The goal of this project is to increase the amount of energy that can be harvested from vibrations and human motion to replace batteries in small wireless electronic devices. There has recently been a massive upsurge in the number of very small wirelessly enabled electronic devices. Many of these are wireless sensing systems that make up a large part of the emerging Internet of Things. As the number of wireless devices grows, periodically replacing batteries becomes very costly or even impossible in some cases. Energy harvesting research seeks to harvest ambient energy to power these wireless sensors. The goal of this specific project is to investigate approaches to increase the amount of energy that can be harvested from vibrations and human motion. The approach we have taken is to systematically investigate what types of structures can harvest the most power from complex vibrations and human motion excitations as a function of features of those excitations. Our group has specifically investigated structures with nonlinear dynamic characteristics and structures that can self-tune their resonance frequencies to better match the source of mechanical excitation.
Specifically, the research project has accomplished the following outcomes:
- We have explicitly proven the upper bound on how much power can be generated from vibrations with certain types of characteristics and established a mathematical framework that can be extended to other vibration types.
- We have systematically characterized two large public vibration databases in terms of the characteristics (frequencies, amplitudes, stability, etc.). This characterization has been published.
- We have determined what types of structures would be most suitable for which classes of vibrations in the databases and confirmed this with simulation.
- We have developed a tunable vibration based harvester architecture with a frequency tuning range of +/- 40%.
- We have characterized human motion under several standard activities, such as walking, jogging, writing, etc. and through mathematical modeling determined the maximum power that can be generated using several different types of energy harvesting structures.
Taken together, these outcomes enhance our understanding of the theoretical limits of harvesting energy from vibrations and human motion and identify optimal energy harvesting structures.
, John Heit
- Rantz, R., and Roundy, S. 2016. “Characterization of Real-World Vibration Sources with a View Toward Optimal Energy Harvesting Architectures”, SPIE Smart Structures and Materials+ Nondestructive Evaluation and Health Monitoring, pp. 98010P-98010P. International Society for Optics and Photonics, 2016. [link]
- Heit, J.D., Roundy, S., 2015. “A Framework to Determine the Upper Bound on Extractable Power as a Function of Input Vibration Parameters”, Energy Harvesting and Systems. March, 2015, DOI: 10.1515/ehs-2014-0059, [link]
- Roundy, S., Tola, J., 2014 “An energy harvester for rotating environments using offset pendulum and nonlinear dynamics”. Smart Materials and Structures, 23 (2014) 105004 [link]
- Heit, J., and S. Roundy. “A Framework for Determining the Maximum Theoretical Power Output for a Given Vibration Energy.” Journal of Physics: Conference Series. Vol. 557. No. 1. IOP Publishing, 2014. [link]
- Heit, J., and Roundy, S., “A Framework to Find the Upper Bound on Power Output as a Function of Input Vibration Parameters”, Proceedings of the ASME 2014 Conference on Smart Materials, Adaptive Structures and Intelligent Systems SMASIS 2014, September 8-10, 2014, Newport, Rhode Island. [link]
- Heit, J., Christensen, D., Roundy, S., 2013. “A Vibration Energy Harvesting Structure, Tunable Over a Wide Frequency Range Using Minimal Actuation.” Proceedings of the ASME 2013 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. SMASIS 2013 (September 16-18, 2013, Snowbird, Utah, USA) [link]