A systematic approach for the structural synthesis of differential-type south pointing chariots

South Pointing Chariot is one of the important mechanical inventions in ancient China. It achieves the purpose of fixing direction by applying mechanical devices. All existing designs can be classified into two types: "fixed-axis type" and "differential type". In this study, firstly, the existing designs are analyzed and decomposed into four parts: two inputs, a transmission part, a passive feedback mechanism, and one output. Secondly, because some existing designs have the same topological structures, new representations are used to identify different axial directions of joints and characteristics of members. Thirdly, a design methodology is proposed to systematically synthesize all feasible design concepts of differential-type South Pointing Chariots. Finally, three examples are provided.