Type synthesis of parallel mechanisms with three translational degrees of freedom

A simple but effective type synthesis method for spatial parallel mechanisms with three translational degrees of freedom (DOF) based on the screw theory is presented. 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 translational three-DOF parallel mechanisms has been made in a systematic and detailed way. As a result, dozens of novel parallel mechanisms generating spatial translation have been obtained. To verify the significance of type synthesis for this kind of mechanism, this paper also gives an example of application, which is used for a micromanipulator for manipulating cells.