Automated, sliding mode, 4WS control based on centers of percussion of front and rear wheels

A simple, stable, and robust path following controller is derived for 4WS vehicles. Front and rear viewpoints are defined as centers of percussion of rear and front wheels, respectively. The controller uses the two viewpoints as datum points to determine course errors. Front and rear course errors follow second order differential equations, where the yaw rate and vehicle body slip angle are inputs to the equations. The controller can cope with unknown cornering power parameters. Steady state values are derived from the lock-on capability. Simulation results on a packed-snow road are given for the controller assuming dry asphalt parameters