Dual-Modal Tactile Perception and Exploration

Tactile sensing is required for human-like control with robotic manipulators. Multimodality is an essential component for these tactile sensors, for robots to achieve both the perceptual accuracy required for precise control, as well as the robustness to maintain a stable grasp without causing damage to the object or the robot itself. In this study, we present a cheap, 3D-printed, compliant, dual-modal, optical tactile sensor that is capable of both high (temporal) speed sensing, analogous to pain reception in humans and high (spatial) resolution sensing, analogous to the sensing provided by Merkel cell complexes in the human fingertip. We apply three tasks for testing the sensing capabilities in both modes; first, a depth modulation task, requiring the robot to follow a target trajectory using the high-speed mode; second, a high-resolution perception task, where the sensor perceives angle and radial position relative to an object edge; and third, a tactile exploration task, where the robot uses the high-resolution mode to perceive an edge and subsequently follow the object contour. The robot is capable of modulating contact depth using the high-speed mode, high accuracy in the perception task, and accurate control using the high-resolution mode.