Design and Motion Control of a Propeller–Leg Hybrid Multimodal Underwater Adhesion Robot

For underwater tasks that require an efficient approach over long distances and stable adhesion for close‐range crawling, this paper proposes a propeller–leg hybrid underwater adhesion robot with integrated swimming and crawling capabilities. First, we present the overall design of a robot that integrates a bionic leg–foot mechanism and a propeller propulsion system. Second, we design a hydrogel biomimetic sucker with reversible adhesion and detachment, accompanied by an adhesion performance test. A dual‐criterion system for static stability margin and adhesion force reliability was proposed during the robot crawling stage. On the basis of computational fluid dynamics simulation results, a critical instability model was developed to quantify the effects of flow velocity, slope, and load on system stability. We have developed a crawling–swimming collaborative control strategy to address the mode‐switching issue during locomotion. This strategy employs a hierarchical control architecture guided by stability criteria, in which central pattern generator–based rhythmic control dynamically integrates with sliding‐mode propulsion compensation via switching signals. The experimental results show that the proposed robot can achieve stable attachment motion through propeller–leg coordination under special working conditions (inverted surfaces and slopes). The proposed robot provides a multimodal solution for underwater operations that require a rapid target approach in open water, followed by stable attachment and adhesive crawling on structural surfaces.