An integrated system for design of mechanisms by an expert system—DOMES

Abstract

Methodologies have been developed and implemented in LISP and OPS-S languages which address type synthesis of mechanisms. Graph theory and separation of structure from function concepts have been integrated into an expert system called DOMES (Design Of Mechanism by an Expert System) to effectively implement the following three activities: 1. enumeration of all non-isomorphic labelled graphs; 2. identification of those graphs which satisfy structural constraints; 3. sketching of mechanisms corresponding to a given graph.Developed theories and algorithms are applied to a robot gripper design and a variable-stroke piston engine design. The results from these two applications indicate that the automated techniques effectively identify all previously obtained solutions via manual techniques. Additional solutions are also identified and several errors of the manual process are detected. The developed methodologies and software appear to perform a complete and unbiased search of all possible candidate designs and are not prone to the errors of the manual process. Other important features of DOMES are: 1. it can learn and reason, by analogy, about a new design problem based on its experience of the problems previously solved by the system: 2. it has the capability to incrementally expand its knowledge base of rejection criteria by converting into LISP code information obtained through a query-based interactive session with a human designer; 3. it can select the set of rejection criteria relevant to a design problem from its knowledge base of rejection criteria. These procedures could become a powerful tool for design engineers, especially at the conceptual stage of design.

Kinematic synthesis with configuration spaces

“…Expert system techniques [20] for synthesizing special classes of mechanisms e.g., cam-follower mechanisms, occupy an interesting middle ground between pre-parametric design schemes which requires high-level qualitative specifications and the numerical optimization packages which require very detailed kinematic specifications . Case-based methods [15,17] for synthesis of mechanical systems begin with a known library of designs and use the goal specification to index relevant designs.…”

“…Sophisticated numerical packages are available for detailed design or dimensional synthesis [13, pg . 618], and research is now active [2,3,7,9,11,17,18,19,20] in the area of conceptual design or type and number synthesis .…”

“…This is also difficult to solve as it involves deriving geometry from motion . Most of the current work on conceptual design of mechanisms focuses on this problem [3,7,9,10,11,20] . Our paper extends the work in this area by providing a foundation for building compositional motion synthesis algorithms, and by designing and implementing a new, practical, constraint-based motion synthesis method.…”

An approach to the selection of mechanism types in computer-aided conceptual design

“…For the selection of mechanism types, there have been two foundation theories, i.e. graph theory [1][2][3] and matrix theory [4]. Because the appreciation of the function quality of mechanisms would relate to the processing technology of fuzzy information, the theories-based systems for selection of mechanism types could not provide the appraisal.…”