Rigid Flexible Coupling Dynamics Modeling And Vibration Control Of Space Flexible Base Robot

With the development of space technology and the improvement of engineering requirements,the demand for large-scale space structures such as large-diameter parabolic antenna and large-scale optical system in deep space exploration,strategic reconnaissance and other fields is gradually increasing,and the space structure in the aerospace field is developing towards the direction of large-scale,light and thin.Through the modularization of space system,the way of on orbit assembly by intelligent space robot is an ideal way to construct large space structure.Due to the characteristics of large size and small stiffness of space system module components,the motion of the robot is easy to induce the vibration of the base when assembling on orbit,and the influence of the elastic vibration of the base on the motion control of the robot can not be ignored.At the same time,the residual vibration of the base will also affect the fast and accurate positioning of the end of the robot.The modeling and control of the flexible base robot system and the analysis of the response of the flexible base under the motion of the robot are of great significance for the completion of the on orbit assembly task.In this paper,the on orbit assembly robot with flexible base is taken as the research object.The relationship between the vibration of flexible base and the motion of robot is analyzed by the method of theoretical analysis and numerical simulation,and the control methods that can be used to improve the motion control accuracy and suppress the vibration of base are explored and verified.The main research contents are as follows:1.Based on the assumed mode method and the second kind of Lagrange equation,the dynamic model of the flexible base single bar robot is established.Adams and MATLAB are used to verify the correctness of forward and inverse kinematics solution,Jacobian matrix derivation and Dynamics Equation Derivation of single link model on flexible base.2.The dynamics control simulation of rigid base and flexible base six DOF robot is carried out respectively,and the simulation results are compared and analyzed.Using ADAMS to establish the rigid flexible coupling robot system model and derive it to Matlab for joint simulation,and analyze the vibration of the base when the robot moves with no load and load,the front three joints and the back three joints separately.According to the robot joint trajectory planning,three kinds of interpolation methods are simulated and analyzed,and the effect of different interpolation methods in the robot point-to-point motion trajectory planning is obtained,and the methods that can be used to reduce the vibration of the base are summarized.3.Aiming at the problem that the vibration of flexible base leads to the low precision of the robot end control,the control algorithm of space flexible base robot based on the direct feedback of robot end position detection and trajectory compensation is studied and simulated.The simulation results show that the control algorithm based on the robot end position detection can improve the end control accuracy when the base vibration is slightly changed,but the base process vibration and residual vibration are not suppressed.At the same time,the simulation analysis of the influence of the end position refresh frequency parameters on the control effect is carried out.4.Aiming at the problem that the residual vibration of the flexible base of the robot can not be controlled due to the robot end position detection control and the traditional PID control,the iterative learning control is used to control the flexible base robot.Based on the used control method,the iterative control scheme is constructed to control the space flexible base robot.According to the simulation results,the iterative control law is improved.The piecewise iterative control law is proposed and the improved iterative law is used for simulation analysis.The simulation results show that the improved ILC can not only improve the terminal accuracy,but also restrain the residual vibration of the base.In addition,when the refresh frequency of the terminal position is fixed,the iterative learning control which is processed by the mean filter also achieves good control effect.