A proposal of optical and electrical measurement method for tactile sensor using phototransistor

We propose a new tactile sensing method for simultaneous measurement of the indentation on the sensor surface and the material properties of test objects by single sensor. The proposed sensor consists of electrodes and phototransistors with light emitting diode (LED). In the proposed method, the admittance between electrodes and phototransistors is measured while changing of light emission by the LED. The electrical property of the object is measured by the admittance between electrodes, and the indentation on the sensor surface measured by the admittance between phototransistors. In the experiment, discrimination of four kinds of materials (Acrylic, POM, Glass and Aluminium) and detection of the indentation on the sensor surface were demonstrated. The proposed sensor may be applicable for a tactile sensor in robots.