Effects of Vibration Direction and Pressing Force on Finger Vibrotactile Perception and Force Control

Abstract

This paper reports about the effects of vibration direction and finger-pressing force on vibrotactile perception, with the goal of improving the effectiveness of haptic feedback on interactive surfaces. An experiment was conducted to assess the sensitivity to normal or tangential vibration at 250 Hz of a finger exerting constant pressing forces of 0.5 or 4.9 N. Results show that perception thresholds for normal vibration depend on the applied pressing force, significantly decreasing for the stronger force level. Conversely, perception thresholds for tangential vibrations are independent of the applied force, and approximately equal the lowest thresholds measured for normal vibration.

Vibrotactile Thresholds on the Wrist for Vibrations Normal to the Skin

“…Generally, once a participant found a comfortable tightness, adding a notch to the bracelet would make the vibrator lift off the skin while removing a notch generated too much tension on the bracelet so the magnets did not resist. With this tightening, participants exerted forces between 0.6 and 1.4 N (the mean value is 1 N, see Section VI), which is range of value already observed in a comparable study [13].…”

“…Nevertheless, the perception and detection of vibrotactile signals is dependent on the context of the experiment, such as the type of vibrator [9], [10], the force exerted on it [11]- [13], the shape in contact with the skin [14], [15] and the user themselves (hairiness [15], [16], age [17], temperature [18]). Naturally, the area of the body that is excited induces significant variations: this was measured on the finger [19]- [23], the arm [24], the back [24], the thigh [25], the skull [26] or the mouth [27].…”

Skin Sensitivity Assessment Using Smartphone Haptic Feedback

“…While this could be physiological, unable to be observed with the monofilament test, it could also be behavioral. As VPTs can vary with force [34] , [35] , it might be necessary in future work to find a way to control applied forces. This is an important future consideration for adoption as this type of touchscreen force sensing has not been present in smartphones since 2018.…”

Design and Assessment of Digital Musical Devices Yielding Vibrotactile Feedback

“…In particular, we employed relatively large sample sizes and modern statistical analysis techniques, and implemented strict control over experimental conditions. Additionally, we developed measurement tools and conducted several psychophysical experiments to investigate vibration perception under active touch conditions commonly found in musical performance De Pra et al (2021Pra et al ( , 2022; Papetti et al (2017), often obtaining radically diverging results when compared to the existing literature Askenfelt and Jansson (1992); Verrillo (1992). Finally, we ensured accurate measurement and characterization of the haptic feedback provided by our interfaces, on the one hand to comply with psychophysical results, and on the other hand to enable the interpretation of experimental results based on objective quantities.…”