Method and device for safeguarding a hazardous area

• US 20050207618A1
• Filed: 03/23/2005
• Published: 09/22/2005
• Est. Priority Date: 09/24/2002
• Status: Active Grant

• Current Assignee: PILZ GmbH & Company KG
• Original Assignee: PILZ GmbH & Company, Daimler Chrysler Company LLC (Stellantis NV)
• Inventors: Wohler, Christian, Kruger, Lars, Wendler, Martin, Progscha, Werner, Dottling, Dietmar
• Granted Patent: US 7,729,511 B2
• Time in Patent Office: Days
• US Class Current: 382/103
• CPC Class Codes: B25J 19/06 Safety devices
• CPC Class Codes: B25J 9/1674 characterised by safety, monitoring, diagnostic
• CPC Class Codes: B25J 9/1697 Vision controlled systems
• CPC Class Codes: F16P 3/142 using image capturing devices
• CPC Class Codes: G06T 2207/10012 Stereo images
• CPC Class Codes: G06T 2207/30108 Industrial image inspection
• CPC Class Codes: G06T 2207/30196 Human being; Person
• CPC Class Codes: G06T 7/001 using an image reference approach

Abstract

In order to safeguard a hazardous area, in particular the hazardous area of an automatically operating machine, images of the hazardous area are recorded with at least a first and a second image recording unit that are arranged offset from one another. The images of the scene are subjected to three-dimensional scene analyses using different three-dimensional scene analysis methods, and the hazardous area is safeguarded when at least one of the scene analysis methods detects a foreign object.

Claims

1. A method for safeguarding a hazardous area of an automatically operating machine against intrusion of foreign objects, comprising the steps of:

providing at least a first and a second image recording unit which are arranged offset from one another,

recording at least a first image of the hazardous area by means of the first image recording unit and a second image of the hazardous area by means of the second image recording unit, and

carrying out a first and a second scene analysis on the basis of the first and second images in order to detect foreign objects in the hazardous area,

wherein the first and second scene analyses are carried out using at least two algorithmically different methods, and

wherein the machine is brought into a safe state when at least one of the scene analysis methods detects a foreign object.

2. The method of claim 1, wherein each of the scene analysis methods is carried out using the first and the second images.

3. The method of claim 1, wherein one of the scene analysis methods comprises a correlation-based scene analysis, and another one comprises a contour-based scene analysis.

4. The method of claim 1, further comprising the step of providing a reference image of the hazardous area, the reference image being free from foreign objects to be detected, wherein at least one of the scene analysis methods processes only such image regions in the first and second images that differ significantly from the reference image.

5. The method of claim 1, wherein at least three images of the hazardous area are recorded using at least three image recording units that are not arranged in line.

6. The method of claim 5, wherein the at least three images are grouped into at least two image pairs, with each two image pairs having one of the at least three images in common.

7. The method of claim 1, wherein all scene analysis methods are applied to all the images.

8. The method of claim 1, further comprising the step of evaluating a number of temporally successive groups of the at least first and second images in order to determine at least one movement parameter of a foreign object detected.

9. The method of claim 1, wherein an exposure time for each image recording unit is set as a function of the image recorded by it.

10. The method of claim 1, wherein a three-dimensional representation of the scene is established by minimizing a target function to be determined from all the images simultaneously.

11. A method for safeguarding a hazardous area, wherein at least two images of the hazardous area are recorded by means of at least a first and a second image recording unit, the image recording units being arranged offset from one another, and wherein foreign objects in the hazardous area are detected by means of a scene analysis of the first and second images, wherein the scene analysis is carried out on the basis of the at least two images using at least two algorithmically different methods, and wherein the hazardous area is safeguarded when at least one of the methods detects a foreign object.

12. A device for safeguarding a hazardous area of an automatically operating machine, having at least a first and a second image recording unit for recording at least a first and a second image of the hazardous area, the image recording units being arranged offset from one another, having an evaluation unit adapted for detecting foreign objects in the hazardous area by means of a scene analysis on the basis of the first and second images, and having a switch that is responsive to the evaluation unit in order to safeguard the machine upon detection of a foreign object in the hazardous area, wherein the evaluation unit is designed for carrying out the scene analysis using at least two algorithmically different methods, and wherein the switch is activated when at least one of the scene analysis methods detects a foreign object.

13. The device of claim 12, wherein the evaluation unit is set up to apply all the scene analysis methods to all of the images of the scene.

14. The device of claim 12, further comprising at least a third image recording unit for recording a third image of the hazardous area, the evaluation unit being designed to apply at least one of the two scene analysis methods to the at least three images.

15. The device of claim 12, wherein at least two of the image recording units are arranged in a common housing.

16. The device of claim 12, wherein the evaluation unit is designed for establishing a three-dimensional. representation of the scene by minimizing a target function to be determined from all images simultaneously.