METHOD AND APPARATUS FOR MONITORING A THREE-DIMENSIONAL SPATIAL AREA

• US 20090268029A1
• Filed: 05/20/2009
• Published: 10/29/2009
• Est. Priority Date: 11/24/2006
• Status: Active Grant

• Current Assignee: PILZ GmbH & Company KG
• Original Assignee: PILZ GmbH & Company KG
• Inventors: Haussmann, Joerg, Hader, Soeren
• Granted Patent: US 8,988,527 B2
• Time in Patent Office: Days
• US Class Current: 348/153
• CPC Class Codes: B25J 9/1676 Avoiding collision or forbidden zones
• CPC Class Codes: F16P 3/14 the means being photocells or other devices sensitive without mechanical contact
• CPC Class Codes: F16P 3/142 using image capturing devices

Abstract

A spatial area is monitored by means of at least a first and a second image recording unit that have a common viewing area. At least one virtual protection zone is defined within the common viewing area. A first and a second image of the spatial area are recorded by means of the first and a second image recording unit. The images are compared with one another in order to identify mutually disjoint image regions in the images. An alarm signal is generated when a disjoint image region covers the virtual protection zone.

Claims

1. A method for monitoring a three-dimensional spatial area (18), in particular for protecting an automatically operating installation (20), comprising the steps of:

providing at least a first and a second image recording unit (14, 16) directed to the spatial area (18) with a common viewing area (64),

defining at least one virtual protection zone (28) within the common viewing area (64) such that an intrusion of a foreign object (30) into the virtual protection zone (28) triggers an alarm signal (104),

recording a first image (38) of the spatial area (18) by means of the first image recording unit (14), and recording a second image (40) of the spatial area (18) by means of the second image recording unit (16),

comparing the first and second images (38, 40) in order to identify mutually disjoint image regions (68) in the first and second images (38, 40), and

generating the alarm signal (104) as a function of the disjoint image regions (68) and the virtual protection zone (28),

characterized in that the alarm signal (104) is generated when a disjoint image region (68) covers the virtual protection zone (28).

2. The method of claim 1, characterized in that at least a first distance value (110) is determined, which distance value is representative of the spatial position of at least one foreign object (30) in the common viewing area (64), and the alarm signal (104) is further generated as a function of the first distance value.

3. The method of claim 2, characterized in that the first distance value is determined by means of a propagation time measuring method.

4. The method of claim 2 or 3, characterized in that the first distance value is determined by means of a stereoscopic comparison between the first and second images (38, 40).

5. The method of one of claims 2 to 4, characterized in that the virtual protection zone (28) is defined by means of at least a second distance value (88), the alarm signal (104) being generated when the second distance value is greater than the first distance value (112).

6. The method of claim 5, characterized in that the disjoint image region (68) is assigned a third distance value (98) which is smaller than the second distance value.

7. The method of one of claims 2 to 6, characterized in that the comparison (100) for identifying disjoint image regions (68) is carried out before the first distance value (110) is determined.

8. The method of one of claims 1 to 7, characterized in that the first and the second images (38, 40) are recorded with a higher first resolution, and the comparison (100) for identifying disjoint image regions (68) is performed by means of modified first and second images (96) that have a lower second resolution.

9. The method of one of claims 1 to 8, characterized in that the first and the second images (38, 40) are compared at least approximately over the entire image area in order to identify disjoint image regions.

10. The method of one of claims 1 to 9, characterized in that a third image recording unit (76) is provided in order to record a third image of the spatial area (18), the first, second and third image recording units (14, 16, 76) being arranged along two nonparallel straight lines (78, 80), and comprising viewing areas (42, 44) that are substantially parallel to one another.

11. An apparatus for monitoring a three-dimensional spatial area (18), in particular for protecting an automatically operating installation (20), comprising at least a first and a second image recording unit (14, 16) directed to the spatial area (18) with a common viewing area (64), the first image recording unit (14) being designed to record a first image (38) of the spatial area (18) and the second image recording unit (16) being designed to record a second image (40) of the spatial area (18), and comprising an evaluation unit (46) with a memory (48) for storing a data record that defines at least one virtual protection zone (28) within the common viewing area (64), the evaluation unit (46) being designed to trigger an alarm signal as a function of at least one of the images (38, 40) when a foreign object (30) intrudes into the virtual protection zone (28), and the evaluation unit (46) being further designed to compare the first and second images (38, 40) in order to identify mutually disjoint image regions (68) in the first and second images (38, 40), characterized in that the evaluation unit (46) is further designed to generate the alarm signal when a disjoint image region (68) covers the virtual protection zone (28).