RFID TAG LOCATIONING USING DYNAMIC BEACON TAG ASSOCIATION

• US 20160139237A1
• Filed: 11/13/2014
• Published: 05/19/2016
• Est. Priority Date: 11/13/2014
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: WULFF, THOMAS E., CONNOLLY, SEAN A.
• Granted Patent: US 9,733,335 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01S 13/751 wherein the responder or reflector radiates a coded signal
• CPC Class Codes: G01S 13/82 wherein continuous-type signals are transmitted
• CPC Class Codes: G01S 3/14 Systems for determining direction or deviation from predetermined direction aerial arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00; combinations of different interacting aerial units for giving a desired directional characteristic H01Q21/29; aerials or aerial systems providing at least two radiation patterns H01Q25/00
• CPC Class Codes: G01S 5/0284 Relative positioning
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: G06K 7/10009 sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
• CPC Class Codes: G06Q 10/08 Logistics, e.g. warehousing, loading or distribution; Inventory or stock management
• CPC Class Codes: G06V 40/10 Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
• CPC Class Codes: G07C 2209/63 Comprising locating means for detecting the position of the data carrier, i.e. within the vehicle or within a certain distance from the vehicle
• CPC Class Codes: G07C 2209/64 using a proximity sensor

Abstract

A method and apparatus for determining the position of a RFID tag. The method includes the following: (1) measuring the position of an active device to an accuracy of better than 1.0 meter using a radio locating system to determine the position of a reference point; (2) detecting a first RF signal from a reference RFID tag near the reference point with an RF receiver in an RFID reading system; (3) detecting a second RF signal from a RFID tag of interest with the RF receiver in the RFID reading system; and (4) processing both the first RF signal and the second RF signal and relying upon at least partially the position of the reference point to determine the position of the RFID tag of interest.

Claims

1. A method for using with radio frequency identification (RFID) tags comprising:

measuring the position of an active device to an accuracy of better than 1.0 meter using a radio locating system to determine the position of a reference point;

detecting a first RF signal from a reference RFID tag with an RF receiver in an RFID reading system, wherein the reference RFID tag is located essentially at the same position of the reference point, with the distance between the reference RFID tag and the reference point being less than 0.2 meter, and wherein the distance between the reference RFID tag and the RF receiver in the RFID reading system is more than 3.0 meter;

detecting a second RF signal from a RFID tag of interest with the RF receiver in the RFID reading system; and

processing both the first RF signal and the second RF signal and relying upon at least partially the position of the reference point to determine the position of the RFID tag of interest.

2. The method of claim 1, wherein the radio locating system comprises:

a plurality of radio locating devices distributed at multiple locations.

3. The method of claim 1, wherein said processing comprises at least one of:

processing the difference between the time stamp of the first RF signal and the time stamp of the second RF signal;

processing the difference between the received signal strength indicator (RSSI) of the first RF signal and the RSSI of the second RF signal; and

processing the difference between the phase of the first RF signal and the phase of the second RF signal.

4. The method of claim 1, wherein said processing comprises:

processing both the first RF signal and the second RF signal to determine an offset between the position of the RFID tag of interest and the position of the reference point.

5. The method of claim 1, wherein said measuring the position of the active device comprises at least one of:

measuring the angle of arrival of a radio signal; and

measuring the angle of departure of a radio signal.

6. The method of claim 1, wherein said measuring the position of the active device comprises:

measuring the time of flight of a radio signal.

7. The method of claim 1, wherein the reference RFID tag and the RFID tag of interest have substantially identical antenna design.

8. The method of claim 1, wherein the reference RFID tag and the RFID tag of interest have substantially identical backscattering characteristics at the RF frequency of an interrogating signal from the RFID reading system.

9. The method of claim 1, wherein both the reference RFID tag and the RFID tag of interest are passive RFID devices.

10. The method of claim 1, wherein the active device is a mobile computing device including one of a smartphone, a tablet computer, a smart badge, and a smart watch.

11. The method of claim 1, wherein the active device is configured to establish wireless connections with the radio locating system based upon a standard including one of BLUETOOTH™

and ZIGBEE™

.

12. The method of claim 1, further comprising:

transmitting from the active device to the radio locating system one or more digital communication packet containing the Electronic Product Code (EPC) of the reference RFID tag.

13. The method of claim 1, wherein the active device has a media access control address (MAC address) for establishing digital communication with the radio locating system.

14. The method of claim 13, further comprising:

transmitting from the reference RFID tag to the RFID reading system the MAC address of the active device.

15. The method of claim 1, further comprising:

triggering beacon activity on the active device with a radio signal from one of the RFID tags including the reference RFID tag and the RFID tag of interest.

16. The method of claim 15, further comprising:

generating said radio signal from said one of the RFID tags in response to said one of the RFID tags being interrogated by the RFID reading system.

17. The method of claim 1, wherein the distance between the reference RFID tag and the reference point is less than 0.1 meter.

18. The method of claim 1, wherein the distance between the reference RFID tag and the reference point is less than 0.05 meter.

19. The method of claim 1, wherein the distance between the reference RFID tag and the reference point is less than 0.01 meter.

20. An apparatus for using with radio frequency identification (RFID) tags comprising:

a radio locating system configured to measure the position of an active device to an accuracy of better than 1.0 meter to determine the position of a reference point;

an RFID reading system having a RF receiver configured to detect a first RF signal from a reference RFID tag that is more than 3.0 meter away from said RF receiver, wherein the reference RFID tag is located essentially at the same position of the reference point, with the distance between the reference RFID tag and the reference point being less than 0.2 meter, and wherein said RF receiver in the RFID reading system is further configured to detect a second RF signal from a RFID tag of interest; and

a controller configured to process both the first RF signal and the second RF signal and relying upon at least partially the position of the reference point to determine the position of the RFID tag of interest.

21. The apparatus of claim 20, wherein the radio locating system comprises:

a plurality of radio locating devices distributed at multiple locations.

22. The apparatus of claim 20, wherein the controller is configured to process at least one of:

the difference between the time stamp of the first RF signal and the time stamp of the second RF signal;

the difference between the received signal strength indicator (RSSI) of the first RF signal and the RSSI of the second RF signal; and

the difference between the phase of the first RF signal and the phase of the second RF signal.

23. The apparatus of claim 20, wherein the controller is configured to process both the first RF signal and the second RF signal to determine an offset between the position of the RFID tag of interest and the position of the reference point.

24. The apparatus of claim 20, wherein the radio locating system is configured to measure the angle of arrival of a radio signal to measure the position of the active device.

25. The apparatus of claim 20, wherein the radio locating system is configured to measure the angle of departure of a radio signal to measure the position of the active device.

26. The apparatus of claim 20, wherein the radio locating system is configured to measure the time of flight of a radio signal to measure the position of the active device.

27. The apparatus of claim 20, wherein the reference RFID tag and the RFID tag of interest have substantially identical antenna design.

28. The apparatus of claim 20, wherein the reference RFID tag and the RFID tag of interest have substantially identical backscattering characteristics at the RF frequency of an interrogating signal from the RFID reading system.

29. The apparatus of claim 20, wherein both the reference RFID tag and the RFID tag of interest are passive RFID devices.

30. The apparatus of claim 20, wherein the active device has a battery therein.

31. The apparatus of claim 20, wherein the active device is a mobile computing device including one of a smartphone, a tablet computer, and a smart watch.

32. The apparatus of claim 20, wherein the active device is configured to establish wireless connections with the radio locating system based upon a standard including one of BLUETOOTH™

and ZIGBEE™

.

33. The apparatus of claim 20, wherein the active device is configured to transmit to the radio locating system one or more digital communication packet containing the Electronic Product Code (EPC) of the reference RFID tag.

34. The apparatus of claim 20, wherein the active device has a media access control address (MAC address) for establishing digital communication with the radio locating system.

35. The apparatus of claim 34, wherein the reference RFID tag is configured to transmit to the RFID reading system the MAC address of the active device.

36. The apparatus of claim 20, wherein the active device is configured to start beacon activity upon triggering by a radio signal from one of the RFID tags including the reference RFID tag and the RFID tag of interest.