Research On High Precision Position Control Strategy Of Low Speed Flexible Joint

With the rapid development of the human space exploration activities, the space manipulators are widely used in the on-orbit servicing, space docking and planetary exploration and some other important places. Especially for those heavy and complicated tasks, meanwhile high accuracy is required and have a bad work environment, the manipulators are essential needed to replace human, the high accuracy and robust control technology of space manipulator has become an important research issue in the field of robotics. This paper comes from the Doctoral Fund of Ministry of education project "low speed space flexible manipulator high precision positioning and rapid vibration suppression", deeply focus on the dynamic and high accuracy control strategies of flexible joint of manipulator, the main work is as follows:Firstly, focus on the research and application of manipulator, based on the analysis of factors that affect the flexible joint control performance, the model of flexible joint is established, and the dynamic equation is given.Secondly, in order to overcome the impact of joint flexibility, friction, clearance and disturbance, the Active Disturbance Rejection Control (ADRC) is introduced to finish the double position closed loop feedback ADRC system, numerical simulation and experiment are designed to verify the control strategies.Thirdly, analyze the shortcoming of the traditional Backstepping control design of flexible joint, the Dynamic Surface Control(DSC) based Extended State Observer (ESO) control strategy is proposed. Apply the ESO to observed system status, the global stability and robustness controller is designed using DSC technique under the Lyapunov function, the stability analysis and numerical simulation and experiment are given. The proposed control strategy not only overcome the "calculation of explosion" in Backstepping design, but without the measurement of motor velocity and joint velocity.Again, study the neural network control strategy of flexible joint and the Self-Recurrent Wavelet Neural Network-Dynamic Surface Control strategy (SRWNN-DSC) is proposed. The strategy apply the SRWNN to approach uncertain items of flexible joint system, further combined with DSC design technique to accomplish the global stability SRWNN-DSC system of flexible joint. The applied network has a fast learning ability and convergence; the designed controller can quickly adjust its output to inhibit a variety of uncertainties and disturbance and ensure the high precision tracking performance of flexible joint.Finally, design a flexible joint experimental platform, write and download the movement control program to verify the proposed control strategies.