A Methodology for Conceptual Design of Mechanisms by Parsing Design Specifications

In this paper, design specifications for the conceptual design of mechanisms are parsed into three coherent categories: functional requirements, structural requirements, and design constraints. Based on functional requirements, the functioning kinematic chain of a mechanism can be constructed by connecting the functioning links accordingly. From structural requirements, admissible kinematic structures are searched from the existing atlases of kinematic structures. Those admissible kinematic structures, which comprise at least one segment with the same characteristics of the functioning kinematic chain, are identified as compatible kinematic structures. Thus, feasible mechanisms that fulfill design specifications can be yielded by labeling joints in the compatible kinematic structures subject to design constraints. With this methodology, classified design specifications are used to guide designer through various stages of the conceptual design process in a systematic manner. The creation of the variable-stroke engine mechanism [Freudenstein, F., Maki, E. R., 1983, “Development of an Optimum Variable-Stroke Internal-Combustion Engine Mechanism From the Viewpoint of Kinematic Structure ,” ASME J. Mech., Trans., Automat., Des., Vol. 105, pp. 259–267] is used as an illustrative example.