A 6R linkage reconfigurable between the line-symmetric Bricard linkage and the Bennett linkage

This paper explores the feasibility of constructing mechanisms reconfigurable between 6R and 4R overconstrained linkages. Spatial triangle and Bennett linkage are used as the building blocks to form the reconfigurable Bricard linkage. Due to the different directions of the joint axes, the Bennett linkage can be setup in either asymmetric or line-symmetric manners. Subsequently, two 6R linkages are constructed in asymmetric and line-symmetric configurations, respectively. Their potential of reconfiguration is investigated through bifurcation analysis. The result shows that the asymmetric one can be reconfigured between Bennett linkage and general line-symmetric Bricard linkage through bifurcation points, while the line-symmetric one only functions as a Bennett linkage with two additional fixed joints.