An Acoustic Tactile Sensing Element with Five Dimensional Sensitivity

Abstract

This paper describes a newly developed tactile sensing cell utilizing precise formation and detection of ultrasound wavefronts in a flexible medium. We assume a cell structure which consists of a 2 x 2 ultrasonic transmitter matrix and a 2 x 2 ultrasonic sensing matrix which are placed face to face with an interval of a few tens of wavelength. These cells are embedded in a flexible spherical finger-tip- like body of a tactile sensor. First, we show an ultrasonic transduction principle of small deformation in five dimension; a center-to-center distance between the transducer matrices and a pair of surface angles of the matrices with respect to a line of the distance. Then, we describe a tactile sensor using a single element of this cell, and show. that the sensor can measure 1) 10/spl mu/m change of 15-30mm distance, and 2) 0.001rad change of angles. An application of this sensor to a robot finger which can not only sense its contact force with arbitrary orientation but also predict the slip of the grasping object is shown.