Design of An Electromagnetically Modulated Resistance Mechanism to Realize Compact Passive Force-Feedback Wearable Devices

Abstract

Passive haptic feedback devices are designed to be lightweight, compact, and easier to control than their active counterparts. However, most existing passive force feedback wearable devices rely on mechanical locking or jamming mechanisms, which are bulky and often require large external power sources such as air compressors, fluid pressure systems, or high-voltage supplies for stiffness modulation. This study introduces a new electromagnetically modulated resistance mechanism to achieve compact and efficient passive force feedback in wearable devices. The proposed system employs two electromagnets to dynamically modulate tendon tension, generating resistance forces for the fingers. This approach enables passive force feedback without bulky mechanisms, complex actuation, or intricate control strategies. To validate the effectiveness of the proposed mechanism, we developed a kinesthetic wearable device for the index finger and thumb. Experimental evaluations demonstrated that the device achieved a peak tendon locking force of 5.8N with a current of 0.1A at 9V. A user study with nine participants assessed stiffness discrimination using resistive force feedback in three tasks: index finger only, thumb only, and pinch action. The study yielded accuracy rates of 75%, 66%, and 69%, respectively. Participants found the device comfortable and easy to use, highlighting its potential for realizing compact, lightweight, and effective passive force feedback devices.