Adaptive fuzzy logic-based sliding mode control for a nonholonomic mobile robot in the presence of dynamic uncertainties

This paper is concerned with the trajectory tracking control of wheeled mobile robot in the presence of nonholonomic constraint on the robot kinematics and unpredictable uncertainties related to robot dynamics. In this study, by analyzing the practical implementation of the wheeled mobile robot, the unavoidable model errors and external disturbances are merged into a synthesized term which is defined as uncertain dynamics. For attenuating the effects of static tracking error, a PI-type sliding mode manifold is proposed; particularly, in order to suppress inherent chattering, a fuzzy logic system is employed to estimate the uncertain dynamics due to its universal approximation capability. Also, adaptive schemes are applied which make the controllers much more adaptability to overcome the changing environment. Eventually, with the aid of a double closed-loop control structure, the coordinated control objectives of robot posture and uncertainties rejection are able to achieve simultaneously. Simulation studies verify the feasibility and effectiveness of the proposed control approaches.