A tactile and proximity sensor by optical and electrical measurement

We proposed a novel proximity and tactile sensing method by simultaneous measurement of optical and electrical properties by single sensor. The proposed sensor consists of a pair of electrodes and photodiode with light emitting diode (LED). In the proposed method, the admittance between electrodes and photodiodes are measured. The electrical property of the object is measured by the admittance between electrodes. In addition, the optical property of the sensor surface (indentation) is measured by the admittance of photodiode. In this paper, we consider the electrical condition of the surroundings because the measured electrical property also changes according to the electrical condition of the surroundings. In the experiment, when the base is two kinds (grounded conductor and dielectric (acrylic)), identification of the material (grounded conductors such as human or not), and detection of the indentation on the sensor surface were demonstrated on contact. In addition, the object was detected before contact (proximity range). The proposed sensor may be applicable for a tactile sensor in robots.