System design and test of the cuttlefish-like underwater robot

ObjectiveAiming at the insufficient adaptability of underwater robots in complex environments, a dual-drive cuttlefish-like underwater robot was designed by drawing on the morphological characteristics of cuttlefish and its undulating-jet composite motion mode to realize multimodal collaborative propulsion and improve the flexibility and adaptability of underwater operations.MethodsFirstly, an undulating-quasi-jet composite drive system was constructed. The undulating propulsion mechanism drove flexible fins to oscillate through multiple sets of swing rods and cam links, while the quasi-jet mechanism controlled the volume of the pressure-resistant airbag via a screw-linked six-group linkage to adjust displacement and generate propulsive force. Secondly, motion simulation was used to verify the rationality of the actuator trajectory, and the swing rod structure was optimized to reduce stress concentration. Then, the optimal material for flexible fins was selected through material comparison tests. Finally, a physical prototype was developed to conduct multimodal motion tests such as snorkeling and swimming.ResultsThe results of simulations and tests show that the front length of the swing rod’s moving section is optimized from 60 mm to 70 mm, and the clamp plate thickness from 4 mm to 6 mm, with significant reductions in stress and displacement peaks. The robot’s average snorkeling speed is 0.125 m/s and average swimming speed is 0.25 m/s, with rubber flexible fins achieving the best propulsion efficiency. The composite drive scheme is feasible, providing a reference for the design of complex underwater robots.