Method and apparatus for location estimation

• US 20070201421A1
• Filed: 04/30/2007
• Published: 08/30/2007
• Est. Priority Date: 12/09/2005
• Status: Active Grant

• Current Assignee: Ademco Inc. (Resideo Technologies, Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: Huseth, Steve
• Granted Patent: US 7,733,836 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/0258 by combining or switching between measurements derived from different systems
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

In one embodiment, a method of estimating location of a mobile beaconing device within a building includes steps: concurrently transmitting from the beaconing device at least first and second signals, which respectively indicates at least first and second transmit power levels thereof; receiving the at least first and second signals by a plurality of anchor devices at different known locations; estimating first distances between the beaconing device and each anchor device as a function of signal power levels of the first signal received by each anchor device, and second distances between the beaconing device and each anchor device as a function of signal power levels of the second signal received by each anchor devices; and calculating an estimated location of the beaconing device as a function of the estimated first distances and second distances.

Claims

1. A method of estimating location of a beaconing device within a building, comprising:

concurrently transmitting from the beaconing device at least first and second signals respectively indicating at least first and second transmit power levels thereof;

receiving the at least first and second signals by a plurality of anchor devices at different known locations;

estimating first distances between the beaconing device and each anchor device as a function of signal power levels of the first signal received by each anchor device, and second distances between the beaconing device and each anchor device as a function of signal power levels of the second signal received by each anchor devices; and

calculating an estimated location of the beaconing device as a function of the estimated first distances and second distances.

2. The method of claim 1, further comprising:

when calculating the estimated location of the beaconing device, assigning a weighting factor to each estimated distance as a function of the transmit power level transmitted from the beaconing device and the corresponding signal power level received by each anchor device, wherein the weighting factor to each estimated distance using a lower power level weights over the weighting factor using a higher power level.

3. The method of claim 1, further comprising:

periodically repeating transmission of the at least first and second signals from the beaconing device at a constant time interval.

4. The method of claim 3, wherein the constant time interval is in a range from 0.5 second to 1 minute.

5. The method of claim 1, wherein each signal is radio frequency (RF) signal.

6. The method of claim 1, wherein calculating the estimated location of the beaconing device is performed by solving:

$\begin{array}{c}{J}_{\mathrm{ik}}=\sqrt{{\left(X_i-X_b\right)}^2+{\left(Y_i-Y_b\right)}^2+{\left(Z_i-Z_b\right)}^2}-d_{\mathrm{ik}}\\ \underset{X_b,Y_b,Z_b}{\min }<br><br>\underset{i=1,k=1}{\overset{\mathrm{nxm}}{\sum <br><br>}}<br><br>W_{\mathrm{ik}}<br><br>J_{\mathrm{ik}}^2\end{array}$

where

i is an index identifying one of the known locations;

k is an index identifying one of the transmit power levels transmitted from the beaconing device;

n is number of the known locations;

m is number of the transmit power levels transmitted from the beaconing device;

X_b, Y_b and Z_b are estimated Euclidian coordinates of the beaconing device;

X_i, Y_i and Z_i are Euclidean coordinates of the known location i;

d_ik is an estimated distance between the beaconing device and the known location i as a function of a transmit power level of index k transmitted from the beaconing device and signal power level received by the anchor device i; and

W_ik is a weighting factor as a function of a transmit power level of index k transmitted from the beaconing device and a corresponding signal power level received by the anchor device i, wherein W_ik decreases while the power level of index k increases.

7. The method of claim 6, wherein

$W_{\mathrm{ik}}=\frac{\mathrm{the}}{}$

 

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signal ⁢

 

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strength ⁢

 

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received ⁢

 

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by ⁢

 

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the ⁢

 

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anchor ⁢

 

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device ⁢

 

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i the ⁢

 

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transmit ⁢

 

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power ⁢

 

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level ⁢

 

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of ⁢

 

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index ⁢

 

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k .

8. The method of claim 6, wherein

$W_{\mathrm{ik}}=\exp$

( the ⁢

 

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signal ⁢

 

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strength ⁢

 

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received ⁢

 

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by ⁢

 

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the ⁢

 

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anchor ⁢

 

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device ⁢

 

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i the ⁢

 

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transmit ⁢

 

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power ⁢

 

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level ⁢

 

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of ⁢

 

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index ⁢

 

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k ) .

9. The method of claim 6, wherein

$W_{\mathrm{ik}}={(\frac{\mathrm{the}}{}}^{}$

 

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signal ⁢

 

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strength ⁢

 

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received ⁢

 

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by ⁢

 

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the ⁢

 

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anchor ⁢

 

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device ⁢

 

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i the ⁢

 

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transmit ⁢

 

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power ⁢

 

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level ⁢

 

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of ⁢

 

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index ⁢

 

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k ) p .

10. A method of estimating location of a mobile beaconing device within a building, comprising:

concurrently transmitting from a plurality of anchor devices at different known locations at least first and second signals, each signal indicates a transmit power level thereof and an identifier of each anchor device;

receiving the at least first and second signals by the beaconing device;

estimating first distances between the beaconing device and each anchor device as a function of signal power levels of the first signal transmitted from each anchor device, and second distances between the beaconing device and each anchor device as a function of signal power levels of the second signal transmitted from each anchor device; and

calculating an estimated location of the beaconing device as a function of the estimated first distances and second distances.

11. The method of claim 10, further comprising:

when calculating the estimated location of the beaconing device, assigning a weighting factor to each estimated distance as a function of the transmit power level transmitted from each anchor device and the corresponding signal power level received by the beaconing device, wherein the weighting factor to each estimated distance using a lower power level weights over the weighting factor using a higher power level.

12. The method of claim 10, further comprising:

periodically repeating transmission of the at least first and second signals from each anchor device at a constant time interval.

13. The method of claim 10, wherein calculating the estimated location of the beaconing device is performed by solving:

$\begin{array}{c}{J}_{\mathrm{ik}}=\sqrt{{\left(X_i-X_b\right)}^2+{\left(Y_i-Y_b\right)}^2+{\left(Z_i-Z_b\right)}^2}-d_{\mathrm{ik}}\\ \underset{X_b,Y_b,Z_b}{\min }<br><br>\underset{i=1,k=1}{\overset{\mathrm{nxm}}{\sum <br><br>}}<br><br>W_{\mathrm{ik}}<br><br>J_{\mathrm{ik}}^2\end{array}$

where

i is an index identifying one of the known locations;

k is an index identifying one of the signal transmitted from each anchor device;

n is number of the known locations;

m is number of the power levels transmitted from each anchor device;

X_b, Y_b and Z_b are estimated Euclidian coordinates of the beaconing device;

X_i, Y_i and Z_i are Euclidean coordinates of the known location i;

d_ik is an estimated distance between the beaconing device and the known location i as a function of a transmit power level of index k from the anchor device i and a corresponding signal power level received by the beaconing device; and

W_ik is a weighting factor as a function of a transmit power level of index k from the anchor device i and a corresponding signal power level received by the beaconing device, wherein W_ik decreases while the power level of index k increases.

14. A system for estimating location of a mobile beaconing device within a building, comprising:

a beaconing device for concurrently transmitting at least first and second signals, each signal indicating the transmit power level thereof;

a plurality of anchor devices positioned at different known locations for receiving the at least first and second signals;

a first circuit for estimating first distances between the beaconing device and each anchor device as a function of signal power levels of the first signal received by each anchor device, and second distances between the beaconing device and each anchor device as a function of signal power levels of the second signal received by each anchor devices; and

a second circuit for calculating a estimated location of the beaconing device as a function of the estimated first distances and second distances.

15. The system of claim 14, wherein the second circuit assigns a weighting factor, when calculating the estimated location of the beaconing device, to each estimated distance as a function of the transmit power level transmitted from each anchor device and the corresponding signal power level received by the beaconing device, wherein the weighting factor to each estimated distance using a lower power level weights over the weighting factor using a higher power level.

16. The system of claim 14, wherein the beaconing device periodically repeats transmission of the at least first and second signals from each anchor device at a constant time interval.

17. The system of claim 14, wherein the second circuit calculates the estimated location of the beaconing device by solving:

$J_{\mathrm{ik}}=\sqrt{{\left(X_i-X_b\right)}^2+{\left(Y_i-Y_b\right)}^2+{\left(Z_i-Z_b\right)}^2}-d_{\mathrm{ik}}$ $\underset{X_b,Y_b,Z_b}{\min }<br><br>\underset{i=1,k=1}{\overset{n\times <br><br>m}{\sum <br><br>}}<br><br>W_{\mathrm{ik}}<br><br>J_{\mathrm{ik}}^2$

where

i is an index identifying one of the known locations;

k is an index identifying one of the transmit power levels transmitted from the beaconing device;

n is number of the known locations;

m is number of the transmit power levels transmitted from the beaconing device;

X_b, Y_b and Z_b are estimated Euclidian coordinates of the beaconing device;

X_i, Y_i and Z_i are Euclidean coordinates of the known location i;

d_ik is an estimated distance between the beaconing device and the known location i as a function of a transmit power level of index k transmitted from the beaconing device and signal power level received by the anchor device i; and

W_ik is a weighting factor as a function of a transmit power level of index k transmitted from the beaconing device and a corresponding signal power level received by the anchor device i, wherein W_ik decreases while the power level of index k increases.

18. A system for estimating location of a mobile beaconing device within a building, comprising:

a plurality of anchor devices at different known locations for concurrently transmitting at least first and second signals, each signal indicates a transmit power level thereof and an identifier of each anchor device;

a beaconing device for receiving the at least first and second signals transmitted from the plurality of anchor devices;

a first circuit for estimating first distances between the beaconing device and each anchor device as a function of signal power levels of the first signal transmitted from each anchor device, and second distances between the beaconing device and each anchor device as a function of signal power levels of the second signal transmitted from each anchor device; and

a second circuit for calculating an estimated location of the beaconing device as a function of the estimated first distances and second distances.

19. The system of claim 18, wherein the second circuit assigns a weighting factor, when calculating the estimated location of the beaconing device, to each estimated distance as a function of the transmit power level transmitted from each anchor device and the corresponding signal power level received by the beaconing device, wherein the weighting factor to each estimated distance using a lower power level weights over the weighting factor using a higher power level.

20. The system of claim 18, wherein each anchor device periodically repeats transmission of the at least first and second signals at a constant time interval.