TRAJECTORY-TRACKING CONTROL OF A NONHOLONOMIC MOBILE ROBOT: BACKSTEPPING KINEMATICS INTO DYNAMICS WITH UNCERTAIN DISTURBANCES

In this study, a double closed-loop control structure with a disturbance observer is reported. This combining structure could globally realize postures-tracking stabilization and have disturbance adaptive capability. On the outer loop, a new function having sinusoidal and inverse tangent characteristics, which are continuously differentiable, is applied to construct the velocity controller by using backstepping technology. Meanwhile, a disturbance-observer-based controller is applied to the inner loop to estimate the dynamic disturbances acting on the wheels; these disturbances are unavoidable and uncertain in an unstructured environment. To enhance the robustness of the system, sliding-mode control technology is applied to construct the system's dynamic controller. Finally, simulations are carried out to verify the effectiveness of the proposed control methods.