Methods and systems of determining physical characteristics associated with objects tagged with RFID tags

• US 7,859,408 B2
• Filed: 03/28/2007
• Issued: 12/28/2010
• Est. Priority Date: 03/28/2007
• Status: Expired due to Fees

• Current Assignee: Round Rock Research LLC
• Original Assignee: Round Rock Research LLC
• Inventors: Tuttle, John R
• Primary Examiner(s): Bugg; George A
• Assistant Examiner(s): MCNALLY, KERRI L
• Application Number:
  US11/692,538
• Publication Number:
  US 20080238685A1
• Time in Patent Office: 1,371 Days
• Field of Search: 340/572.7, 340/572.1, 340/10.1
• US Class Current: 340/572.1
• CPC Class Codes: G01S 13/62 Sense-of-movement determination G01S13/589 takes precedence
• CPC Class Codes: G01S 13/74 Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
• CPC Class Codes: G01S 7/024 using polarisation effects in waveguides H01P1/165; for aerials H01Q, e.g. H01Q15/22, H01Q15/24, H01Q19/195

Abstract

Methods and systems of determining physical characteristics associated with objects tagged with Radio Frequency Identification (RFID) tags. At least some of the illustrative embodiments are methods comprising making a first reading of a RFID tag coupled to an object (an electromagnetic signal received from the RFID tag having a first received signal strength indication (RSSI)), making a second reading of the RFID tag (an electromagnetic signal received from the RFID tag having a second RSSI), and a determining whether the object is moving using (at least in part) the first and second RSSI. Other illustrative embodiments, may determine (in addition to or in place of determining movement) orientation of the object based, at least in part, on the electromagnetic signals.

Claims

1. A computer implemented method comprising:

receiving, using a computing device, a first electromagnetic signal from a radio frequency identification (RFID) tag coupled to an object;

calculating a first received signal strength indication (RSSI) based on the first electromagnetic signal;

receiving a second electromagnetic signal from the RFID tag;

calculating a second RSSI based on the second electromagnetic signal;

determining whether the object is moving using, at least in part, the first and second RSSI; and

determining a rotational orientation of the RFID tag by receiving the first electromagnetic signal with a particular polarization and determining which side of the RFID tag faces a reading antenna.

2. The method of claim 1 wherein the determining whether the object is moving further comprises determining whether the object is moving toward or away from the reading antenna, the determining based, at least in part, on the first and second RSSI.

3. The method of claim 1 wherein each of the receiving a first electromagnetic signal and the receiving a second electromagnetic signal further comprises receiving from the RFID tag having an antenna being one or more selected from the group consisting of:

a dipole antenna;

a loop antenna;

a patch antenna; and

a dual-sided patch antenna.

4. The method of claim 1 wherein determining the rotational orientation of the RFID tag further comprises one or more selected from the group consisting of:

receiving a value from the RFID tag that indicates which side of the RFID tag faces the reading antenna; and

receiving the electromagnetic signal with the particular polarization, the polarization indicating which side of the RFID tag faces the reading antenna.

5. A system comprising:

a frequency identification (RFID) tag configured to couple to an object;

a reading antenna in operational relationship to the RFID tag; and

a reader circuit coupled to the reading antenna, the reader circuit configured to generate a received signal strength indication (RSSI) for each interrogation of the RFID tag;

wherein the system is configured to determine whether the RFID tag is moving based on RSSI as between two interrogations of the RFID tag;

wherein the RFID tag has two faces;

wherein the system is configured to determine which face of the RFID tag is exposed to the reading antenna;

wherein the RFID tag further comprises a dual-sided patch antenna, each particular patch of the dual-sided patch antenna transmits an electromagnetic signal when the particular patch is interrogated;

wherein the system is configured to determine which face of the RFID tag is exposed to the reading antenna based on the electromagnetic signal corresponding to the interrogated patch.

6. The system of claim 5 wherein the reader circuit is configured to determine whether the RFID tag is moving.

7. The system of claim 5 further comprising an electronic system coupled to the reader circuit, wherein the electronic system is configured to determine whether the RFID tag is moving.

8. The system of claim 5 wherein the system is configured to determine a direction of movement of the RFID tag.

9. The system of claim 8 wherein the system is configured to determine whether the RFID tag is moving toward or away from the reading antenna based, at least in part, on RSSI as between two interrogations.

10. The system of claim 5 wherein the system is configured to determine orientation of the object by determining which side of the RFID tag faces the reading antenna.

11. The system of claim 5 wherein the system is configured to determine which face of the RFID tag is exposed to the reading antenna based on data payload encoded in the electromagnetic signal corresponding to the interrogated patch.

12. The system of claim 5 wherein the system is configured to determine which face of the RFID tag is exposed to the reading antenna based on a polarization of the electromagnetic signal corresponding to the interrogated patch.

13. The system of claim 12 further comprising:

wherein the reading antenna comprises;

a first antenna having a first polarization; and

a second antenna having a second polarization different than the first polarization;

wherein the system is configured to determine polarization of the electromagnetic signals based, at least in part, on which of the first or second antennas have greater RSSI for the electromagnetic signal corresponding to the interrogated patch.

14. A system comprising:

a frequency identification (RFID) tag configured to couple to an object;

a reading antenna in operational relationship to the RFID tag; and

a reader circuit coupled to the reading antenna, the reader circuit configured to generate a received signal strength indication (RSSI) for each interrogation of the RFID tag;

wherein the system is configured to determine whether the RFID tag is moving based on RSSI as between two interrogations of the RFID tag;

wherein the RFID tag couples to a first side of the object;

a second RFID tag couples to a second side of the object;

wherein the system is configured to determine which side of the object faces the reading antenna;

wherein the RFID tag has a tag antenna with a first polarization;

wherein the second RFID tag has a tag antenna with a second polarization different than the first polarization; and

wherein the system is configured to determine which RFID tag faces the reading antenna based on polarization of an electromagnetic signal received by the reading antenna.

15. The system of claim 14 further comprising:

wherein the RFID tag has a first identification value;

wherein the second RFID tag has a second identification value different than the first identification value; and

wherein the system is configured to determine which RFID tag faces the reading antenna based on which of the first or second identification values are received from an interrogation.

16. The system of claim 14 further comprising an electronic system coupled to the reader circuit, wherein the electronic system is configured to determine whether the RFID tag or the second RFID tag is moving.

17. The system of claim 14 wherein the system is configured to determine a direction of movement of the RFID tag or the second RFID tag.

18. The system of claim 14 wherein the system is configured to determine whether the RFID tag or the second RFID tag is moving toward or away from the reading antenna based, at least in part, on RSSI as between two interrogations.

19. The system of claim 14 wherein the system is configured to determine orientation of the object by determining which of the RFID tag or the second RFID tag faces the reading antenna.

20. The system of claim 14 wherein the system is configured to determine orientation of the object by determining which of a plurality of RFID tags faces the reading antenna.

21. The system of claim 14 wherein the first polarization or the second polarization is vertical electric field polarization.

22. The system of claim 14 wherein the first polarization or the second polarization is horizontal electric field polarization.

23. A system comprising:

a frequency identification (RFID) tag configured to couple to an object;

a reading antenna in operational relationship to the RFID tag; and

a reader circuit coupled to the reading antenna, the reader circuit configured to generate a received signal strength indication (RSSI) for each interrogation of the RFID tag;

wherein the system is configured to determine whether the RFID tag is moving based on RSSI as between two interrogations of the RFID tag;

wherein the system is configured to determine rotational orientation of the RFID tag by determining;

polarization of an electromagnetic signal, and

which of a plurality of RFID tags faces the reading antenna.

24. The system of claim 23 further comprising:

wherein the reading antenna further comprises;

a first antenna having a first polarization; and

a second antenna having a second polarization different than the first polarization;

wherein the system is configured to determine the rotational orientation of the RFID tag based, at least in part, on portions of the electromagnetic signal received by each of the first and second receiving antennas.

25. The system of claim 23 wherein a determination whether the object is moving toward or away from the reading antenna is based, at least in part, on a first and a second RSSI.

26. The system of claim 23 wherein the RFID tag comprises an antenna being one or more selected from the group consisting of a dipole antenna;

a loop antenna;

a patch antenna; and

a dual-sided patch antenna.

27. The system of claim 23 wherein the polarization is vertical electric field polarization.

28. The system of claim 23 wherein the polarization is horizontal electric field polarization.

29. A tangible machine-readable medium having stored thereon a set of instructions which when executed perform a method comprising:

receiving a first electromagnetic signal from a radio frequency identification (RFID) tag coupled to an object, wherein the RFID tag is one of a plurality of RFID tags;

calculating a first received signal strength indication (RSSI) based on the first electromagnetic signal;

receiving a second electromagnetic signal from the RFID tag;

calculating a second RSSI based on the second electromagnetic signal;

determining whether the object is moving using, at least in part, the first and second RSSI; and

determining rotational orientation of the RFID tag by receiving the first electromagnetic signal with a particular polarization, indicative of the rotational orientation of the RFID tag and determining which of the plurality of RFID tags faces a reading antenna.

30. The machine-readable medium of claim 29 wherein the determining whether the object is moving further comprises determining whether the object is moving toward or away from the reading antenna, the determining based, at least in part, on the first and second RSSI.

31. The machine-readable medium of claim 29 wherein each of the receiving a first electromagnetic signal and the receiving a second electromagnetic signal further comprises receiving from the RFID tag having an antenna being one or more selected from the group consisting of:

a dipole antenna;

a loop antenna;

a patch antenna; and

a dual-sided patch antenna.

32. The machine-readable medium of claim 29 wherein determining the rotational orientation of the RFID tag further comprises one or more selected from the group consisting of:

receiving an identification value that indicates which of the plurality of RFID tags faces the reading antenna; and

receiving the first electromagnetic signal with the particular polarization, wherein the polarization indicates which of the plurality of RFID tags faces the reading antenna.