Synergetic Effect of Contact Surface Area and Elbow Joint Angle on Tendon Vibration-Induced Illusory Movement

Abstract

Tendon vibration causes illusory movement in human limbs, which is a kinesthetic sensation experienced in the absence of any actual joint movement. This phenomenon can be effectively used to generate kinesthetic sensation in virtual-reality settings, which can solve various problems. However, because of the previously unknown relationship between the stimulus and perceptual characteristics, its implementation is limited. This study investigated the synergetic effect of the contact surface area and the joint angle. A vibration device was used to stimulate the biceps brachii tendons in four participants’ dominant-side arms for 30 s at 100 Hz and 120 m/s². This device was fixed to a customized vibration fixture base, and the contact head was attached on top of the vibration device. Contact heads with different diameters (φ10, φ15, and φ20) were adopted. The shoulder was flexed at 90° on an armrest, while the elbow was flexed at 30°, both in the midsagittal plane, with palms facing upwards. After the experiment, they were asked to take two subjective evaluations of the vividness and range of extension of their elbow-joint angle. Three diameter conditions were ranked. During the illusory motion, both parameters increased with the contact surface area and the flection angle of the elbow joint. Thus, the contact surface area and joint angle had a synergistic effect on the perceptual characteristics of the illusory movement.