Type Synthesis of Three-DOF Translational Parallel Mechanisms

This paper presents a simple but effective type synthesis method for spatial parallel mechanisms with three translational degrees of freedom based on the screw theory. Firstly all possible connecting-chain structures of three-DOF parallel mechanisms are enumerated. According to the reciprocal relationship between screw constraint forces and the motion screw, a novel synthesis method is presented. By using this method, type synthesis for three-DOF translational parallel mechanisms has been made in a systematic and detailed way. As a result, some novel parallel mechanisms generating spatial translation have been obtained. To verify the significance of type synthesis for this kind of mechanism, the paper also gives a concrete application instance, which is used for a micromanipulator for manipulating the bio-cells.