Abstract
Hinge angle detection in wearable devices introduces size, weight, and power penalties when secondary inertial sensors are added. Magnet-based hinge sensors suffer from mechanical wear and magnetic interference with directional sensors.
This paper presents an approach for evaluating hinge orientation using dual magnetic field sensors. A primary three-axis magnetic field sensor is positioned within a main front frame, and a secondary low-power three-axis magnetic field sensor is positioned within a temple arm component. Ambient magnetic field vectors are measured across both local sensor coordinate frames. Sensor readings are calibrated for hard-iron offsets and soft-iron matrices, normalized, and processed via vector dot product operations to yield angular displacement values. External field non-uniformities are identified using vector magnitude differentials and error values.
Device placement state determinations are generated via hysteresis evaluation to control power management without requiring dedicated magnets or secondary inertial sensors.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Wang, Cheng and Zhang, Qiyue, "Dual Magnetometer Hinge Angle Detection System for Wearable Device Don/Doff Sensing", Technical Disclosure Commons, ()
https://www.tdcommons.org/dpubs_series/12887