Trajectory Tracking And Coordinated Control For The In-Wheel Motor Actuated Autonomous Vehicles

Electric and intelligent vehicle have gradually become the main component of the future traffic.The trajectory tracking is an important guarantee for the automatic driving.Electric vehicle is the best platform for the automatic driving technology.The in-wheel motor actuated vehicle has become an important research direction for EV,because of its multiple dynamic control,high efficiency and energy saving.The trajectory tracking control and coordinated control for automatic driving vehicle has been researched,which combines the advantages of differential control and active steering for the in-wheel motor actuated vehicleFirstly,the trajectory tracking with active steering control has been researched.The trajectory tracking controller with the model predictive algorithm is designed based on vehicle dynamics and tire model.The optimal solution through the standard quadratic programming(QP)is studied by combing constraints and optimization objectives.Meanwhile,CarSim-Simulink joint simulation model of in-wheel motor actuated autonomous electric vehicle is build.The simulation results shows that the model predictive trajectory tracking control can complete trajectory tracking task and ensure the stability of the vehicle.Besides,the preview time adaptive control also has been proposed and fuzzy controller has been designed based on the vehicle trajectory error and the curvature of the road.The simulation experiments shows that the preview time adaptive control effectively improve the trajectory tracking accuracy and running stability of the vehicle.Secondly,the trajectory tracking with coordinated control has been researched.According to the characteristics of torque independent control and conducting skid-steering by differential control,the differential control trajectory tracking strategy has been proposed.The trajectory tracking is realized by using PID control algorithm.The trajectory tracking has been realized by distributing the torque of left and right in-wheel motor.Besides,the coordinated control for trajectory tracking based on the weight coefficient method has been proposed,because the vehicle trajectory tracking with active steering or differential control are two different ways torealize trajectory tracking.The weight coefficient of active steering and differential control influence on the trajectory tracking has been researched,and the range of two weight coefficient has been determined.The simulation results found that the trajectory tracking with coordinated control strategy can improve vehicle steering response.The improvement rates of the trajectory deviation mean square root are14.2%,15.9% and 18% respectively in the speed of 30km/h,45km/h and 60km/h,indicating that the coordination control can improve the accuracy of trajectory tracking control.Finally,the two-wheel in-wheel motor actuated autonomous electric vehicle has been build,in order to verify the feasibility of the trajectory tracking with coordinated control.The vehicle driving system,steering system and braking system has been refitted and has been equipped with the various sensors.Meanwhile,The vehicle control system,trajectory tracking control system,and differential control system are built based on the rapid prototyping.The vehicle road test under active steering and coordinate control has been completed in the change lane and double change lane two conditions.The experiment results show that the trajectory tracking with active steering can complete the path following task.Meanwhile,the trajectory tracking with coordinate control is feasible and can effectively following the reference path.The coordinate control also can increase the steering response and effectively improve the unmanned vehicle trajectory tracking accuracy.