Distributed Drive Electric Vehicle Trajectory Tracking Control Research Based On Steering Control And Electronic Differential

In recent years,there has been a rapid development towards intelligent and electric vehicles in the automotive industry.The full-featured distributed electric vehicle uses a wire-controlled integrated chassis,which can achieve four-wheel steering and fourwheel independent drive/braking,changing the power characteristics of traditional fuel-powered vehicles and providing the vehicle with more driving possibilities.However,this also leads to more complex nonlinear relationships in the vehicle’s dynamic characteristics,which increases the difficulty of control.Therefore,researching the electronic differential and trajectory tracking control of distributed electric vehicles has important theoretical and engineering value.This thesis constructs a vehicle model using Car Sim software for a distributed electric vehicle,and designs an electronic differential system with two-wheel steering and four-wheel independent drive(2WS-4WID)based on the kinematic model.Using a front-wheel steering three-degree-of-freedom vehicle dynamics model,a model predictive control(MPC)trajectory tracking controller is built.To improve the tracking accuracy and stability of the trajectory tracking control algorithm under different working conditions,a particle swarm optimization(PSO)algorithm-based MPC trajectory tracking control strategy is proposed to automatically optimize the controller’s parameters and achieve a balance between trajectory tracking accuracy,vehicle stability,and control increment.This improves the robustness of the trajectory tracking controller.The study shows that compared with traditional mechanical differential systems,the 2WS-4WID electronic differential system can not only perform the inner and outer wheel speed difference function under turning conditions but also improve the vehicle’s stability and trajectory tracking ability by controlling the wheel slip rate.Compared with traditional MPC control,the PSO-optimized MPC control can effectively improve the trajectory tracking accuracy and vehicle stability.The lateral displacement error is reduced by 23.8%,and the yaw angle error is reduced by 33.3%.Furthermore,an electronic differential system with four-wheel steering and fourwheel independent drive(4WS-4WID)is designed,and a three-degree-of-freedom four-wheel steering model is established.An adaptive parameter MPC trajectory tracking control strategy is proposed,and the weighting coefficients under different working conditions optimized by PSO can be quickly updated into the four-wheel steering trajectory tracking controller through a table look-up method.The study shows that the 4WS-4WID electronic differential system can still improve the vehicle’s stability and trajectory tracking ability under various complex working conditions,and the four-wheel steering trajectory tracking controller has advantages over the frontwheel steering trajectory tracking controller in trajectory tracking control.The maximum lateral error is reduced by 14%,and the maximum lateral acceleration is reduced by 26%.Finally,based on the entire vehicle experimental platform,a sensing acquisition and vehicle control system are constructed.The global positioning system(GPS),inertial measurement unit(IMU),and other sensors are connected through the Speedgoat rapid control prototype(RCP)to obtain vehicle posture and position information.Real vehicle experiments are conducted on an asphalt road with a speed of 20 km/h using two control strategies,front-wheel steering,and four-wheel steering.The experimental results show that the four-wheel steering control strategy effectively reduces the tracking error,with a maximum reduction of 58%,and the control system exhibits excellent stability and robustness.