Acoustic wave approach for multi-touch tactile sensing

In this communication, we present a high resolution tactile plate that can localize one or two contact fingers. The localization principle is based on Lamb wave absorption. Fingers´ contact will generate absorption signals while Lamb waves are propagating in a thin finite copper plate. These signals can be related to the contact positions and can be calibrated before the use of tactile plate. Fingers´ contact positions are calculated by finding the closest calibration signal to the measured signal. Positions are carried out in less than 10 ms with a spatial resolution of 2 mm for one finger localization. Multi-points localization by this technology is developed and a two-point case is initialized and tested. Several optimization methods are also presented in this paper, as the double validation check which could improve the accuracy of single-point localization from 94.63% to 99.5%.