True azimuth and north finding method and system

• US 7,451,059 B2
• Filed: 07/24/2006
• Issued: 11/11/2008
• Est. Priority Date: 03/02/2003
• Status: Active Grant

• Current Assignee: Tomer Malchi, Yaniv Malchi
• Original Assignee: Tomer Malchi, Yaniv Malchi
• Inventors: Malchi, Yaniv, Malchi, Tomer
• Primary Examiner(s): Barlow, Jr.; John E.
• Assistant Examiner(s): Kundu; Sujoy K
• Application Number:
  US11/492,134
• Publication Number:
  US 20070010965A1
• Time in Patent Office: 841 Days
• Field of Search: 702/92, 702150-153, 340/945, 340/961, 340/970, 340/968, 342/29, 342/357.14, 342/458, 701/200, 701207-208, 701224-225
• US Class Current: 702/151
• CPC Class Codes: G01C 1/02 Theodolites
• CPC Class Codes: G01C 17/00 Compasses; Devices for ascertaining true or magnetic north for navigation or surveying purposes using gyroscopic effect G01C19/00
• CPC Class Codes: G01C 19/34 for indicating a direction in the horizontal plane, e.g. directional gyroscopes
• CPC Class Codes: G01C 21/005 with correlation of navigation data from several sources, e.g. map or contour matching G01C21/30 takes precedence
• CPC Class Codes: G01C 3/06 Use of electric means to obtain final indication
• CPC Class Codes: G01S 19/51 Relative positioning
• CPC Class Codes: G01S 3/08 Means for reducing polarisation errors, e.g. by use of Adcock or spaced loop antenna systems
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves

Abstract

A method and a system are recited for obtaining a true azimuth heading for correcting a coarse azimuth heading measured from an observation position to a specific selected target by operating a data acquisition system disposed at the observation position. In principle, data is acquired and measurements are taken to allow calculation of a calculated target, including error area limits. The calculated target surrounded by error area limits is presented as a search zone to an operator for searching, finding and indicating on a display, on which is superimposed at least one map, of the specific selected target. Once found, calculations of the true azimuth are performed, allowing the derivation of the true North. The method and a system are operative with a variety of maps, including digital terrain models and stellar maps.

Claims

1. A method for obtaining a true azimuth heading for correcting a coarse azimuth heading measured from an observation position to a specific selected target by operating a data acquisition system disposed at the observation position, comprising:

a computer module running computer programs including at least one dedicated computer program and at least one map,

a computer display coupled to the computer module for;

displaying output data to the operator in superimposition onto the at least one map, and for

responding to an operator input designating a selected location thereon by operation of the computer module for;

retrieval of location data of the selected location, and

replacement of location data for a previously calculated location with location data of the selected location,

a sighting device aimed at the specific selected target and coupled to the computer module for input therein of data including location data and target data, the sighting device including;

access to a source of location data,

devices for measuring target data, including elevation angle, relative horizontal yaw angle, coarse azimuth heading, and means for deriving range data,

the method comprising the steps of;

feeding input data into the computer module including location data, target data and associated errors limits, and operating the computer module for;

displaying the at least one map selected according to observation position location data,

running the at least one dedicated computer program to provide calculated target location data for the specific selected target according to input data, and to calculate an error area delimited by data error limits and displayed as a search zone, the calculated target location being disposed within the search zone containing the specific selected target, and

superimposing the search zone on the at least one displayed map,

prompting the operator to search within the search zone limits shown on the display module for the true location of the specific selected target, which when found and indicated, operates the computer module for;

retrieval of location data of the specific selected target, and

replacement of location data of the previously calculated target location with the true location data of the specific selected target, and

operating the at least one dedicated computer program to calculate and accept the sighting device'"'"'s heading aimed at the specific selected target as the true azimuth, to feedback the true azimuth to the sighting device, and to display calculation result data,

whereby the data acquisition system provides true azimuth from which a true North direction may be derived and used as input for further operation.

2. The method according to 1, wherein:

the source of location data for input into the computer module is selected alone and in combination from the group consisting of a source external to the sighting device, internal to the sighting device, external to the data acquisition system, and internal to the data acquisition system.

3. The method according to claim 1, wherein:

means for deriving range data include the sighting device, a dedicated computer program, maps and listings,

wherein maps are selected alone and in combination from the group of maps consisting of digital terrain maps, ortho-photo maps, aerial photographs, space photographs, tactical maps, infrared maps, radar maps and geographical maps.

4. The method according to claim 1, wherein:

range data are derived as a distance taken from either one of both an active range measurement device and an inactive range data source.

5. The method according to claim 1, wherein:

the search zone is delimited by range measurement error limits, by coarse azimuth heading error limits, and by position error limits.

6. The method according to claim 1, wherein:

the at least one map is selected alone and in combination from the group of maps consisting of digital terrain maps, ortho-photo maps, aerial photographs, space photographs, tactical maps, infrared maps, radar maps and geographical maps.

7. The method according to claim 1, wherein:

more than at least one map are superimposed on the computer display.

8. The method according to claim 1, wherein:

the dedicated computer program is a PTAS computer program being fed with input data including observation position location, range data, azimuth and elevation angle measurements, and associated data error limits.

9. The method according to claim 1, wherein:

the data acquisition system points to a sighted celestial body,

the computer module runs computer programs including at least one dedicated celestial computer program and at least one celestial map,

the sighting device aims at the sighted celestial body and is coupled to the computer module for input therein of data including location data and target data, the sighting device including;

access to a source of location data,

target data measuring devices to measure elevation angle and coarse azimuth heading,

and wherein;

acquired data including observation position location data, elevation angle and coarse azimuth heading and

measurement-associated errors limits are fed as input data into the computer module which is operated for;

displaying the at least one celestial map selected according to the observation position location data, current date and current time,

running the at least one celestial computer program to provide calculated star location data for the sighted celestial body according to input data, and to calculate an error area displayed as a search zone delimited by data error limits, the calculated star location being disposed within the search zone containing the sighted celestial body, and

superimposing the search zone on the at least one displayed celestial map,

prompting the operator to search within the search zone limits shown on the display module for the true sighted celestial body, which when found and indicated, operates the computer module for;

retrieval of location data of the sighted celestial body, and

replacement of location data of the previously calculated star location with the true location data of the sighted celestial body as corrective data for input into the computer module, and

operating the at least one celestial computer program to calculate and accept the sighting device'"'"'s heading aimed at the sighted celestial body as the true azimuth, feeding back the true azimuth to the sighting device, and providing calculation result data,

whereby the data acquisition system provides true azimuth from which a true North direction may be derived and used as input for further operation.

10. The method according to claim 9, wherein:

the source of location data for input into the computer module is selected alone and in combination from the group consisting of a source external to the sighting device, internal to the sighting device, external to the data acquisition system, and internal to the data acquisition system.

11. The method according to claim 9, wherein:

more than at least one map are superimposed on the computer display.

12. The method according to claim 9, wherein:

the at least one map for display is selected alone and in combination from the group of maps consisting of stellar maps, constellation maps, and satellite maps.

13. The method according to claim 9, wherein:

the search zone is delimited by coarse azimuth heading error limits, by elevation angle error limits, and by position error limits.

14. The method according to claim 9, wherein:

the dedicated celestial computer program is a PTAS computer program being fed with input data including observation position location data, elevation angle, coarse azimuth heading and associated error limits.

15. The method according to claim 1, for operation of the data acquisition system with either one of both a GPS deficient environment and an inoperative GPS receiver, as a procedure to derive a true azimuth and observation position location data, wherein:

the sighting device is aimed at a specific selected target that is chosen and recognized by the operator and for which location data are available,

the operator selects at least one appropriate map for display on the computer display,

the operator is prompted to search for the specific selected target on the computer display, which when found and indicated, operates the computer module for retrieval of location data of the specific selected target, together with associated error limits, for input into the computer module, and

the sighting device is operated to derive and feed coarse azimuth heading, relative horizontal yaw angle, elevation angle, range, and associated data error limits, as input data into the computer module,

the computer module is commanded to;

accept the specific selected target having known location data as a temporary observation position, and accept the actual observation position having unknown location data as a temporary target, by adding p radians to or subtracting p radians from the measured coarse azimuth heading and by multiplying the measured elevation angle by −

1, and

run at least one dedicated computer program to calculate and display the temporary target surrounded by an error area delimited by the data error limits and displayed as a search zone, and to provide temporary target location data, and

the operator being prompted to search within the search zone limits shown on the computer display for the true location of the temporary target, and when found and indicated, the data acquisition system replaces the location data of the temporary target with the location data of the actual observation position as input into the computer module, enabling true azimuth calculation and feedback to the sighting device,

whereby a true azimuth is obtained from which a true North direction may be derived, in addition to the location data of the observation position, all useable as input for further operation.

16. The method according to claim 15, wherein:

the procedure is repeatable in successive sequences, each sequence requiring one additional specific selected target recognized by and having location data which are available to the operator, to display one additional search zone for superimposition on a previously displayed search zone, whereby a common-area overlap of search zones reduces the size of the area to be searched by the operator.

17. The method according to claim 15, wherein:

the at least one map for display is selected alone and in combination from the group of maps consisting of digital terrain maps, ortho-photo maps, aerial photographs, space photographs, tactical maps, infrared maps, radar maps, and geographical maps.

18. The method according to claim 15, wherein:

more than at least one map are superimposed on the computer display.

19. The method according to claim 15, wherein:

the at least one computer program is a PTAS computer program receiving temporary observation position, coarse azimuth heading, elevation angle, range, and associated error limits as input data.

20. The method according to claim 15, wherein:

the procedure is repeatable in sequence with at least one additional specific selected target recognized by and having location data which are available to the operator, to display at least one additional search zone for superimposition on a previously displayed search zone,

whereby an overlap area of search zones reduces the size of the area to be searched by the operator.

21. The method according to claim 15, wherein:

the range is derived by means including the sighting device, a dedicated computer program, maps and listings,

wherein maps are selected alone and in combination from the group of maps consisting of digital terrain maps, ortho-photo maps, aerial photographs, space photographs, tactical maps, infrared maps, radar maps and geographical maps.

22. The method according to claim 15, wherein:

the range is derived as a distance taken from either one of both an active range measurement device and an inactive range data source.

23. The method according to claim 15, wherein:

the at least one map for display is selected as a digital terrain map.

24. The method according to claim 15, wherein:

the at least one map for display is selected alone and in combination from the group of maps consisting of digital terrain maps, ortho-photo maps, aerial photographs, space photographs, tactical maps, infrared maps, radar maps and geographical maps.

25. The method according to claim 15, wherein:

more than at least one map are superimposed on the computer display.

26. A system for correcting a coarse azimuth heading with a true azimuth heading, the coarse azimuth heading being measured from an observation point to a specific selected target by operating a data acquisition system disposed at the observation point, comprising:

a computer module running computer programs including at least one dedicated computer program and at least one map,

a computer display coupled to the computer module, which commands;

display of output data to the operator in superimposition onto at least one map, and

response to an operator input designating a selected location thereon by operation of the computer module for;

retrieval of location data of the selected location, and

replacement of location data for a previously calculated location with location data of the selected location,

a sighting device aimed at the specific selected target and coupled to the computer module for input therein of measured data including location data and target data, the sighting device including;

access to a source of location data,

devices for measuring target data, measurement of elevation angle, relative horizontal yaw angle, coarse azimuth heading, and means for deriving range data,

the system comprising;

input data including location data, target data and associated errors limits,

being fed as input into the computer module which is operated to command;

display of the at least one map selected according to observation point location data,

operation of at least one dedicated computer program to provide calculated target location data for the specific selected target according to input data, and to calculate an error area delimited by data error limits and displayed as a search zone, the calculated target location being disposed within the search zone containing the specific selected target, and

superimposition of the search zone on the at least one displayed map,

the operator being prompted to search within the search zone limits shown on the display module for the true location of the specific selected target, which when found and indicated, operates the computer module for;

retrieval of location data of the specific selected target, and

replacement of location data of the previously calculated target location with the true location data of the specific selected target, and

the dedicated computer program being operated to calculate and accept the sighting device'"'"'s heading aimed at the specific selected target as the true azimuth, to feedback the true azimuth to the sighting device, and to display calculation result data, whereby the data acquisition system provides true azimuth from which a true North direction may be derived and used as input for further operation.

27. The system according to claim 26, wherein:

the source of location data for input into the computer module is selected alone and in combination from the group consisting of a source external to the sighting device, internal to the sighting device, external to the data acquisition system, and internal to the data acquisition system.

28. The system according to claim 26, wherein:

means for deriving range data include the sighting device, a dedicated computer program, maps and listings,

wherein maps are selected alone and in combination from the group of maps consisting of digital terrain maps, ortho-photo maps, aerial photographs, space photographs, tactical maps, infrared maps, radar maps and geographical maps.

29. The system according to claim 26, wherein:

range data is derived as a distance taken from either one of both an active range measurement device and an inactive range data source.

30. The system according to claim 26, wherein:

the search zone is delimited by range measurement error limits, by coarse azimuth heading error limits, and by position error limits.

31. The system according to claim 26, wherein:

the at least one map is selected alone and in combination from the group of maps consisting of digital terrain maps, ortho-photo maps, aerial photographs, space photographs, tactical maps, infrared maps, radar maps and geographical maps.

32. The system according to claim 26, wherein:

more than at least one map are superimposed on the computer display.

33. The system according to claim 26, wherein:

the dedicated computer program is a PTAS computer program being fed with input data including observation position location, range data, azimuth and elevation angle measurements, and associated data error limits.

34. The system according to claim 26, wherein:

the data acquisition system points to a sighted celestial body,

the computer module runs computer programs including at least one dedicated celestial computer program and at least one celestial map,

the sighting device aims at the sighted celestial body and is coupled to the computer module for input therein of data including location data and target data, the sighting device including;

access to a source of location data,

target data measuring devices to measure elevation angle and coarse azimuth heading,

and wherein;

acquired data including observation position location data, elevation angle and coarse azimuth heading and

measurement-associated errors limits are fed as input data into the computer module which is operated for;

displaying the at least one celestial map selected according to the observation position location data, current date and current time,

running the at least one celestial computer program to provide calculated star location data for the sighted celestial body according to input data, and to calculate an error area displayed as a search zone delimited by data error limits, the calculated star location being disposed within the search zone containing the sighted celestial body, and

superimposing the search zone on the at least one displayed celestial map,

prompting the operator to search within the search zone limits shown on the display module for the true sighted celestial body, which when found and indicated, operates the computer module for;

retrieval of location data of the sighted celestial body, and

replacement of location data of the previously calculated star location with the true location data of the sighted celestial body as corrective data for input into the computer module, and

operating the at least one celestial computer program to calculate and accept the sighting device'"'"'s heading aimed at the sighted celestial body as the true azimuth, feeding back the true azimuth to the sighting device, and providing calculation result data,

whereby the data acquisition system provides true azimuth from which a true North direction may be derived and used as input for further operation.

35. The system according to claim 34, wherein:

the source of location data for input into the computer module is selected alone and in combination from the group consisting of a source external to the sighting device, internal to the sighting device, external to the data acquisition system, and internal to the data acquisition system.

36. The system according to claim 34, wherein:

more than at least one map are superimposed on the computer display.

37. The system according to claim 34, wherein:

the at least one map for display is selected alone and in combination from the group of maps consisting of stellar maps, constellation maps, and satellite maps.

38. The system according to claim 34, wherein:

the search zone is delimited by coarse azimuth heading measurement error limits, by elevation angle measurement error limits, and by position error limits.

39. The system according to claim 34, wherein:

the dedicated celestial computer program is a PTAS computer program being fed with input data including observation position location data, elevation angle, coarse azimuth heading and associated error limits.

40. The system according to claim 26, for operation of the data acquisition system with either one of both a GPS deficient environment and an inoperative GPS receiver, as a procedure to derive a true azimuth and observation position location data, wherein:

the sighting device is aimed at a specific selected target that is chosen and recognized by the operator and for which location data are available,

the operator selects at least one appropriate map for display on the computer display,

the operator is prompted to search for the specific selected target on the computer display, which when found and indicated, operates the computer module for retrieval of location data of the specific selected target, together with associated error limits, for input into the computer module, and

the sighting device is operated to derive and feed coarse azimuth heading, relative horizontal yaw angle, elevation angle, range, and associated data error limits, as input data into the computer module,

the computer module is commanded to;

accept the specific selected target having known location data as a temporary observation position, and accept the actual observation position having unknown location data as a temporary target, by adding p radians to or subtracting p radians from the measured coarse azimuth heading and by multiplying the measured elevation angle by −

1, and

run a dedicated computer program to calculate and display the temporary target surrounded by a search zone, which is delimited by the error limits of the range and of the coarse azimuth heading, and to display the specific selected target location, and

the operator is prompted to search within the search zone limits shown on the computer display for the true location of the temporary target, and when found and indicated, replaces the location data of the temporary target with the location data of the actual observation position as input into the computer module, enabling true azimuth calculation and feed back to the sighting device,

whereby a true azimuth is obtained from which a true North direction may be derived, in addition to the location data of the observation position, all useable as input for further operation.

41. The system according to claim 40, wherein:

the procedure is repeatable in successive sequences, each sequence requiring one additional specific selected target recognized by and having location data which are available to the operator, to display one additional search zone for superimposition on a previously displayed search zone,

whereby a common-area overlap of search zones reduces the size of the area to be searched by the operator.

42. The system according to claim 40, wherein:

the at least one map for display is selected alone and in combination from the group of maps consisting of digital terrain maps, ortho-photo maps, aerial photographs, space photographs, tactical maps, infrared maps, radar maps, and geographical maps.

43. The system according to claim 40, wherein:

more than at least one map are superimposed on the computer display.

44. The system according to claim 40, wherein:

the at least one computer program is a PTAS computer program receiving temporary observation position, coarse azimuth heading, elevation angle, range, and associated error limits as input data.

45. The system according to claim 40, wherein:

the procedure is repeatable in sequence with at least one additional specific selected target recognized by and having location data which are available to the operator, to display at least one additional search zone for superimposition on a previously displayed search zone,

whereby an overlap area of search zones reduces the size of the area to be searched by the operator.

46. The system according to claim 40, wherein:

the range is derived by means including the sighting device, a dedicated computer program, maps and listings,

wherein maps are selected alone and in combination from the group of maps consisting of digital terrain maps, ortho-photo maps, aerial photographs, space photographs, tactical maps, infrared maps, radar maps and geographical maps.

47. The system according to claim 40, wherein:

the range is derived as a distance taken from either one of both an active range measurement device and an inactive range data source.

48. The system according to claim 40, wherein:

the at least one map for display is selected as a digital terrain map.

49. The system according to claim 40, wherein:

the at least one map for display is selected alone and in combination from the group of maps consisting of digital terrain maps, ortho-photo maps, aerial photographs, space photographs, tactical maps, infrared maps, radar maps and geographical maps.

50. The method according to claim 40, wherein:

more than at least one map are superimposed on the computer display.