Systems and methods to determine motion parameters using RFID tags

摘要

Systems and methods to determine motion parameters of physical objects using radio frequency identification (RFID) tags attached to the objects. In one embodiment, a method implemented in a radio frequency identification (RFID) system includes determining a motion parameter of the RFID tag based on detecting a Doppler frequency shift in a radio frequency signal received from the RFID tag.

主权项

1. A system, comprising:
a plurality of devices disposed in a field, each respective device in the plurality of devices having a memory to store an identifier to uniquely identify the respective device among the plurality of devices, the respective device configured to selectively respond to radio frequency signals broadcast to the field based on the identifier stored in the memory and commands modulated on the radio frequency signals; and a reader having a data processing system and configured to:
transmit at least one first radio frequency signal to the plurality of devices to request a first device having a first identifier in the plurality of devices to response to a subsequent radio frequency signal and to request second devices having second identifiers different from the first identifier in the plurality of devices to generate no response to the subsequent radio frequency signal;transmit the subsequent radio frequency signal, in response to which the first device having the first identifier is configured to provide at least one second radio frequency signal;receive a first signal of the at least one second radio frequency signal using a first antenna disposed at a first location;receive a second signal of the at least one second radio frequency signal using a second antenna disposed at a second location;determine a frequency difference between the first signal received at the first antenna and the second signal received at the second antenna;determine the Doppler frequency shift from the frequency difference; anddetermine a motion of the first device, based on the Doppler frequency shift.