Research On The Performance Analysis And Motion Planning Of The 3-UPS/S Prototype

3-UPS/S spherical parallel mechanism, a kind of typical lower-mobility parallel mechanism, which could rotate in three directions of space around the designated, has a good application prospect. Basing on studying the kinematics and optimization deeply, our research group designed and fabricated a prototype. Therefore, this article takes the prototype. as research object, and researches the performance in a certain depth.First of all, basing on the T&T angle, the inverse resolution model of the prototype is established. The first order and second order influence coefficient matrixes are built with the influence coefficient method of the screw theory.Secondly, through the inverse solution model, the influence of various factors such as rod length range, range of angle and link interference on the workspace is analyzed by using the method of computer search. The rod constraint space and angle constraint space is established, and the complete workspace is obtained through superposition of the results above. The singular feature of the prototype is analyzed based on Jacobian condition number, and then obtain the quality workspace of the prototype.Thirdly, the static equilibrium equations of the moving platform and branches is established by the dismantle bar method, and through solving simultaneous equations, the whole static solution is obtained. Based on the static analysis and principle of virtual work, the relationship between the elastic deformation of each branches and the attitude variation of moving platform is analyzed, thus the stiffness model is established and the force, stiffness and deformation in the process of moving and in the initial posture are analyzed.Finally, the straight line path passed two points and the arc path passed three points are planned in workspace of the prototype, then the kinematics track of the prototype is planned with the method of the combined trajectory curve. According to the results of trajectory planning, the completion of the kinematics experimental of prototype verifies the kinematics analysis, workspace analysis and motion planning analysis.