Selecting multi-freedom multi-loop kinematic chains to suit a given task

Developments of number synthesis and the means of enumerating kinematic cha ins have not lead to a significant flow of novel kinematic structures to su ccessful mechanical designs. This paper addresses one of the difficulties, namely how to select a pertinent kinematic chain from the many that can be enumerated. To this end, a new and important concept called the variety of a kinematic chain is explained and discussed with particular attention to i ts relationship to the motion capabilities of mechanisms such as robot mani pulators and gear trains. Many motion tasks have an inherent hierarchy of f reedoms that closely relates to the variety of a kinematic chain, and hence variety can be used to select those candidate mechanisms best suited to an intended function. An epicyclic transmission is used to demonstrate this t echnique. (C) 2001 Elsevier Science Ltd. All rights reserved.