Optical localization of passive UHF RFID tags with integrated LEDs

The ability to accurately localize passive UHF RFID tags in uncontrolled and unstructured environments is limited by multipath propagation. Therefore, in order to increase the spatial resolution of RF based localization methods we propose to combine them with additional sensing capabilities. In this work we enhance passive UHF RFID tags with LEDs, using the Wireless Identification and Sensing Platform (WISP). This allows both humans and computer systems (with cameras) to optically locate tagged items with millimeter accuracy. In order to show the effectiveness of this approach, a PR2 robot is equipped with an EPC Gen2 RFID reader and camera. Using the RFID reader alone, the PR2 is able to identify and coarsely locate tagged items in an unstructured environment. Once the robot has navigated to the vicinity of the LED-enhanced passive RFID tags, it uses the optical location method to precisely locate and autonomously grasp tagged items from a table.