Wearable motion sensors can track and record the motion of patients with movement disorders, which can be helpful for diagnosis and treatment. However, these devices have limited endurance because they rely on batteries that have to be recharged. In this research, an electromagnetic oscillatory weight vibration energy harvester is proposed to prolong the endurance of a wearable commercial motion sensor. Oscillatory weight energy harvesters have been used in watch industry extensively, and there is currently growing attention for similar mechanisms to harvest power from low-frequency vibrations. By a series of connected gears, oscillatory weight in a watch converts the low-velocity hand motion to high velocity, subsequently used by the electromagnetic transducer to generate electric output. In this research, the output voltage from a commercial energy harvester is studied as a function of excitation frequency and amplitude for vertical and horizontal orientations. It is observed that the oscillatory system can exhibit complex response under large base excitation in addition to resonance, including parametric resonance, period-doubling bifurcation, chaos, quasi-periodic, and periodic motions. The critical frequency and amplitude in which the system’s response shifts from oscillatory motion to continuous (monotonic) rotation are investigated.


Analysis of Electromagnetic Oscillatory Weight Vibration Energy Harvester Systems for Wearable Devices

Division / Sponsors: 
Aerospace Division

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

SMASIS2020 - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.