Research On Path Tracking And Front Axle Variable Load EPS System Of Intelligent Commercial Vehicle

With the rapid development of intelligent vehicles,people pay more and more attention to the driving experience,driving safety and riding comfort.Lateral control is closely related to vehicle handling stability,active safety and other issues,so it is the key technology of intelligent vehicle research.Because the application scenario of commercial vehicles is relatively single,it is easier to achieve driverless.Nowadays,driverless vehicle is still in the stage of development,and driver’s active intervention and control are still needed when necessary.In addition,the load of commercial vehicles varies greatly,which will have a greater impact on the lateral control effect of the vehicle.In view of the above considerations,this paper mainly studies how to achieve vehicle path tracking control by controlling the steering of intelligent commercial vehicle.If necessary,the driver intervenes in vehicle steering and gains steering control.The steering assist system can provide the optimal steering assist moment for the driver,so as to enhance the driver’s driving experience.The main contents of this paper are as follows.Firstly,the structure system of path tracking system and electric power steering system for intelligent commercial vehicle lateral control is introduced.The composition and functional requirements of the lateral control system are analyzed.In order to avoid human-machine conflict when the driver intervenes,the driver operation state identification module is designed.Secondly,the vehicle dynamics model and tire model are analyzed.Based on the optimal preview control strategy,the path tracking control strategy is built.According to the relationship between the vehicle heading angle and the tangent angle of the reference path,feedback control is added to the control strategy.The influence of different preview distance on path tracking effect is analyzed,and a variable weight multipoint preview method is proposed.Through the co-simulation of TruckSim and Simulink,the influence of vehicle speed,vehicle weight and road adhesion coefficient on the optimal preview control strategy is analyzed.The results show that the vehicle with high speed can not follow the reference path on the road with low adhesion coefficient and loses its driving stability.In view of the above problems,the model predictive control strategy with constraint control is studied,and a linear time-varying model predictive controller is established.The tire cornering constraint is added to the controller to improve the anti-jamming ability of commercial vehicles and ensure the driving stability.Through co-simulation analysis,the model predictive control strategy can make the vehicle have better path tracking effect and stability under different speed,weight and road adhesion coefficient.It is verified that the control strategy has better adaptability to speed and road adhesion coefficient.When the driver interferes with the steering,the EPS system provides steering assist torque.Considering that the steering resistance torque of commercial vehicles is larger due to the larger vehicle weight,and the steering resistance torque of vehicles varies greatly under different loads,a dual-motor electric power steering system with variable front axle load is proposed in this paper.In order to ensure that the driver can get better road feeling and steering portability under different loads,and improve driving experience,this paper designs EPS system control strategy of front axle variable load assist characteristics.In addition,two current distribution control strategies and corresponding fault-tolerant control schemes are proposed according to the working characteristics of dual-motor EPS system.Finally,through co-simulation,this paper verifies that the driver can obtain the operation control when intervenes in steering,and the front-axle variable-load dual-motor EPS can provide the driver with appropriate steering torque,which can overcome the impact of load on steering performance,ensure that the driver can obtain the steering portability at low speed,and have a clear road feeling at high speed.Compared with traditional EPS,it can make the driver get a clearer feeling of the road and improve the handling stability,thereby improving the driver’s steering and driving experience.In addition,the feasibility of current distribution control strategies and fault-tolerant control schemes are verified by co-simulation experiments.