Indoor navigation via multi beam laser projection

• US 10,643,351 B2
• Filed: 03/20/2013
• Issued: 05/05/2020
• Est. Priority Date: 03/20/2013
• Status: Active Grant

• Current Assignee: Trimble Inc.
• Original Assignee: Trimble Inc.
• Inventors: Sharp, Kevin A. I.
• Primary Examiner(s): Schnurr, John R
• Assistant Examiner(s): Lotfi, Kyle M
• Application Number:
  US13/847,585
• Publication Number:
  US 20140285630A1
• Time in Patent Office: 2,603 Days
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves
• CPC Class Codes: G06T 2207/10012 Stereo images
• CPC Class Codes: G06T 7/73 using feature-based methods
• CPC Class Codes: G06T 7/85 Stereo camera calibration
• CPC Class Codes: G06T 7/97 Determining parameters from multiple pictures depth or shape recovery from multiple images G06T7/55; stereo camera calibration G06T7/85
• CPC Class Codes: H03M 7/3059 Digital compression and data reduction techniques where the original information is represented by a subset or similar information, e.g. lossy compression
• CPC Class Codes: H03M 7/3062 Compressive sampling or sensing

Abstract

An indoor navigation system is based on a multi-beam laser projector, a set of calibrated cameras, and a processor that uses knowledge of the projector design and data on laser spot locations observed by the cameras to solve the space resection problem to find the location and orientation of the projector.

Claims

1. An indoor navigation system comprising:

a laser projector configured to emit four or more laser beams in four or more different predetermined directions, no more than two laser beams of the four or more laser beams extending along a same plane, and an angle between each pair of the four or more laser beams being different from an angle between any other pair of the four or more laser beams, wherein the four or more different predetermined directions and the angle between each pair of the four or more laser beams corresponds to a reference coordinate system associated with the laser projector;

two or more cameras configured to capture images of at least four spots formed by the four or more laser beams on surfaces of an indoor space, the two or more cameras each disposed in a fixed position and having a known location and pose in a world coordinate system; and

one or more processors in communication with the two or more cameras, the one or more processors configured to;

estimate three-dimensional locations of the at least four spots using the images captured by at least two of the two or more cameras, wherein each of the three-dimensional locations of the at least four spots corresponds to the world coordinate system, and wherein the world coordinate system is associated with the indoor space; and

estimate a position and an orientation of the laser projector in the world coordinate system in the indoor space by space resection using the four or more different directions corresponding to the reference coordinate system and the three-dimensional locations corresponding to the world coordinate system of the at least four spots.

2. The system of claim 1, wherein the four or more different directions coincide at a point.

3. The system of claim 1, wherein the four or more laser beams have an infrared wavelength and the two or more cameras are equipped with infrared filters to select the infrared wavelength in preference to background light.

4. The system of claim 1, wherein each of the four or more laser beams is modulated with a modulation signal that distinguishes the laser beam from all others of the four or more laser beams, and each of the two or more cameras demodulate the modulation signal to identify a correspondence between the at least four spots and the four or more different directions.

5. The system of claim 4, wherein the modulation signal is sinusoidal.

6. The system of claim 4, wherein the modulation signal is a pseudorandom code.

7. A method for indoor navigation comprising:

emitting, using a laser projector, four or more laser beams in four or more different predetermined directions, the four or more laser beams being non-coplanar, and an angle between each pair of the four or more laser beams being different from an angle between any other pair of the four or more laser beams, wherein the four or more different predetermined directions and the angle between each pair of the four or more laser beams corresponds to a reference coordinate system associated with the laser projector;

capturing, with two or more cameras each disposed in a fixed position and at a known location and pose in a world coordinate system associated with an indoor space, images of at least four spots formed by the four or more laser beams on surfaces of the indoor space;

thereafter

estimating three-dimensional locations of the at least four spots in the world coordinate system using the images and the known location and pose of each of the two or more cameras; and

estimating a position and an orientation of the laser projector in the world coordinate system by space resection using the four or more different directions corresponding to the reference coordinate system and the three-dimensional locations of the at least four spots corresponding to the world coordinate system.

8. The method of claim 7, wherein the space resection includes:

creating a virtual point not coplanar with three actual spot locations used in the resection;

using correspondences between locations of the three actual spots and the virtual point expressed with respect to the indoor space and the laser projector to establish a transformation matrix; and

using the transformation matrix to test a fourth actual spot to resolve geometric ambiguities in resection.

9. The method of claim 7, wherein each of the four or more laser beams is modulated with a modulation signal that distinguishes the laser beam from all others of the four or more laser beams, and each of the two or more cameras demodulate the modulation signal to identify a correspondence between the at least four spots and the four or more different directions.

10. The method of claim 9, wherein the modulation signal is sinusoidal.

11. The method of claim 9, wherein the modulation signal is a pseudorandom code.

12. The method of claim 7, wherein the four or more different directions coincide at a point.

13. The method of claim 7, wherein the four or more laser beams have an infrared wavelength and the two or more cameras are equipped with infrared filters to select the infrared wavelength in preference to background light.

14. The method of claim 7, wherein the one or more surfaces of the indoor space comprise at least two surfaces, and at least two of the at least four spots are formed on two different surfaces of the at least two surfaces.