Research On Cooperative Grinding Technology For Weak Rigid Workpiece With Dual-manipulators Based On Impendence Control

In recent years,modern manufacturing industry has made great progress in the direction of automation and intelligence,and industrial robots are playing an increasingly important role in production.For the weakly rigid components,if the single robot is used,the workpiece will be deformed because of its weak rigidity,which makes it difficult to guarantee the quality and accuracy of the machined surface.The dual-manipulators support each side can provide a new solution for the processing of weak rigid components.Based on the impedance control strategy,this paper proposes a dual manipulators contralateral compliance control strategy for grinding thin-walled weakly rigid components.By using the mutual offset of mirror processing forces,the force and deformation of the workpiece in the process are reduced,and the possible over-wear phenomenon in the process is avoided by the compliance control strategy,so as to improve the surface processing quality and reduce the rate of defective products.The main achievements of this thesis includes:Firstly,the kinematics and dynamics modeling method of 6-DOF cooperative robot is studied.For the UR5 robot used in this paper,the forward and inverse kinematics modeling is completed,and the positioning error compensation model and Jacobi matrix of the UR5 robot are solved by differential kinematics.Finally,according to the 3-DOF space robot model,the dynamic model is established,and the mapping relationship between the robot configuration and the joint moment is established.Secondly,according to the problems of over-grinding and rigid collision in machining,a compliance control strategy for manipulators based on position impedance control principle is proposed.For a single robot,the controller is designed with the joint angular velocity increment as the control variable,and two control strategies(linear and non-linear)are proposed according to the mapping relationship between the external torque and the control variable.For the dual-manipulators machining system,the interaction force between two robots is used as the input of force feedback closed-loop.Linear and non-linear control strategies are proposed respectively.The trajectory tracking and force compliance performance of the controllers are verified by simulation,which proves the effectiveness of the control strategies.Then,based on the kinematics and dynamics model of the robot,the optimal compliance joints are selected from motion range and response speed.In view of the difference between force response characteristics in each control strategy,the stability of the controller under different parameters is analyzed,and the optimal controller parameters are selected to enhance the robustness of the control system.Finally,calibrate the structural parameters of dual-manipulators by using binocular vision calibration platform.Study the single-manipulator and dual-manipulators controller system by using dual-manipulators force-controlled grinding platform.By analyzing the change of the end force and torque,comparing the surface quality of each group of parameters,determining the optimal controller parameters,and verifying the conclusion of simulation analysis.