Managed traverse system and method to acquire accurate survey data in absence of precise GPS data

• US 20070139262A1
• Filed: 12/15/2005
• Published: 06/21/2007
• Est. Priority Date: 12/15/2005
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Scherzinger, Bruno
• Granted Patent: US 7,541,974 B2
• Time in Patent Office: Days
• US Class Current: 342/357.320
• CPC Class Codes: G01C 15/00 Surveying instruments or accessories not provided for in groups G01C1/00 - G01C13/00
• CPC Class Codes: G01C 15/06 Surveyors' staffs; Movable markers
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01S 19/485 whereby the further system is an optical system or imaging system
• CPC Class Codes: G01S 19/49 whereby the further system is an inertial position system, e.g. loosely-coupled
• CPC Class Codes: G01S 19/51 Relative positioning

Abstract

A method and system obtains precise survey-grade position data of target points in zones where precise GPS data cannot be obtained, due to natural or man-made objects such as foliage and buildings. The system comprises a GPS receiver mounted on a survey pole, with an inertial measurement unit (IMU) and an electronic distance meter (EDM) also mounted on the pole. The system and method obtains GPS data when outside the zone and uses the IMU inside the zone to traverse to a target point, using the EDM to obtain data reduce accumulated errors which occur with the IMU.

Claims

1. A method of determining the position of a target comprising the steps of:

determining the position of a starting point spaced apart from the target;

traversing from the starting point to the target while keeping track of positions using a tracking method that is subject to the accumulation of tracking errors;

en route to the target, reducing the accumulated errors by determining position relative to at least one reference location.

2. The method of determining the position of a target according to claim 1, wherein the reference location is the starting point.

3. The method of determining the position of a target according to claim 1, wherein the reference location is spaced apart from the starting point.

4. The method of determining the position of a target according to claim 1, wherein the step of determining the position of a starting point comprises using a GPS receiver.

5. The method of determining the position of a target according to claim 1, wherein the step of traversing uses a tracking method with an IMU.

6. The method of determining the position of a target according to claim 1, wherein the step of reducing accumulated errors comprises obtaining aiding information with an EDM.

7. A method of determining the location of an object in a zone, comprising:

a. defining a first reference point near the perimeter of the zone;

b. locating a GPS receiver at a first GPS receiver location outside the zone near the first reference point;

c. determining the position of the GPS receiver at the first GPS receiver location using GPS signals;

d. determining the position of the first reference point relative to the GPS receiver at the first GPS receiver location;

e. traversing, from the first GPS receiver position into the zone, to the location of the object using a tracking method that is subject to the accumulation of errors,;

f. obtaining first relative position information of the object location relative to the first reference point;

g. obtaining aiding position information to reduce the accumulation of errors obtained during at least one of steps (e) and (f); and

h. determining the location of the object using the information obtained in steps (c), (d), (e), (f) and (g).

8. The method according to claim 7, wherein the zone is a region where precise survey-grade position information cannot be obtained using GPS.

9. The method according to claim 7 wherein step (d) comprises using an EDM to determine the position of the reference point relative to the GPS receiver at the GPS receiver location.

10. The method according to claim 7, wherein step (f) comprises using an EDM to obtain first relative position information of the object location relative to the first reference point.

11. The method according to claim 7, wherein step (g) comprises using an IMU to obtain aiding information.

12. The method according to claim 7, wherein step (a) comprises locating a retroreflector on the first reference point.

13. The method according to claim 7, further including locating a retroreflector at the object location, and wherein step (f) comprises using an EDM with a laser to obtain first relative position information.

14. The method according to claim 7, further including using a survey pole with a GPS receiver and EDM mounted thereon.

15. The method according to claim 7, further including using a survey pole with a GPS receiver and IMU mounted thereon.

16. The method according to claim 7, further including using a survey pole with a GPS receiver, EDM and IMU mounted thereon.

17. The method according to claim 7, wherein step (f) comprises using an EDM and wherein step (g) comprises using an IMU.

19. The method according to claim 15, wherein the first and second reference points are different.

18. A method of determining the location of an object in a zone, comprising:

a. defining first and second reference points near the perimeter of the zone;

b. locating a GPS receiver at a first GPS receiver location outside the zone near the first reference point;

c. determining the position of the GPS receiver, at the first GPS receiver location using GPS signals;

d. determining the position of the first reference point relative to the GPS receiver at the first GPS receiver location;

e. traversing, from the first GPS receiver position into the zone, to the location of the object using a tracking method that is subject to the accumulation of errors;

f. obtaining first relative position information of the object location relative to the first reference point;

g. traversing from the object location to a second GPS receiver position outside the zone and near the second reference point using a tracking method that is subject to the accumulation of errors,

h. locating a GPS receiver at the second GPS receiver location;

i. determining the position of the GPS receiver at the second GPS receiver location using GPS signals;

j. determining the position of the second reference point relative to the GPS receiver at the second receiver location;

k. obtaining second relative position information of the object location relative to the second reference point;

l. obtaining aiding position information to reduce the accumulation of errors obtained during at least one of steps (e), (f), (g) and (k); and

m. determining the location of the object using the information obtained in steps (c), (d), (f), (i), (j), (k) and (l).

20. The method according to claim 18, wherein the first and second reference points are the same.

21. The method according to claim 18, wherein the first GPS receiver location and the first reference point are the same.

22. The method according to claim 18, wherein the second GPS receiver location and the second reference point are the same.

23. The method according to claim 18, wherein step (d) comprises using an EDM to determine the position of the first reference point relative to the GPS receiver at GPS receiver location.

24. The method according to claim 18, wherein step (f) comprises using an IMU to obtain first relative position information of the object location relative to the first reference point.

25. The method according to claim 18, wherein step (l) comprises using an EDM to obtain aiding information.

26. The method according to claim 18, wherein step (l) comprises using an EDM to obtain information on the position of the GPS receiver at the second GPS receiver location relative to first GPS receiver location.

27. The method according to claim 18, wherein step (j) comprises using an EDM to determine the position of the second reference point relative to the second GPS receiver location.

28. The method according to claim 18, wherein step (k) comprises using an IMU to obtain second relative position information of the object location relative to the second reference point.

29. The method according to claim 18, further including locating a retroreflector at the object location, and wherein steps (f) and (k) comprise using an IMU to obtain first and second relative position information.

30. The method according to claim 18, further including using a survey pole with a GPS receiver and EDM mounted thereon.

31. The method according to claim 18, further including using a survey pole with a GPS receiver and IMU mounted thereon.

32. The method according to claim 18, further including using a survey pole with a GPS receiver, EDM and IMU mounted thereon.

33. The method according to claim 18, further including using an IMU to obtain information in steps (f) and (k), and wherein step (m) determines the location of the object using a smoothed estimation process which combines forward and reverse time estimation processes to reduce position error.

34. The method according to claim 18, wherein the zone is a region where precise survey-grade position information cannot be obtained using GPS.

35. A surveying system for determining the position of a target in a zone in which precise survey grade location data cannot be obtained using GPS receivers, comprising:

a GPS receiver for determining the position of a starting point near the perimeter of the zone;

a measurement system for obtaining relative position information as one traverses from the starting point to the target, said measurement system subject to the accumulation of tracking errors during said traversal and for obtaining aiding position information to reduce the accumulation of errors during said traversal; and

a processing system for computing the position of the target using the starting point position, the relative position information, and the aiding position information, whereby the position of the target so computed has greater precision than that computed using only relative position information.

36. The system according to claim 35, further comprising a survey pole onto which the GPS receiver is mounted, and wherein the measurement system comprises an EDM with a laser mounted on the pole.

37. The system according to claim 35, further comprising a survey pole onto which the GPS receiver is mounted, and wherein the measurement system comprises an IMU mounted on the pole.

38. The system according to claim 35, further comprising a survey pole onto which the GPS receiver is mounted, and wherein the measurement system comprises an EDM with a laser, and an IMU mounted on the pole.

39. The system according to claim 37, wherein the measurement system obtains relative position information of a plurality of intermediate reference points within the zone as one traverses from the starting point to the target said relative position information at each point being relative to the previous point, and wherein the measurement system obtains aiding information for at least one of the intermediate reference points by obtaining relative position data from the intermediate reference point to the starting point.

40. The system according to claim 39, wherein the measurement system comprises an IMU to obtain relative position information, and wherein the measurement system comprises an EDM to obtain the aiding information.

41. A surveying system for determining the position of an object in a zone where a GPS receiver cannot locate the object with sufficient precision for a survey grade application, comprising:

a position locator for determining the position of a first reference point near a perimeter of the zone using a GPS receiver and GPS signals, said position locator obtaining relative position information of the object location relative to the first reference point during a traversal inside the zone from the first reference point toward the object, accumulating tracking errors during said traversal; and

an aiding device for reducing the accumulated tracking errors during traversal to the target inside the zone, by determining position relative to at least one reference location whose position is known.

42. A surveying system for determining the position of a target comprising:

a position locator for determining the position of a starting point spaced apart from the target point;

, said position locater keeping track of positions, as one traverses from the starting point to the target, using a tracking method which is subject to the accumulation of tracking errors during the traversing, and

an aiding device for reducing the accumulated tracking errors during traversing to the target inside the zone by determining position relative to at least one reference location whose position is known.