithm,the appropriate output and control amount are selected,the constraints of the actuator are considered,the post-touch stability controller and the post-touch trajectory controller are designed,and multiple sets of simulation experiments are performed to verify the control effect of the controller.Subsequently,the controllable range of the controller is studied.Compared with no control,the area where the vehicle can resume stable driving after collision is significantly expanded,indicating that the designed linear controller played a certain role in control.However,the lateral displacement of the vehicle is too large and even hits the guardrail provided near the lane in some extreme collisions,.In order to improve the control effect of the controller after the collision of the vehicle under extreme conditions,a nonlinear tire model and a nonlinear collision model are built.A nonlinear post-impact controller is designed based on the nonlinear model,and the control effect of the nonlinear post-impact controller is compared with the linear post-impact controller.Considering that the current sensor perception system and the degree of intelligence are constantly improving,and the upcoming danger can be discovered earlier,it is proposed to apply a pre-steering action to the vehicle under the condition that the collision is unavoidable to reduce the impact of the collision.Then,based on the pre-steering control strategy,the nonlinear post-impact controller is improved.The simulation results show that vehicle lateral offset has been improved to a certain extent.