VIRTUAL MULTIPLE APERTURE 3-D RANGE SENSOR

• US 20010001578A1
• Filed: 02/04/1999
• Published: 05/24/2001
• Est. Priority Date: 02/04/1999
• Status: Active Grant

• Current Assignee: National Research Council Canada
• Original Assignee: National Research Council Canada
• Inventors: BLAIS, FRANCOIS
• Granted Patent: US 6,271,918 B2
• Time in Patent Office: Days
• US Class Current: 356/601
• CPC Class Codes: G01C 3/14 with binocular observation at a single point, e.g. stereoscopic type G01C3/20 takes precedence

Abstract

A 3-D range sensor for measuring range from the sensor to a target surface by imaging a plurality of points projected onto the target surface is disclosed. The range sensor comprises an optical system for imaging a first image and a second other image of each of the plurality of points on the target surface, whereby the second other image is obtained from a different predetermined location than the first image. The optical system comprises an optical medium for combining the first image and the second other image, at least a reflective means for imaging at least one of the first and the second other image and for reflecting it to the optical medium such that the first image and the second other image are combined and a converging lens system for focussing the first image and the second other image. A position sensitive light detector detects the focussed first image and the focussed second other image. Using a processor, a distance between the detected first image and the detected second other image is determined and based on the determined distance and a known spatial relation between the first and the second other image the range is then calculated.

Claims

1. A range sensor for measuring a range from the range sensor to a target point on a surface comprising:

a light source for projecting a target at the target point on the surface;

a first detector for capturing a first image;

a second detector for capturing a second other image;

a first optical path for providing the first image of the target point to the first detector the first image provided from a first viewing angle;

a second optical path for providing a second image of the same target point to the second detector from a different viewing angle;

a processor for determining a distance measurement in dependence upon the two captured images, the distance measurement determined using at least two imaged target points, imaged target point positions used to determine a range measurement, the processor for validating the determined range measurement.

2. A range sensor as defined in

claim 1

wherein the imaging device comprises a first lens for focussing the first image onto the first detector;

the first lens having a focal axis; and

,

wherein the second imaging device comprises a second lens for focussing the second other image onto the second detector;

the second lens having a focal axis;

see above!

3. A range sensor as defined in

claim 2

wherein at least one of the first lens and the second lens comprise a pinhole lens.

4. A range sensor as defined in

claim 1

wherein the processor comprises means for executing suitably programmed instructions for performing the steps of:

selecting a first detected target point position;

determining from the first detected target point position a corresponding position of another detected target point, the corresponding position of a target point imaged along a different optical path and relating to an approximately same determined range measurement;

determining a presence or absence of a target point at the corresponding position; and

,

when a target point is detected at the corresponding position, determining a range measurement from the two corresponding target point positions and validating the determined range measurement.

5. A range sensor as defined in

claim 1

wherein the processor comprises means for executing suitably programmed instructions for performing the steps of:

a) selecting a first detected target point position;

b) determining from the first detected target point position a corresponding position of another detected target point, the corresponding position of a target point imaged along a different optical path and relating to an approximately same determined range measurement;

c) determining a presence or absence of a target point at the corresponding position;

d) when a target point is detected at the corresponding position, determining a range measurement from the two corresponding target point positions and validating the determined range measurement; and

, when no target point is detected at the corresponding position, selecting a new first target point position and repeating steps (b), (c) and (d).

6. A range sensor for measuring a range from the range sensor to a target point on a surface comprising:

a light source for projecting a target at the target point on the surface;

a detector for capturing an image;

a lens for focussing the first image and the second other image onto the detector;

a first optical path having a first optical axis for providing the first image of the target point to the detector the first image provided from a first viewing angle;

a second optical path having a second different optical axis for providing a second image of the same target point to the detector from a different viewing angle;

a processor for determining a distance measurement in dependence upon a captured image, the distance measurement determined using at least detected target points.

7. A range sensor as defined in

claim 6

comprising a combiner for combining light from the first optical path and the second optical path.

8. A range sensor as defined in

claim 6

wherein the processor comprises means for validating the determined range.

9. A range sensor as defined in

claim 6

wherein the processor comprises means for executing suitably programmed instructions for performing the steps of:

selecting a first detected target point having a position;

determining from the first detected target point position a corresponding position of another detected target point, the corresponding position of a target point imaged along a different optical path and relating to an approximately same determined range measurement;

determining a presence or absence of a target point at the corresponding position; and

,

when a target point is detected at the corresponding position, determining a range measurement from the two corresponding target point positions and validating the determined range measurement.

10. A range sensor as defined in

claim 6

wherein the processor comprises means for executing suitably programmed instructions for performing the steps of:

a) selecting a first detected target point having a position;

b) determining from the first detected target point position a corresponding position of another detected target point, the corresponding position of a target point imaged along a different optical path and relating to an approximately same determined range measurement;

c) determining a presence or absence of a target point at the corresponding position;

d) when a target point is detected at the corresponding position, determining a range measurement from the two corresponding target point positions and validating the determined range measurement; and

, when no target point is detected at the corresponding position, selecting a new first target point position and repeating steps (b), (c) and (d).

11. A range sensor as defined in

claim 6

wherein the target consists of a single point of light.

12. A range sensor as defined in

claim 6

wherein the target comprises a pattern of points of light.

13. A range sensor as defined in

claim 12

wherein the pattern consists of one or more straight lines of light.

14. A method of determining a distance between a detector and a surface comprising the steps of:

projecting a target from a source onto the surface;

using a detector, imaging the target through two different optical paths, each optical path having a different optical axis; and

determining the distance to the surface based on the location of the source, the location of the detector, and the images of the target, the distance determined using triangulation.

15. A method as defined in

claim 14

comprising the steps of

detecting target point positions within an image captured with the detector;

selecting a first detected target point position;

determining from the first detected target point position a corresponding position of another detected target point, the corresponding position of a target point imaged along a different optical path and relating to an approximately same determined range measurement;

determining a presence or absence of a target point at the corresponding position; and

,

when a target point is detected at the corresponding position, determining a range measurement from the two corresponding target point positions and validating the determined range measurement.

16. A method as defined in

claim 15

wherein corresponding peak positions are disposed on different scan lines of the imaged image.

17. A method as defined in

claim 15

wherein corresponding peak positions are determined accounting for scaling resulting from differences in optical path lengths between the first optical path and the second optical path.

18. A method as defined in

claim 14

comprising the steps of

a) detecting target point positions within an image captured with the detector;

b) selecting a first detected target point position;

c) determining from the first detected target point position a corresponding position of another detected target point, the corresponding position of a target point imaged along a different optical path and relating to an approximately same determined range measurement;

d) determining a presence or absence of a target point at the corresponding position;

e) when a target point is detected at the corresponding position, determining a range measurement from the two corresponding target point positions and validating the determined range measurement; and

, when no target point is detected at the corresponding position, selecting a new first target point position and repeating steps (c), (d) and (e).

19. A method as defined in

claim 18

wherein a new first target point position is selected in dependence upon a known target geometry and previously validated first target point positions.

20. A method as defined in

claim 19

comprising the step of validating determined corresponding peak positions in dependence upon other corresponding peak positions and the known target geometry.

21. A method as defined in

claim 18

wherein a range measurement is determined based on the two corresponding peak positions and the distance therebetween.

22. A method as defined in

claim 15

wherein for a first target point position, a single unique position exists for another corresponding target point for validating a range determined from the first target point position, the target point position assumed detected along a first optical path.