Model Predictive Control for Path Tracking with PID Speed Control Considering Minimum time Speed Profile Design
In this report, we implemented a model predictive control (MPC) strategy for path tracking and PID control for speed tracking to ensure the autonomous vehicle follows a desired path (an 8 shaped curve and speed profile. In addition, we generated a minimum time speed profile as the speed reference for the vehicle to track the path as fast as possible. In the simulation, we considered three cases for the speed reference: Case A the longitudinal velocity is constant at 10m/s; Case B the longitudinal velocity is varied along the curved path; and, Case C designing a minimum time travel speed profile. For the path tracking, we used MPC controller to generate the optimal front wheel steering angle; for the speed tracking, we used a PID controller embedded in the model predictive control to generate the total accelerating or braking wheel torque. The front wheel steering angle and total wheel torque are passed simultaneously to the plant as inputs to calculate the vehicle state. The simulation results of tracking performance in these three cases are presented and compared with the reference objectives. The tracking errors between the plant and the objectives, such as the heading angle 'ps' the lateral displacement 'Y of vehicle center of mass (C.M. and the speed, are relatively small. The work presented here draws on MPC concepts introduced earlier [1,2] and goes one step beyond the studies reported in [3,4] To that end, it uses three vehicle models discussed in [5]