Abstract
Analysing character of object's motion under constraints is important to understand the mechanism of assembly tasks. Such analyses have been studied to solve the contact state transition problem. In those studies, the state of a manipulated object is often represented only by a combination of contacts between the manipulated object and objects in the environment. However, such a representation does not describe all the feature of motion in environments with concave or multiple objects. This paper points out some defects in traditional representation and suggest a solution addressing to the problem.
