Research On Motion Analysis And Control Method Of 3UPS/PU Parallel Robot

In modern times,due to its inherent ills,serial robot is increasingly difficult to meet the needs of industrial production.Parallel robot with better comprehensive performance has been paid more and more attention,and has gradually become the favorite of the engineering market.The research background of this paper is to design piping welding device.This paper takes 3UPS/PU parallel robot as an example to study the kinematics and dynamics analysis,workspace analysis and control methods of 2R1 T parallel robot.In the kinematics analysis of parallel robot,the corresponding coordinate system and closed-loop vector equation are established by analyzing the geometric configuration of the robot.The homotopy continuation method is used to solve the end position of parallel robot in this paper.Compared with the traditional method,the homotopy continuation method is more advantageous in solving the positive and inverse solutions of parallel mechanism.Then the velocity analysis and acceleration analysis of the mechanism are completed by using screw theory and closed loop vector method respectively.Finally,the robot model is imported into Adams to complete the simulation verification of the whole analysis process.Then,based on the results of kinematic analysis,the motion information of the mass center of each component is obtained by closed-loop vector derivation method.And the simulation results are verified by ADAMS software.The information of the mass center motion is expressed as a function of generalized coordinates.Then the dynamic equation is established by the principle of virtual work and the displacement of the generalized coordinate is eliminated.The general form of dynamic equation and the solution of the matrix of related parameters are obtained.Considering the attributes of 3UPS/PU parallel robot,we redefined the workspace of the mechanism.After given the constraints,we used the method of dividing grid and searching constraint boundary to obtain the accessible corner set of the moving platform at different heights.And we completed the height optimization.In other words,the height optimal solution at the maximum corner space was found.In the research of control method of parallel mechanism,the traditional control strategy is firstly studied,and the computational torque controller are designed.By analyzing their defects,the targeted improvement is proposed.Then the feedforward torque compensation PD controller and the robust adaptive compensation PD controller are designed,and good control effect is achieved.Finally,this paper focuses on the sliding mode control.By designing the sliding surface and improving the sliding mode reaching law,the inherent torque chattering phenomenon of the traditional sliding mode control is eliminated.A robust adaptive sliding mode controller with superior comprehensive performance is proposed based on the problem that the improved controller is still unable to restrain its own parameter changes and external interference.The problem of excessive initial torque is solved by nonlinear treatment of the parameters of the controller.The adaptive law with certain learning function is applied to replace the linear adaptive law,which makes the system have good robustness.