Simplification and Abstraction of Kinemati c Behaviors : Hierarchical Reasoning in Mechanical Devices

Efficient problem-solving in any physical domain requires two main capabilities : the ability to ignore detail by reasoning at different levels of resolutio n (abstraction), and the ability to ignore irrelevant information by incorporatin g constraints and assumptions (simplification) . Existing analysis methods for mechanical devices derive qualitative descriptions of a mechanism's kinemati c behavior from the shape and the initial position of its parts . Although qualitative, these descriptions are sometimes too detailed and exceedingly complex . making the automation of common analysis and design tasks difficult, or even impossible . This paper presents a set of operators to simplify and abstract kine matic descriptions derived from configuration spaces . These operators defin e the hierarchy of resolutions necessary to effectively automate common reasoning tasks about mechanical devices . We show how mechanism comparison — determining when two mechanisms are kinematically equivalent — can only b e done with simplification and abstraction operators . (Also Sub ,fled t'o SJCJ}183 )