Multi-directional Dynamics And Path Following Control Of Autonomous Vehicle

With the development of vehicle electronic control technology and the updating of vehicle control theory,the four-wheel independent actuated vehicle and automatic driving technology can improve the driving safety,riding comfort and greatly alleviate the problems of resources,environment and road traffic.The vehicle dynamics and path following control are the essential parts of automatic driving technology and the keys of having a better driving stability,safety,riding comfort and road utilization.Therefore,in this thesis,the problems of multi-directional dynamics and path following control are studied for the four-wheel independent actuated vehicle.（1）In the vehicle dynamics control,time-varying longitudinal velocity,uncertainty of tire cornering stiffness,actuator saturation,hard constraints of suspension structure and the unmeasurement of state parameters are taken into consideration.An observer-based gain scheduled robust H_∞/GH₂ multi-objective integrated controller is designed based on the direct yaw moment control and active suspension system.Moreover,an improved polytope method is adopted to describe the velocity-dependent parameters and reduce the conservatism of the controller.A distribution strategy of external yaw moment is adopted to calculate the expect output torque of each in-wheel motors.Finally,the simulation results under different conditions illustrate that the observed value follows the actual value well,the distribution error of four-wheel torque is controlled at a low level,the designed controller can ensure the stability,maneuverability,safety and ride comfort of the vehicle.（2）In the vehicle path following control,based on the strategy of sampled-data control and the consideration of tire cornering stiffness uncertainty and time-varying longitudinal velocity,the system is described as a linear parameter varying system with time-delay and uncertainty.Moreover,due to the limits of front wheel steering angle and torque of four in-wheel motors,actuator saturation was considered in the controller design.Since some state variables are unmeasurable,a dynamic output-feedback controller based on the direct yaw moment control and the active steering system is designed.Finally,the performance of proposed control method is verified in different scenarios.