Research On Control Method Of 3D Of Parallel Robot Based On Constraint-Following Theory

Parallel robot has the advantages of compact structure,strong bearing capacity,high precision,small self weight load ratio,good dynamic performance and so on.It is widely used in processing and manufacturing,aerospace,medical rehabilitation and bioengineering.With the application of parallel robots in the above fields,many parallel mechanisms with complex structures have been designed to complete accurate operation tasks.However,the complexity of the structure of the parallel robot will increase the coupling and nonlinearity of the system,which leads to the difficulty of dynamic modeling and control system design.Therefore,how to establish dynamic model and realize high precision control for complex parallel robot has become the focus and difficulty of research.In order to solve the above problems,this paper takes a(U+2UPS)P 3-DOF parallel robot as the research object,carries out the dynamic modeling of the parallel robot based on the hierarchical clustering method,and studies the control method of the parallel robot by using the constraint following theory.Firstly,the structure of(U+2UPS)P 3-DOF parallel robot is analyzed,and the inverse kinematics problem and velocity Jacobian matrix of the robot are solved.The dynamic analytical model of the 3-DOF parallel robot is established by using hierarchical clustering modeling method,and the dimension of the model is reduced by using virtual work principle.Secondly,according to the servo constraint theory,the second-order servo constraint of the position control of the parallel robot is designed,and the constraint following controller of the robot is established based on the Udwadia-Kalaba equation.Then,aiming at the uncertain factors of the parallel robot system,the uncertain information of the robot is estimated online by means of adaptive parameters.Based on the estimated uncertain information,a high-order fractional robust controller is designed,and the stability of the designed controller is analyzed by using the boundedness theory.Finally,with the help of Solid Works and MATLAB software,the virtual prototype and controller of the 3-DOF parallel robot are built,and the simulation experiments of the robot under different load conditions are carried out to verify the effectiveness and feasibility of the proposed control method.