Magnetostrictive vibration power generator from vehicle-induced highway vibrations for battery free LPWA module with titanium wire sensor

In recent years, the periodic inspection of aging transport infrastructure has become a global problem incurring significant costs and requiring the extensive use of manpower. As a solution, we propose a magnetostrictive vibration power generator that makes use of vehicle-induced highway vibrations to power a battery-free low power wide area (LPWA) module incorporating a titanium wire sensor. This system makes use of an LPWA module with a transmission range of over 1 km, and a titanium wire sensor which was inexpensive, easy to install, and could be used to inspect aging infrastructure. Using this system, infrastructure inspection, can be conducted without the need for conventional maintenance on the system, such as battery replacement. Our main research objective was the magnetostrictive vibration power generator. The generator was suitable for supplying power to the system because it was simple, robust, and was capable of high power output. First, the generator was scaled up to increase the output power in order to generate practically useful electric power with highway vibrations. The large generator was 150 mm×60 mm×50 mm in size and 0.6 kg in weight, incorporating a 16 mm×2 mm×50 mm plate of iron-gallium (Fe-Ga) alloy. We then reproduced the highway vibrations experimentally in a laboratory to ascertain the generator characteristics. We confirmed that it generated a peak voltage of 7 V, instantaneous maximum power of 36 mW, and total energy output of 52 mJ from the simulated highway vibrations over a period of 5 min. Finally, we field tested the system and succeeded in activating the battery-free LPWA modules within 16.5 min using vehicleinduced highway vibrations.