Backstepping Trajectory Tracking Based on Fuzzy Sliding Mode Control for Differential Mobile Robots

Differential wheeled mobile robot (DWMR) is a typical nonholonomic complex system with the practical importance and theoretically interesting properties. A novel backstepping & fuzzy sliding mode controller (BFSMC) is proposed for trajectory tracking of the DWMR in the presence of model uncertainties and external disturbances. Backstepping control technique is used to eliminate the pose deviations of the mobile robot based on the kinematic model. Sliding mode control is adopted at the dynamic level for velocity tracking of the driving wheels, in which the gain of switching control is adjusted adaptively by means of fuzzy logic inference, in order to mitigate the chattering problem. The tracking error convergence of the BFSMC is demonstrated by means of the Lyapunov stability criteria. Numerical simulation shows that the BFSMC has the better accuracy, rapidity, smoothness and robustness, when compared to the conventional SMC. A vision-guided mobile robot with an onboard camera is developed for the experiment of path tracking. The experimental results further validate the feasibility and effectiveness of the BFSMC.