A fuzzy model relating vibrotactile signal characteristics to haptic sensory evaluations

Nowadays tactile surfaces are slowly replacing the mechanical interfaces of our electronic devices, and the actual trend is toward a quasi-total touch interaction. This transition has however one important side effect, i.e the lack of feedback from the device, which in certain situations can be crucial. In order to overcome this, it has been suggested that feedback has to be delivered to the finger through vibrations that should be both detectable and comfortable. This paper aims to define a perception model for the sensory evaluations of the vibrotactile signals using fuzzy set theory. First of all, the hypothesis that haptic perception is strongly related to physical characteristics of the signals was evaluated and confirmed with a 93% correlation rate, based on psychophysical studies of the tactile sense. Secondly, using the previous analysis as a knowledge base we have implemented a fuzzy inference system which forecasts the preference values for vibrotactile signals. The preliminary results show that for 15 out of 18 signals, the preference is correctly predicted within a reasonable uncertainty interval.