Indoor navigation via multi beam laser projection

• US 20140285630A1
• Filed: 03/20/2013
• Published: 09/25/2014
• Est. Priority Date: 03/20/2013
• Status: Active Grant

• Current Assignee: Trimble Inc.
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Sharp, Kevin A. I.
• Granted Patent: US 10,643,351 B2
• Time in Patent Office: Days
• US Class Current: 348/47
• 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 that emits laser beams in four or more different directions;

two or more cameras that capture images of spots made by the laser beams on surfaces of an indoor space, the cameras calibrated such that three-dimensional locations of the spots can be estimated from images captured by at least two cameras; and

,

a processor in communication with the cameras, the processor estimating the position and orientation of the laser projector in the indoor space by space resection given the four or more different directions and the three-dimensional locations of the spots.

2. The system of claim 1, each pair of directions of the four or more defining an angle different from that of any other pair.

3. The system of claim 1, the four or more different directions coinciding at a point.

4. The system of claim 1, the laser beams having an infrared wavelength and the cameras equipped with infrared filters to select the wavelength in preference to background light.

5. The system of claim 1, each laser beam modulated with a modulation signal that distinguishes it from all of the other laser beams, and each camera demodulating the signal to identify a correspondence between spots and laser beam directions.

6. The system of claim 5, the modulation signal being sinusoidal.

7. The system of claim 5, the modulation signal being a pseudorandom code.

8. A method for indoor navigation comprising:

capturing, with two or more cameras, images of spots made by laser beams on surfaces of an indoor space, the laser beams emitted by a laser projector in four or more different directions;

estimating three-dimensional locations of the spots from images captured by at least two cameras; and

,

estimating the position and orientation of the laser projector in the indoor space by space resection given the four or more different directions and the three-dimensional locations of the spots.

9. The method of claim 8, the cameras calibrated by:

(a) capturing simultaneously with two or more cameras images of four or more spots on a planar surface;

(b) determining homographies between pairs of cameras by identifying corresponding spots in the images captured in step (a);

(c) determining from the homographies;

relative poses between pairs of cameras, and orientation of the planar surface with respect to the cameras;

(d) fitting the orientation of the planar surface to a model of the indoor space; and

,

(e) determining the location and pose of each camera in the indoor space.

10. The method of claim 8, the space resection including:

creating a virtual point not coplanar with three actual spot locations used in 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.

11. The method of claim 8, each laser beam modulated with a modulation signal that distinguishes it from all of the other laser beams, and each camera demodulating the signal to identify a correspondence between spots and laser beam directions.

12. The method of claim 11, the modulation signal being sinusoidal.

13. The method of claim 11, the modulation signal being a pseudorandom code.

14. The method of claim 8, each pair of directions of the four or more defining an angle different from that of any other pair.

15. The method of claim 8, the four or more different directions coinciding at a point.

16. The method of claim 8, the laser beams having an infrared wavelength and the cameras equipped with infrared filters to select the wavelength in preference to background light.