Efficient, Highly Maneuverable Artificial Fish for Stealthy Surveillance

Experimental and computational studies have indicated the benefits of fish swimming propulsion for efficiency and fast maneuvering capability. The biological paradigm of using unsteady body motion to generate and manipulate flow vorticity for desired hydrodynamic thrust marks a shift from the quasi-steady treatments used in practice for the engineering of vehicle hydrodynamics. A key component to fish efficiency and maneuvering capability is the precision evolutionary tuning of structural properties of the fish body. This tuning allows the fish to lock in efficient natural fluid-structural modes of propulsion with minimal energy input. The storage and re-release of structural potential energy into the flow permit high swimming efficiencies and the large power deliveries required for fast maneuvering. The proposed vehicle follows the biological design of an underactuated structurally tuned flexible primary propulsor, utilizing natural dynamics of the system to realize locomotive efficiencies. The single point modally actuated flexible tail propulsor is complemented by a pair of two-degree-of-freedom three-dimensional foils to be used in quasi-static mode as control surfaces, and in flapping mode for maneuvering. Vehicle design will be built upon previous studies into passive and actuated fluid-structural modes and propulsion of tuned flexible bodies, and maneuvering control using three-dimensional flapping foils.