A Reconfigurable 6R Linkage With Six Motion Modes and Three Topological Structures

Abstract

In this paper, a new reconfigurable 6R linkage is obtained by combining two identical equilateral Bennett linkages arranged in a planesymmetric manner, and a detailed kinematic analysis is conducted which shows that there are six distinct motion modes and three topological structures of the derived mechanism without changing the types of kinematic joints. Explicit relationships among the kinematic variables are obtained with D–H method and various modes are discussed in detail. Bifurcation points are derived and the reconfigurations are analyzed. The result shows that the mechanism has six motion modes which contain a special case of a planesymmetric 6R mode and a special case of a twofold symmetric 6R mode, an Xshaped motion mode, and two Vshaped motion modes. A physical prototype is fabricated to verify the derivation and it shows that the mechanism can transform among all the motion modes without the need of reassembling.