Maneuvering of biomimetic fish by integrating a buoyancy body 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. The layout and workspace of the modular fin segments are considered and analyzed. The relationship of the individual fin segment and phase angles with the overall fin trajectory is also discussed. A gymnotiform knifesh robot, as an example, has been developed to demonstrate the design methodology and prototype 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 knife fish robot and its buoyancy performance in 4 m deep water.