Double-level reconfigurable variation of Bennett-induced 8R mechanism and its evolved metamorphic 7R mechanism family

Abstract

Reconfigurable mechanisms are widely utilized in the design of intelligent robots and devices capable of adapting to diverse environments and requirements. While the design of reconfigurable mechanisms has garnered significant attention, previous studies have primarily focused on single types of reconfiguration, limiting the diversity and potential applications of such mechanisms. This paper introduces a double-level reconfigurable variation that integrates two reconfiguration approaches: joint rigidization and geometric constraints. This variation is derived from an 8R mechanism created by adding four joints to an equilateral Bennett mechanism. The original 8R mechanism serves as a foundation for generating a family of metamorphic mechanisms, including four distinct 7R mechanisms, through selective joint rigidization. Each of these 7R mechanisms exhibits multiple motion branches and singular configurations, which are analyzed in detail, with their metamorphic motion cycles illustrated graphically. In total, the mechanism family encompasses 39 unique motion branches. Some of these branches and singular configurations overlap, enabling transitions between mechanisms by altering rigidization patterns, thereby achieving a double-level reconfigurable variation. This study elucidates the interrelationships among the metamorphic mechanisms within this family, offering valuable insights for advancing the configuration synthesis and application of metamorphic mechanisms.