Application of Optimal Control Method to Path Tracking Problem of Vehicle

Path tracking is an essential stage for vehicle safety control. The study proposes an optimal control method for path tracking problem. Firstly, a nonlinear 4-DOF vehicle model is established. Secondly, the path optimization problem of vehicle is transformed into a nonlinear programming problem(NLP) by discretizing both control variables and state variables using the local collocation method. Then, in order to improve the efficiency of solving the NLP, an efficient calculation method for partial derivatives is established. Finally, a real vehicle test is executed to verify the rationality of the proposed model and methodology. The results show that by decomposing the partial derivative of the NLP into the partial derivative of the original path optimization problem the computational complexity of the first order partial derivative of NLP is significantly reduced improving computational efficiency even more significantly.