Composite nonlinear feedback control for path following of four-wheel independently actuated autonomous ground vehicles

This paper studies the path following control problem for four-wheel independently actuated (FWIA) autonomous ground vehicles (AGVs) through integrated control of active front-wheel steering (AFS) and direct yaw-moment control (DYC). A modified composite nonlinear feedback (CNF) strategy is proposed to improve the transient performance and eliminate the steady-state errors in the path following control considering the tire force saturations, in the presence of the time-varying road curvature for the desired path. The path following is achieved through vehicle lateral and yaw control, i.e., the lateral velocity and yaw rate are simultaneously controlled to track their respective desired values, where the desired yaw rate is generated according to the path following demand. CarSim-Simulink joint simulation results indicate that the proposed CNF controller can effectively improve the transient response performance, inhibit the overshoots and eliminate the steady-state errors in path following within the tire forces saturation limits.