Research On Control Algorithm And HIL Test Of Emergency Collision Avoidance System For Autonomous Vehicle

With the development of automobile industry and artificial intelligence technology,it has brought great convenience to people,but it also brings many hidden safety dangers,causing people to different degrees of loss.Although autonomous vehicles are coming into reality,however,the autonomous driving technology is not mature at the current stage.When autonomous vehicles leave research laboratory and enter into public traffic,they must be able to deal with emergencies situations and avoid traffic accidents.This paper proposed a collision avoidance system for autonomous vehicle in emergency situations.Meanwhile,the important basic theories and key technical involved in motion control are researched.Firstly,considering system uncertainty,nonlinearity and unknown external disturbance,Combined with the back stepping control mechanism and variable structure control theory,the design of the steering controller of the autonomous vehicles is completed.At the same time,the brake yaw torque controller is designed by using the layered control scheme,it can make up for the vehicle's insufficient or excessive steering characteristics by actively boosting of individual wheels while emergency steering.Secondly,the underlying pressure controller is designed by using the layered control method.Finally,the vehicle model and road model were built by CarSim software,the upper layer simulation controller was built by MATLAB/Simulink,And use the path following co-simulation to verify the control effect of the control system designed in this paper.The proposed scheme can solve the problem that the vehicle is difficult to control at driving limits,and it can also improve robustness and stability of the closed-loop system.Secondly,the fifth-order polynomial equation is adopted to calculate a collision-free trajectory considering the constraints of kinematics and dynamics.Then,from the aspect of kinematics,an ideal vehicle yaw rate formula is derived from the collision avoidance trajectory equation,and the equivalent maximum expression of the desired yaw rate is obtained by global optimal solution.Meanwhile,from the aspect of dynamics,the maximum expression of vehicle yaw rate is derived from the constraint condition of road surface adhesion.Finally,through the reasonable design of lateral collision avoidance displacement and terminal point coordinates for the collision-free trajectory,the vehicle can track the desired collision avoidance trajectory during the emergency collision avoidance process and avoid collision along the optimal path.a risk assessment model which can simultaneously consider the risk associated with collision and destabilization is derived.The proposed scheme can solve the problem that how to effectively quantify and evaluate the risk for autonomous vehicle in emergency situations.Finally,the simulation analysis and experimental study are performed using the co-simulation platform and the hardware-in-the-loop(HIL)system respectively.The results show that the control system designed in this paper can not only effectively control the autonomous vehicles to perform the emergency collision avoidance function in the simulation,but also can perform the collision avoidance task well when controlling the real actuator.