| Intelligent robot which can meet the requirements of light weight,heavy load,high speed and high precision has been widely concerned in the field of advanced manufacturing.However,the manipulator required by such working conditions is generally more flexible,and strong residual vibration will appear in the process of movement,which has a serious impact on the response accuracy and control accuracy of the manipulator.Because of the low stiffness of the flexible arm connecting rod,the vibration generated by the flexible arm system can not be quickly eliminated only by its own damping.Therefore,with the support of the National Natural Science Foundation of China(52075294,U22A20204)and the Natural Science Foundation of Shenzhen Municipality(JCYJ20190812170811682,JCYJ20220530141006015),The dynamic modeling,vibration characteristics and motion control of flexible robot manipulator are studied.Firstly,the dynamic equation of the flexible manipulator was derived by using the assumed mode method and Lagrange dynamic equation.The modal and other dynamic characteristics of the flexible manipulator were analyzed,and the model was simplified from the aspects of modal truncation and nonlinear weakening.On this basis,the influence laws of the structural parameters,physical parameters and initial excitation of the flexible manipulator on the vibration characteristics were studied.Secondly,the control principle of the optimal control LQR of the flexible manipulator is analyzed,and the influence law of the weighted matrix Q and R on the system dynamics characteristics is studied.The fuzzy algorithm is used to optimize the weighted matrix Q.In order to improve the response speed of feedback control and reduce the burden of feedback control,input shaping feedforward is introduced into feedback fuzzy LQR control,and the control effect of the new controller is studied.The simulation results show that the optimized fuzzy optimal control can rapidly attenuate the vibration of the end of the manipulator,and the feedforward and feedback controller can further improve the response speed of the end of the manipulator and improve the effect of vibration suppression.In addition,in order to further improve the long time to stabilize the flexible manipulator,a control method of controllable damping and motor drive is proposed.A dynamic model of flexible manipulator with controllable damping was established by introducing Mr Damper.Taking the elastic deformation of the end as the input,the output current is controlled by PID controller,and then the damping size of the magnetorheological damper is controlled.The simulation results show that,compared with the single controller,the time for the joint control flexible arm to reach stability is greatly reduced,and the control effect is good.Finally,the vibration test platform of the flexible manipulator was built,and the test parameters were set and optimized to verify the accuracy of the simplified dynamic model of the flexible manipulator.Then,the motion process of the manipulator is simulated,and the control performance of the input shaping controller and the influence of damping on the residual vibration attenuation time of the flexible manipulator are verified by experiments under the condition of speed and load changes.The experiment shows that the amplitude of vibration can be reduced by the input shaping controller,and the time to reach stability can be greatly reduced by increasing damping. |
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