A Highly Compatible Variable-Diameter Spherical Shell Based on Arc-Shaped Four-Bar Linkage Mechanism

Conventional spherical robots that employ rigid monolithic shells face constraints in environmental adaptability. This paper proposes a novel morphing spherical shell based on arc-shaped four-bar linkage mechanism, which enables the shell's diameter to change within the range of 40-50 cm, enhancing the robot's adaptability in complicated environments. The morphing spherical shell constitutes an independent system exhibiting high compatibility with various driving methods. It also provides adequate placement space for internal components with a high internal space ratio of 70% in its contracted state. And the soft outer covering film of the shell ensures the sealing and waterproof properties. This paper primarily encompasses the geometric model of the morphing spherical shell, mechanical structure of the morphing spherical shell system and prototype experimental validation through deformation testing.