An LED-based Tactile Sensor for Multi-sensing over Large Areas

We present an optical-based tactile sensor that utilizes light emitting diodes (LEDs) in combination with a semi-opaque compliant medium. Previously we have presented this technology in application to sensing either force or a combination of point force and position. In this paper we now consider the application of this sensor to the sensing of object size. We propose a modification that enables sensing of the size on an incident object whilst retaining the previous sensing abilities. This is achieved by introducing a second deformable layer that may optionally have different compressive and/or optically transmission properties. We present results of sensing the size of different objects using this modified sensor and consider the simultaneous measurement of force, size and position. This triple-sensing action, along with the soft nature of the sensor medium, is especially important in applications where the sensing elements may be widely dispersed, for example in safe and compliant robot skin covering.