Maneuvering and Buoyancy Control of Robotic Fish Integrating with Modular Undulating Fins

Biomimetic robots borrow their senses and structure from animals, such as insects, fishes and human. Development of underwater vehicles is one of the areas where biomimetic robots can potentially perform better than conventional robots. In this paper, an undulating fin mechanism has been developed and used as the propulsion system of fish in various fin types. A gymnotiform knifefish robot, as an example, has been developed to demonstrate the design performance. The maneuvering and the buoyancy control can be achieved by the integration of a buoyancy tank with the undulating fin. Experiments were conducted in the laboratory tank and the variation of velocity with respect to several swimming parameters was analyzed. Field trials have also been conducted in an outdoor pool to demonstrate the swimming capability of the knifefish robot and its buoyancy performance in 4-m depth water.