A Biomimetic Flexible Sliding Suction Cup Suitable for Curved Surfaces

The sliding suction robots designed for wall-climbing functions could have accuracy defects due to suction cup sealing, friction interference, and surface adaptability. Hence, this work develops a biomimetic, flexible, sliding suction cup suitable for crawling on curved surfaces. Inspired by the hypostomus plecostomus's mouth, we designed a biomimetic low-contact force flow channel structure and a matrix of friction-reducing protrusions along the lip edge of the sliding suction cup. This design reduces frictional resistance on the sliding interface and the flexible nature of the suction cup, allowing it to be used on curved or vertical surfaces of different materials. Several simulation-based optimization analyses and experimental tests are conducted on the biomimetic low-contact force flow channel structure, and various structural design principles are explored for achieving high adhesion and low-contact force. Additionally, a friction reduction model for the matrix structure is designed to verify the effects of parameters such as load, protrusion size, and quantity on the friction coefficient of the matrix structure surface through friction tests. The sliding suction cup prototype presents an average crawling speed of about 0.4 m/s on a horizontal plane and 0.7 m/s for crawling on vertical walls and the inner surface of a cylindrical rail.