Synthesis of a complete set of contracted graphs for planar non-fractionated simple-jointed kinematic chains with all possible DOFs

The contracted graph shows the primary topological structure of kinematic chains and is the foundation for constructing kinematic structures of mechanisms. In this paper, a fully-automatic method is proposed to synthesize a complete set of contracted graphs for planar non-fractionated simple-jointed kinematic chains with all possible degrees of freedom. First, based on the 4-parameter index and link assortment array, the relationships of link assortment arrays and non-fractionated contracted graphs for different types of kinematic chains are revealed. Then, the general steps to generate the adjacency matrices of contracted graphs from the synthesis equation set are given. Efficient methods to detect fractionated structures and isomorphism are also addressed. Finally, a human–machine interactive synthesis program is developed, and the complete list of both contracted graphs and valid contracted graphs for planar non-fractionated simple-jointed kinematic chains with up to 19 links and all possible degrees of freedom is presented for the first time.

► A general method is proposed to synthesize contracted graphs with all DOFs.
► The relationships of link assortment arrays and contracted graphs are revealed.
► A fully-automatic program is developed to verify the synthesis method.
► The complete set of contracted graphs up to 19 links and all DOFs is obtained.