System and method for efficient surface measurement using a laser displacement sensor

Patent metadata

Field	Value
Publication number	US-9605950-B2
Application number	US-201414149774-A
Country	US
Kind code	B2
Filing date	Jan 7, 2014
Priority date	May 22, 2013
Publication date	Mar 28, 2017
Grant date	Mar 28, 2017

Abstract

This invention provides a system for measuring displacement of an object surface having a displacement sensor that projects a line on the object surface and receives light from the projected line at an imager in a manner defines a plurality of displacement values in a height direction. A vision system processor operates on rows of imager pixels to determine a laser line center in columns of imager pixels in each of a plurality of regions of interest. Each region of interest defines a plurality of rows that correspond with expected locations of the projected line on the object surface. A GUI can be used to establish the regions. In further embodiments, the system generates grayscale images with the imager. These grayscale images can be compared to a generated height image to compensate for contrast-induced false height readings. Imager pixels can be compared to a reference voltage to locate the line.

First claim

What is claimed is:

1. A system for correcting a suspect pixel in a grayscale image, comprising:
a computer processor; and
a memory including instructions thereon that, when executed by the processor, cause the processor to:
generate laser line position data and corresponding laser line intensity data based in part on an acquired image of an object, where the laser line position data comprises at least one laser line position datum corresponding with an associated pixel within the acquired image;
identify at least one laser line position datum associated with a suspect pixel location;
substitute, using the processor, an original value of the laser line intensity datum corresponding to the identified laser line position datum with a substitute value for the imaged pixel of the laser line intensity datum; and
generate the grayscale image from the laser line position data and corresponding substituted laser line intensity data.

2. The system of claim 1 , wherein the laser line position datum associated with the suspect pixel location is within a predetermined distance of the suspect pixel location.

3. The system of claim 1 , further comprising generating a substitute pixel by at least one of: computing an average of adjacent pixels and setting the substitute pixel value to a predetermined value.

4. The system of claim 1 , wherein the suspect pixel location is identified using a suspect pixel map.

5. A system for generating a uniformly scaled grayscale image corresponding to a height image, comprising:
a computer processor; and
a memory including instructions thereon that, when executed by the processor, cause the processor to:
generate laser line position data and laser line intensity data, each pixel of the laser line intensity data including an indicia corresponding to a measured intensity;
map each pixel of the laser line position data into a coordinate system representing a physical space, at least two of the mapped pixels having a connection feature disposed therebetween, the connection feature including indicia corresponding to the measured intensity;
compute, with the processor, a representative position value and a representative indicia value for a plurality of bins, each of the plurality of bins corresponding to one or more of the mapped pixels and a portion of the connection feature; and
output the uniformly scaled grayscale image using the representative indicia values and outputting a height image using the representative position values.

6. The system of claim 5 , wherein the representative position value comprises an average position value, and the representative indicia value comprises an average indicia value.

7. The system of claim 5 , wherein the mapping of each pixel comprises plotting each pixel of the laser line position data into a coordinate system representing a physical space.

8. The system of claim 5 , wherein the connection feature comprises a line segment.

Assignees

• Cognex Corp

Inventors

• Wolff Robert A
• Moed Michael C
• Akopyan Mikhail
• Tremblay Robert
• Foster Willard
• Wallack Aaron S

Classifications

• G01B11/026

  by measuring distance between sensor and object (G01B11/0608 takes precedence) · CPC title

• G01B11/2522 Primary

  the position of the object changing and being recorded · CPC title

• G06T7/74

  involving reference images or patches · CPC title

• G06T2207/20072

  Graph-based image processing · CPC title

• G06T2200/24

  involving graphical user interfaces [GUIs] · CPC title