Intelligent Control for an Uncertain Mobile Robot with External Disturbances Estimator

Abstract

In this chapter, a new control approach for trajectory tracking problem of nonholonomic wheeled mobile robot (WMR) is proposed to cope with both uncertainties and external torque disturbances. The main contribution is the simultaneous exact estimation and cancelation of uncertainties and external torque disturbances without the requirement of torque measurement. First, a kinematic backstepping controller is proposed to achieve perfect velocity tracking. Then, a robust dynamic adaptive control algorithm with two update laws is developed to estimate and compensate the dynamic uncertainties and the unmeasured external torque disturbances. The design of the update laws use only position and velocity measurements and are derived from the Lyapunov stability theorem. Consequently, the proposed controllers prove that they not only can guarantee the stability and the trajectory tracking error is as small as possible but also the boundedness of all the states and signals of the closed-loop system and the convergence of the estimated disturbance to the real values. Finally, the simulation results demonstrate good tracking performance and robustness of the proposed controller.