Adaptive Tracking Control for Wheeled Mobile Robots with Unknown Skidding

This paper aims to present an adaptive control law for trajectory tracking control of wheeled mobile robots (WMR) with unknown skidding at kinematic level. A new modified kinematic model induced from perturbed nonholonomic constraints is constructed, and an adaptive controller used to estimate the skidding ratio is designed. Without limitation to the reference trajectory, the controller proposed in this paper can be implemented to achieve "Point tracking" of WMR without extra sensors to measure skidding velocity or skidding angle. It is also shown that the estimated skidding ratio converges to its true value through the use of the adaptive controller with the heading error of WMR converges to a constant associated with the "True value" mentioned before. Numerical simulations are carried out to show the effectiveness of the controller by comparison.