Use of a sky polarization sensor for absolute orientation determination in position determining systems

Patent metadata

Field	Value
Publication number	US-9562764-B2
Application number	US-201313830955-A
Country	US
Kind code	B2
Filing date	Mar 14, 2013
Priority date	Jul 23, 2012
Publication date	Feb 7, 2017
Grant date	Feb 7, 2017

Abstract

A method for determining absolute orientation of a platform is disclosed. In one embodiment, a first sky polarization data set for a first time Ti is measured using a sky polarization sensor disposed on a platform. A second sky polarization data set is obtained at a second time Tj. A difference in orientation between the first sky polarization data set and the second sky polarization data set is determined using an orientation determiner. The difference in orientation is provided as at least one orientation parameter for the platform at time Tj. The at least one orientation parameter is used to provide a direction relative to a reference point on the platform.

First claim

What is claimed is:

1. A method for obtaining position data for a target, comprising:
orienting a visual sighting device and a sky polarization sensor toward a target, wherein said visual sighting device comprises a range measurement system and is disposed in a known spatial relationship with said sky polarization sensor;
determining an absolute orientation of said visual sighting device based on a sky polarization data measurement using the sky polarization sensor;
determining a distance from said visual sighting device to said target using the range measurement system;
determining a position of a first location having a known spatial relationship to said visual sighting device; and
calculating a position of said target based on said position of said first location, said distance from said visual sighting device to said target, and said absolute orientation of said visual sighting device.

2. The method of claim 1 wherein said visual sighting device comprises an optical survey instrument.

3. The method of claim 2 determining wherein said position of said first location is determined by a resection survey process with said optical survey instrument.

4. The method of claim 2 further comprising:
establishing said visual sighting device approximately above said first location without levelling said visual sighting device and wherein there is a known distance and orientation between said first location and said optical survey instrument.

5. The method of claim 2 further comprising:
establishing said visual sighting device vertically above said first location and leveled, and wherein there is a known distance between said first location and said optical survey instrument.

6. The method of claim 1 wherein said visual sighting device comprises an integrated electronic distance measurement (EDM) system.

7. The method of claim 1 wherein said visual sighting device further comprises a camera with a display.

8. The method of claim 1 wherein said position of said first location is determined by using a Global Navigation Satellite System (GNSS) receiver.

9. The method of claim 1 wherein said visual sighting device and sky polarization sensor are integrated with a Global Navigation Satellite System (GNSS) receiver in a known spatial relationship.

10. The method of claim 9 wherein said GNSS receiver, said visual sighting device and said sky polarization sensor are affixed to a pole in a known spatial relationship.

11. The method of claim 10 wherein said pole comprises said visual sighting device and said range measurement system.

12. The method of claim 1 further comprising:
using a processing system to translate said sky polarization data measurement into an orientation in a coordinate system for said visual sighting device.

13. The method of claim 12 further comprising:
translating said orientation into the World Geodetic System (WGS) 84 coordinate system.

14. The method of claim 12 wherein said processing system translates said sky polarization data measurement into a local coordinate system.

15. The method of claim 12 further comprising:
receiving a sky polarization data set at a known time T(i);
accessing a sun almanac to determine azimuth and elevation angles of the sun at said time T(i) and for said first location;
calculating a plurality of predicted polarization values for a plurality of respective sample points across the sky at said time T(i) and for said first location;
correlating a sky polarization measurement captured using said sky polarization sensor with at least one of said plurality of predicted polarization values, and calculating translation and rotation parameters of a transform between said sky polarization measurement and said at least one of said plurality of predicted polarization values;
converting said translation and rotation parameters of said transform from image-space to real-world coordinate frame; and
adding said rotation parameters in the real-world coordinate frame to the azimuth and elevation angles determined from said sun almanac, to determine the yaw, pitch and roll orientation parameters for said visual sighting device.

16. The method of claim 15 further comprising:
determining at least one orientation angle to a remote target wherein said at least one orientation angle is matched to a coordinate system by a setup procedure comprising:
establishing a platform vertically over a known position;
measuring a vertical distance from said known position to said platform;
determining a level orientation for said sky polarization sensor, as determined by a bubble-level; and
establishing said orientation of said platform in terms of said coordinate system by aiming said visual sighting device at a backsight of either a known azimuth or a known position while measuring said sky polarization data set.

17. The method of claim 16 further comprising:
using a polarization reference station, comprising a second sky polarization sensor having measurement axes which are aligned in a known orientation with respect to True North and a local gravity vector, to generate a sky polarization reference data set; and
storing said sky polarization reference data set at a sequence of known times including said known time T(i) using a first data storage system.

18. The method of claim 17 further comprising:
transmitting said sky polarization measurement from said polarization reference station to an orientation determiner coupled with said visual sighting device and said sky polarization sensor using a communications link.

19. The method of claim 18 further comprising:
transmitting said sky polarization measurement from a mobile device comprising said visual sighting device and said orientation determiner to a storage and processing system via a communications link;
sending said sky polarization reference data set from said first storage system to said storage and processing system; and
determining an orientation for said visual sighting device at said storage and processing system.

20. The method of claim 18 further comprising:
transmitting said sky polarization measurement from said orientation determiner to said polarization reference station;
processing said sky polarization measurement with reference data taken proximate to said known time T(i) to bring said sky polarization measurement and said sky polarization reference data set into congruence by calculating a series of axis rotations with resultant defined angles;
using said resultant defined angles as at least one orientation parameter for said visual sighting device at time T(i); and
transmitting said resultant defined angles to said orientation determiner as the orientation parameters for the time T(i) of the visual sighting system.

21. The method of claim 18 wherein said sky polarization reference data set is sent after receiving a request via said communications link from said orientation determiner for data captured proximate to time T(i).

22. The method of claim 1 wherein the sky polarization sensor comprises a photo-diode-based polarization detection system.

23. The method of claim 1 wherein the sky polarization sensor comprises a camera-based polarization detection system.

24. The method of claim 1 further comprising:
using a differential polarization process to determine said absolute orientation of said visual sighting device.

25. A method for obtaining position data for a target w

Assignees

• Trimble Navigation Ltd
• Trimble Inc

Inventors

• France Peter Glen

Classifications

• G06G7/70

  for vehicles, e.g. to determine permissible loading of ships {, centre of gravity, necessary fuel} · CPC title

• G01B11/26 Primary

  for measuring angles or tapers; for testing the alignment of axes · CPC title

• G01J4/04

  Polarimeters using electric detection means (G01J4/02 takes precedence) · CPC title

• G01C15/00 Primary

  Surveying instruments or accessories not provided for in groups G01C1/00 - G01C13/00 · CPC title

• G01S19/43

  using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry · CPC title