Seungjae Oh

Vibrotactile Sensitivity+Pressure

Effects of Contact Force and Vibration Frequency on Vibrotactile Sensitivity During Active Touch
(IEEE Transactions on Haptics)

Experiment

Abstract

Humans require precise force control to execute fine manual tasks, which is generally facilitated to the great extent by providing adequate feedback. Currently, such dexterous manual tasks can be an input source of computing. To design appropriate vibrotactile stimuli for manual tasks, it is essential to quantify human vibrotactile sensitivity over a large range of contact forces.

In this paper, we report the psychophysical detection thresholds for vibrotactile stimuli measured for five pressing forces that cover the range of forces encountered during ordinary manual tasks. The experimental results showed stark contrasts between stimulus frequencies, depending on actively exerted pressing force. The detection thresholds for 40 Hz stimuli first increased then decreased as the pressing force increased, but the detection thresholds for 250 Hz stimuli generally decreased as the force increased. These results have immediate consequences on the design of vibrotactile feedback for manual tasks in many applications of tangible interaction, tele-operation, and VR.

Publication

Figure

HW Our Experimental Setup.

Result Absolute thresholds in terms of peak acceleration in dB measured in all experimental conditions. Error bars show standard errors.

Conclusion

In this paper, we explored how the perceptual characteristics of vibrotactile stimuli is affected by two experimental variables, active pressing force and vibration frequency, concentrating on the sensitivity.We measured the absolute thresholds for two sinusoidal vibrations (40 and 250 Hz) under five pressing forces (0.2, 2.0, 4.9, 7.8, and 10.8 N). The results showed distinctive tendencies in the sensitivity over the pressing forces at the two levels of frequency.

The main findings of our experiment were as follows: 1) the sensitivity to 250 Hz stimuli generally increased with increasing pressing force; 2) the sensitivity to 40 Hz stimuli initially decreased but then increased after the contact force exceeded 2 N; and 3) the participants were more sensitive to 250 Hz stimuli than 40 Hz stimuli by at least 39.33 dB (at 0.2 N), and the sensitivity gap between the two frequencies generally increased as the pressing force increased.

In future studies, we will investigate the effectiveness of vibrotactile rendering based on the results of this study and explore the design space of vibrotactile feedback and force-sensitive input.