Synthesis and cross-section design of a new family of single-loop 7R deployable polygon mechanisms

Abstract

In this paper, two design methods for different stages in the development of a single-degree-of-freedom (DOF) single-loop 7R deployable polygon mechanism (DGM) without overconstraints are presented, encompassing schematic synthesis and cross-section design methods for 7R DGMs. Firstly, two classes of revolute pair axes in DGMs are reviewed, detailing their value ranges and parameter definitions. A schematic synthesis method for single-DOF single-loop 7R DGMs is then proposed, followed by the development of a cross-section design method to enable desired cross-sections in these mechanisms. By applying these methods, three types of 7R DGMs were created and prototyped, with their folding sequences demonstrated and input singularity analysis conducted. Through the utilization of the presented design method, all single-DOF single-loop 7R DGMs can be designed. This work introduces a new family of DGMs and addresses the gap in the domain of general spatial single-DOF single-loop DGMs that are not overconstrained. It demonstrates the feasibility of designs whose expanded shapes form general planar polygons. This effort expands the variety and quantity of DGMs, paving the way for more innovative deployable network mechanisms.