RFID sensor array

• US 7,614,555 B2
• Filed: 09/09/2004
• Issued: 11/10/2009
• Est. Priority Date: 09/09/2004
• Status: Active Grant

• Current Assignee: The Gillette Company LLC (The Procter & Gamble Company)
• Original Assignee: Gillette Company (The Procter & Gamble Company)
• Inventors: Dubash, Jamshed H., Sullivan, Michael S.
• Primary Examiner(s): WALSH, DANIEL I
• Application Number:
  US10/936,971
• Publication Number:
  US 20060049249A1
• Time in Patent Office: 1,888 Days
• Field of Search: 340/572.1, 340/572.4, 340/825.69, 340/825.72, 340/539.1, 340/573.1, 340/539.32, 340/539.2, 340/539.21, 340/539.13, 235/435, 235/487, 235/492, 235/493, 235/451, 455/404.2, 455/456.1
• US Class Current: 235/451
• CPC Class Codes: G06K 17/0022 arrangements or provisious for transferring data to distant stations, e.g. from a sensing device "transfer between computer elements G06F13/00 "; data-transmission H04L
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10079 the collision being resolved in the spatial domain, e.g. temporary shields for blindfolding the interrogator in specific directions

Abstract

An RFID performance monitoring system may include systems, methods, or computer program products for collecting information related to the performance of an RFID system. One source of performance-related information can be the RFID readers, both during an active (reading) period and an inactive (listening) period. In various embodiments described herein, a performance monitoring system may collect performance-related information from RFID readers during both during their active and inactive periods.

Claims

1. A method of monitoring an environment in which a radio frequency identification (RFID) system tracks the movement of articles through a supply chain, each article having attached thereto an RFID tag, the method comprising:

electromagnetically receiving first information that comprises the signal strength of a detected radio frequency (RF) signal at one or more of a plurality of RFID readers (readers) that are located within the environment, wherein the received first information is sent from one or more detecting readers that were not attempting to read any RFID tags while the RF signal was being detected;

storing into a memory device values representing a level of interference with RFID system performance, wherein each stored value is based on the received first information; and

electromagnetically locating the source of the detected RF signal, wherein locating the source of the detected RF signal comprises estimating the relative position of the source of the detected RF signal based on the relative strengths of the detected RF signal at each reader and predetermined information about the positions of each of the detecting readers.

2. The method of claim 1, further comprising if any one of the stored values exceeds a corresponding predetermined thresholds during a read attempt, performing a corrective action.

3. The method of claim 2, wherein the corrective action comprises repeating one or more attempts to read tags that were made while one or more of the stored values exceeded a predetermined threshold, the repeating being performed after the stored values fall below a second predetermined threshold.

4. The method of claim 2, wherein the corrective action comprises adjusting the power level of one or more readers.

5. The method of claim 2, wherein the corrective action comprises selecting two or more readers to multiplex based on the stored values, and operating the selected readers to attempt to read RFID tags only at non-overlapping times.

6. The method of claim 2, wherein the corrective action comprises sending a predetermined signal for display on a display device.

7. The method of claim 2, wherein the corrective action comprises displaying a two-dimensional reader collision map based on the received first information.

8. The method of claim 1, wherein estimating the relative position of the source of the detected RF signal is further based on a characterization map, the characterization map being based on RF signal strength measurements of a known RF signal source at a plurality of predetermined positions in the environment.

9. The method of claim 1, wherein estimating the relative position of the source of the detected RF signal comprises calculating the approximate location of the source of the detected RF signal from the received first information sent by at least two detecting readers whose positions are known.

10. A method of monitoring an environment in which a radio frequency identification (RFID) system tracks the movement of articles through a supply chain, each article having attached thereto an RFID tag, the method comprising:

electromagnetically receiving first information that comprises the signal strength of a detected radio frequency (RF) signal at one or more of a plurality of RFID readers (readers) that are located within the environment, wherein the received first information is sent from one or more detecting readers that were not attempting to read any RFID tags while the RF signal was being detected;

storing into a memory device one or more values representing a level of interference with RFID system performance, wherein each stored value comprises a measurement of the RF signal strength detected at a corresponding one of the detecting readers;

if any one of the stored values exceeds a corresponding predetermined threshold during a read attempt, performing a corrective action; and

electromagnetically locating the source of the detected RF signal by estimating the relative position of the source of the detected RF signal based on the relative strengths of the detected RF signal at each reader, wherein the corrective action comprises repeating one or more attempts to electromagnetically read tags while any one of the stored values exceeded the corresponding predetermined threshold, the repeating being performed after the strength of the detected RF signal falls below a second predetermined threshold.

11. The method of claim 10, wherein the corrective action further comprises adjusting the power level of one or more readers.

12. The method of claim 10, wherein estimating the relative position of the source of the detected RF signal is further based on predetermined information about the positions of each of the detecting readers.

13. The method of claim 12, wherein estimating the relative position of the source of the detected RF signal is further based on a characterization map, the characterization map being based on RF signal strength measurements at the detecting readers of a known RF signal source, the measurements being made with the known RF signal source at a plurality of predetermined positions in the environment.

14. A method of monitoring an environment in which a radio frequency identification (RFID) system tracks the movement of articles through a supply chain, each article having attached thereto an RFID tag, the method comprising:

electromagnetically sending a command to one of a plurality of RFID readers (readers) in the RFID system to transmit a radio frequency (RF) signal encoded with information that identifies the transmitting reader;

electromagnetically receiving first information that comprises information about the signal strength of a detected radio frequency (RF) signal at one or more of a plurality of readers that are located within the environment, wherein the received first information further comprises information that identifies the transmitting reader, and the received first information is sent from one or more detecting readers that were not attempting to read any RFID tags while the RF signal was being detected;

storing into a memory device one or more values representing a level of interference with RFID system performance, wherein each stored value comprises a measurement of the RF signal strength detected at a corresponding one of the detecting readers;

if any one of the stored values exceeds a corresponding predetermined threshold, then;

(1) selecting two or more readers to multiplex based the stored values; and

(2) operating the selected readers to attempt to read RFID tags only at non-overlapping times; and

displaying a two-dimensional reader collision map based on the received first information.

15. The method of claims 14, wherein the stored value associated with one of the selected readers comprises a cumulative strength of the combination of RF signals that could be detected if all the other selected readers were operated to read tags at overlapping times.

16. The method of claim 14, further comprising repeating the steps of the method during operation of the RFID system.

17. A method of monitoring an environment in which a radio frequency identification (RFID) system tracks the movement of articles through a supply chain, each article having attached thereto an RFID tag, the method comprising:

electromagnetically receiving first information that comprises the signal strength of a detected radio frequency (RF) signal at one or more of a plurality of RFID readers (readers) that are located within the environment, wherein the received first information is sent from one or more detecting readers that were not attempting to read any RFID tags while the RF signal was being detected;

storing into a memory device values representing a level of interference with RFID system performance, wherein each stored value is based on the received first information; and

if any one of the stored values exceeds a corresponding predetermined threshold during a electromagnetically read attempt, performing a corrective action comprising repeating one or more attempts to electromagnetically read tags that were made while one or more of the stored values exceeded a predetermined threshold, the repeating being performed after the stored values fall below a second predetermined threshold.

18. The method of claim 17, wherein the stored level of interference comprises a measurement of the RF signal strength detected at each of the detecting readers.

19. The method of claim 17, further comprising sending a command to one of the readers in the RFID system to transmit an RF signal encoded with information that identifies the transmitting reader.

20. The method of claim 19, wherein the received first information further comprises information that identifies the transmitting reader.

21. The method of claim 20, further comprising if the strength of the RF signal detected at one of the detecting readers exceeds a predetermined threshold, then operating the detecting reader and the transmitting reader to attempt to read RFID tags only at non-overlapping times.

22. The method of claim 20, further comprising selecting two or more readers to multiplex based on the stored values, and operating the selected readers to attempt to read RFID tags only at non-overlapping times.

23. The method of claim 22, wherein storing the values for each selected reader comprises storing a value representing the cumulative level of interference associated with the combined effect of RF signals that may be transmitted by one or more of the selected readers if operated to read tags at the same time.

24. The method of claim 17, further comprising repeating the steps of the method during operation of the RFID system.

25. A method of monitoring an environment in which a radio frequency identification (RFID) system tracks the movement of articles through a supply chain, each article having attached thereto an RFID tag, the method comprising:

electromagnetically receiving first information that comprises the signal strength of a detected radio frequency (RF) signal at one or more of a plurality of RFID readers (readers) that are located within the environment, wherein the received first information is sent from one or more detecting readers that were not attempting to read any RFID tags while the RF signal was being detected;

storing into a memory device values representing a level of interference with RFID system performance, wherein each stored value is based on the received first information; and

if any one of the stored values exceeds a corresponding predetermined threshold during a read attempt, performing a corrective action comprising displaying a two-dimensional reader collision map based on the received first information.

26. A method of monitoring an environment in which a radio frequency identification (RFID) system tracks the movement of articles through a supply chain, each article having attached thereto an RFID tag, the method comprising:

electromagnetically receiving first information comprising a signal strength of a detected radio frequency (RF) signal at one or more of a plurality of RFID readers (readers) that are located within the environment and information that identifies the transmitting reader, wherein the received first information is sent from one or more detecting readers that were not attempting to read any RFID tags while the RF signal was being detected;

storing into a memory device values representing a level of interference with RFID system performance, wherein each stored value is based on the received first information;

sending a command to one of the readers in the RFID system to transmit an RF signal encoded with information that identifies the transmitting reader;

if the strength of the RF signal detected at one of the detecting readers exceeds a predetermined threshold, then operating the detecting reader and the transmitting reader to attempt to read RFID tags only at non-overlapping times; and

selecting two or more readers to multiplex based on the stored values, and operating the selected readers to attempt to read RFID tags only at non-overlapping times, wherein storing the values for each selected reader comprises storing a value representing the cumulative level of interference associated with the combined effect of RF signals that may be transmitted by one or more of the selected readers if operated to read tags at the same time.