The Issues of Development of Renewable Energy Sources for Marine Autonomous Underwater Robotic Complexes

Abstract

The paper considers the options of renewable power sources development for marine objects operated in absence of solar energy. Operation of many undersea vehicles is evidently limited by their battery charge. When operating at shallow depths, such vehicles experience pitch and roll in the wave-perturbed environment. Buoys floating on the water surface are also disturbed by sea waves. Moreover, when they are operated during polar night, solar energy cannot be used for charging their batteries. To solve this problem, it is proposed to use the energy of surface waves or the vehicle pitch and roll. It is quite possible to transform the energy of wave current and the orbital velocity of water particles motion into propeller rotation. Basic theory of using such devices for energy accumulation and their capabilities are studied. It is stated that several such devices installed in orthogonal directions relative to each other will transform the energy that is also generated by the undersea vehicle's propulsion when its depth is changing. Furthermore, the vehicle pitch/roll energy transformation into electric power is discussed. This idea is extremely attractive, so it is not new. However, generators of this type have never been used on undersea robotic vehicles. The paper presents an induction generator designed and patented by the author. It is shown that its operation is described by a differential equation of the 2^nd order. It is proposed to adjust the electromechanical system of such transformers to be resonant with the dominant pitch/roll oscillations. This can be done by varying the degree of the oscillating system damping. Potential engineering solutions and physical principles of their operation are discussed. The proposed small-size transformers are estimated in terms of power capacity and compared to the existing similar devices. It is demonstrated that the proposed generators are able to generate power of a few dozens Watt.