Kinematics Analysis And Application Of The Symmetric 3-PCR Parallel Mechanism

Compared with the general 6-DOF (degrees of freedom) parallel mechanism, lower- mobility parallel mechanisms have advantages of simple structure, easy control and low cost in manufacturing. Particularly, the symmetrical three-translation parallel mechanism, which characterizes identical limbs, symmetrical arrangement and isotropy, has great potentials in practical application, so scholars of this filed give extensive concern to this type parallel mechanisms. In this paper, the type synthesis of three-translation parallel mechanisms was studied by screw theory, on this basis, we take symmetrical 3-PCR parallel mechanisms as a research object and do a indepth analysis to it .The content of this paper mainly covers 5 aspects which are as follows:First, the type of limb constraint screw system is proposed by reciprocal relations between constraint screw and motion screw , on this basis, the type synthesis of three-translation parallel mechanisms is performed by synthesis theory of constraint screw.Second, following the goal of design, we select the symmetrical 3-PCR parallel mechanism as a subject of studying and do a research about its kinematics characteristics.Third, the virtual prototype of the 3-PCR parallel mechanism was created by using the the software Unigraphics and ADAMS, then the simulation trials were done on several kinds of trajectory in ADAMS.Fourth, Trajectory planning of 3-PCR parallel mechanism was studied based on curves parameterization theory and inverse kinematics theory. The method of trajectory planning was put forward about two kinds of different trajectorys and the rules of motion applied to the driving sliders were determined in order to make 3-PCR parallel mechanism move according to the expected path.Finally, the application of 3-PCR parallel mechanism on high pressure water jet cutting machine was discussed meaningfully, and the feasibility of this application was prove to be reasonable by using two water cutting exampleThrough above analysis and studies, we have had a clear and deeply knowledge about the structural and kinematics properties of 3-PCR parallel mechanism, the methods of trajectory planning based on inverse kinematics theory are also enriched further, and all of this have made a good foundation for the manufacture and conrol ways of real prototype of 3-PCR parallel mechanism and also is a prepared work for the research and manufacture as a high pressure water jet cutting machine for 3-PCR parallel mechanism.