Research On Lateral And Longitudinal Dynamic Coupling Control Of High-speed Vehicle

In this paper, aimed at the control problem of the intelligent vehicle dynamic system, a lateral and longitudinal dynamic coupling vehicle control system is designed for improving the dynamic performance of the vehicle. Firstly, a process by which the longitudinal dynamics and the lateral dynamics affect each other is identified and described based on the analysis of the vehicle dynamics. Then, a simplified simulation vehicle model is presented considering the coupling effects, and a coupled controller is designed based on the model. To keep the vehicle centered in the desired road curve and meanwhile keep the desired safe distance from the leading vehicle, simulation is conducted on the coupling vehicle control system to control the vehicle more precisely, enhance the vehicle driving safety and harmony, and offer a theoretical basis for the intelligent transport system. The main research works are presented as follows:Through the analysis of the vehicle dynamic system, three coupling effects including dynamic coupling, tire force coupling and weight shift coupling are identified and described. Then, a vehicle dynamic model combined the longitudinal and the lateral dynamic coupling effects is proposed taking the longitudinal velocity, lateral velocity, yaw rate, wheel speed and slip ratio as the states.Based on the control purpose of the vehicle control system, the spacing control strategy and preview control strategy are presented after the discussion of the strategy for longitudinal and lateral control. Sliding mode control and Dynamic Surface Control methods are used to design a coupled controller, which compensate for the coupling effects.The coupled control system is tested under different vehicle mass, velocity, and adhesion coefficient, and is compared against the decoupled control system through simulation. The simulation results indicate that the combined controller dose improve the dynamic performance of the vehicle, and is more robust than the controller neglecting the coupling effects.At the end of the paper, a lateral velocity observer is designed combined the vehicle dynamic model and the preview kinematics model since there is no lateral velocity measurement available. The simulation results indicate that the control performance is good taking the observer as the state input.