Development of an electromagnetic energy harvester for ultra-low frequency pitch vibration of unmanned marine devices

Pitch vibrations can be commonly observed in unmanned marine devices under wave excitation, but there is relatively little research on harvesting the energy from the pitch vibrations with ultra-low frequency. This work develops a novel built-in electromagnetic energy harvester using rope transmission to provide sustainable power supply for onboard electronics. It has the advantages of low friction and compact structure, which is suitable for installation inside an autonomous underwater vehicle with slender cylindrical shape. Dynamic modeling and linearization approach are employed to analyze its energy harvesting performance theoretically. A scalable prototype is fabricated and tested on a motion platform with six degrees of freedom by simulating periodic pitch vibration. The results show that the prototype can output electrical power with the peak value of 1663 mW and the average value of 315 mW at the excitation frequency of 0.6 Hz. It also has competitive energy extraction efficiency and the maximum value reaches 33.23%. The experimental data are in good agreement with the theoretical data, which verifies the effectiveness of the theoretical model. The developed energy harvester can serve as a potential candidate for powering the electronics on unmanned marine devices.