Structural Synthesis, Dynamic Modeling and Analysis of a 3-DOF Asymmetric Parallel Mechanism

摘要

Most research papers about parallel kinematic chain mechanisms investigate symmetric robot manipulators, in which all the limbs connecting the end-effector to the fixed based are composed by the same sequence of links and joints. Contrarily, in some manipulation tasks the velocity and stiffness requirements are anisotropic. In such cases, the asymmetric parallel kinematic chain mechanisms may offer advantages. This work objective is to present the synthesis, dynamic modeling and analysis of a 3-dof asymmetric parallel chain mechanism, conceived as a robot manipulator for pick-and-place operations. First, a structural synthesis, resulting in a three translations end-effector, and a kinematic modeling are carried out. Then, the inverse dynamic modeling is developed by employing the virtual work principle. Based on the model equations and on the saturation of the mechanism actuators, a maximum acceleration analysis is performed and shows that although the mechanism has a parallel architecture its actuators influences on the 3-dof are quite decoupled.