Patent ID: 8222996

Claim:
An apparatus, comprising: a radio frequency identification (RFID) tag with at least one light emitting diode (LED) that is controlled by a logic in the RFID tag and powered by a power harvesting circuit in the RFID tag; wherein said RFID tag powers said LED when an operating voltage is reached, which discharges its storage capacitor and wherein when a minimum operating voltage is reached, the LED is turned off, at which point the storage capacitor recharges and therefore an LED flashing rate is proportional to an input power, but brightness of any single flash is constant; wherein said RFID tag is interrogated by an RFID reader and reporting its unique identification number by RF backscatter and/or controlling an illumination state of said at least one LED; wherein said illumination is controlled either by an explicit LED-control command from said RFID reader, or locally by said RFID tag; wherein said LED is configured to provide visual feedback to a human operator, or to a video camera/machine vision system and wherein said vision system is mounted on a robot for localization or in a fixed configuration; wherein a camera light collection duty cycle is set high by setting a shutter time to be as close as possible to camera frame rate to enable observation of said at least one LED included with said RFID tag by said camera.