Device for monitoring an area of coverage on a work tool

• US 20050207619A1
• Filed: 05/04/2005
• Published: 09/22/2005
• Est. Priority Date: 12/20/2003
• Status: Active Grant

• Current Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Original Assignee: Leuze Lumiflex GmbH & Co. KG
• Inventors: Lohmann, Lutz
• Granted Patent: US 8,698,893 B2
• Time in Patent Office: Days
• US Class Current: 382/103
• CPC Class Codes: F16P 3/142 using image capturing devices
• CPC Class Codes: F16P 3/144 using light grids
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 17/89 for mapping or imaging

Abstract

A device for monitoring an area of coverage on a work tool may comprise a sensor, a camera, an evaluation unit, and at least one circuit output to activate the work tool only if no object is located in the area of coverage. The sensor may comprise a lighting unit to emit light rays to illuminate the area of coverage and a camera to detect three-dimensional images of the area of coverage, where the camera may include receiving elements in a matrix-type arrangement, the receiving elements to generate output signals. The evaluation unit is adapted to measure the output signals, to determine a distance value for each receiving element based on emitted light rays from the lighting unit traveling to the area of coverage and being reflected back.

Claims

1. A device for monitoring an area of coverage on a work tool, comprising:

a sensor, comprising;

a lighting unit to emit light rays to illuminate the area of coverage; and

a camera to detect three-dimensional images of the area of coverage, the camera including receiving elements in a matrix-type arrangement, the receiving elements to generate output signals;

an evaluation unit to measure the output signals, to determine a distance value for each receiving element based on emitted light rays from the lighting unit traveling to the area of coverage and being reflected back; and

at least one circuit output to activate the work tool only if no object is located in the area of coverage.

2. The device according to claim 1, wherein the camera is provided with a device selected from the group consisting of a CCD chip and a CMOS chip, the chip having a rectangular or square arrangement of receiving elements.

3. The device according to claim 1, wherein the lighting unit comprises:

at least one transmitter to emit light rays; and

transmitting optics, arranged downstream of the transmitter, to focus the light rays on the area of coverage.

4. The device according to claim 3, wherein the transmitter of the lighting unit comprises at least one of the group consisting of a light-emitting diode and a laser diode.

5. The device according to claim 1, wherein the device is adapted to determine distance values by a pulse transit-time methodology.

6. The device according to claim 5, wherein the transmitter emits light rays in the form of light pulses.

7. The device according to claim 1, wherein the device is adapted to determine distance values by a phase-measuring methodology.

8. The device according to claim 7, wherein the transmitter emits light rays that are imprinted with an amplitude modulation having at least one predetermined modulation frequency.

9. The device according to claim 1, wherein the evaluation unit is adapted to distinguish between safety-critical objects and non safety-critical objects and to send an activating signal only if no safety-critical object is located in the coverage area.

10. The device according to claim 9, wherein the evaluation unit is adapted to discriminate between non safety-critical and safety-critical objects based on stored data obtained via a learning process.

11. The device according to claim 10, wherein the stored data includes contours of non safety-critical objects.

12. The device according to claim 10, wherein the stored data includes path movements of non safety-critical objects.

13. The device according to claim 1, wherein the area of coverage includes at least one safety zone and at least one non safety-critical area, and wherein the circuit output is adapted to activate the work tool only when no objects are detected in the safety zone.

14. The device according to claim 13, wherein at least a portion of the non safety-critical area includes a warning zone, and wherein the evaluation unit generates a warning signal if an object is detected in the warning zone.

15. The device according to claim 13, wherein the non safety-critical areas are defined in dependence on the positions of either safety-critical or non safety-critical objects within the area of coverage.

16. The device according to claim 13, wherein the at least one non safety-critical area is defined in dependence on signals from one or more external sensors.

17. The device according to claim 1, wherein the sensor unit has a single-channel design.

18. The device according to claim 17, wherein the sensor further includes an automatic error control mechanism.

19. The device according to claim 18, wherein the sensor is adapted to operate on the basis of a pulse transit-time method, and wherein the automatic error control mechanism involves an adaptation that includes delay of light pulses transmitted by the lighting unit at predetermined time intervals and evaluation of resulting changed distance values of the receiving elements.

20. The device according to claim 18, wherein the sensor is adapted to operate on the basis of a pulse transit-time method, and wherein the automatic error control mechanism involves an adaptation that includes delay of light pulses transmitted by the lighting unit at predetermined time intervals and evaluation of resulting changed distance values of the receiving elements.

21. The device according to claim 18, wherein the sensor is adapted to operate based on a phase-measuring method, and wherein the phase-measuring method involves an adaptation involving displacement of a phase of an amplitude modulation imprinted on the light rays emitted by the lighting unit and evaluation of resulting changed distance values of the receiving elements.

22. The device according to claim 1, wherein the evaluation unit has a two-channel design.

23. The device according to claim 22, wherein the evaluation unit comprises two computer units that mutually monitor each other.

24. A mobile work arrangement comprising:

a mobile work tool; and

the device according to claim 1, wherein the device is positioned to monitor an area of coverage in front of the mobile work tool.