Reflection refuting laser scanner

• US 10,551,179 B2
• Filed: 04/29/2019
• Issued: 02/04/2020
• Est. Priority Date: 04/30/2018
• Status: Active Grant

• Current Assignee: Path Robotics, Inc.
• Original Assignee: Path Robotics, Inc.
• Inventors: Lonsberry, Alexander James, Lonsberry, Andrew Gordon
• Primary Examiner(s): Mistry, Oneal R
• Application Number:
  US16/397,428
• Publication Number:
  US 20190331480A1
• Time in Patent Office: 281 Days
• CPC Class Codes: G01B 11/2513 with several lines being projected in more than one direction, e.g. grids, patterns
• CPC Class Codes: G01B 11/2518 Projection by scanning of the object
• CPC Class Codes: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light

Abstract

Some embodiments described herein relate to optical systems and methods for determining the shape and/or size of objects that include projecting a pattern of light onto the object. The pattern of light can be configured such that first-order reflections can be distinguished from second- and/or higher-order reflections, which can be rejected. Thus, even in instances in which the pattern of light is reflected onto the object multiple times, the original, or first-order, reflection can be detected, distinguished, and/or used for laser triangulation. In some embodiments, a pattern of light that does not have reflection and/or rotational symmetry is projected onto the object, such that second-order and/or higher-order reflections can be distinguished from the first-order reflection.

Claims

1. An apparatus, comprising:

a light source configured to project a pattern onto a part, the pattern having a predetermined geometry such that a first-order reflection of the pattern has a geometry that is distinguishable from a geometry of second-order reflections of the pattern;

a detector configured to capture an image the part; and

a compute device communicatively coupled to the detector, the compute device configured to process the image to identify a first-order reflection of the pattern based on the geometry of the first-order reflection and to filter second-order reflections of the pattern based on the geometry of the second-order reflections.

2. The apparatus of claim 1, wherein the compute device is further configured to identify a shape of a portion of the part onto which the pattern is projected based on the first-order reflection of the pattern.

3. The apparatus of claim 1, wherein:

the light source is configured to scan the pattern over the part;

the image is from a plurality of images;

the detector is configured to capture the plurality of images, a different portion of the part producing a first-order reflection of the pattern in each image from the plurality of images; and

the compute device is configured to process the plurality of images to identify the first-order reflection of the pattern in each image from the plurality of images and filter second-order reflections of the pattern from each image from the plurality of images.

4. The apparatus of claim 3, wherein the compute device is further configured to identify a shape of a surface of the part based on the first-order reflection of the pattern in each image from the plurality of images.

5. The apparatus of claim 3, wherein the compute device is further configured to generate a three-dimensional model of a surface of the part based on the first-order reflection of the pattern in each image from the plurality of images.

6. The apparatus of claim 1, wherein the predetermined geometry does not have reflection symmetry.

7. The apparatus of claim 1, wherein the predetermined geometry does not have rotational symmetry.

8. The apparatus of claim 1, wherein the light source is configured to project a first portion of the pattern in a first color and a second portion of the pattern in a second color.

9. A method, comprising:

projecting a predefined non-symmetric pattern from a light source onto a part such that the light source produces a first-order reflection of the predefined non-symmetric pattern at a first portion of the part where the predefined non-symmetric pattern first illuminates the part and such that the first portion of the part reflects the predefined non-symmetric pattern to a second portion of the part thereby producing a second-order reflection of the predefined non-symmetric pattern;

capturing an image of the part including the first-order reflection of the predefined non-symmetric pattern and the second-order reflection of the non-symmetric pattern;

processing the image of the part to remove the second-order reflection of the predefined non-symmetric pattern; and

identifying a shape of the first portion of the part based on deviations of the predefined non-symmetric pattern in the image of the first-order reflection.

10. The method of claim 9, further comprising:

scanning the predefined non-symmetric pattern over the part;

capturing a plurality of images of the part including the image;

processing each image from the plurality of images to remove second-order reflections of the predefined non-symmetric pattern; and

generating a three-dimensional model of a surface of the part based on deviations of the predefined non-symmetric pattern in first-order reflections depicted in the plurality of images.

11. The method of claim 9, wherein the predefined non-symmetric pattern includes a linear portion and a non-symmetric portion.

12. The method of claim 11, wherein identifying the shape of the first portion of the part includes identifying nonlinear portions of the first-order reflection of the linear portion of the predefined non-symmetric pattern.

13. The method of claim 9, wherein the predefined non-symmetric pattern includes a plurality of non-isosceles right triangles.

14. The method of claim 9, wherein at least a portion of the predefined non-symmetric pattern is projected from a laser line projector.

15. The method of claim 9, wherein the light source is a first light source and the non-symmetric pattern is a first predetermined non-symmetric pattern, the method further comprising:

projecting a second predetermined non-symmetric pattern from a second light source onto the part;

processing the image of the part to remove greater-than-first-order reflections of the second predetermined non-symmetric pattern; and

identifying a shape of a third portion of the part based on nonlinear portions of a first-order reflection of a linear portion of the second predetermined non-symmetric pattern.

16. A non-transitory processor readable medium storing code configured to be executed by a processor, the code comprising code to cause the processor to:

receive a plurality of images of a part illuminated by a pattern having a predetermined geometry, each image from the plurality of images including a first-order reflection of the pattern, and at least one image from the plurality of images including a second-order reflection of the pattern;

filter the second-order reflection of the pattern from the at least one image by comparing a geometry of the second-order reflection to the predetermined geometry; and

generate a three-dimensional model of at least a portion of the part based on triangulating a linear portion of the pattern in first-order reflections captured in the plurality of images.

17. The non-transitory processor readable medium of claim 16, wherein the predetermined geometry does not have rotational or reflection symmetry.

18. The non-transitory processor readable medium of claim 16, wherein:

the predetermined geometry does not have rotational or reflection symmetry such that each second-order reflection of the pattern has a geometry different from the predetermined geometry; and

the code to cause the processor to filter the second-order reflection of the pattern further includes code to cause the processor filter all reflections of the pattern that have a geometry other than the predetermined geometry.

19. The non-transitory processor medium of claim 16, wherein:

the linear portion of the pattern has a first color; and

a second portion of the pattern that lacks rotational and reflection symmetry has a second color.

20. The non-transitory processor medium of claim 16, wherein the three-dimensional model of at least a portion of the part is generated based, at least in part, on a stored location of an imaging device that captured the plurality of images and a stored location of a light source that projected the pattern onto the part.