Development of a Robotic Flying Fish With Cross‐Medium Capability

Abstract

Many fish species are capable of leaping out of water, and several robotic fish have been developed to mimic this behavior. However, enhancing jumping performance and achieving low‐altitude gliding—as seen in flying fish—remain challenging. This study presents a bionic flying‐fish robot capable of efficient high‐speed swimming and water‐exiting motion. Its morphology is reconstructed from a 3D scan of a flying fish, a representative cross‐medium organism. Unlike conventional jumping robotic fish, the proposed design features an optimized body shape and an improved tail‐drive mechanism, which reduce kinetic energy loss during high‐frequency oscillation. Experimental tests and analyses of the Strouhal number (St) and Reynolds number (Re) confirm efficient propulsion and swimming characteristics comparable to real fish, with a maximum speed of 2.54 m/s. The simplified pectoral‐fin structure further enables agile steering and pitching control. During high‐speed swimming, the Froude number (Fr) exceeds 1, demonstrating the robot's ability to fully exit the water. In the test, the robotic fish was able to leap out of the water to a height of 0.5–0.55 m at a sprint angle of to . These results highlight the robot's exceptional locomotion performance and provide insights for the design of cross‐medium robotic systems.