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Device Technologies and Biomedical Robotics

Device Technologies and Biomedical Robotics - Poster Session E

Poster J13 - Validation of Continuously Variable Fan System for Surfing Virtual Reality Environment

Saturday, October 26, 2024

10:00 AM - 11:00 AM EST

Location: Exhibit Hall E, F & G

Presenting Author(s)

Lauren Tomita (she/her/hers)

Associated Students of Biomedical Engineering President
University of Southern California Associated Students of Biomedical Engineering
Las Vegas, Nevada, United States

Introduction: Within the research community, surf therapy has emerged as an approach to treat post-traumatic stress disorder (PTSD). Our research focuses on if surfing could be used in the reduction of pain in patients with complex chronic pain and if the effects of surfing could be engineered in virtual reality (VR). Various tests were conducted to optimize fan control in the environment to guide future experimentation in immersion and simulator sickness. Specifically, we studied the optimization of fan control in a VR surfing environment using Unity software and an Oculus headset. There were three primary goals within the study. First, we worked to engineer a servo motor-fan system to interact with an Arduino and Unity to vary the speed of the fan. Second, we explored the relationship between fan wind velocity and servo motor rotation angle. Third, we investigated the minimum angle of rotation required for the fan’s wind to be perceived as well as the relationship between user height and air flow.

Materials and

Methods: The fan control system collected velocity data from Unity, reflecting the user’s experience in VR. This data was sent to Arduino, causing the servo motor's rotation and ultimately, the fan dial's rotation angle to change. This altered fan speed, matching it to the user's VR velocity. At 270°, the fan reached maximum speed, while at 0°, it produced no wind. To explore the relationship between fan speed and rotation angle, random angles from 0° to 270° were generated. VelGrid technology measured the fan's face velocity at various angles. It was secured 35 inches from the front of the board and height of 20 inches from the board's surface to enable recordings at a perpendicular orientation.

For the second part of the experiment, the threshold of perception was measured in three ways. First, servo motor angles were increased by 10° increments from 0° until participants felt a “breeze.” Then, angles were decreased from 200° until the “breeze” was no longer felt. The average of the first perceived angle and the previous angle was recorded. Additionally, the rotation angle was set to highest value of 200° and then lowered to 100°. Based on participants' responses, the angle was incremented to an average between lowest perceived angle and highest non-perceived angle until threshold was determined.

Further research into height influence on perceived airflow involved recording fan speed (in FPM) with the VelGrid at various heights, chosen based on the expected pelvis to head heights of participants on the surfboard motion platform system.

Results, Conclusions, and Discussions: Through this experiment, a dynamic servo motor-fan system was successfully engineered to interact with Arduino and Unity, enabling variable fan speed control in the VR surfing environment. Future work will focus on enhancing its adaptability to user interactions within the VR environment. When further examining the relationship between fan wind velocity and servo motor rotation angle, an exponential relationship between fan wind velocity and servo motor rotation angle was found, providing insights into optimizing fan control for consistent and predictable wind speeds. As shown in the associated figures, the curves greatly overlap one another, demonstrating the ability of the fan control system to reproduce consistent rotation and fan speeds. Additionally, the average data points were plotted with the error bars representing the standard deviation. Next steps will include developing algorithms to dynamically adjust fan speed based on user velocity to create a more immersive and realistic VR surfing experience. With regards to the minimum angle of rotation required for the fan's wind to be perceived, significant servo motor rotation angles were determined to be necessary for perceptible fan wind speeds, guiding future development of the VR environment to enhance realism. Additionally, the user height appears to be a large factor in the amount of air flow experienced. These findings have revealed that custom fan angles may need to be designated on the basis of participants’ heights. Future research would address how variable wind can mitigate the effect of motion sickness and user immersion in related Simulator Sickness Questionnaire (SSQ) studies. With validation of the continuously variable fan speed system, later work will focus on additional ways immersion and motion sickness may be improved in the VR environment in pursuit of a potential pain therapy treatment delivered through VR.

Acknowledgements (Optional): This work is supported in part by:
● University of Southern California Center for Undergraduate Research in
Viterbi Engineering (CURVE) Fellowship
● University of Southern California Viterbi Fellow Program
● SC CTSI (NIH/NCATS) through Grant UL1TR001855