Method and System for Obtaining Information about RFID-Equipped Objects

• US 20080018475A1
• Filed: 05/30/2007
• Published: 01/24/2008
• Est. Priority Date: 02/16/2001
• Status: Active Grant

• Current Assignee: American Vehicular Sciences LLC (Acacia Research Corporation)
• Original Assignee: Automotive Technologies International Incorporated
• Inventors: Breed, David, DuVall, Wilbur, Johnson, Wendell
• Granted Patent: US 7,911,324 B2
• Time in Patent Office: Days
• US Class Current: 340/572.7
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G06K 17/00 Methods or arrangements for effecting co-operative working between equipments covered by two or more of main groups G06K1/00 - G06K15/00, e.g. automatic card files incorporating conveying and reading operations
• 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
• CPC Class Codes: H01Q 1/2208 associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems methods or arrangements for sensing record carriers, e.g. for reading patterns G06K7/00; record carrier for use with machines and with at least a part designed to carry digital markings G06K19/00

Abstract

Method and arrangement for obtaining information about a radio-frequency identification (RFID) device or an object on which the RFID device is mounted when the RFID device is in a space defined by a frame includes arranging a plurality of antennas on the frame to enable transmission of signals into the space and reception of signals from the space, controlling transmission of signals by the antennas by means of an interrogator, and directing radio frequency signals from at least one of the antennas into the space to cause a RFID device in the space to return a signal if it receives any signal from any of the antennas. The return signals from the RFID device are received, e.g., by the interrogator or an associated receiver, and information about the RFID device or object to which the RFID device is attached is derived based on the return signals.

Claims

1. A method for obtaining information about a radio-frequency identification (RFID) device or an object on which the RFID device is mounted when the RFID device is in a space defined by a frame, comprising:

arranging a plurality of antennas on the frame to enable transmission of signals into the space and reception of signals from the space;

controlling transmission of signals by the antennas by means of an interrogator;

directing radio frequency signals from at least one of the antennas into the space to cause a RFID device in the space to return a signal if it receives any signal from any of the antennas;

receiving the return signals from the RFID device; and

deriving information about the RFID device or an object to which the RFID device is attached based on the return signals.

2. The method of claim 1, wherein the step of arranging the plurality of antennas comprises arranging three antennas on a common side of the space.

3. The method of claim 1, wherein the frame is a cargo container having a pair of opposed side walls, a pair of opposed front and rear walls, a roof and a floor, the step of arranging the plurality of antennas comprising arranging three antennas on the front wall of the frame.

4. The method of claim 1, wherein the frame is a cargo container having a pair of opposed side walls, a pair of opposed front and rear walls, a roof and a floor, the step of arranging the plurality of antennas comprising arranging three antennas on the roof or one of the walls of the frame.

5. The method of claim 1, wherein the step of arranging the plurality of antennas comprises arranging three antennas on the frame in a triangular configuration, further comprising arranging the interrogator within the triangle defined by the antennas.

6. The method of claim 1, wherein the step of arranging the plurality of antennas comprises arranging at least three antennas and the step of deriving information about the RFID device or object to which the RFID device is attached comprises determining a location of the device based on measurements of a distance between each of the antennas and the device.

7. The method of claim 1, further comprising:

arranging a communications device on the frame;

coupling the communications device to the interrogator; and

transmitting the information about the device to a remote site using the communications device.

8. The method of claim 1, wherein the frame is interposed between the interrogator and the space, further comprising arranging at least one RF window on the frame to enable passage of signals between the interrogator and the space.

9. The method of claim 1, wherein the interrogator is separate and apart from the frame, further comprising:

coupling the antennas to an antenna multiplexer;

coupling the antenna multiplexer to an external antenna extending outside of the frame and which communicates with the interrogator; and

controlling transmission and reception of signals by the antennas via the multiplexer.

10. The method of claim 9, further comprising associating each of the antennas with a defined portion of the space, the step of deriving information about the RFID device or object to which the RFID device is attached comprising determining the location of the RFID device by analyzing strength of return signals to all of the antennas to determine which antenna provides the largest return signal whereby the RFID device is considered to be located in that portion of the space associated with the antenna which provides the largest return signal.

11. The method of claim 10, further comprising partitioning the space into a plurality of discrete longitudinal portions, each antenna being associated with only a single one of the portions.

12. The method of claim 1, further comprising:

arranging an electricity-generating system on the frame; and

coupling the electricity-generating system to the interrogator and antennas to provide electricity for operation thereof.

13. The method of claim 1, further comprising:

providing the interrogator and the RFID device with a clock;

arranging the RFID device to synchronize its clock upon reception of any signal from any of the antennas relative to the interrogator'"'"'s clock; and

arranging the RFID device to return the signal if it receives any signal from any of the antennas only after synchronization of its clock to the interrogator'"'"'s clock; and

arranging the interrogator to predict a transmit time at which the RFID device will return a signal after reception of a signal from one of the antennas whose transmission is controlled by the interrogator;

the step of deriving information about the RFID device or the object to which the RFID device is attached comprising analyzing an arrival time of the return signal from the RFID device and the predicted transmit time to enable a measurement of a distance between the RFID device and the antenna to be determined.

14. The method of claim 13, wherein the step of arranging the RFID device to return the signal only after synchronization of its clock to the interrogator'"'"'s clock comprises arranging the RFID device to return the signal at a specific time relative to the reception of the signal from the antenna, at a specific time relative to a time when the signal from the antenna was sent or at a predesignated time.

15. The method of claim 1, wherein the step of directing radio frequency signals from at least one of the antennas into the space comprises directing radio frequency signals from a plurality of antennas into the space, further comprising arranging the RFID device to provide information in the return signal indicative of a phase or relative time of reception of signals from multiple antennas.

16. An asset with an integral system for obtaining information about a radio-frequency identification (RFID) device or an object on which the RFID device is mounted when the RFID device or object is in or in connection with the asset, comprising:

a frame defining an interior space of the asset;

a plurality of antennas arranged on said frame and enabling transmission of radio frequency signals into the space and reception of signals from the space;

an interrogator coupled to said antennas and arranged to control transmission of signals by said antennas whereby when a RFID device in the space receives a transmitted signal, it generates a return signal, said antennas being arranged to receive the return signals generated by any RFID devices in the space; and

a processor coupled to said antennas and said interrogator for receiving and analyzing the return signals received by said antennas to derive information about the RFID device or object on which the RFID device is mounted based on the return signals.

17. The asset of claim 16, wherein said antennas comprise three antennas arranged on a common side of said frame.

18. The asset of claim 16, wherein said frame is a cargo container having a pair of opposed side walls, a pair of opposed front and rear walls, a roof and a floor, said antennas comprising three antennas arranged on said front wall of said frame or on said roof of said frame.

19. The asset of claim 16, wherein said antennas comprise three antennas arranged on said frame in a triangular configuration, said interrogator being arranged within the triangle defined by said three antennas.

20. The asset of claim 16, wherein said antennas comprise at least three antennas and said processor is arranged to determine a location of the RFID device based on measurements of a distance between each of said antennas and the RFID device.

21. The asset of claim 16, further comprising a communications device arranged on said frame and coupled to said interrogator, said communications device being arranged to transmit the information about the RFID device obtained by said processor a remote site.

22. The asset of claim 16, wherein said frame is interposed between said interrogator and the space, said frame including at least one RF window which enables passage of signals between said interrogator and the space.

23. The asset of claim 16, wherein said frame is interposed between said interrogator and said space, further comprising:

an antenna multiplexer coupled to said antennas; and

an external antenna coupled to said antenna multiplexer and extending outside of said frame and communicating with said interrogator, transmission and reception of signals by said antennas being effected through said multiplexer.

24. The asset of claim 16, wherein each of said antennas are spaced from one another along one dimension of said frame, said processor being arranged to determine the location of the RFID device by analyzing strength of return signals to all of said antennas to determine which of said antennas provides the largest return signal whereby the RFID device is considered to be located in a portion of the space associated with said antenna which provides the largest return signal.

25. The asset of claim 16, further comprising an electricity-generating system arranged on said frame and coupled to said interrogator and said antennas to provide electricity for operation thereof.

26. The asset of claim 16, wherein said frame is a frame of a truck, a frame of truck trailer, a frame of shipping container, a frame of a boat, a frame of an airplane or a frame of another vehicle.

27. The asset of claim 16, wherein said interrogator has a clock and the RFID device has a clock, the RFID device being arranged to synchronize its clock upon reception of any signal from any of said antennas relative to said clock of said interrogator and return the signal if it receives any signal from any of said antennas only after synchronization of its clock to said clock of said interrogator, said processor being arranged to predict a transmit time at which the RFID device will return a signal after reception of a signal from one of said antennas whose transmission is controlled by said interrogator and analyze an arrival time of the return signal from the RFID device with the predicted transmit time to enable a measurement of a distance between the RFID device and said antenna to be determined.

28. A monitoring system for monitoring objects in an asset, comprising:

a frame defining an interior space of the asset;

a plurality of antennas arranged on said frame and enabling transmission of radio frequency signals into the space and reception of signals from the space;

a radio-frequency identification (RFID) device arranged in connection with each object to be monitored;

an interrogator coupled to said antennas and arranged to control transmission of signals by said antennas whereby when one of said RFID devices present in the space receives a transmitted signal, it generates a return signal, said antennas being arranged to receive the return signals generated by any of said RFID devices in the space; and

a processor coupled to said antennas and said interrogator for receiving and analyzing the return signals received by said antennas to derive information about said RFID device or object on which said RFID device is mounted based on the return signals.

29. The system of claim 28, wherein said interrogator has a clock and each of said RFID devices has a clock and is arranged to synchronize its clock upon reception of any signal from any of said antennas relative to said clock of said interrogator and return the signal if it receives any signal from any of said antennas only after synchronization of its clock to said clock of said interrogator, said processor being arranged to predict a transmit time at which each of said RFID devices will return a signal after reception of a signal whose transmission is controlled by said interrogator and analyze an arrival time of the return signal from any of said RFID devices with the predicted transmit time to enable a measurement of a distance between said RFID device and said interrogator to be determined.

30. The system of claim 29, wherein each of said RFID devices are arranged to return the signal at a specific time relative to the reception of the signal from any of said antenna, at a specific time relative to a time when the signal from any of said antennas was sent or at a predesignated time.

31. The system of claim 28, wherein said RFID devices are arranged to provide information in the return signal indicative of a phase or relative time of reception of signals from a plurality of said antennas.