Trajectory Tracking Control Methods For Wheeled Differential Drive Mobile Robots

Wheeled differential-drive mobile robots are typical nonholonomic and nonlinear systems. In the past decade, wheeled mobile robots have been paid more and more attention by researchers thanks to their potential application. This thesis mainly focuses on the trajectory tracking methods for wheeled differential-drive mobile robots.Firstly, according to back-stepping design method, trajectory tracking control laws which are based on the kinematic and the dynamic models of differential-drive mobile robots are designed, respectively. The global asymptotical stability is proved by a constructed Lyapunov function. The effectiveness of the control laws is validated by tracking circular and straight-line trajectories in the MATLAB simulation environment.Secondly, sliding mode variable structure control is used to establish trajectory tracking algorithms on the basis of the kinematic and dynamic models of the robot. The MATLAB simulation results are analyzed.Thirdly, a fuzzy control method is introduced into the trajectory tracking. A new error model is adopted to design the fuzzy controller. Simulation results of tracking circular and straight-line trajectories prove the method's validity.On the basis of the kinematic model, the back-stepping method is chosen to control a real differential-drive wheeled mobile robot tracking circular trajectories. The velocity and acceleration of the robot are limited to ensure that the mobile robot move smoothly. Experiment results also validate the control algorithm.Finally, the advantage and disadvantage of three tracking control methods are compared and summarized.