Mechanism design automation support requires developing a representation language for describing mechanism behavior. The language is necessary to specify design requirements, to describe existing mechanisms, and to catalog them for design reuse. This paper presents a simple and expressive language for describing the behavior of fixed-axes mechanisms. The language symbolically captures the important aspects of the kinematics and simple dynamics. It uses predicates and algebraic relations to describe the configurations and motions of each part of the mechanism and the relationships between them. It allows both accurate and complete descriptions and partial, abstract, and underspecified descriptions. We show that the language is computationally viable by describing how to automatically derive behavioral descriptions stated in the language from the mechanism structure. To test its usefulness, we describe a design validation program that determines if a given mechanism structure can produce desired behaviors stated in the language.
