Ultrasonic emission tactile sensor for contact localization and characterization

This paper describes our primary study for a new type of tactile sensing devices which are based on instantaneous localization of acoustic emissions caused necessarily by touch and/or contact movement. We assume the sensor structure which consists of a flexible spherical fingertip-like body and a quadruple PVDF sound sensing matrix is placed at a center of the body. The PVDF matrix works as a wideband acoustic emission (AE) transducers which is capable to detect the arrival direction of a wave packet. Therefore it can resolve and localize multiple ultrasonic emissions at a sensor surface caused by a touch and slip. In order to realize this type of tactile sensor, we present the theory of wave generation at collision, and apply the newly developed sound localization algorithm for an auditory sensor. By assuming the use of this algorithm, and from several experiments under various contact and slip conditions, we show the following features and tactile information: 1) quick localization of touch and detouch, 2) sensation of texture under movement, and 3) quick detection of precursor of slip