Multiple object localisation with a network of receivers

• US 8,004,464 B2
• Filed: 01/16/2009
• Issued: 08/23/2011
• Est. Priority Date: 01/18/2008
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Koutsogiannis, Grigorios, Machowski, Wojciech
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): McGue; Frank
• Application Number:
  US12/863,563
• Publication Number:
  US 20100295723A1
• Time in Patent Office: 949 Days
• Field of Search: 342/453
• US Class Current: 342/453
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence

Abstract

A technique is described for determining the correct locations of a plurality of objects by processing signals emitted by a transmitter and reflected by the objects to a plurality of receivers, No angle or elevation information is used. Object-receiver pair time difference of arrival measurements are made to calculate the time difference of arrival between the signals received at each pair of receivers from each object. Hyperbolic localisation is then performed to identify possible locations for each object. Direct-reflected signal time reception measurements are made for each receiver-object pair to calculate the time difference between the reception by the receiver of the direct signal from the transmitter and the signal reflected by the object. The direct-reflected signal time reception measurements are associated with the object-receiver pair time difference of arrival measurements, and the results are used to identify the correct object positions by associating the locations determined by the hyperbolic localisation to the direct-reflected signal time reception measurements.

Claims

1. A method of determining the positions of a plurality of objects by processing signals emitted from at least one transmitter, reflected by the objects and received by a plurality of receivers, the method comprising:

processing signals from the receivers to generate a respective object-receiver pair time difference of arrival measurement for each object and each pair of receivers comprising the time difference of arrival between the signals received at each of the receivers in the pair from the object;

processing the generated object-receiver pair time difference of arrival measurements to calculate a respective hyperbola for each object and each pair of receivers with the positions of the receivers as foci points and the hyperbola defining the set of possible positions for the object;

calculating the intersections of the generated hyperbolae and identifying the intersections corresponding to possible positions for each individual object, wherein each possible position is either a true position or a phantom position;

processing signals from the receivers to generate a direct-reflected signal time reception measurement for each receiver-object pair comprising the time difference between the reception by the receiver of the direct signal from the transmitter and the reception by the receiver of the signal reflected by the object;

associating the generated direct-reflected signal time reception measurements with the generated object-receiver pair time difference of arrival measurements to generate measurement association results; and

determining the true positions of the objects by relating the calculated intersections of the generated hyperbolae to the generated direct-reflected signal time reception measurements using the measurement association results.

2. A method according to claim 1, wherein the object-receiver pair time difference of arrival measurements are generated by performing cross-correlation of the signals from the receivers.

3. A method according to claim 1, wherein the direct-reflected signal time reception measurements are generated by performing auto-correlation of the signals from the receivers.

4. A method according to claim 1, wherein the processing to associate the generated direct-reflected signal time reception measurements with the generated object-receiver pair time difference of arrival measurements comprises:

combining the direct-reflected signal time reception measurements for the same object, to generate a first set of combined values;

calculating object-receiver pair time difference of arrival combined values corresponding to the direct-reflected signal time reception combined values, thereby generating a second set of combined values; and

comparing the first and second sets of combined values to associate the direct-reflected signal time reception measurements with the object-receiver pair time difference of arrival measurements.

5. A method according to claim 4, wherein the direct-reflected signal time reception measurements are combined by calculating, for each object and each pair of receivers, the difference between the direct-reflection signal time reception measurement for the object and the first receiver in the pair and the direct-reflected signal time reception measurement for the object and the second receiver in the pair.

6. A method according to claim 4, wherein the object-receiver pair time difference of arrival combined values are calculated in dependence upon the calculated intersections of the generated hyperbolae.

7. A method according to claim 6, wherein the object-receiver pair time difference of arrival combined values are calculated in dependence upon the distance between the intersections of the generated hyperbolae and the points corresponding to the positions of the receivers.

8. A method according to claim 1, wherein the processing to determine the positions of the objects by relating the calculated intersections of the generated hyperbolae to the generated direct-reflected signal time reception measurements comprises:

calculating an objective number by evaluating at least one testing function of the direct-reflected signal time reception measurements;

for each of a plurality of combinations of possible object positions identified from the hyperbolae, evaluating at least one hypothesis function corresponding to the testing function to calculate an hypothesised number for the combination of possible object positions; and

selecting the combination of possible object positions for which the difference between the hypothesised number and the objective number is smallest.

9. A method according to claim 8, wherein the objective number is calculated by evaluating a testing function comprising at least one direct-reflected signal time reception measurement for each object and at least one direct-reflected signal time reception measurement for each receiver.

10. Apparatus for determining the positions of a plurality of objects by processing signals emitted from at least one transmitter, reflected by the objects and received by a plurality of receivers, the apparatus comprising:

an object-receiver pair time difference of arrival calculator operable to process signals from the receivers to generate a respective object-receiver pair time difference of arrival measurement for each object and each pair of receivers comprising the time difference of arrival between the signals received at each of the receivers in the pair from the object;

an hyperbolae processor operable to process the generated object-receiver pair time difference of arrival measurements to calculate a respective hyperbola for each object and each pair of receivers with the positions of the receivers as foci points and the hyperbola defining the set of possible positions for the object, and further operable to calculate the intersections of the generated hyperbolae and identify the intersections corresponding to possible positions for each individual object, wherein each possible position is either a true position or a phantom position;

a direct-reflected signal time difference calculator operable to process signals from the receivers to generate a direct-reflected signal time reception measurement for each receiver-object pair comprising the time difference between the reception by the receiver of the direct signal from the transmitter and the reception by the receiver of the signal reflected by the object; and

a time measurement associator operable to associate the generated direct-reflected signal time reception measurements with the generated object-receiver pair time difference of arrival measurements to generate measurement association results, and further operable to determine the true positions of the objects by relating the calculated intersections of the generated hyperbolae to the generated direct-reflected signal time reception measurements using the measurement association results.

11. Apparatus according to claim 10, wherein the object-receiver pair time difference of arrival calculator is operable to generate the object-receiver pair time difference of arrival measurements by performing cross-correlation of the signals from the receivers.

12. Apparatus according to claim 10, wherein the direct-reflected signal time difference calculator is operable to generate the direct-reflected signal time reception measurements by perfoiming auto-correlation of the signals from the receivers.

13. Apparatus according to claim 10, wherein the time measurement associator comprises:

a measurement combiner operable to combine the direct-reflected signal time reception measurements for the same object, to generate a first set of combined values;

a combined value calculator operable to calculate object-receiver pair time difference of arrival combined values corresponding to the direct-reflected signal time reception combined values, thereby generating a second set of combined values; and

a comparer operable to compare the first and second sets of combined values to associate the direct-reflected signal time reception measurements with the object-receiver pair time difference of arrival measurements.

14. Apparatus according to claim 13, wherein the measurement combiner is operable to combine the direct-reflected signal time reception measurements by calculating, for each object and each pair of receivers, the difference between the direct-reflection signal time reception measurement for the object and the first receiver in the pair and the direct-reflected signal time reception measurement for the object and the second receiver in the pair.

15. Apparatus according to claim 13, wherein the combined value calculator is operable to calculate the values in dependence upon the calculated intersections of the generated hyperbolae.

16. Apparatus according to claim 15, wherein the combined value calculator is operable to calculate the values in dependence upon the distance between the intersections of the generated hyperbolae and the points corresponding to the positions of the receivers.

17. Apparatus according to claim 10, wherein the time measurement associator comprises:

an objective number calculator operable to calculate an objective number by evaluating at least one testing function of the direct-reflected signal time reception measurements;

an hypothesised number calculator operable to evaluate, for each of a plurality of combinations of possible object positions identified from the hyperbolae, at least one hypothesis function corresponding to the testing function to calculate an hypothesised number for the combination of possible object positions; and

a selector operable to select the combination of possible object positions for which the difference between the hypothesised number and the objective number is smallest.

18. Apparatus according to claim 17, wherein the objective number calculator is operable to calculate the objective number by evaluating a testing function comprising at least one direct-reflected signal time reception measurement for each object and at least one direct-reflected signal time reception measurement for each receiver.

19. A computer-readable medium having computer-readable instructions stored thereon that, if executed by a computer, cause the computer to determine the positions of a plurality of objects by processing signals emitted from at least one transmitter, reflected by the objects and received by a plurality of receivers, by performing processing operations copmrising:

processing signals from the receivers to generate a respective object-receiver pair time difference of arrival measurement for each object and each pair of receivers comprising the time difference of arrival between the signals received at each of the receivers in the pair from the object;

processing the generated object-receiver pair time difference of arrival measurements to calculate a respective hyperbola for each object and each pair of receivers with the positions of the receivers as foci points and the hyperbola defining the set of possible positions for the object;

calculating the intersections of the generated hyperbolae and identifying the intersections corresponding to possible positions for each individual object, wherein each possible position is either a true position or a phantom position;

processing signals from the receivers to generate a direct-reflected signal time reception measurement for each receiver-object pair comprising the time difference between the reception by the receiver of the direct signal from the transmitter and the reception by the receiver of the signal reflected by the object;

associating the generated direct-reflected signal time reception measurements with the generated object-receiver pair time difference of arrival measurements to generate measurement association results; and

determining the true positions of the objects by relating the calculated intersections of the generated hyperbolae to the generated direct-reflected signal time reception measurements using the measurement association results.

20. A computer-readable medium according to claim 19, wherein the computer-readable instructions, if executed, cause the computer to perform the processing to associate the generated direct-reflected signal time reception measurements with the generated object-receiver pair time difference of arrival measurements by:

combining the direct-reflected signal time reception measurements for the same object, to generate a first set of combined values;

calculating object-receiver pair time difference of arrival combined values corresponding to the direct-reflected signal time reception combined values, thereby generating a second set of combined values; and

comparing the first and second sets of combined values to associate the direct-reflected signal time reception measurements with the object-receiver pair time difference of arrival measurements.

21. A computer-readable medium according to claim 20, wherein the computer-readable instructions, if executed, cause the computer to combine the direct-reflected signal time reception measurements by calculating, for each object and each pair of receivers, the difference between the direct-reflection signal time reception measurement for the object and the first receiver in the pair and the direct-reflected signal time reception measurement for the object and the second receiver in the pair.

22. A computer-readable medium according to claim 20, wherein the computer-readable instructions, if executed, cause the computer to calculate the object-receiver pair time difference of arrival combined values in dependence upon the calculated intersections of the generated hyperbolae.

23. A computer-readable medium according to claim 22, wherein the computer-readable instructions, if executed, cause the computer to calculate the object-receiver pair time difference of arrival combined values in dependence upon the distance between the intersections of the generated hyperbolae and the points corresponding to the positions of the receivers.

24. A computer-readable medium according to claim 19, wherein the computer-readable instructions, if executed, cause the computer to perfoim the processing to determine the positions of the objects by relating the calculated intersections of the generated hyperbolae to the generated direct-reflected signal time reception measurements by:

calculating an objective number by evaluating at least one testing function of the direct-reflected signal time reception measurements;

for each of a plurality of combinations of possible object positions identified from the hyperbolae, evaluating at least one hypothesis function corresponding to the testing function to calculate an hypothesised number for the combination of possible object positions; and

selecting the combination of possible object positions for which the difference between the hypothesised number and the objective number is smallest.

25. A computer-readable medium according to claim 24, wherein the computer-readable instructions, if executed, cause the computer to calculate the objective number by evaluating a testing function comprising at least one direct-reflected signal time reception measurement for each object and at least one direct-reflected signal time reception measurement for each receiver.