1. Department of Civil and Earth Resources Engineering, Kyoto University, Kyoto, Japan
2. JVCKENWOOD Public & Industrial Systems Corporation, Kanagawa, Japan
3. JVCKENWOOD Corporation, Kanagawa, Japan
Email: chang.kaichun.4z@kyoto-u.ac.jp (K.C.C.); nishino.tomoki.7z@kyoto-u.ac.jp (T.N.)
*Corresponding author
Manuscript received October 24, 2023; revised January 12, 2024; accepted February 10, 2024; published May 14, 2024
Abstract—Advanced structural health monitoring is essential for infrastructure maintenance and management in developing a smart city and could contribute to a carbon-neutral smart city. For long-term bridge health monitoring (BHM), to power various types of wireless sensors, developing a stand-alone sustainable power supply system is of great engineering interest. Solar and wind energy harvesting techniques have been introduced into the long-term BHM field, but they could hardly work well on some monitoring targets that are closed, shadowed, or little sunlight or wind available. Vibrational energy harvesting could be an alternative energy harvesting technique, since almost all bridges vibrate when they are excited by external dynamic forces.
This study focused on developing a vibrational energy harvesting device transformed from a commercial speaker, which is tailored for practical long-term BHM and characterized by simple structure, durability, commercial availability, and low cost. To develop this device, first the theoretical background on the vehicle-induced bridge vibrations and speaker principles were reviewed, then the fundamental concept of the commercial speaker-transformed vibrational energy harvesting device was presented. The basic idea was to transform a commercial speaker into a vibrational energy harvester that can convert the kinematic energy of low-frequency bridge vibrations into electric energy to charge batteries or to power sensor nodes.
This concept was verified in a laboratory experiment on a model bridge loaded by a moving model vehicle. In this experiment, the current energy harvester could output a maximum voltage of 2.49 mV and an Root Mean Squared (RMS) voltage of 0.14 mV from the bridge vibrations of a maximum acceleration 0.3 m/s2 and an RMS acceleration 0.04 m/s2. Also, it was observed that the energy harvester’s output voltage was negatively correlated to bridge displacement but positively correlated to bridge acceleration. It suggests that, to harvest more energy from the bridge vibrations using the present device, any means that could excite the bridge with larger acceleration amplitudes might help, e.g., letting vehicles run faster.
Keywords—bridge structural health monitoring, bridge vibrations, commercial speaker, vibrational energy harvester
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Cite: K. C. Chang, T. Nishino, M. Onishi, W. Murata, K. Sugihara, T. Onodera, S. Okada, and H. Tanigawa, "A Commercial Speaker-Transformed Vibrational Energy Harvesting Device-Conceptual Study and Laboratory Trial on a Model Bridge," International Journal of Engineering and Technology vol. 16, no. 2, pp. 98-103, 2024.
