Portable vibration-based generator using a permanent magnet rolling on an arced rail

The authors propose a portable vibration-based generator consisting of a coil and a cylindrical permanent magnet rolling on an arced rail. The power produced by a relative motion between the magnet and the coil is increased by a mechanical resonance of the magnet-rail system. Since a natural frequency of a pendulum tends to be low, the generator is suitable for power generation from a low-frequency vibration such as a movement caused by a human walking motion. Following a discussion of an optimal design of the generator, a prototype is fabricated. The performance of the generator is examined through experiments using a vibration exciter that can imitate a vibration at a waist of a walking human. The results show that the generated power reaches 1.0 mW when a frequency and an amplitude of an excitation are 1.8 Hz and 2.5 m/s2, respectively.