Bifurcation variations and motion-ruled-surface evolution of a novel Schatz linkage induced metamorphic mechanism

This paper presents a novel 7R metamorphic mechanism induced by Schatz linkage. The mechanism can realize the reconfigurable switch between two assembly configurations of Schatz linkage without disassembly and reassembly. The mechanism has four different motion branches and twelve bifurcation points. Two of these motion branches are two assembly configurations of Schatz linkage, and the others are two different single degree-of-freedom spatial 7R mechanisms. Bifurcation variations of the mechanism are presented by the configuration space, which is obtained by using the numerical approach of closed-loop equations. Then, twelve bifurcation points are identified by first- and second-order constraint equations. Moreover, motion ruled surfaces of the coupler link are generated, which proves that the mechanism has four motion branches and can switch from one assembly configuration of Schatz linkage to the other assembly configuration through another two motion branches.