METHOD AND SYSTEMS FOR LOCALIZING OBJECTS USING PASSIVE RFID TAGs

• US 20090121843A1
• Filed: 04/04/2007
• Published: 05/14/2009
• Est. Priority Date: 05/15/2006
• Status: Active Grant

• Current Assignee: ServiceNow Incorporated
• Original Assignee: International Business Machines Corporation
• Inventors: Marmigere, Gerard, Clement, Jean-Yves, Bauchot, Frederic, Picon, Joaquin
• Granted Patent: US 8,159,350 B2
• Time in Patent Office: Days
• US Class Current: 340/10.310
• 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: G06K 7/10336 the antenna being of the near field type, inductive coil
• CPC Class Codes: G06K 7/10346 the antenna being of the far field type, e.g. HF types or dipoles
• CPC Class Codes: G06K 7/10861 sensing of data fields affixed to objects or articles, e.g. coded labels postal sorting B07C3/14, conveying articles B65G47/48

Abstract

Method and system for localizing an object in a stack of objects. A passive radio frequency identification (RFID) tag is attached to each object. Each RFID tag includes a unique identifier of the object to which the RFID tag is attached. A RFID reader has multiple antennas. Each antenna is positioned to transmit a signal that can be detected by different RFID tags attached to the objects within a reading range of the transmitted signal from each antenna. The antennas are sequentially selected and powered to transmit to the stack a read signal including object'"'"'s identifier for the object to be localized. If a response to the read signal is received by a selected and powered antenna from a RFID tag that matched the object'"'"'s identifier with its unique identifier, then a light emitting diode (LED) is lighted to identify a location of the object being localized.

Claims

1-13. -13. (canceled)

14. A method for localizing an object in a stack of objects, said method comprising determining a location of the object being localized, wherein a radio frequency identification (RFID) tag is attached to each object, wherein each RFID tag is a passive RFID tag that comprises a unique identifier of the object to which each RFID tag is attached and further comprises a respective light emitting diode (LED) and a chip configured to control the LED, wherein a RFID reader comprises a plurality of antennas, wherein each antenna is positioned differently and configured to transmit a read signal comprising a read command that can be detected by only a different plurality of RFID tags attached to the objects in the stack of objects within a reading range of the transmitted signal from each antenna, and wherein said determining the location of the object comprises:

said RFID reader selecting an antenna of the plurality of antennas, said selected antenna not previously selected by the RFID reader;

said RFID reader powering the selected antenna;

said RFID reader transmitting, via the selected and powered antenna, the read signal comprising the read command to the stack, wherein the read signal comprises an identifier of one object in the stack, and wherein the one object is the object being localized in the stack;

after said transmitting, said RFID reader waiting for a first specified period of time for a response to the read signal from a responsive RFID tag that detected the read signal and determined that the identifier of the one object in the read signal matches the unique identifier in the responsive RFID tag comprised by the one object;

if said RFID reader receives the response during the first specified period of time via the selected and powered antenna, then said RFID reader powering the selected antenna for a second specified period of time which triggers the selected and powered antenna to transmit another read signal to the responsive RFID tag to cause the responsive RFID tag to light its respective LED during the second specified period of time for a duration sufficient for a user to see the lighted LED during the second specified period of time, wherein the second specified period of time immediately follows the first specified period of time;

if said RFID reader does not receive the response during the first specified period of time, then said RFID reader stop powering the selected antenna, deselecting the selected antenna, and repeating said selecting, said powering, said transmitting, and said waiting for another antenna of the plurality of antennas until the selected antenna results in said RFID reader receiving the response during the first specified period of time,

wherein said RFID reader receives the response during the first specified period of time for one selected antenna of the selected antennas.

15. The method of claim 14, wherein the one selected antenna is selected during a first performance of said selecting.

16. The method of claim 14, wherein the one selected antenna is not selected during a first performance of said selecting, and wherein the one selected antenna is selected during a performance of said selecting subsequent to the first performance of said selecting.

17. The method of claim 14, said determining the location of the object further comprising determining that the response received from the responsive RFID tag is greater than any response received by the RFID reader from any other RFID tag attached to an object in the stack.

18. The method of claim 14, wherein the different plurality of RFID tags in the reading range of each antenna of the plurality of antennas does not include any RFID tag in the reading range of any other antenna of the plurality of antennas.

19. The method of claim 14, wherein the different plurality of RFID tags in the reading range of a first antenna of the plurality of antennas includes a RFID tag in the reading range of a second antenna of the plurality of antennas.

20. The method of claim 14, wherein each object in the stack is a compact disc, wherein the compacts discs in the stack are oriented parallel to one another, and wherein the LEDs comprised by the respective RFID tags attached to the objects in the stack are aligned parallel to one another and are simultaneously visible to a user.

21. A system for localizing an object in a stack of objects, said system comprising a RFID reader, wherein a radio frequency identification (RFID) tag is attached to each object, wherein each RFID tag is a passive RFID tag that comprises a unique identifier of the object to which each RFID tag is attached and further comprises a respective light emitting diode (LED) and a chip configured to control the LED, wherein the RFID reader comprises a plurality of antennas, wherein each antenna is positioned differently and configured to transmit a read signal comprising a read command that can be detected by only a different plurality of RFID tags attached to the objects in the stack of objects within a reading range of the transmitted signal from each antenna, wherein the RFID reader is configured to implement a method comprising determining a location of the object being localized, and wherein said determining the location of the object comprises:

said RFID reader selecting an antenna of the plurality of antennas, said selected antenna not previously selected by the RFID reader;

said RFID reader powering the selected antenna;

said RFID reader transmitting, via the selected and powered antenna, the read signal comprising the read command to the stack, wherein the read signal comprises an identifier of one object in the stack, and wherein the one object is the object being localized in the stack;

after said transmitting, said RFID reader waiting for a first specified period of time for a response to the read signal from a responsive RFID tag that detected the read signal and determined that the identifier of the one object in the read signal matches the unique identifier in the responsive RFID tag comprised by the one object;

if said RFID reader receives the response during the first specified period of time via the selected and powered antenna, then said RFID reader powering the selected antenna for a second specified period of time which triggers the selected and powered antenna to transmit another read signal to the responsive RFID tag to cause the responsive RFID tag to light its respective LED during the second specified period of time for a duration sufficient for a user to see the lighted LED during the second specified period of time, wherein the second specified period of time immediately follows the first specified period of time;

if said RFID reader does not receive the response during the first specified period of time, then said RFID reader stop powering the selected antenna, deselecting the selected antenna, and repeating said selecting, said powering, said transmitting, and said waiting for another antenna of the plurality of antennas until the selected antenna results in said RFID reader receiving the response during the first specified period of time,

wherein said RFID reader receives the response during the first specified period of time for one selected antenna of the selected antennas.

22. The system of claim 21, wherein the one selected antenna is selected during a first performance of said selecting.

23. The system of claim 21, wherein the one selected antenna is not selected during a first performance of said selecting, and wherein the one selected antenna is selected during a performance of said selecting subsequent to the first performance of said selecting.

24. The system of claim 21, said determining the location of the object

further comprising determining that the response received from the responsive RFID tag is greater than any response received by the RFID reader from any other RFID tag attached to an object in the stack.

25. The system of claim 21, wherein the different plurality of RFID tags in the reading range of each antenna of the plurality of antennas does not include any RFID tag in the reading range of any other antenna of the plurality of antennas.

26. The system of claim 21, wherein the different plurality of RFID tags in the reading range of a first antenna of the plurality of antennas includes a RFID tag in the reading range of a second antenna of the plurality of antennas.

27. The system of claim 21, wherein each object in the stack is a compact disc, wherein the compacts discs in the stack are oriented parallel to one another, and wherein the LEDs comprised by the respective RFID tags attached to the objects in the stack are aligned parallel to one another and are simultaneously visible to a user.

28. A method for localizing an object in a stack of objects, said method comprising determining a location of the object being localized, wherein a radio frequency identification (RFID) tag is attached to each object, wherein each RFID tag is a passive RFID tag that comprises a unique identifier of the object to which each RFID tag is attached, wherein a RFID reader comprises a plurality of antennas, wherein each antenna is positioned differently and configured to transmit a read signal comprising a read command that can be detected by only a different plurality of RFID tags attached to the objects in the stack of objects within a reading range of the transmitted signal from each antenna, wherein each antenna is coupled to an associated light emitting diode (LED), and wherein said determining the location of the object comprises:

performing a process for each antenna of the plurality of antennas, said process for each antenna comprising;

said RFID reader selecting each antenna from the plurality of antennas, said selected antenna not previously selected by the RFID reader;

said RFID reader powering the selected antenna;

said RFID reader transmitting, via the selected and powered antenna, the read signal comprising the read command to the stack, wherein the read signal comprises an identifier of one object in the stack, and wherein the one object is the object being localized in the stack;

after said transmitting, said RFID reader waiting for a specified period of time for a response to the read signal from a responsive RFID tag that detected the read signal and determined that the identifier of the one object in the read signal matches the unique identifier in the responsive RFID tag comprised by the one object;

if said RFID reader receives the response during the specified period of time via the selected and powered antenna, then said RFID reader recording a signal level of the response and associating the recorded signal level with the selected antenna,

wherein said RFID reader has received the response during the specified period of time for one or more antennas of the selected antennas;

after said performing said process for all antennas of the plurality of antennas, said RFID reader ascertaining at least one antenna of the one or more antennas as being associated with a highest recorded signal level of the recorded signal levels; and

after said ascertaining, said RFID reader lighting the LED associated with each antenna of the at least one antenna.

29. The method of claim 28, wherein the different plurality of RFID tags in the reading range of each antenna of the plurality of antennas does not include any RFID tag in the reading range of any other antenna of the plurality of antennas.

30. The method of claim 28, wherein the different plurality of RFID tags in the reading range of a first antenna of the plurality of antennas includes a RFID tag in the reading range of a second antenna of the plurality of antennas.

31. The method of claim 28, wherein each object in the stack is a compact disc, wherein the compacts discs in the stack are oriented parallel to one another, and wherein the LEDs comprised by the respective RFID tags attached to the objects in the stack are aligned parallel to one another and are simultaneously visible to a user.

32. The method of claim 28, wherein the at least one antenna consists of at least two antennas.

33. A system for localizing an object in a stack of objects, said system comprising a RFID reader, wherein a radio frequency identification (RFID) tag is attached to each object, wherein each RFID tag is a passive RFID tag that comprises a unique identifier of the object to which each RFID tag is attached, wherein the RFID reader comprises a plurality of antennas, wherein each antenna is positioned differently and configured to transmit a read signal comprising a read command that can be detected by only a different plurality of RFID tags attached to the objects in the stack of objects within a reading range of the transmitted signal from each antenna, wherein each antenna is coupled to an associated light emitting diode (LED), wherein the RFID reader is configured to implement a method comprising determining a location of the object being localized, and wherein said determining the location of the object comprises:

performing a process for each antenna of the plurality of antennas, said process for each antenna comprising;

said RFID reader selecting each antenna from the plurality of antennas, said selected antenna not previously selected by the RFID reader;

said RFID reader powering the selected antenna;

said selected and powered antenna transmitting the read signal comprising the read command to the stack, said read signal comprising an identifier of one object in the stack, wherein the one object is the object being localized in the stack;

after said transmitting, said RFID reader waiting for a specified period of time for a response to the read signal from a responsive RFID tag that detected the read signal and determined that the identifier of the one object in the read signal matches the unique identifier in the responsive RFID tag comprised by the one object;

if said RFID reader receives the response during the specified period of time via the selected and powered antenna, then said RFID reader recording a signal level of the response and associating the recorded signal level with the selected antenna,

wherein said RFID reader has received the response during the specified period of time for one or more antennas of the selected antennas;

after said performing said process for all antennas of the plurality of antennas, said RFID reader ascertaining at least one antenna of the one or more antennas as being associated with a highest recorded signal level of the recorded signal levels; and

after said ascertaining, said RFID reader lighting the LED associated with each antenna of the at least one antenna.

34. The system of claim 33, wherein the different plurality of RFID tags in the reading range of each antenna of the plurality of antennas does not include any RFID tag in the reading range of any other antenna of the plurality of antennas.

35. The system of claim 33, wherein the different plurality of RFID tags in the reading range of a first antenna of the plurality of antennas includes a RFID tag in the reading range of a second antenna of the plurality of antennas.

36. The system of claim 33, wherein each object in the stack is a compact disc, wherein the compacts discs in the stack are oriented parallel to one another, and wherein the LEDs comprised by the respective RFID tags attached to the objects in the stack are aligned parallel to one another and are simultaneously visible to a user.

37. The system of claim 33, wherein the at least one antenna consists of at least two antennas.