Virtual-Point-Based Fault-Tolerant Lateral and Longitudinal Control of 4W-Steering Vehicles

This paper studies the lateral and longitudinal path tracking control of four-wheel steering autonomous vehicles. A robust and adaptive fault-tolerant tracking control strategy is proposed to simultaneously counteract modeling uncertainties, unexpected disturbances, coupling effects, as well as actuator failures. By introducing the virtual points along the longitudinal centerline of the vehicle and utilizing a state transformation, a special feature of the control gain matrix is revealed, which allows for the development of structurally simple and computationally inexpensive robust adaptive and fault-tolerant control algorithms. The closed-loop stability issues of the control scheme are analyzed using a Lyapunov-based method. A nonlinear dynamic model of a passenger vehicle is developed to simulate the performance of control design. The controller is tested and validated via computer simulations in the presence of parametric uncertainties and varying driving conditions.