Research On Yaw Stability Control Strategy For Automatic Emergency Obstacle Avoidance Of Commercial Vehicles

With the vigorous development of my country’s transportation industry,the number of commercial vehicles is increasing year by year,and major traffic accidents caused by commercial vehicles also occur frequently.Therefore,how to ensure the driving safety of commercial vehicles has become an important issue to be solved urgently in the commercial vehicle industry.In order to improve the driving safety of emergency obstacle avoidance for commercial vehicles under automatic driving conditions,this paper focuses on the yaw stability control problem of automatic emergency obstacle avoidance for commercial vehicles based on differential braking.The main research contents of this paper include: commercial vehicle dynamics model,electronic braking system simulation model,obstacle avoidance trajectory planning algorithm,trajectory tracking control strategy and differential braking yaw stability control strategy.The electronic braking system actuator control strategy,trajectory tracking control strategy and differential braking yaw stability control strategy of commercial vehicles are simulated,verified and analyzed under typical working conditions.The specific research contents of this paper are as follows:（1）The research status at home and abroad.Focusing on the selected topic of this paper,the research background and significance are analyzed,and the research status of trajectory planning algorithm,trajectory tracking control strategy and yaw stability control strategy at home and abroad are reviewed,and the research content of this paper is clarified.（2）Establish a commercial vehicle dynamics model and an electronic braking system model.Firstly,the 8-DOF vehicle dynamics model of the commercial vehicle and the tire model based on the magic formula are established for the design of the yaw stability control strategy in the following,and the accuracy of the built simulation model is verified.Secondly,based on the tire magic formula,the cornering stiffness and longitudinal stiffness estimation problems of tires are studied and used for the design of the trajectory tracking control strategy in the following.Finally,based on the existing research results of the research group,the configuration scheme and working principle of the electronic braking system for commercial vehicles are analyzed,and built its simulation model on the AMESim platform for the simulation verification of the subsequent control strategy.（3）Design the automatic driving obstacle avoidance trajectory planning algorithm and trajectory tracking control strategy.Firstly,considering the boundary condition constraints and lateral stability constraints of the obstacle avoidance trajectory,the obstacle avoidance trajectory planning algorithm is designed based on the quintic polynomial curve,and the simulation results of trajectory planning are analyzed.Then,the trajectory tracking control strategy is designed based on the model predictive control algorithm,which mainly includes the simplification of the vehicle dynamics model,the linearization of the nonlinear model,the discretization of the continuous model,the establishment of the prediction model,the establishment of the cost function and constraints conditions,and the calculation method.（4）Design emergency obstacle avoidance yaw stability control strategy based on differential braking.Firstly,the overall structure of the emergency obstacle avoidance yaw stability control strategy is designed.Then,the vehicle yaw stability control strategy is designed,mainly including vehicle yaw stability criterion design,vehicle state estimator design based on CKF algorithm,yaw stability fuzzy PID controller design,differential braking strategy and braking torque distribution strategy design.Finally,the control strategy of the commercial vehicle electronic braking system actuator is designed based on the logic threshold control.（5）Simulate and verify the yaw stability control strategy of automatic emergency obstacle avoidance for commercial vehicles.Firstly,based on Truck Sim,Matlab/Simulink and AMESim software,a joint simulation platform is built.Secondly,simulation verification and analysis are carried out on the control strategy of the electronic braking system,trajectory tracking control strategy and differential braking yaw stability control strategy of commercial vehicle under typical working conditions.The simulation results show that: 1)The control strategy of the electronic brake system actuator based on logic threshold control can control the overshoot of the actual brake pressure within 0.04MPa;2)The trajectory tracking control strategy based on model predictive control has a large trajectory tracking lateral displacement error without yaw stability control,and its peak value reaches 38 cm,but after yaw stability control,trajectory tracking lateral displacement error is significantly reduced,and can control it within 21cm;3)The yaw stability control strategy based on fuzzy PID control can reduce the yaw rate of the vehicle by46%-57% and the side-slip angle of the center of mass by 60%-73% under different working conditions,which significantly improves the vehicle’s yaw stability.In addition,the yaw stability can also play a certain role in restraining the body roll on the high adhesion road.It can be seen that the yaw stability control strategy designed in this paper can not only effectively improve the yaw stability of commercial vehicles,but also greatly improve the tracking performance of the vehicles to the desired trajectory.（6）Summarize the full article,and look forward to the issues that need to be deeply explored during the research.