Jixie chuandong (Sep 2021)
Performance Analysis and Dimensional Multi-objective Optimization for an Asymmetry 2UPS-UP Parallel Mechanism
Abstract
Taking an asymmetry 2UPS-UP parallel mechanism with two rotational and one translational degrees of freedom as the research object， the performance analysis and multi-objective optimization of dimensional parameters for the mechanism are presented. The degrees of freedom of the mechanism are determined by the suitable constraint branch UP， so the mechanism can perform two rotational motions around the center of U pair and one translational motion along the P pair of the branch. The symbolic solutions to the forward and inverse displacement analysis are derived. This mechanism with the partial motion-decoupling characteristics is of great benefit to subsequent research such as error analysis， motion trajectory planning， and control. This study proposes the analytic expressions of velocity analysis by means of the vector method. With the aid of the singularity of speed Jacobian matrix， the possible singular configurations of the mechanism are analyzed. Screw algebra is used as a mathematic tool to give the evaluation indices for motion and force transmission performances of the mechanism. Based on the performance evaluation and workspace analysis， an expensive constrained optimization model is constructed to formulate the design problem of dimensional parameters. Furthermore， a multi-objective evolutionary algorithm is employed to solve this problem， and multiple Pareto optimal solutions are obtained.
