Type synthesis of 2T2R, 1T2R and 2R parallel mechanisms

Based on the integration of configuration evolution and Lie group theory, a method for the type synthesis of parallel mechanisms (PM) is presented. Using the proposed approach, parallel mechanisms with two-translational two-rotational (2T2R) degrees of freedoms (DOFs), one-translational two-rotational (1T2R) DOFs and two-rotational (2R) DOFs are synthesized systematically. A large number of parallel mechanisms with 2T2R, 1T2R and 2R motion are obtained, which substantially enriches the topologies of lower-mobility parallel manipulators.