A novel tactile sensor using a matrix of LEDs operating in both photoemitter and photodetector modes

We present a novel tactile sensor based on a matrix of light emitting diodes (LEDs). Unlike previous optical-based tactile sensors this approach relies on only one matrix of elements to perform the roles of both light source and light detector. This is possible by exploiting the little-known property of LEDs to act as photodetectors when operated in the photovoltaic or photoconductive modes. The tactile sensor is composed of a pliable foam surface over a substrate onto which a matrix of LEDs is mounted. A two-way detection process enables a point force and position pair to be calculated directly using just two LEDs. Initial results are presented from a 4times4 prototype tactile sensor using infrared LEDs. Experimental results using a neural network function approximator show a sensor accuracy of 94.7%