PRECISION LOCATION METHOD AND SYSTEM

• US 20120293372A1
• Filed: 01/19/2011
• Published: 11/22/2012
• Est. Priority Date: 01/20/2010
• Status: Active Grant

• Current Assignee: Worcester Polytechnic Institute
• Original Assignee: Worcester Polytechnic Institute
• Inventors: Duckworth, R. James, Cyganski, David, Amendolare, Vincent Thomas
• Granted Patent: US 9,658,309 B2
• Time in Patent Office: Days
• US Class Current: 342/451
• CPC Class Codes: G01S 5/0205 Details
• CPC Class Codes: G01S 5/0226 Transmitters
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 4/33 for indoor environments, e.g. buildings

Abstract

Systems and methods for locating an object are disclosed herein. The locator system includes a plurality of reference units and a processor in communication with the reference units. The reference units are positioned about a region in which a mobile unit is located, and each reference unit includes a transceiver for transmitting and receiving a transaction-based location signal to and from the mobile unit. The processor is configured for estimating time offsets between the mobile unit and reference units and aligning the transaction-based location signals from the reference units by removing the time offsets. The processor is further configured for collectively processing data representative of the aligned location signals based on a plurality of potential locations to identify at least one of the potential locations as a likely mobile unit location.

Claims

1. A system for locating an object, comprising:

a plurality of reference units for positioning about a region in which a mobile unit is located, each reference unit including a transceiver for transmitting and receiving a transaction-based location signal to and from the mobile unit; and

at least one processor configured for;

estimating time offsets between the mobile unit and the plurality of reference units;

aligning the transaction-based location signals by removing the time offsets; and

collectively processing data representative of the aligned location signals received from the plurality of reference units based on a plurality of potential locations to identify at least one of the potential locations as a likely mobile unit location.

2. The system of claim 1, wherein the collective processing of the representative data comprises:

creating a matrix of range rephased signals from the plurality of received location signals at each of the plurality of potential mobile unit locations; and

identifying at least one potential location of the plurality of potential locations at which the magnitude of the range rephased signal has a maximum DC component relative to a remainder of the potential locations.

3. The system of claim 1, further comprising a display in communication with the processor for displaying the at least one identified position.

4. The system of claim 1, wherein the representative data corresponding to a location signal comprises a frequency domain representation of the location signal.

5. The system of claim 1, wherein the representative data corresponding to a location signal comprises samples of the location signal.

6. The system of claim 1, further comprising a mobile unit for transmitting and receiving a plurality of transaction-based location signals;

7. The system of claim 6, wherein the system further comprises a second mobile unit for transmitting a second location signal and the processor is configured to determine the location of the second mobile unit.

8. The system of claim 1, wherein each reference unit receives a second location signal from a second mobile unit, and distinguishes the location signal and the second location signal based upon a predetermined timing difference between the location signal and the second location signal, and wherein each reference unit transmits data representative of the received location signal and the second location signal as they are received by the respective reference unit.

9. The system of claim 1, wherein each reference unit receives a second location signal from a second mobile unit, and distinguishes the location signal and the second location signal based upon a predetermined difference in frequencies of the location signal and the second location signal, and wherein each reference unit transmits data representative of the received location signal and the second location signal as they are received by the respective reference unit.

10. The system of claim 1, wherein each reference unit receives a second location signal from a second mobile unit, and wherein each reference unit transmits data representative of the received location signal and the second location signal as they are received by the respective reference unit.

11. The system of claim 1, wherein the system further comprises a plurality of wireless transmitters for transmitting a plurality of location signals.

12. The system of claim 1, wherein collectively processing data representative of the aligned signals comprises:

creating a matrix R where the columns of the matrix R are frequency domain data of the aligned signals;

iterating through a set of hypothetical time delays by selecting a hypothetical time delay at each iteration; and

creating a rephased version of matrix R at each hypothetical position.

13. A system for locating an object comprising:

a plurality of reference units for positioning about a region in which a mobile unit is located, each reference unit including a transceiver for transmitting and receiving unaligned transaction-based location signals to and from the mobile unit; and

at least one processor for;

estimating time offsets between the mobile unit and the plurality of reference units;

aligning the transaction-based location signals by removing the time offsets; and

collectively processing data representative of the unaligned location signals and the aligned location signals to identify at least one of the potential locations as a likely mobile unit location, wherein collectively processing data comprises;

calculating a first metric at the plurality of potential locations based on the aligned signals;

calculating a second metric at the plurality of positional locations based on unaligned signals; and

calculating a posterior probability distribution at the plurality of potential locations based at least the first metric and the second metric.

14. A method for locating an object, comprising:

positioning a plurality of reference units about a region in which a mobile unit is located, each reference unit including a transceiver for transmitting and receiving a transaction-based location signal to and from the mobile unit;

estimating time offsets between the mobile unit and the plurality of reference units;

aligning the transaction-based location signals by removing the time offsets; and

collectively processing data representative of the aligned location signals received from the plurality of reference units based on a plurality of potential locations to identify at least one of the potential locations as a likely mobile unit location.

15. The method of claim 14, wherein the collective processing of the representative data comprises:

creating a matrix of range rephased signals from the plurality of received location signals at each of the plurality of potential mobile unit locations; and

identifying at least one potential location of the plurality of potential locations at which the magnitude of the range rephased signal has a maximum DC component relative to a remainder of the potential locations.

16. The method of claim 14, further comprising displaying the at least one identified position.

17. The method of claim 14, wherein the representative data corresponding to a location signal comprises a frequency domain representation of the location signal.

18. The method of claim 14, wherein the representative data corresponding to a location signal comprises samples of the location signal.

19. The method of claim 14, further comprising identifying at least one potential location of a second mobile unit.

20. The method of claim 14, further comprising receiving a second location signal from a second mobile unit, and wherein each reference unit transmits data representative of the received location signal and the second location signal as they are received by the respective reference unit.

21. The method of claim 14, wherein collectively processing data representative of the aligned signals comprises:

creating a matrix R where the columns of the matrix R are frequency domain data of the aligned signals;

iterating through a set of hypothetical time delays by selecting a hypothetical time delay at each iteration; and

creating a rephased version of matrix R at each hypothetical position.

22. A method for locating an object, comprising:

estimating time offsets between a mobile unit and a plurality of reference units;

aligning transaction-based location signals by removing the time offsets; and

collectively processing data representative of unaligned location signals and the aligned location signals to identify at least one of the potential locations as a likely mobile unit location, wherein collectively processing data comprises;

calculating a first metric at the plurality of potential locations based on the aligned signals;

calculating a second metric at the plurality of positional locations based on unaligned signals; and

calculating a posterior probability distribution at the plurality of potential locations based at least the first metric and the second metric.