Dynamic Modeling And Analysis Of 2PRU-UPR Parallel Mechanism

With the improvement of society's requirements on high-end intelligent manufacturing,traditional machine tools have been unable to meet the requirements of modern manufacturing.Parallel mechanisms with high precision and high stiffness are needed to make up for this deficiency.In this dissertation,2PRU-UPR parallel mechanism(PM)is studied.Kinematics,dynamic and performance analysis of the parallel mechanism are analyzed.The main research work is summarized as follows:Degrees of freedom of 2PRU-UPR PM and the inverse kinematics of its position are firstly analyzed.The mechanism is analyzed by the method of screw theory as a one translational degree of freedom and two rotational degrees of freedom parallel mechanism.Use closed-loop vector method to analyze the inverse solution of the mechanism.The Lagrange equation is used for dynamic modeling of 2PRU-UPR PM.The velocity of the centroid of the moving platform is solved by constraint equation,and the velocity of the centroid of the mechanism components is solved by combining the geometric relationship of the mechanism,then the kinetic energy and potential energy of the mechanism are solved.Using MATLAB to calculate the dynamic model and comparing with the results of ADAMS to check the correctness.The dynamic model of 2PRU-UPR PM is analyzed by screw theory.The relationship among the driving velocity and velocity of links,the driving acceleration and acceleration of links of parallel mechanism is established by screw theory.Based on the virtual work principle the dynamic model of the mechanism is solved.Use MATLAB and ADAMS to check the model.The dynamic model established by the two methods is analyzed.The solving process of the dynamic model based on Lagrange method is simple and logical,but it involves partial differential calculation and is not convenient for real-time control.The solving process of the dynamic model based on the screw theory is simple and clear,and does not involve a lot of differential calculation,which is convenient for real-time control.Dynamic manipulability ellipsoid is used to analyze the dynamic performance of 2PRU-UPR PM.The dynamic performance of the mechanism in rotation and translation is analyzed,and the performance diagram of the mechanism is drawn and analyzed by MATLAB software.It provides theoretical basis for the motion control of the mechanism in the future.The dynamic model of 2PRU-UPR PM established in this paper is helpful to the dynamic control of the mechanism and has guiding significance for the practical application of 2 PRU-UPR PM.