The Study Of The Innovation Of Parallel Robot Mechanism

Parallel robot has the advantages of high rigidity, high precision and low inertia, thus it is widely used in the industrial field. Many scholars at home and abroad are studying on it for further development. With further research on the parallel robot, there is an urgent need to develop parallel mechanism with comprehensive functions and excellent performance to meet the actual needs. The innovation and synthesis of the structure types of parallel mechanism become important issues. The integrated mechanism needs calculating their freedom to test its validity, the number of mechanism initiatives. Due to its complexity, none ideal theory can get the correct results for the space freedom.To address the two issues above, this paper studies on the screw theory. Screw theory does kinetic and dynamic analysis conveniently for the space mechanism. The screw can represent a rigid rotation or movement, and the anti-helix can represent the rigid body mechanics or couple. From analysis, a new method called screw bound is used to calculate the freedom of parallel mechanisms. It is the first time changing the calculation of mechanism freedom to freedom of kinetic platform and also abandons calculating the public and open-bound constraints. It works without human judgment, and have higher accuracy. Besides getting the number of freedom, the freedom nature of kinetic platform can also been obtained. As the kinetic platform of parallel robot is the output component, it is easy to obtain its properties.With screw theory, this paper also presents innovative approach of parallel robots mechanism. That is the reverse binding method. This method uses the kinetic properties of existing movement platform to calculate the constraint of each branch. Then from constraint of each branch calculate the movement type of each branch and determine the kinetic composition of each branch. The screw constraint method and the reverse binding method for freedom calculation are in reverse way. That is, for freedom calculation, the constraint screw is calculated from the kinetic chain and for mechanism innovation, the kinetic chain is from the constraints. Thus the process forming the mechanism is easy and has high efficiency.In this paper, the mechanism 3-PRRR from constraint reverse method is taken experiments on the "three-degree-of-freedom parallel manipulator Integrated Experiment", and proves the feasibility and validation of screw constraint and constraint reverse.