Dual-mode compliant optical tactile sensor

Tactile force sensing and compliance are key elements of safe and natural-feeling human-robot interaction. We present an optical tactile sensor in the form of a compliant elastomer ´fingertip´ tracked by a high-speed low-resolution image sensor with on-board signal processing. We propose a dual-mode bio-mimetic control loop, where in reflex mode the sensor sends fast reflexive action commands directly to actuators, bypassing the central controller to minimise reaction times. For higher-level interpretation, a slower explore mode enables more sophisticated processing of the sensory input by the central controller. We demonstrate sensing of normal force in both modes of operation, showing that in reflex mode we are able to rapidly detect the presence of forces and compute an approximate magnitude estimate while in explore mode we are able to perform more accurate force measurements.