AirRacket
Perceptual Design of Ungrounded, Directional Force Feedback to Improve Virtual Racket Sports Experiences
ACM CHI'22 BEST PAPER AWARD | 15 APRIL 2022
Pong (1927)
AirRacket (2022)
Intro
Racket sports like ping-pong, badminton, and tennis are popular in virtual gaming, with games like Wii Sports selling over 80 million copies. These games often use controller vibration and racket adaptors for realism. Researchers have tried enhancing this with technologies like solenoid actuators and electric muscle stimulation, but replicating the directional impact force of real racket sports remains challenging within a portable form factor.
Our AirRacket project introduces ungrounded, directional force feedback for a more realistic virtual racket sports experience. We used compressed air propulsion jets in devices for ping-pong, badminton, and tennis. Despite the challenge of lower force magnitude in current technologies, our user study showed improved realism compared to standard vibrotactile feedback.
Novel Device + Psychological Insight = Improved VR Experience
However, this is not enough. In the real world, impact events can generate forces exceeding hundreds of newtons, whereas state-of-the-art active force feedback devices, including AirRacket, generally produce forces at or below 10 newtons. To overcome this technical constraint, we delved into perceptual designs aimed at amplifying the maximum perceived force magnitude.
I applied the psychological concept of “temporal integration” – humans perceive extended stimuli as more intense. My findings revealed that the perceived strength of a force is logarithmically related to its duration. By varying the duration to perceptually adjust the intensity of feedback, AirRacket effectively delivers a more authentic sensation for racket strokes feedback and improves users’ precision in targeting.
Implementation
In this project, I crafted multiple iterations of the racket to refine its tactile feel and weight distribution. I also designed, soldered, and prototyped the circuits for the pneumatic control systems. For comprehensive information on the system’s performance and more details, please refer to our paper and the open-sourced folder.
Beyond rackets
In addition to the three racket sports (ping-pong, badminton, and tennis) showcased and tested in our paper, our open-sourced folder includes additional designs for sports such as baseball, hockey, golf, racquetball, and even a sword. We also offer versions compatible with HTC VIVE trackers.