Integrated proximity, contact and force sensing using elastomer-embedded commodity proximity sensors

We describe a combined proximity, contact and force (PCF) sensor based on a commodity infrared distance sensor embedded in a transparent elastomer with applications in robotic manipulation. Prior to contact, the sensor works as a distance sensor, whereas after contact the elastomer magnifies the near field of the proximity sensors letting the sensor interpret the indentation on elastomer as force. Contact occurs at the transition of proximity and force. We describe in detail the sensor design, its principle of operation and experimentally characterize the design parameters including polymer thickness, its mixing ratio, and emitter current of the infrared sensor. We also show that the sensor response has an inflection point at contact that is independent of an object's surface properties, making it a robust detector for contact events. We finally demonstrate a series of use cases for the proposed PCF sensor, including (1) improving pre-grasp alignment, (2) determining contact event with objects, (3) obtaining simple 3D point cloud models of objects using both proximity and contact, and (4) registering self-generated point clouds to those from a RGB-D camera using a Baxter robot and Kinova Jaco arm.