Tactile Manipulation With a TacThumb Integrated on the Open-Hand M2 Gripper

Tactile manipulation will be essential for automating industrial and service tasks currently done by humans. However, the application of tactile feedback to dexterous manipulation remains a challenging unsolved problem, with robot capabilities lagging far behind those of humans. Here, we present the tactile thumb (TacThumb): a cheap, robust, 3-D-printed optical tactile sensor integrated on the Yale GrabLab model M2 gripper. To test tactile manipulation capabilities, a cylinder is rolled along the TacThumb using the opposing nontactile finger. The tactile information permits localization of the test cylinder along the TacThumb to submillimeter accuracy over most of the movement range. In consequence, the M2 gripper can perform accurate inhand tactile manipulation, by providing information that can be used to control the location of the test object within the hand. Tactile manipulation is demonstrated by rolling cylinders with a range of diameters up and down the TacThumb along a target trajectory, using only tactile data to update its current position and move it toward a target. This model-free approach gives a demonstration of basic tactile manipulation without the need for a kinematic model of the hand, in a manner that should generalize to other tactile manipulation tasks.