Time-varying sliding mode control of a Nonholonomic wheeled mobile robot

In this paper, a control method is presented for the trajectory tracking problem of the Nonholonomic wheeled mobile robot with parameter uncertainties and external disturbances. In this method, the kinematic model is combined with the dynamic model, and the actuator voltage is employed as the control input. Based on an auxiliary velocity controller, a time-varying integral terminal sliding mode controller is proposed. To alleviate the chattering problem caused by the sign function in existing controllers, we replace the sign function with its integral. It is proved that the auxiliary velocity tracking errors can converge to zeros in finite time. As a result, the tracking position errors converge asymptotically to zeros with fast response and less chattering than other existing controllers. Simulation results are used to illustrate the effectiveness of the proposed controller.