Research On Trajectory Tracking Control Method For Four-wheel Steering Intelligent Vehicle

In recent years,with the generation and development of automation,computers,artificial intelligence and other high and new technologies,the automobile gradually and these high and new technologies further closely integrated,through these integration to promote the rapid development of automotive intelligence,while intelligent vehicles by the global automotive industry and related aspects of experts and scholars research,making intelligent vehicles in the rapid development of the world.Trajectory tracking control is one of the core technologies of intelligent vehicle research,which plays a crucial role in the practicalization of intelligent vehicles.Compared with the traditional Front-Wheel Steering(FWS)intelligent vehicle,Four-Wheel Steering(4WS)intelligent vehicle has the features of small turning radius and high flexibility at low speed and high stability at high speed.This paper takes 4WS intelligent vehicle as the controlled object and carries out the research of trajectory tracking control method.In order to improve the tracking accuracy and vehicle stability of the intelligent vehicle for the desired driving trajectory,in this paper,for the 4WS intelligent vehicle,firstly,a 4WS intelligent vehicle model is built and the simulation conditions are built in the vehicle dynamics software Car Sim,secondly,the 4WS intelligent vehicle pre-targeting and Model Predictive Control(MPC)trajectory tracking controllers are designed respectively,and finally,the designed two controllers are simulated and verified on the joint simulation platform.tracking controllers,and finally,the two designed controllers are simulated and verified on the joint simulation platform.The details of the design are as follows.(1)Build a 4WS intelligent vehicle model.Firstly,the four-wheel steering(4WS)problem is described;secondly,the model of 4WS intelligent vehicle is reasonably simplified,the lateral and longitudinal dynamics models of the vehicle are built respectively,and the tire model is established;finally,the Car Sim software is used to design the typical simulation conditions for different adhesion surfaces.(2)The design of pre-scanning trajectory tracking controller for four-wheel steering(4WS)intelligent vehicle is carried out.Firstly,the trajectory tracking control problem is described;then the pre-scanning based 4WS trajectory tracking controller design is carried out to establish the functional relationship between the wheel turning angle and the pre-scanning deviation to reduce the error of vehicle and trajectory tracking by controlling the wheel turning angle;finally,the designed reference trajectory is tracked under different vehicle speeds and different adhesion surfaces based on the joint simulation platform respectively,and the pre-scanning trajectory tracking controller is verified to be The effectiveness of the pre-tracking controller is verified by tracking the designed reference trajectory under different vehicle speeds and different adherence surfaces based on the joint simulation platform.(3)The design of MPC trajectory tracking controller for four-wheel steering(4WS)intelligent vehicle is carried out.In order to improve the trajectory tracking accuracy and stability of the 4WS intelligent vehicle,MPC is used as the trajectory tracking controller in this chapter.Firstly,the MPC principle is introduced;based on the linearized vehicle dynamics model,the MPC control algorithm is developed to consider the vehicle dynamic characteristics and the vehicle steering system constraints on the controller state quantity and output quantity in the trajectory tracking process to meet the vehicle stability and feasibility in the trajectory tracking process.At the same time,considering the stability of the vehicle under the extreme working conditions,the front and rear tire side deflection angles are added to the constraints,and the joint simulation platform is built by Car Sim and MATLAB/Simulink software.The simulation results show that the designed controller can achieve accurate tracking of the reference trajectory and ensure good stability of the vehicle.(4)Comparison of simulation results of trajectory tracking with different controllers.The two controllers designed in this paper are used to control the 4WS intelligent vehicle to take driving at low speed and medium-high speed respectively under the designed typical simulation conditions,and the simulation results show that for the four-wheel steering intelligent vehicle,the two controllers designed in this paper are overall better than the pre-scanning controller in terms of trajectory tracking accuracy and stability compared to the MPC controller,but both the designed MPC controller and the pre-scanning controller can effectively track the reference trajectory and ensure the vehicle has good stability.