Deformable skin design to enhance response of a biomimetic tactile sensor

Grasping of objects by robotic hands in unstructured environments demands a sensor surface that is durable, compliant, and responsive to various force and slip conditions. A compliant and robust skin can be as critical to grasping objects as the sensor it protects. In an effort to combine compliant mechanics and robust sensing, a biomimetic tactile sensor is being developed. Deformations of its skin can be detected by displacing a conductive fluid from the vicinity of electrodes on a rigid core. In this study, we used simplified finite element models to understand the effects of various textures for the inner surface of the skin and then produced the more promising textures by molding the elastomeric skin material against negatives made by stereolithography. The impedance vs. force relationships obtained with these molded skins had the predicted and desired wide dynamic range. By selecting the appropriate materials for the skin and fluid, previously described problems with hysteresis and diffusion losses have been greatly reduced.