Tongue-based electrotactile feedback to perceive objects grasped by a robotic manipulator: preliminary results

A sensate robotic gripper was developed and interfaced to an electrotactile tongue stimulation system. The prototype system permits grasped object recognition by the user without visual sensory input. Modifications of an existing two finger robotic gripper included the addition of six conductive polymer force sensors mounted in a pentagonal (24 mm diameter) pattern with the sixth sensor placed in the center. Shape information from the robot gripper in contact with a test object is relayed to the user via patterned electrotactile stimulation on a micro-fabricated flexible tongue array. A previously developed Tongue Display Unit (TDU) provides the electrotactile stimulation, which pattern maps information from the six sensors to discrete groupings of electrodes on the 12 × 12 matrix tongue array. Modification of an existing software program facilitated a tongue mapping closely resembling the spatial layout of the six force sensors. A preliminary human subject study was performed to demonstrate the accuracy of recognition when presented with one of four basic shapes. Results indicate sensor resolution and orientation influence performance, but even a limited configuration provides highly accurate shape recognition.