Classification of Parallel Mechanisms

Abstract

One of the first challenges to be addressed in the type synthesis of PMs with less than 6 DOF (or constrained mobility) is the accurate and unambiguous description of the desired motion. In some instances, this issue is not trivial, as evidenced by the plurality of notations and conventions used in the literature to describe the motion of 4-DOF and 5-DOF PMs. This chapter aims at proposing a classification of the motion spaces of PMs in order to make the synthesis more systematic. To this end, the concepts of motion pattern and virtual chain are introduced to represent the motion of the moving platform of PMs. A preliminary classification of the motion patterns and PMs is then proposed. This chapter, together with Chaps. 2 and 3, lays the foundation for the type synthesis of PMs generating a specified motion pattern presented in the following chapters.