Sensitivity of Resonant Moving Magnet Actuators to Haptic Environments

Description

Haptic feedback devices are used in many electronic interfaces, such as game controllers, to enhance the
user experience. The experimental characterization of a common haptic feedback device, the so-called moving magnet
actuator (MMA), comprising an electromagnetically actuated permanent magnet, reveals significant variations when
interacting with human users. Impedance spectra of three MMAs were recorded in free-hanging and rigidly clamped
configurations, as well as in various user-interaction scenarios. Initial measurements in non-user cases showed distinct,
narrow peaks associated with high quality factors and different resonance frequencies for each configuration, while user
interaction led to notable changes in resonance frequency and quality factor. When placed in a user’s hand, the device’s
resonance frequency is nearly identical to the free-hanging configuration, albeit with a significantly lower quality factor.
Closing the hand and increasing the grip strength initially shifts the resonance frequency downwards towards the
clamped configuration. At higher grip strength, however, the compression of the tissue reduces its damping effect,
increasing the quality factor associated with the resonance. Similar behavior can be observed when holding the MMA
between two fingers. This indicates that by varying the grip strength, the resonance behavior shifts between the edge
cases of free-hanging and clamped configurations, suggesting that the resonance properties of such actuators may be
a feasible method for determining a user’s grip strength and handling style of electronic devices. Further work is planned
to develop a robust model for parameter estimation from measured impedance spectra and to create a system for real
time measurement of grip strength.

Period	22 Oct 2025
Event title	IEEE Sensors 2025
Event type	Conference
Location	Vancouver, Canada, British ColumbiaShow on map
Degree of Recognition	International