Trajectory Tracking Control Of Spherical Robot Considering Friction And Motor Dynamics

Spherical robots have good application prospects in the fields of industry and life,due to its dexterous motion,with no overturning during its rolling and the simple structure.Motion control of a spherical robot is a prerequisite for accomplishing the task.However,during the motion process,the point contact characteristics of the spherical robot increase the design difficulty of the motion controller.Trajectory tracking problem is the most widely used motion control problem in practical applications.Therefore,research on the trajectory tracking controller of spherical robot has important theoretical significance and application prospects.The research work of this paper focuses on the trajectory tracking problem of spherical robots,focusing on the effects of friction,drive motor,parameter uncertainty and other factors on trajectory tracking control.The trajectory tracking controller is designed to improve the tracking accuracy of the system trajectory.The following aspects are contained in this paper.At the beginning of the paper,the kinematics and dynamics model of spherical robots derived from the Kane equation is the theoretical basis for the subsequent controller design.Secondly,the trajectory tracking control problem of spherical robot based on dynamic model is studied.Starting from any starting position,the sliding mode torque controller based on the double power reaching law can guarantee the convergence speed of the system is higher than other common traditional approach laws(exponential approach law,etc.).This control strategy ensures that the system can track the desired trajectory in a fixed time,the chattering is suppressed,and the control precision is improved.Thirdly,considering the effect of friction on the motion characteristics of spherical robots and controller design.According to the compensation idea based on friction model,this paper first designs an extended state observer,which can guarantee global finite time stability.Then,a sliding mode trajectory tracking controller based on extended state observer is designed by using the double power reaching law.The final simulation results show that the proposed trajectory tracking controller can quickly estimate and utilize the system friction information,thereby reducing the influence of friction,improving the stability of the system,and tracking the desired trajectory.Finally,in order to improve the trajectory tracking performance,the influence of the motor characteristics and system uncertainty is further considered on the basis of the spherical robot dynamics model.An adaptive high-order sliding mode trajectory tracking controller with motor voltage as control input is designed to meet the high-precision trajectory tracking requirements of spherical robots.The final simulation shows that the controller can realize the trajectory of the system for limited time tracking,ensure the continuity of the system input,and effectively suppress the system chattering.