A special Wohlhart’s double-goldberg 6R linkage and its multiple operation forms among 4R and 6R linkages

Abstract

For Wohlhart’s double-Goldberg 6R linkage constructed from two original Goldberg 5R linkages, there are two constructive forms and one non-constructive form, which can be reconfigured through bifurcation points. A special Wohlhart’s double-Goldberg 6R linkage is proposed by introducing a special geometry constraint. One of the constructive forms of the resultant linkage is degenerated into a pseudo 4R linkage, which is essentially a Bennett linkage. Therefore, the special Wohlhart’s double-Goldberg 6R linkage achieves multiple forms among 4R and 6R linkages. Physical models are also made to validate the special Wohlhart’s double-Goldberg 6R linkage in different operation forms.