METHOD AND APPARATUS FOR USING RFID TAGS TO DETERMINE THE POSTION OF AN OBJECT

• US 20040113787A1
• Filed: 12/12/2002
• Published: 06/17/2004
• Est. Priority Date: 12/12/2002
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Smith, Randall B.
• Granted Patent: US 6,750,769 B1
• Time in Patent Office: Days
• US Class Current: 340/572.1
• CPC Class Codes: G01S 13/751 wherein the responder or reflector radiates a coded signal
• 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
• CPC Class Codes: G08B 13/2402 Electronic Article Surveillance [EAS], i.e. systems using tags for detecting removal of a tagged item from a secure area, e.g. tags for detecting shoplifting mechanical aspects of the tags, e.g. related to locking E05B73/0017; RFID readers G06K7/00; RFID tags G06K19/00; access control systems G07C9/00; anti-theft control in point of sale systems G07G3/003; security seals G09F3/03

Abstract

One embodiment of the present invention provides a system that uses Radio Frequency Identification (RFID) tags to determine the position of an object. During operation, the system receives signals from an array of RFID tags at an RFID tag reader, wherein a mask of known size and shape is interposed between the array of RFID tags and the RFID tag reader, thereby obscuring signals from a subset of the RFID tags. Next, the system determines the position of the object by analyzing the pattern of obscured RFID tags, wherein the analysis is based on a known spatial relationship between the object, the mask and the array of RFID tags.

Claims

1. A method for using Radio Frequency ID (RFID) tags to determine the position of an object, comprising:

receiving RF signals from an array of RFID tags at a RFID tag reader, wherein a mask of known size and shape blocks RF signals from a subset of the array of RFID tags, so that the RF signals from the subset of RFID tags do not reach the RFID tag reader;

determining a pattern of obscured RFID tags in the array of RFID tags; and

analyzing the pattern of obscured RFID tags to determine the position of the object, wherein the analysis is based on a known spatial relationship between the object, the mask and the array of RFID tags.

2. The method of claim 1,

wherein the array of RFID tags resides at a fixed location and the mask of known size and shape is coupled to the object;

and

wherein the physical object is interposed between the array of RFID tags and the RFID tag reader so that the mask obscures the subset of RFID tags.

3. The method of claim 2, wherein the object contains a separate RFID tag that facilitates identifying the object.

4. The method of claim 1,

wherein the mask of known size and shape resides at a fixed location and the array of RFID tags is coupled to the object;

and

wherein the mask of known size and shape is interposed between the object and the RFID tag reader so that a pattern on the mask obscures the subset of RFID tags.

5. The method of claim 4, wherein identifiers received from RFID tags in the array of RFID tags facilitate in identifying the object.

6. The method of claim 1, wherein analyzing the pattern of obscured RFID tags further involves determining the orientation of the object.

7. The method of claim 1, wherein each RFID tag in the array of RFID tags is a passive, unpowered circuit that transmits a unique ID in response to an RF signal.

8. A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for using Radio Frequency ID (RFID) tags to determine the position of an object, the method comprising:

receiving RF signals from an array of RFID tags at a RFID tag reader, wherein a mask of known size and shape blocks RF signals from a subset of the array of RFID tags, so that the RF signals from the subset of RFID tags do not reach the RFID tag reader;

determining a pattern of obscured RFID tags in the array of RFID tags; and

analyzing the pattern of obscured RFID tags to determine the position of the object, wherein the analysis is based on a known spatial relationship between the object, the mask and the array of RFID tags.

9. The computer-readable storage medium of claim 8,

wherein the array of RFID tags resides at a fixed location and the mask of known size and shape is coupled to the object;

and

wherein the physical object is interposed between the array of RFID tags and the RFID tag reader so that the mask obscures the subset of RFID tags.

10. The computer-readable storage medium of claim 9, wherein the object contains a separate RFID tag that facilitates identifying the object.

11. The computer-readable storage medium of claim 8,

wherein the mask of known size and shape resides at a fixed location and the array of RFID tags is coupled to the object;

and

wherein the mask of known size and shape is interposed between the object and the RFID tag reader so that a pattern on the mask obscures the subset of RFID tags.

12. The computer-readable storage medium of claim 11, wherein identifiers received from RFID tags in the array of RFID tags facilitate in identifying the object.

13. The computer-readable storage medium of claim 8, wherein analyzing the pattern of obscured RFID tags further involves determining the orientation of the object.

14. The computer-readable storage medium of claim 8, wherein each RFID tag in the array of RFID tags is a passive, unpowered circuit that transmits a unique ID in response to an RF signal.

15. An apparatus for using Radio Frequency ID (RFID) tags to determine the position of an object, comprising:

a receiving mechanism configured to receive RF signals from an array of RFID tags at a RFID tag reader, wherein a mask of known size and shape blocks RF signals from a subset of the array of RFID tags, so that the RF signals from the subset of RFID tags do not reach the RFID tag reader;

a determination mechanism configured to determine a pattern of obscured RFID tags in the array of RFID tags; and

an analysis mechanism configured to analyze the pattern of obscured RFID tags to determine the position of the object, wherein the analysis is based on a known spatial relationship between the object, the mask and the array of RFID tags.

16. The apparatus of claim 15,

wherein the array of RFID tags resides at a fixed location and the mask of known size and shape is coupled to the object;

and

wherein the physical object is interposed between the array of RFID tags and the RFID tag reader so that the mask obscures the subset of RFID tags.

17. The apparatus of claim 16, wherein the object contains a separate RFID tag that facilitates identifying the object.

18. The apparatus of claim 15,

wherein the mask of known size and shape resides at a fixed location and the array of RFID tags is coupled to the object;

and

wherein the mask of known size and shape is interposed between the object and the RFID tag reader so that a pattern on the mask obscures the subset of RFID tags.

19. The apparatus of claim 18, wherein identifiers received from RFID tags in the array of RFID tags facilitate in identifying the object.

20. The apparatus of claim 15, wherein the analysis mechanism is further configured to determine the orientation of the object.

21. The apparatus of claim 15, wherein each RFID tag in the array of RFID tags is a passive, unpowered circuit that transmits a unique ID in response to an RF signal.

22. A means for using Radio Frequency ID (RFID) tags to determine the position of an object, comprising:

a receiving means for receiving RF signals from an array of RFID tags at a RFID tag reader, wherein a mask of known size and shape blocks RF signals from a subset of the array of RFID tags, so-that the RF signals from the subset of RFID tags does not reach the RFID tag reader;

a determination means for determining a pattern of obscured RFID tags in the array of RFID tags; and

an analysis means for analyzing the pattern of obscured RFID tags to determine the position of the object, wherein the analysis is based on a known spatial relationship between the object, the mask and the array of RFID tags.