Systems and methods for object localization and path identification based on RFID sensing

• US 7,898,419 B2
• Filed: 07/27/2007
• Issued: 03/01/2011
• Est. Priority Date: 07/27/2007
• Status: Active Grant

• Current Assignee: Lucomm Technologies, Inc.
• Original Assignee: Lucomm Technologies, Inc.
• Inventors: Cristache, Lucian
• Primary Examiner(s): Zimmerman; Brian A
• Assistant Examiner(s): Khan; Omer S
• Application Number:
  US11/829,695
• Publication Number:
  US 20090027203A1
• Time in Patent Office: 1,313 Days
• Field of Search: 340/572.1, 340/10.1, 340/10.2
• US Class Current: 340/572.1
• 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 5/0278 involving statistical or probabilistic considerations G01S5/0252, G01S5/0294 take precedence
• CPC Class Codes: G06K 7/10366 the interrogation device being adapted for miscellaneous applications
• CPC Class Codes: H04B 5/77 for interrogation

Abstract

A networked radio frequency identification system includes a plurality of radio frequency identification (RFID) tag readers, a computer in signal communication with the RFID tag readers over a network, and a software module for storage on and operable by the computer that localizes RFID tags based on information received from the RFID tag readers using a network model having endpoints and oriented links. In an additional example, at least one of the RFID tag readers includes an adjustable configuration setting selected from RF signal strength, antenna gain, antenna polarization, and antenna orientation. In a further aspect, the system localizes RFID tags based on hierarchical threshold limit calculations. In an additional aspect, the system controls a locking device associated with an access point based on localization of an authorized RFID tag at the access point and reception of additional authorizing information from an input device.

Claims

1. A networked radio frequency identification system for localizing an RFID tag at an endpoint represented as E.sub.i comprising:

a plurality of radio frequency identification (RFID) tag readers, each RFID tag reader including at least one adjustable setting selected from RF signal strength, antenna gain, antenna polarization, and antenna orientation, and each RFID tag reader including a radio frequency (RF) interrogator;

a computer in signal communication with the plurality of RFID tag readers over a network; and

a software module for storage on and operable by the computer that localizes RFID tags based on information received from the RFID tag readers using hierarchical threshold limit calculations;

wherein the hierarchical threshold limit calculations are based on accumulated reading factors from groups of settings for the RFID tag readers,

wherein the software module is configured to;

collect data for each setting of the RFID tag readers during an interval of time;

calculate an aggregate result for each RFID tag reader based on an algorithm that uses a weighting function that includes W.sub.k,l and NR.sub.k,l as parameters where NR.sub.k,l represents the number of RFID tag readings at an interrogator ‘

k’

configured with a setting ‘

l’ and

W.sub.k,l represents a weighting factor assigned to the interrogator ‘

k’

configured with the setting ‘

l’

, and the algorithm spans all settings ‘

l’

for the interrogator ‘

k’

;

aggregate the calculated aggregate results based on a second weighting function to determine an aggregation result for an endpoint; and

compare the aggregation result for the endpoint to at least one of a threshold value or threshold interval to determine whether the RFID tag is localized at the endpoint.

2. The system of claim 1, wherein groups of the RFID tag readers are configurable to have a group setting and wherein the hierarchical threshold limit calculations are based on accumulated reading factors from settings of groups of RFID tag readers.

3. The system of claim 2, wherein the software module is configured to:

collect data for each group setting of a group of RFID tag readers during an interval of time;

calculate an aggregate result for each group setting based on an algorithm that uses a weighting function that includes W.sub.k,l and NR.sub.k,l as parameters where NR.sub.k,l represents the number of RFID tag readings at an interrogator ‘

k’

configured with a group setting ‘

l’ and

W.sub.k,l represents a weighting factor assigned to the interrogator ‘

k’

configured with the group setting ‘

l’

, and the algorithm spans all group settings ‘

l’

for the interrogator ‘

k’

;

aggregate the calculated aggregate results based on a second weighting function to determine an aggregation result for an endpoint; and

compare the aggregation result for the endpoint to at least one of a threshold value or threshold interval to determine whether the RFID tag is localized at the endpoint.

4. A networked radio frequency identification system for localizing an RFID tag at an endpoint represented as E.sub.i comprising:

a plurality of radio frequency identification (RFID) tag readers, each RFID tag reader including at least one adjustable setting selected from RF signal strength, antenna gain, antenna polarization, and antenna orientation, and each RFID tag reader including a radio frequency (RF) interrogator;

a computer in signal communication with the plurality of RFID tag readers over a network; and

a software module for storage on and operable by the computer that localizes RFID tags based on information received from the RFID tag readers using probabilistic threshold calculations;

wherein the probabilistic threshold calculations are based on accumulated probabilities from groups of settings for RFID tag readers,

wherein the software module is configured to;

collect data for each setting of the RFID tag readers during an interval of time;

calculate an aggregate result for each RFID tag reader based on an algorithm that uses a weighting function that includes W.sub.k,l and P.sub.k,l as parameters where P.sub.k,l=PF.sub.k,l(NR.sub.k,l, C.sub.k,l) is the probability that the RFID tag is at endpoint E.sub.i as detected from interrogator ‘

k’

with settings ‘

l’

calculated with the function PF.sub.k,l with NR.sub.k,l representing the number of RFID tag readings at interrogator ‘

k’

configured with settings ‘

l’ and

C.sub.k,l representing a reference reading value for interrogator ‘

k’

configured with settings ‘

l’ and

where W.sub.k,l represents a weighting factor assigned to the interrogator ‘

k’

configured with the settings ‘

l’

, and the algorithm spans all settings ‘

l’

for the interrogator ‘

k’

;

aggregate the calculated aggregate results based on a second weighting function to determine an aggregation result for an endpoint; and

compare the aggregation result for the endpoint to at least one of a threshold value or threshold interval to determine whether the RFID tag is localized at the endpoint.

5. The system of claim 4, wherein groups of the RFID tag readers are configurable to have a group setting and wherein the probabilistic threshold calculations are based on accumulated probabilities from settings of groups of RFID tag readers.

6. The system of claim 5, wherein the software module is configured to:

collect data for each group setting of a group of RFID tag readers during an interval of time;

calculate an aggregate result for each group setting based on an algorithm that uses a weighting function that includes Wk,l and Pk,l as parameters where P.sub.k,l=PF.sub.k,l(NR.sub.k,l, C.sub.k,l) is the probability that the RFID tag is at endpoint E.sub.i as detected from interrogator ‘

k’

with group settings ‘

l’

calculated with the function PF.sub.k,l with NR.sub.k,l representing the number of RFID tag readings at interrogator ‘

k’

configured with group settings ‘

l’ and

C.sub.k,l representing a reference reading value for interrogator ‘

k’

configured with group settings ‘

I’ and

where W.sub.k,l represents a weighting factor assigned to the interrogator ‘

k’

configured with the group settings ‘

l’

, and the algorithm spans all group settings ‘

l’

for the interrogator ‘

k’

;

aggregate the calculated aggregate results based on a second weighting function to determine an aggregation result for an endpoint; and

compare the aggregation result for the endpoint to at least one of a threshold value or threshold interval to determine whether the RFID tag is localized at the endpoint.

7. A method of localizing an RFID tag using a system that includes a plurality of radio frequency identification (RFID) tag readers each of which includes at least one adjustable configuration setting selected from RF signal strength, antenna gain, antenna polarization, and antenna orientation, a computer in signal communication with the plurality of RFID tag readers over a network, and a software module for storage on and operable by the computer, the method comprising:

collecting data for each setting of the RFID tag readers during an interval of time;

calculating an aggregate result for each RFID tag reader based on an algorithm that uses a weighting function that includes W.sub.k,l and NR.sub.k,l as parameters where NR.sub.k,l represents the number of RFID tag readings at an interrogator ‘

k’

configured with a setting ‘

l’ and

W.sub.k,l represents a weighting factor assigned to the interrogator ‘

k’

configured with the setting ‘

l’

, and the algorithm spans all settings ‘

l’

for the interrogator ‘

k’

;

aggregating the calculated aggregate results based on a second weighting function to determine an aggregation result for an endpoint; and

comparing the aggregation result for the endpoint to at least one of a threshold value or threshold interval to determine whether the RFID tag is localized at the endpoint.

8. A method of localizing an RFID tag using a system that includes a plurality of radio frequency identification (RFID) tag readers which include at least one adjustable group configuration setting selected from RF signal strength, antenna gain, antenna polarization, and antenna orientation, a computer in signal communication with the plurality of RFID tag readers over a network, and a software module for storage on and operable by the computer, the method comprising:

collecting data for each group setting of a group of RFID tag readers during an interval of time;

calculating an aggregate result for each group setting based on an algorithm that uses a weighting function that includes W.sub.k,l and P.sub.k,l as parameters where P.sub.k,l=PF.sub.k,l(NR.sub.k,l, C.sub.k,l) is the probability that the RFID tag is at endpoint E.sub.i as detected from interrogator ‘

k’

with group settings ‘

l’

calculated with the function PF.sub.k,l with NR.sub.k,l representing the number of RFID tag readings at interrogator ‘

k’

configured with group settings ‘

l’ and

C.sub.k,l representing a reference reading value for interrogator ‘

k’

configured with group settings ‘

l’ and

where W.sub.k,l represents a weighting factor assigned to the interrogator ‘

k’

configured with the group settings ‘

l’

, and the algorithm spans all group settings ‘

l’

for the interrogator ‘

k’

;

aggregating the calculated aggregate results based on a second weighting function to determine an aggregation result for an endpoint; and

comparing the aggregation result for the endpoint to at least one of a threshold value or threshold interval to determine whether the RFID tag is localized at the endpoint.

9. A method of localizing an RFID tag using a system that includes a plurality of radio frequency identification (RFID) tag readers which include at least one adjustable group configuration setting selected from RF signal strength, antenna gain, antenna polarization, and antenna orientation, a computer in signal communication with the plurality of RFID tag readers over a network, and a software module for storage on and operable by the computer, the method comprising:

collecting data for each group setting of a group of RFID tag readers during an interval of time;

calculating an aggregate result for each group setting based on an algorithm that uses a weighting function that includes W.sub.k,l and NR.sub.k,l as parameters where NR.sub.k,l represents the number of RFID tag readings at an interrogator ‘

k’

configured with a group setting ‘

l’ and

W.sub.k,l represents a weighting factor assigned to the interrogator ‘

k’

configured with the group setting ‘

l’

, and the algorithm spans all settings ‘

l’

for the interrogator ‘

k’

;

aggregating the calculated aggregate results based on a second weighting function to determine an aggregation result for an endpoint; and

comparing the aggregation result for the endpoint to at least one of a threshold value or threshold interval to determine whether the RFID tag is localized at the endpoint.

10. A method of localizing an RFID tag using a system that includes a plurality of radio frequency identification (RFID) tag readers each of which includes at least one adjustable configuration setting selected from RF signal strength, antenna gain, antenna polarization, and antenna orientation, a computer in signal communication with the plurality of RFID tag readers over a network, and a software module for storage on and operable by the computer, the method comprising:

collecting data for each setting of the RFID tag readers during an interval of time;

calculating an aggregate result for each RFID tag reader based on an algorithm that uses a weighting function that includes W.sub.k,l and P.sub.k,l as parameters where P.sub.k,l=PF.sub.k,l(NR.sub.k,l, C.sub.k,l) is the probability that the RFID tag is at endpoint E.sub.i as detected from interrogator ‘

k’

with settings ‘

l’

calculated with the function PF.sub.k,l with NR.sub.k,l representing the number of RFID tag readings at interrogator ‘

k’

configured with settings ‘

l’ and

C.sub.k,l representing a reference reading value for interrogator ‘

k’

configured with settings ‘

l’ and

where W.sub.k,l represents a weighting factor assigned to the interrogator ‘

k’

configured with the settings ‘

l’

, and the algorithm spans all settings ‘

l’

for the interrogator ‘

k’

;

aggregating the calculated aggregate results based on a second weighting function to determine an aggregation result for an endpoint; and

comparing the aggregation result for the endpoint to at least one of a threshold value or threshold interval to determine whether the RFID tag is localized at the endpoint.