Perceived Intensity of Pneumatic Vibrotactile Stimuli: Effects of Pressure, Frequency, and Stiffness
Krishna Dheeraj Kommuri, Femke van Beek, Irene Kuling
AI summary
Problem
While electromechanical vibrotactile feedback is well-studied, the perceptual effects of soft pneumatic actuators remain underexplored. This study investigates how stimulus pressure, frequency, and actuator stiffness jointly influence the perceived intensity of vibrotactile stimuli on the fingertip.
Approach
Sixteen participants completed adaptive psychophysical experiments using the AEPsych toolbox to map perceived intensity across varying pressures (4–30 kPa), frequencies (20–100 Hz), and two actuator stiffness levels.
Key results
- Pressure and frequency both positively correlate with perceived intensity
- Pressure and frequency exhibit a synergistic interaction effect
- Pressure variations yield more perceptually distinct stimuli than frequency variations
- Stiffer actuators produce higher perceived intensity than compliant ones
Why it matters
Provides critical perceptual mapping guidelines for designing intuitive and effective soft pneumatic haptic interfaces in VR, gaming, and wearable technology.
Abstract
Vibrotactile actuators are used in many different haptic devices, e.g. game controllers and smartphones. These vibrotactile actuators are typically made of rigid materials. In this paper, we use soft pneumatic actuators known as Pneumatic Unit Cell (PUC) to characterize the perceived intensity of vibrotactile stimuli when presented at the tip of the index finger. This study investigates how three parameters—stimulus pressure (4 to 30 kPa), inflation-deflation frequency (20 to 100 Hz), and actuator stiffness (determined by top layer thicknesses of 0.9 mm and 1.2 mm)—influence the perceptual intensity of the stimuli. Psychophysical experiments involving 16 participants were conducted using the AEPsych toolbox. These reveal that all the three parameters - pressure, frequency, and actuator stiffness significantly affect perceptual intensity. The findings indicate that both pressure and frequency exhibit a positive main effect and a positive interaction effect on perceived vibrotactile intensity. Additionally, the results show that, for a given frequency, pressure variations produce more perceptually distinct stimuli than frequency variations for a given pressure. Finally, presenting vibrotactile stimuli on a less stiff PUC actuator was perceived as being less intense than when the same stimulus was presented on a stiffer PUC actuator. Overall, this study provides key insights into the combined influence of pressure, frequency and actuator stiffness on the perceived vibrotactile intensity.