Robust Backstepping Tracking Control of Mobile Robot Based on Nonlinear Disturbance Observer

This paper presents a robust backstepping control (BC) method based on nonlinear disturbance observer (NDOB) for trajectory tracking of the nonholonomic wheeled mobile robot (WMR) in the presence of external disturbances and parameters uncertainties. At first, a bounded Fuzzy logic based backstepping controller (BFLBC) is designed to control the WMR without considering the effects of the external disturbances and the parameters uncertainties. Typically, the conventional BC controller depends upon the state tracking errors analysis, where unbounded velocity signal is produced for the applications that have huge tracking errors. Therefore, a fuzzy logic controller (FLC) is introduced in this research in order to normalize the state tracking errors, so that the input errors to the BC are bounded to a finite interval. Finally, the designed BFLBC is integrated with the nonlinear disturbance observer in order to attenuate the external disturbances and model uncertainties. The simulation results show the effectiveness of the proposed controller to generate a bounded velocity signal as well as to stabilize the tracking errors to zero. In addition, the results prove that the proposed controller provide an excellent disturbance attenuation as well as robustness against the parameters uncertainties

Time varying backstepping control for trajectory tracking of mobile robot

This paper presents a time varying backstepping tracking controller (TVBTC) for the kinematic model of the non-holonomic wheeled mobile robot (WMR) that can improves the transient performances of the standard backstepping control scheme. The proposed TVBTC is derived based on the analysis of the error dynamic, as well as the stability conditions of the controlled system. The asymptotic stability of the system and the convergence of the posture errors to zero are guaranteed using the Lyapunov stability theory. In comparison with the other tracking control methods for the mobile robot, the simulation results demonstrate that the transient performance can be improved significantly using the proposed TVBTC, which is capable to track a circular path with faster settling time and minimal overshoot. In addition, the TVBTC can efficiently handle a situation with arbitrarily large initial tracking errors and it is capable to produce smooth and bounded velocity output in a finite time interval. The simulation results show the effectiveness of the proposed tracking controller at the starting time