The Effects of Simultaneous Multi-point Vibratory Stimulation on Kinesthetic Illusion

Abstract

Kinesthetic sensation is important for improving presence and immersion in VR environments. However, presenting kinesthetic sensation usually requires a large space so as to avoid users colliding with objects or other users. One of the ways to tackle this issue is to use kinesthetic illusion, which is a way of presenting kinesthetic sensation without physical motion. However, realizing dynamic motion and fast movement remains difficult. Considering that multiple synergist muscles are usually involved in a movement such as walking or even simple arm movement, stimulating multiple synergist muscles might enhance the illusion. Thus, we investigated whether multi-point vibratory stimulation to multiple synergist muscles enhances induced kinesthetic illusions. We found that stimulating multiple synergist muscles created more vivid illusions. Additionally, we found that our method was effective for inducing steady illusions. We also calculated the contribution of each proposed stimulation point to the illusion.

Synergistic Illusions: Enhancing Perceptual Effects of Pseudo-Attraction Force by Kinesthetic Illusory Hand Movement

“…The illusion of limb movement in the direction of muscle stretching is induced by vibration stimulation [9], as muscle spindles serve as position and motion sensors [21]. Methods exist for applying vibrations to tendons, such as placing the tendon in contact with a grounded vibration device [22] or using bands to secure vibrators at the location of the tendon [23]. In this study, this vibration method was used to present a kinesthetic illusion.…”

“…However, directly pressing the vibrator against the arm would cause the entire arm to be driven by the vibrator, resulting in a weak perception of vibration and making inducing a kinesthetic illusion difficult. Therefore, referring to a previous study [23], we designed a vibrator case with a built-in spring (Fig. 1) to apply vibrations to the target area.…”

“…We decided to adopt a relatively weak pressing force, as the vibrated tendons, frequency, and acceleration amplitude of vibration in the study by Honda et al were similar to those in this study. Following previous research [23] aimed at inducing a more distinct illusion based on a similar consideration, the pressing force was set within the range of 1.5-2.5 N. The vibrator case was equipped with four springs, each with a spring constant of 0.25 N/mm. The overall spring constant of the device was 1.0 N/mm.…”