Abstract:
To solve the problems of low precision and poor reliability in the path following control of autonomous vehicles, a hierarchical path following control strategy was presented basis on Hamilton theory for four wheel independent drive and four wheel independent steering autonomous vehicles. Integrating vehicle dynamic model and path following model, an error model of path following was presented. According to the control target of path following system, the Hamilton theory was applied to design the upper layer vehicle controller, used to achieve the stabilization and convergence of path following error model and improve the accuracy and robustness of vehicle path following system. Moreover, in the lower layer controller, a distribution algorithm was designed for four-wheel longitudinal tire force to meet control demand of upper layer with dynamic orientated distribution of tire force. A simulation model for vehicle path following was established in CarSim and Simulink software and the simulation verification was carried out. The results show that the proposed hierarchical path following control strategy of autonomous vehicles can restrain the lateral offset and heading error during process of path following control, synchronously improve the accuracy of path following and ensure the reliability of path following control system by real-time control of front and rear wheel steering angle and distribution of four wheel tire forces.