Give the rapid development of the Internet of Things (IoT) technology, ubiquitous sensing and computing are likely to penetrate every area of human life in the coming decade. One of the most extensively needed applications is ubiquitous motion detection. With the vision of the Internet of Moving Things (IoMT), there will be tons of movement detectors in our surroundings in the future. If chemical batteries still power all the devices, the required labor cost of frequent battery replacement must become unaffordable. Harvesting energy from the environment provides unprecedented convenience and opportunity to extend application lifetime and reduce maintenance cost, especially for extensively deployed and long-lasting motion detectors.

The mechanical plucking mechanism was investigated for the frequency-up conversion in the research of energy harvesting, mostly in the mechanical domain, when connected to the simple linear electrical load. Seldom studies crossed the interdisciplinary boundaries for considering the dynamic interaction among the mechanical, electrical, and cyber parts, which are all necessary towards the realization of a motion-powered (MP) IoMT device. This paper introduces the co-design of such cyber-electromechanical synergy. In our design, a piezo-magneto-elastic structure, which is composed of a low-cost piezoelectric cantilever and a pair of magnets, is used to carry out the plucking excitation and power generation under a transient and one-way movement. An energy management circuit, which is composed of a self-powered synchronized switch harvesting on inductor (SSHI) interface circuit and a voltage regulator, is utilized for efficient energy conversion. Through the sophisticated collaboration between the mechatronic design and software code, the motion direction can also be identified and send out with a Blooth Low Energy (BLE) module. The cyber-electromechanical synergy among mechanical dynamics, power conditioning circuit, and low-power embedded system is emphasized towards the successful implementation of such MP-IoMT device. The prototyped devices are deployed in various scenarios, such as door movement and stuff-pick-up detection. Experimental results show that during the open-door or close-door motions, the design can robustly harvest 920 uJ or 1000 uJ electric energy, respectively. On the other hand, one round of temperature sensing and BLE data transmission takes less than 100 uJ energy. The energy harvested from a single plucking motion is sufficient to carry out several rounds of sensing and BLE transmission with our prototyped device. This study provides valuable guidance for the design and optimization of future MP-IoMT devices.


System Design and Implementation of a Transient-Motion-Powered\x0bIotT Sensor Node

Division / Sponsors: 
Aerospace Division

Paper Proceedings: https://asmedigitalcollection.asme.org/SMASIS/SMASIS2020/volume/84027

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