Utilization of motion and spatial identification in mobile RFID interrogator

• US 9,047,522 B1
• Filed: 11/06/2010
• Issued: 06/02/2015
• Est. Priority Date: 02/14/2008
• Status: Active Grant

• Current Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Original Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Inventors: Nikitin, Pavel V., Spiess, Gary Neal, Leland, Hunter Martin, Hingst, Lynn Carl, Sherman, John Howland
• Primary Examiner(s): Mehmood, Jennifer
• Assistant Examiner(s): Jiang, Yong Hang
• Application Number:
  US12/941,043
• Time in Patent Office: 1,669 Days
• Field of Search: 340/10.1, 340/10.2, 340/10.3, 340/10.31, 340/10.32, 340/10.4, 340/10.41, 340/10.42, 340/572.1
• US Class Current: 1/1
• 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 7/10009 sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
• 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 7/10108 interrogating only those RFIDs that fulfill a predetermined requirement, e.g. selecting all RFIDs having the same speed and moving in a cloud like fashion, e.g. on the same train; interrogating only RFIDs having a certain predetermined temperature, e.g. in the same fridge, another possibility being the active ignoring of a group of tags that fulfill a predetermined requirement, equivalent to the Boolean NOT operation
• CPC Class Codes: G06K 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas

Abstract

An RFID system is used to detect whether an RFID tag is part of the load of a forklift or other transport device. In one aspect where the load is in motion relative to an RFID reader system, the RFID system obtains tag readings and derives tag vector motion information which can be compared to the known motion of the load to distinguish tags that are part of the load from false positives which are unavoidably also within the field of the reader system. A forklift antenna system may also make readings from load pickup to load deposit in a truck trailer, and utilize computed tag vector motion information to distinguish tags that are part of the load from false positives. The tag vector information my relate to tag velocity, tag acceleration, and/or rate of change of tag acceleration. The two components of the RFID system may communicate information on identified tags, and/or interact (e.g. by silencing tags), so as to cooperate in identifying true positive tags in the load. A portal or reader system location along the path of the forklift can be activated prior to arrival of the load to eliminate certain false positives from requiring evaluation while the forklift load is moving through the field region of such reader system. Vertical motion of the load can be utilized as a way of discriminating between true positive tags in the load and false positives.

Claims

1. A system comprising,

a mobile RFID system which moves with at least one load tag in a load;

and

a fixed RFID system that reads field tags in a field of the fixed RFID system;

wherein the mobile RFID system determines the at least one load tag is in the load by comparing motion parameters of scanned tags read by the mobile RFID system and motion parameters of the field tags read by the fixed RFID system.

2. The RFID system according to claim 1, wherein said fixed RFID system receiving motion parameter information concerning the movement of said mobile RFID system, and utilizing the motion parameter information to aid in distinguishing between tags moving with the load, and extraneous tags which are not part of the load.

3. The RFID system according to claim 1, wherein said fixed RFID system receiving motion parameter information concerning the movement of said mobile RFID system, and utilizing the motion parameter information in the form of a value representing velocity of the load to aid in distinguishing between tags moving with the load, and extraneous tags which are not part of the load.

4. The RFID system according to claim 1, wherein said fixed RFID system receiving motion parameter information concerning the movement of said mobile RFID system, and utilizing the motion parameter information in the form of a value representing acceleration of the load to aid in distinguishing between tags moving with the load, and extraneous tags which are not part of the load.

5. The RFID system according to claim 1, wherein said fixed RFID system receiving motion parameter information concerning the movement of said mobile RFID system, and utilizing the motion parameter information in the form of a value representing rate of change of acceleration of the load to aid in distinguishing between tags moving with the load, and extraneous tags which are not part of the load.

6. The RFID system according to claim 1, wherein said fixed RFID system receiving motion parameter information concerning the movement of said mobile RFID system, and utilizing the motion parameter information in the form of a vector value to aid in distinguishing between tags moving with the load, and extraneous tags which are not part of the load.

7. The RFID system according to claim 1, wherein said fixed RFID system receiving motion parameter information concerning the movement of said mobile system, and utilizing the motion parameter information in the form of a vector value having at least a substantial vertical component reflecting movement of the load with at least a substantial vertical component, to aid in distinguishing between tags moving with the load, and extraneous tags which are not part of the load.

8. The RFID system according to claim 1, wherein said fixed RFID system utilizing its antenna system while the load is not in its field to identify the field tags which are not part of the load.

9. The RFID system according to claim 1, wherein said fixed RFID system silencing the identified field tags that are not part of the load so that the identified field tags do not respond to the mobile RFID system.

10. The RFID system according to claim 1, wherein said mobile RFID system utilizing its mobile antenna system while the load is not in the field of the fixed RFID system to identify tags which are part of the load, and to silence the identified tags that are part of the load so that the identified tags do not respond to a request from the fixed RFID system.

11. A RFID system, comprising:

a reader system that reads field tags in a field of the reader system; and

a decision system providing a decision as to whether the read field tags represent a load tag indicating the load tag is on a load of a moving vehicle or an extraneous tag indicating the extraneous tag is not on the load of the moving vehicle based at least in part on information derived from comparison of movements of the read field tags and movements of the load tags.

12. The RFID system according to claim 11, wherein said decision system further receiving quantitative motion information representing the motion of the load tag for comparison with the information based on the read field tags.

13. The RFID system according to claim 11, wherein said decision system comparing derived quantitative value information representing a time derivative of tag velocity based on tag readings with quantitative motion information representing a corresponding time derivative of velocity for the load tag.

14. The RFID system according to claim 11, wherein said decision system further receiving quantitative motion information as a vector representing the motion of the load tag for comparison with the corresponding vector of the information based on the read field tags.

15. The RFID system according to claim 11, wherein said decision system comparing derived quantitative value information representing as a vector a time derivative of tag velocity based on tag readings with quantitative motion information representing as a vector the corresponding time derivative of velocity for a load tag.

16. The RFID system according to claim 11, wherein said decision system further receiving quantitative motion information as a vector representing the motion of a load tag with at least a substantial component of vertical motion, for comparison with the corresponding vector of the derived quantitative value information based on the read field tags.

17. The RFID system according to claim 11, wherein said antenna system comprising one or more antennas having a rotary component of motion.

18. The RFID system according to claim 11, said antenna system comprising one or more antennas having a successively shifting field pattern.

19. A method of distinguishing a radio frequency identification (“

RFID”

) tag within a load of a vehicle from an extraneous tag, said method comprising;

moving the load of the vehicle through a field of a RFID reader system, wherein the load comprises items that each have load RFID tags;

obtaining, from an RFID system of the vehicle, a load motion parameter which is a function of the movement of the load;

reading, using the RFID reader system, field tags within the field of the RFID reader system during movement of the load through the field of the RFID reader system; and

comparing load motion information for the load based on the load motion parameter with tag motion information derived from the tag readings.

20. The method according to claim 19, wherein said load motion information and said tag motion information representing corresponding time derivatives of velocity.