Adaptive Trajectory Tracking Control Of Wheeled Mobile Robots

In recent years,wheeled mobile robot has been widely used in the fields of industry,agriculture,national defense and space exploration due to their simple structure and easy control.Among many researches on wheeled mobile robot,the most important and fundamental one is the research on robot trajectory tracking control algorithm.So,there is an in-depth study on trajectory tracking control of wheeled mobile robot under the ideal condition of pure rolling without sliding in this thesis.The main work contents are as follows:(1)Aiming at the adverse effects of unknown external interference,unknown model parameters and system uncertainty on robot trajectory tracking control,there is an adaptive trajectory tracking controller is designed based on robot kinematics model and dynamics model in this thesis.Firstly,on the premise that the geometric center and the center of mass of the robot coincide,the dynamic characteristics of the two-wheel differential mobile robot are analyzed,and the dynamic model of the robot under non-holonomic constraints is established.Secondly,the uncertainty and external disturbance of the robot model are regarded as lumped disturbance,and the adaptive law is designed for the unknown parameters in the lumped disturbance,and then the adaptive controller is designed.Based on the stability theory of Lyapunov,it is proved that the controller can make all the signals in the closed-loop system bounded and the tracking error converge asymptotically to the origin.Finally,the effectiveness of the proposed method is verified by simulation and experiment.(2)Aiming at the chattering effect caused by the sign function sign(x)in the adaptive trajectory tracking controller above,an improved adaptive controller based on speed error,under the ideal condition of pure rolling without sliding,was designed based on the kinematics model and dynamics model of the robot to use to eliminate the chattering effect of sign function.The improved controller replaces the sign function with the smooth function related to the velocity error,and eliminates the source of chattering.Based on the stability theory of Lyapunov,it is proved that the improved controller can make all the signals in the closed-loop system bounded and the tracking error converge asymptotically to the origin.The effectiveness of the improved controller is verified by simulation and experiment.