Robust Asymptotic Output Tracking for Four-Wheel-Steering Vehicles

The problem of controlling the lateral dynamics of four-wheel-steering vehicles is studied using a robust compensator with static state feedback, unity output feedback, integral action and a nominal value dynamic prefilter. The lateral acceleration of the vehicle is controlled using robust asymptotic output step command tracking actuating only the front steering angle of the vehicle. The sideslip angle of the vehicle is set to zero using a dynamic prefilter designed for nominal values of the vehicle parameters. The prefilter action actuates the rear wheel steering angle. Sufficient conditions for the problem of lateral acceleration step command tracking to have a solution are established. The steps to determine the robust tracking controller are analytically presented. A dynamic prefilter for zeroing the side slip angle of the vehicle is also computed. The robustness of the controller under physical system uncertainties is illustrated via simulations