Effect of Natural Frequency of Rotational Electret Energy Harvester for Human Walking

In this paper, we investigate the effect of natural frequency of rotational energy harvester (EH) on power generation characteristics during human walking. Based on electromechanical analysis using the arm swing model, it is found that the output power is significantly affected by the natural frequency of the rotor due to the gravitational force. Rotational electret energy harvesters with different natural frequency of the rotor were prototyped, and their output power were characterized by using a 6-axis parallel link robot, which can mimic the arm swing motion for different walking speeds. It is found that, by adjusting the natural frequency of the rotor at 1 Hz, much higher output power has been obtained for a wide range of the walking speeds.