Method for correcting a 3D location measured by a tracking system assuming a vertical offset

• US 7,526,384 B2
• Filed: 03/09/2006
• Issued: 04/28/2009
• Est. Priority Date: 03/10/2005
• Status: Active Grant

• Current Assignee: Underground Imaging Technologies LLC
• Original Assignee: Witten Technologies Incorporated
• Inventors: MacIntosh, Scott, Birken, Ralf A., Zhu, Qifu
• Primary Examiner(s): Cosimano; Edward R
• Assistant Examiner(s): Le; Toan M
• Application Number:
  US11/371,222
• Publication Number:
  US 20060271298A1
• Time in Patent Office: 1,146 Days
• Field of Search: 702/5, 702/2, 702150-154, 701/205, 701207-208, 701213-215, 701/220, 701/223, 34235701-35703, 342/357.06, 342/357.08, 356/139.01, 356/138, 356/139.04, 356/140, 356/147, 324/326
• US Class Current: 702/5
• CPC Class Codes: G01C 15/00 Surveying instruments or accessories not provided for in groups G01C1/00 - G01C13/00
• CPC Class Codes: G01V 11/00 Prospecting or detecting by methods combining techniques covered by two or more of main groups G01V1/00 - G01V9/00
• CPC Class Codes: G01V 3/38 Processing data, e.g. for analysis, for interpretation, for correction

Abstract

Position measurements by a tracking system associated with a survey tool are corrected for tilt. The tracking station typically incorporates some offset from the surface across which a survey is conducted, and the offset will be subject to angular displacement as the tool tilts with respect to its normal orientation. The tracking system records the 3D position of the survey tool, with angular offset errors. In the disclosed examples, an inertial measurement unit (IMU), a dual axis inclinometer or a combination of two single axis inclinometers measures the amount of angular offset. The angular offset data is used to correct the position data, e.g. to reduce or eliminate errors caused by the angular offset, e.g. from vertical. If the tool provides measurement data, e.g. GPR readings, processing of the measurement data from the survey tool uses the corrected position data, e.g. to produce images of sub-surface features or objects.

Claims

1. A method of generating measurement data and position data from a survey, comprising:

obtaining measurement data representing a measured physical property of a region from a survey tool, when the survey tool is positioned at various points on a surface of the region;

obtaining survey tool position data corresponding to each of the points on the surface of the region;

obtaining angular offset data, representing offset of orientation of the survey tool from a normal orientation, at each of the points on the surface of the region caused by variations in inclination of the surface; and

correcting the corresponding position data, based on the angular offset data, and storing corrected corresponding position data.

2. The method of claim 1, further comprising processing the measurement data based on the corrected corresponding position data.

3. The method of claim 1, wherein the region is a portion of a road or the ground, and the measurement data represents a sub-surface property of said region.

4. The method of claim 3, wherein the processing the measurement data based on the corrected corresponding position data identifies location of objects buried beneath the surface of the region.

5. The method of claim 1, wherein the angular offset data represents variations in orientation of the survey tool due to variations of the surface with respect to horizontal.

6. The method of claim 5, wherein:

the obtained position data corresponding to each of the points indicates position with an offset from the surface, and the angular offset data represents an angle of an axis of the position offset with respect to a vertical orientation over the region.

7. The method of claim 6, wherein the angular offset data comprises angular measurements with respect to at least two axes of the survey tool.

8. The method of claim 1, wherein:

the survey tool moves to traverse the surface of the region; and

the obtaining steps are performed at least periodically as the survey tool traverses the surface of the region.

9. A method of processing position data from a survey, comprising:

obtaining position data corresponding to a point on a surface of a region to be surveyed at which a survey tool is positioned;

obtaining angular offset data, representing offset of orientation of the survey tool from a normal orientation, at the point on the surface of the region; and

correcting the corresponding position data, based on the angular offset data, and storing corrected corresponding position data.

10. A survey system, comprising:

a survey tool;

a position detection device responsive to position of the survey tool, for generating survey tool position data corresponding to a point on a surface at which the survey tool is positioned;

an inclinometer coupled to the survey tool, for providing angular offset data in response to orientation of the survey tool, representing offset of orientation of the survey tool at the point from a normal orientation; and

a data processor for correcting the corresponding position data, based on the angular offset data.

11. The survey system as in claim 10, wherein the survey tool comprises a survey pole, to which an element of the position detection device is attached.

12. The survey system as in claim 11, wherein:

the survey tool comprises at least one sensor taking measurements of a physical property of a region, at least at a plurality of different points on the surface, and providing measurement data from the measurements at the different points;

the position detection device is for generating survey tool position data corresponding to each of the points on the surface of the region as the survey tool provides the measurement data; and

the data processor is for correcting the survey tool position data corresponding to each of the points on the surface, based on respective angular offset data.

13. The survey system as in claim 12, further comprising means for processing the measurement data based on the corrected position data.

14. The survey system as in claim 12, wherein:

the survey tool comprises a movable platform; and

the at least one sensor is mounted on the moveable platform for detecting the physical property of the region as the platform moves over the surface of the region.

15. The survey system as in claim 14, wherein the at least one sensor is selected from the group consisting of:

a ground penetrating radar (GPR) array;

an array of electromagnetic induction antennas;

an array of magnetometers;

an array of vibrometers; and

an array of optical sensors.

16. The survey system as in claim 14, wherein:

the position detection device includes an element mounted on the platform at a location on the platform that will be offset from the surface of the region when the survey tool performs measurements, and the angular offset data represents an angle of an axis of the location offset relative to a vertical orientation over the region.

17. The survey system as in claim 16, wherein the inclinometer is selected from the group consisting of:

an inertial measurement unit (IMU);

a dual axis inclinometer; and

two single axis inclinometers.

18. The survey system as in claim 16, wherein the position detection device comprises:

a self-tracking laser theodolite ground station; and

a reflector attached to the movable platform for reflecting a laser beam from the ground station back to the ground station.

19. The survey system as in claim 16, wherein the position detection device comprises a GPS receiver attached to the movable platform.

20. A data processing system, comprising at least one programmable processor and programming executable by the at least one processor, wherein execution of the programming causes the at least one processor to implement functions comprising:

receiving measurement data representing a measured physical property of a region from a survey tool, when the survey tool is positioned at various points on a surface of the region;

receiving survey tool position data corresponding to each of the points on the surface of the region;

receiving angular offset data, representing offset of orientation of the survey tool from a normal orientation, at each of the points on the surface of the region, caused by variations in inclination of the surface; and

correcting the corresponding position data, based on the angular offset data and storing corrected corresponding position data.

21. The system of claim 20, wherein the functions further comprise processing the measurement data based on the corrected corresponding position data.

22. A product comprising a machine-readable medium and programming comprising instructions executable by at least one programmable processor, wherein execution of the instructions causes the at least one processor to implement functions including:

receiving measurement data representing a measured physical property of a region from a survey tool, when the survey tool is positioned at various points on a surface of the region;

receiving survey tool position data corresponding to each of the points on the surface of the region;

receiving angular offset data, representing offset of orientation of the survey tool from a normal orientation, at each of the points on the surface of the region, caused by variations in inclination of the surface; and

correcting the corresponding position data, based on the angular offset data and storing corrected corresponding position data.

23. The product of claim 22, wherein the functions implemented upon execution of the instructions further include processing the measurement data based on the corrected corresponding position data.