Robust RFID-Based System and Method for Precise In-House Positioning

• US 20070109125A1
• Filed: 07/24/2006
• Published: 05/17/2007
• Est. Priority Date: 07/25/2005
• Status: Active Grant

• Current Assignee: Hong Kong University of Science and Technology
• Original Assignee: Hong Kong University of Science and Technology
• Inventors: LIM, Andrew, DENG, Jiuqing, ZHU, Wenbin, CHE, Chan, ZHANG, Kaicheng
• Granted Patent: US 7,598,865 B2
• Time in Patent Office: Days
• US Class Current: 340/572.100
• CPC Class Codes: G01S 13/876 Combination of several spaced transponders or reflectors of known location for determining the position of a receiver G01S13/874 takes precedence
• CPC Class Codes: G01S 5/02529 not involving signal parameters, i.e. only involving identifiers

Abstract

A robust system, apparatus, and method for precise in-house positioning utilizing RFID (Radio Frequency Identification) technology are described in this invention. The in-house environment is partitioned into separate locations, and a set of RFID tags are scattered in the environment. Reading patterns of RFID tags are collected at each location by an RFID reader as samples. Pattern recognition and classification methods are used, when human, vehicle, or other carrier move around the environment with an RFID reader to estimate its physical location based on the reading pattern. The precision can be within one meter. The method is adaptive to different tag distribution, reader range, defective tags, and other physical constraints.

Claims

1. A method for locating a moving object in an in-door environment, comprising:

receiving signals from a plurality of radio frequency identification (RFID) tags, wherein each of the plurality of RFID tags has an associated identification information transmitted in the signals and the plurality of tags is scattered in the in-door environment with a distribution density high enough to distinguish the in-door environment into a plurality of locations; and

matching a set of associated identification information in the received signals with a set of stored location map to select one location from the plurality of locations for the moving object;

wherein the moving object carrying an RFID antenna and an RFID reader for receiving signals from the plurality of RFID elements and the plurality of RFID elements being only capable of transmitting signals up to a certain distance.

2. The method of claim 1, wherein the associated identification information of each of the plurality of RFID tags comprises a 96-bit string.

3. The method of claim 1, further comprising determining an orientation of the moving object.

4. The method of claim 1, wherein the plurality of the RFID tags is scattered in the ceiling of the in-door environment.

5. The method of claim 1, wherein the matching step further comprises computing

6. The method of claim 1, wherein the matching step further comprises counting all possible locations for each tag from the plurality of RFID tags in the received signals and choosing a location with a maximum number of counts.

7. A method for location identification, comprising:

partitioning an environment into a plurality of locations;

distributing RFID tags in the environment;

validating density of the RFID tags in the environment;

recording sample reads at each of the plurality of locations; and

receiving, by an RFID reader carried on a mobile vehicle, signals from the distributed RFID tags and determining one location from the plurality of locations for the mobile vehicle by comparing the received signals against the recorded sample reads.

8. The method of claim 7, wherein the RFID tags are distributed uniformly in the environment.

9. The method of claim 7, further comprising determining a direction of the mobile vehicle.

10. The method of claim 7, wherein the RFID tags are scattered in the ceiling of the environment.

11. The method of claim 7, wherein the comparing step is performed by a processor mounted on the mobile vehicle.

12. The method of claim 7, wherein the comparing step is performed by a processor connected to the mobile vehicle wirelessly.

13. The method of claim 7, wherein comparing received signals against recorded sample reads further comprises computing

14. The method of claim 7, wherein comparing received signals against recorded sample reads further comprises counting possible locations for the received signals and choosing a location with a maximum number of counts.

15. An in-door location identification system, comprising:

an RFID antenna mounted on a mobile vehicle;

an RFID reader in communication with the RFID antenna for receiving information from a plurality of RFID tags currently within a coverage range of the RFID antenna; and

a location determination processor in electronic communication with the RFID reader for determining a location for the mobile vehicle, said location determination processor having access to pre-recorded sample reads and determining the location for the mobile vehicle by comparing the pre-recorded sample reads with received information from the plurality of RFID tags.

16. The system of claim 15, wherein the plurality of RFID tags is distributed uniformly in an in-door environment.

17. The system of claim 15, wherein the plurality of RFID tags is distributed non-uniformly in an in-door environment.

18. The system of claim 15, wherein the location determination processor further determines an orientation of the mobile vehicle.

19. The system of claim 15, wherein the plurality of the RFID tags are scattered in the ceiling of the in-door environment.

20. The system of claim 15, wherein the location determination processor is connected to the RFID reader with a network cable.