Dynamic Evaluation And Control Of A Parallel Manipulator

With the rapid development of modern manufacturing equipment, the parallel mechanism because of its carrying capacity, structural rigidity, high precision, dynamic performance and a series of advantages received widespread attention. In this paper one kind of 3-DOF parallel manipulator applied in the high-speed hybrid processing equipment is researched. Dynamic modeling, performance evaluation and dynamic feedforward control and other key issues is in-depth theoretically studied aimed at improving its high speed and acceleration performance. The contents are divided into three parts shown as follows.A novel 3-DOF parallel manipulator named 3PRRU is developed. Combining the vector ring method, partial derivative, virtual work principle and other parallel manipulator dynamic modeling method, the dynamic model of the mechanism is built. By using Matlab software, motion simulation set up and the correctness is verified, laying the foundation for the subsequent dynamic evaluation and control of parallel manipulator.3PRRU parallel manipulator performance evaluation is investigated. Based on the Tilt-and-Torsion Angles and pattern analysis method, the workspace, parasitic motions, manipulability is analyzed to describe the kinematic performance of the mechanism. Then the acceleration capability of the parallel machine is evaluated by means of the Dynamic Manipulability Ellipsoid. After discussing and finding the limitations of the traditional evaluation index, two novel dimensional uniform dynamic performance evaluation indexes with definite physical meaning are proposed, which could be more accurate to describe the dynamic behavior of the parallel mechanism character.A dynamic feedforward control system applicable to parallel robots is realized. On one hand, a set of generally derivation method of vibration model is established. With the help of Adams software, 3PRRU vibration modeling is completed. On the other hand, a control system based on the dynamic feedforward is developed and the parameters are defined by adopting Matlab software. Combining two of them, the dynamic control gets a higher accuracy than the conventional one, which shows the dynamic control could improve the response capability of the parallel mechanism under the high speed and acceleration motion.