A Sense of Touch for the Shadow Modular Grasper

In this letter, we have designed and built a set of tactile fingertips for integration with a commercial three-fingered robot hand, the Shadow Modular Grasper. The fingertips are an evolution of an established optical biomimetic tactile sensor, the TacTip. In developing the tactile fingertips, we have progressed the technology in areas such as miniaturization, development of custom-shaped finger-pads, and integration of multiple sensors. From these fingertips, we extract a set of high-level features with intuitive relationships to tactile quantities such as contact location and pressure. We present a simple linear-regression method for predicting roll and pitch of the finger-pad relative to a surface normal and show that the method generalizes to unknown depths and shapes. Finally, we apply this prediction to a grasp-control method with the Modular Grasper and show that it can adjust the grasp on three real-world objects from the YCB object set in order to attain a greater area of contact at each fingertip.