Output Constraint Control on Path Following of Four-Wheel Independently Actuated Autonomous Vehicles

This paper investigates the path following problem for four-wheel independently actuated (FWIA) autonomous vehicles (AVs). A novel output constraint controller is proposed to deal with the lateral offset control in path following and maintain the vehicle lateral stability in the presence of tire sliding effects. The innovation of this work includes the following two aspects: (1) A novel output constraint control strategy, hyperbolic projection method, is proposed to strictly bound the lateral offset to prevent vehicle transgressing the safety bound in the path following; (2) A robust LQR controller, is adopted to obtain the optimal active front steering (AFS) and direct yaw moment (DYC) control inputs, with the vehicle stability consideration, and to eliminate the parameter uncertainties and external disturbances. CarSim-Simulink joint simulation results indicate that the proposed controller can compactly bound the lateral offset to avoid transgressing the safe boundary during path following process, especially in extreme driving condition, in presence of tire sliding effects, system uncertainties and disturbances.