Vector-Field-Orientation Tracking Control for a Mobile Vehicle Disturbed by the Skid-Slip Phenomena

The paper is devoted to the trajectory tracking control task for a differentiallydriven vehicle moving on a plane surface under conditions of the persistent skid-slip phenomena. The Vector Field(s) Orientation (VFO) control strategy, presented originally for undisturbed case in [6], has been reformulated here to the new disturbed motion conditions. The extension of the VFO strategy relies on introduction of the nonlinear skid-slip influence compensator in the feed-forward loop, which in practical implementation involves the real-time estimation of the skid-slip velocities and their time-derivatives. The approach considers the skid-slip effects solely on the kinematic level avoiding the need of modeling a complicated phenomenon of the wheels-ground interaction. Theoretical analysis shows the asymptotic tracking ability for the position trajectory with boundedness of the orientation error. Experimental results included in the paper reveal substantial tracking quality improvement resulting from the utilization of the proposed skid-slip influence compensator.