Trajectory Tracking Of A 4 Wheel Independent-drive Electric Vehicle Using Advanced Steering Method

With most accidents being due to human mistakes,autonomous vehicles appear to be the future of personal vehicles.Now that most recent vehicles are instrumented enough because of driving assistances,one of the first thing to take care of for autonomous applications is the trajectory tracking.One way to approach this matter is to use active steering but this paper will feature a controller that also uses the 4 in wheel motors of the Electric Vehicle(EV)to generate a yaw moment in order to achieve better performance.In order to achieve this control,a 3 degree of freedom(DOF)vehicle model has been simulated in the MATLAB/SIMULINK environment.To get good control performances and easily constraint the system,an MPC Controller incorporating the developped 3DOF vehicle model has been used.To test the controller’s ability to follow the desired path two models were taken on two different roads.The first model uses MPC to control the active steering of the vehicle while the other with identical settings when applicable also controls the yaw moment generated using torque distribution.Both of these two controllers managed to follow the path on a line change maneuver and a sharp sine-shaped chain of turns.Out of the two strategies used,the one giving the best results was the second controller using torque distribution,it reduced the delay between the command and the reaching of the position but also had a smaller overall error.The difference for the first test was small because the maneuver didn’t require advanced control but the second one showed a bigger difference between the two controls.However,there is still work to be done to change the approach made by the MPC controller and reduce the tire wear and the somehow consequent use of the external yaw moment.The control strategy used in this paper is a first step towards advanced performance for path tracking applications and towards fully autonomous vehicles.