An In-Situ Umbrella-Shaped Wave Energy Converter With Adjustable Resonance Period for Ocean Robots

The limited power supply of ocean robots constrains their endurance. A feasible solution is to equip robots with onboard wave energy converters (WECs) to harness wave energy. However, the compact structure of robots restricts the energy capture area of in-situ WECs and their adaptability to waves with varying directions and periods. To address this challenge, this article proposes a novel in-situ umbrella-shaped WEC (U-WEC). U-WEC adopts a multimode working principle to expand the energy capture area and possesses an adjustable resonance period to adapt to changing wave conditions. Its motion response is simulated using a hydrodynamic model and validated through wave tank experiments, which confirm that U-WEC maintains considerable relative motion across the tested wave periods. Based on the validated model, the mechanism by which U-WEC adapts to varying wave periods through resonance period adjustment is revealed under regular wave conditions. Under irregular waves with an energy period of 5 s and a significant wave height of 1.5 m, U-WEC achieves a simulated electrical power output of 13.05 W, corresponding to a power density of 0.087 W/kg.