Investigation of kinesthetic illusion of biceps brachii muscle using a miniature voice coil motor

Abstract

The kinesthetic illusion (KI) is a phenomenon in which transcutaneous vibration stimulation applied to a tendon induces the illusion of body movement. This phenomenon has potential applications in rehabilitation and virtual reality (VR). To effectively apply KI, precise vibration stimulation parameters (such as sine wave vibration with controlled frequency, acceleration, and pressing force against the tendon) must be delivered to various body parts. Thus, to realize this phenomenon, miniature vibrators must be developed and controlled. In this study, we developed a compact vibrator using a miniature voice coil motor to induce KI. We constructed a control system to regulate the target acceleration even in the presence of variations in the reactive forces from the tendon. Using the developed vibrator, we applied KI to the biceps brachii tendon and determined the optimal vibration stimulation conditions. The results revealed that the optimal vibration stimulation conditions for each subject’s biceps brachii muscle were related to the thickness of the upper arm. This result demonstrates the ability to determine guidelines for optimal stimulation conditions based on the physical characteristics of each individual participant. The increased ease of experiencing KI is expected to pave the way for rehabilitation using vibrators in wearable robots.