Type synthesis of parallel mechanisms by utilizing sub-mechanisms and digital topological graphs

A type synthesis of various parallel mechanisms by utilizing sub-mechanisms and digital topology graphs is studied. The conditions for type synthesis of the parallel mechanisms with the sub-mechanisms are determined. Based on the determined conditions, the digital topology graphs are derived from different associated linkages, and the digital topology graphs are transformed into revised digital topology graphs for type synthesis of the parallel mechanisms with redundant constraints. The sub-mechanisms are transformed into simple equivalent limbs and their equivalent relations are analyzed. Seventeen novel parallel mechanisms are synthesized by utilizing the derived digital topology graphs, the revised digital topology graphs and the sub-mechanisms or the combinations of sub-mechanisms. The synthesized parallel mechanisms are simplified by replacing the complex sub-mechanisms with their simple equivalent limbs. Finally, the degrees of freedoms of all the synthesized parallel mechanisms are calculated to verify the correctness and effectiveness of the proposed approach.