Deployable mechanisms constructed by connecting orthogonal Bricard linkages, 8R or 10R single-loop linkages using S joints

Abstract

This paper is to propose a novel construction method for constructing a family of over-constrained multi-loop deployable mechanisms by connecting orthogonal single-loop linkages using spherical (S) joints. An orthogonal single-loop linkage refers to a linkage with an even number of identical links with orthogonal revolute (R)-joint axes and no offset. Two types of multi-loop mechanisms are obtained, including parallel mechanisms (PMs) and loop-coupled mechanisms (LCMs) by connecting orthogonal Bricard linkage, 8R or 10R linkage platforms. The mechanisms constructed by orthogonal Bricard linkages only have one degree-of-freedom (DOF). The volume of the PM is calculated, which indicates that the mechanisms have a high ratio of stowed-to-deployed diameter, without considering link interference. The mechanisms designed using orthogonal 8R or 10R linkages have multiple motion modes and can switch between different modes through singular positions. Finally, the method has been extended to the PMs and LCMs composed of loops that the axes of two adjacent R joints are not perpendicular to each other.