Design of a vibrotactile balance support system with a virtual reality training program

Abstract

This thesis aims to design a vibrotactile feedback(VTF) system to help balance rehabilitation with virtual reality (VR) training. First, the training program was built in a virtual reality platform by using Unity3D and Blender software. Data for visual and vibrotactile psychophysical limits were obtained in several experiments performed by one participant. The VR platform simulated anterior/posterior sways which were conveyed to the participant visually and/or by VTF. Visual experiments consisted of motion detection, angle discrimination, and angular velocity discrimination of an avatar in the VR screen. All motion detection thresholds were found to be lower than 0.04 deg/s. Angle and velocity discrimination limens were in the range of 0.26-0.46 deg and 0.19-0.34 deg/s in the visual avatar. Arduino UNO was used to control six vibration motors placed around the upper arm . Motors were recruited incrementally as the avatar’s sway angle increased. Angular velocity was mapped either by mixed (Pulse-width/pulse-number) or pulse-number modulation to the VTF. Motor distances were adjusted to ensure maximum (%81.2) localization. Next, the participant matched VTF to the postural sway of the avatar while the computer screen was off. Combined identification accuracy of sway angle and angular velocity was 91% by only VTF. Fi nally, the avatar was simulated to cross a road in the VR platform with three conditions (visual on tactile off, visual off tactile on, visual on tactile on) participant. In all condi tions, the participant could control the avatar successfully without any falls. Quickest response was obtained when both feedbacks were on (98.7%), and the worst response was obtained when only VTF was on (92.1%). VTF seems promising in the proof of concept balance support system presented in this thesis.|Keywords : Somatosensory Feedback, Tactile Sensor, Proprioceptive Sensor, Touch, Arduino, Virtual Reality, Augmented Reality, Vestibular System, Balance, Posture, Balance Disorder, Postural Sway, Center of Mass, Center of Pressure, Limit of Stability.