Passive Ultra-High Frequency (UHF) RFID tags are well matched to robots' needs. Unlike low-frequency (LF) and high-frequency (HF) RFID tags, passive UHF RFID tags are readable from across a room, enabling a mobile robot to efficiently discover and locate them. Because they don't have onboard batteries to wear out, their lifetime is virtually unlimited. And unlike bar codes and other visual tags, RFID tags are readable when they're visually occluded. For less than $0.25 per tag, users can apply self-adhesive UHF RFID tags throughout their home.
Two ThingMagic Mercury 5e (M5e) UHF RFID modules form the core of the robot's RFID sensors. One is connected to two body-mounted, long-range patch antennas that can read UHF RFID tags out to ~6 meters. The other is connected to custom, short-range, in-hand antennas embedded in the robot's fingers that can read the exact same UHF tags within ~30cm of the robot's hand. The hardware is annotated in the figure below.
We have demonstrated a number of capabilities enabled by RFID sensing. The following is a brief list. Refer to the publications for a more detailed information:
PPS-Tags: Physical, Perceptual and Semantic Tags for Autonomous Mobile Manipulation: Moderate level of environmental augmentation facilitates robust robot behaviors.
Our work is generously supported in part by the Health Systems Institute and by Travis' NSF Graduate Research Fellowship (GRFP).
RF Vision: RFID Receive Signal Strength Indicator (RSSI) Images for Sensor Fusion and Mobile Manipulation: Long-range UHF RFID sensing and multi-sensor fusion for mobile manipulation.