Adaptive control of a skid-steer mobile robot with uncertain cornering stiffness

This paper presents an adaptive controller for a position tracking problem of a skid-steer mobile robot. First, a non-adaptive control law is designed by the backstepping method, where the reference signals are generated by a non-holonomically constrained kinematic model in order to make it easy to construct a Lyapunov function candidate. Then an estimator for unknown cornering stiffness is designed based on the Immersion and Invariance (I&I) approach, where the manifold is properly designed to reduce the effect of the estimation error on the tracking performance. Finally it is shown that the closed-loop system can be uniformly ultimately bounded, and numerical simulation shows the effectiveness of the proposed controller.