Structured illumination autonomous machine vision system

• US 5,155,775 A
• Filed: 10/13/1988
• Issued: 10/13/1992
• Est. Priority Date: 10/13/1988
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Original Assignee: United States Of America As Represented By The Secretary Of The Army (Government of the United States of America)
• Inventors: Brown, C. David
• Primary Examiner(s): Boudreau, Leo H.
• Assistant Examiner(s): Fox, David
• Application Number:
  US07/260,423
• Time in Patent Office: 1,461 Days
• Field of Search: 382/1, 382/8, 382/25, 382/22, 901/47, 244/3.15, 364/424.01, 364/424.02
• US Class Current: 382/153
• CPC Class Codes: G05D 1/024 in combination with a laser lasers per se H01S
• CPC Class Codes: G05D 1/0251 extracting 3D information from a plurality of images taken from different locations, e.g. stereo vision stereoscopic image analysis H04N13/00; depth recovery from images G06T7/593
• CPC Class Codes: G06T 2207/10012 Stereo images
• CPC Class Codes: G06T 2207/10021 Stereoscopic video; Stereoscopic image sequence
• CPC Class Codes: G06T 2207/30256 Lane; Road marking
• CPC Class Codes: G06T 7/13 Edge detection
• CPC Class Codes: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light
• CPC Class Codes: G06V 10/145 Illumination specially adapted for pattern recognition, e.g. using gratings
• CPC Class Codes: G06V 10/48 by mapping characteristic values of the pattern into a parameter space, e.g. Hough transformation
• CPC Class Codes: H04N 13/207 using a single 2D image sensor
• CPC Class Codes: H04N 13/254 in combination with electromagnetic radiation sources for illuminating objects
• CPC Class Codes: H04N 13/296 Synchronisation thereof; Control thereof
• CPC Class Codes: H04N 2013/0081 Depth or disparity estimation from stereoscopic image signals
• CPC Class Codes: H04N 2013/0092 Image segmentation from stereoscopic image signals

Abstract

A method and apparatus for automatically determining pathway boundaries for autonomous robotic navigation. A structured light pattern consisting of a plurality of lines is projected on the pathway and background and the reflected pattern is detected by a stereoscopically located video camera. Since the texture of the pathway and background are different, the captured image may be processed to distinguish one from the other. Image processing includes Hough transformation of the image field, rank filtering and morphological dilation. The end points of the pathway lines identified by such processing as well as the 3-D coordinates of such end points are determined.

Claims

1. A method of providing information for automatically determining pathway boundaries for autonomous robotic navigation, comprising the steps of:

projecting a structured light pattern of sequentially scanned thin horizontal lines on a pathway and background,

viewing the resultant light pattern which is reflected from the pathway and background with a stereoscopically located video camera,

storing an image field which includes bits which correspond to said resultant light pattern in a memory, and

processing the image field to determine the degree of distortion of said resultant light pattern, wherein the texture of the background is courser than the texture of the pathway, and whereby said information for determining said pathway boundaries is provided as indicated by the scanned lines reflected from the background having a greater degree of discontinuity than those reflected from the pathway, wherein said processing includes taking the Hough transform of said image field to identify lines in said resultant light pattern, and wherein said processing further includes rank filtering said identified lines.

2. The method of claim 1 wherein said processing further includes morphologically dilating said filtered lines.

3. The method of claim 2 wherein said processing further includes detecting the end points of said lines following said morphological dilation.

4. The method of claim 3 wherein said processing further includes deriving the 3-D coordinates of the end points of the lines.