Trajectory Tracking Control of Omnidirectional Robot Based on Center of Gravity Offset Parameter Estimation

Omnidirectional mobile robot is applied in people's daily life. In order to properly assist users, the robot must accurately track the predetermined trajectory. However, the robot's tracking accuracy is severely compromised center of gravity shifts induced by the user. An acceleration proportional differential control strategy based on parameter estimation has been proposed in this paper when the center of gravity of the robot is different from its geometric center. The present paper first investigates the dynamic of mechanical structure and constructs a new dynamic model by considering the interference of the center of gravity shift. Secondly, a parameter estimation strategy is designed to estimate the dynamic center of gravity in real time. Then, an acceleration proportional differential controller with center of gravity offset compensation is designed to control the robot. Next, based on Lyapunov stability theory, stability analysis is carried out to prove the asymptotic stability of the proposed control algorithm. Finally, simulation validation shows that the control accuracy of the proposed method is more accurate than proportional differential and adaptive control because they can estimate the center of gravity offset parameters in real time.