Research On Sliding Mode Control Strategy Of Manipulator Trajectory Tracking Based On Disturbance Observer

With the rapid development of automation technology,robotic arms have been widely used in various fields.In the "14th Five-Year Plan" Intelligent Manufacturing Development Plan,robotic arms are included in the innovation and development of intelligent manufacturing equipment.With the continuous improvement of industrial production technology,the tasks performed by the robotic arm have become more complex.At the same time,the manufacturing industry has transformed from repetitive production to user-customized and personalized production,which puts forward higher requirements for the trajectory tracking control of the robotic arm.Therefore,it is of great value for the research on the trajectory tracking control method of the manipulator.This thesis takes the two-joint manipulator as the research object,and studies its trajectory tracking method on the basis of sliding mode control.The main work of the article is as follows:(1)The thesis first uses the Lagrange equation to analyze the kinetic energy and potential energy of the manipulator,and then obtains the mathematical model of the manipulator.Then,a disturbance observer is designed to observe the external disturbance,and the disturbance estimate is equivalent to the control input,so that the disturbance estimate is obtained.Then,the traditional sliding mode control is used as the control method for simulation verification.The simulation results show that the disturbance observer has the ability to resist external disturbances during the operation of the manipulator.(2)There is chattering in the sliding mode control method.To solve this problem,the power reaching law and the variable speed reaching law are firstly combined,and then the hyperbolic tangent function is used to replace the sign function in the variable speed reaching term,so that the switching process is smoothed,thereby reducing chattering,while preserving the sign function in the power-approaching form,allowing the state variable to approach rapidly when far from the sliding surface.Then,the control law is designed on the basis of the manipulator model after disturbance estimation,and the Lyapunov function is used to prove its stability.Finally,the simulation comparison shows that the proposed control method has strong anti-jamming ability,chattering suppression and fast tracking speed.(3)Based on the nonsingular terminal sliding surface,a nonsingular fast terminal sliding surface with switching sliding surface characteristics is designed,and its stability is proved.Through simulation analysis,its fast convergence ability is verified.Then,combining nonsingular fast terminal sliding mode control with iterative learning control,a nonsingular fast terminal iterative sliding mode control strategy is proposed.The simulation results show that compared with the nonsingular fast terminal sliding mode control,the iterative sliding mode control strategy has a faster approach speed and better ability to reduce chattering,and with the increase of the number of iterations,the convergence speed is improved,further improved tracking accuracy.