A Compact Reconfigurable Terrestrial-Aerial Robot With Foldable Mechanisms for Rolling, Crawling, and Flying

Abstract

A compact reconfigurable terrestrial-aerial robot that is capable of executing seamless transitions between three motion modes—rolling, crawling, and flying—via foldable mechanisms is presented in this letter. The rolling and crawling modes are facilitated by two passive gear-driven, foldable wheel-legged mechanisms, along with an adjustable telescopic tail. A linkage-based foldable mechanism enables bidirectional transformation between the rolling and quadrotor flying modes. Notably, the foldable linkage mechanism enables the propellers to retract into the body during ground locomotion, protecting them from damage while achieving a volume reduction to 23.3% of the flying mode. The linkage parameters and tail length are further optimized to enhance the reliability of mode transitions. Prototype experiments validate the robot's maneuverability, obstacle-crossing capability, and energy efficiency across all three locomotion modes. The results also confirm reliable mode transitions, demonstrating the effectiveness of the foldable compression mechanism and the propeller protection system. These features make the design well-suited for deployment in dynamic and unstructured environments, such as search and rescue missions, surveillance, and environmental monitoring.