The use of wings undergoing an oscillating motion in both heaving and pitching is interesting in many engineering applications (energy extraction, propulsion, flow control).

In the current project where electricity production from water flow is targeted, work must be done by the water flow on the wings in order to maintain their oscillating motion. This work represents a fraction, typically less than 40%, of the kinetic energy associated with the flow velocity.

To assure that energy is being transferred from the water to the wings, the wings motion amplitudes and oscillating frequencies must be carefully tuned to make sure that the instantaneous angle of attack yields a resulting hydrodynamic force which tends to maintain the cyclic motion.

The wings oscillating motion is then mechanically converted to a rotating motion driving a shaft connected to an electric generator.