Optoelectronic detection of objects by measurement of angular position to determine relative movement of a deflection unit

Patent metadata

Field	Value
Publication number	US-10488550-B2
Application number	US-201715626411-A
Country	US
Kind code	B2
Filing date	Jun 19, 2017
Priority date	Jun 24, 2016
Publication date	Nov 26, 2019
Grant date	Nov 26, 2019

Abstract

An optoelectronic sensor ( 10 ) for detecting objects comprises a light transmitter ( 12 ) for transmitting a light beam ( 16 ), a rotatable deflection unit ( 18 ) for periodically deflecting the light beam ( 16 ), an angle measuring unit ( 30 ) for determining an angular position of the deflection unit ( 18 ), a light receiver ( 26 ) for generating a reception signal from a reflected light beam ( 22 ), wherein the angle measuring unit ( 30 ) comprises an image sensor ( 32 ) moving with the deflection unit and arranged in the direction of a stationary part ( 44, 46 ) of the sensor ( 10 ), or a stationary image sensor ( 32 ) arranged in the direction of the deflection unit ( 18 ), further comprising a computing unit ( 36 ) to determine a relative movement of the deflection unit ( 18 ) with respect to the sensor ( 10 ) from a signal of the image sensor ( 32 ).

First claim

The invention claimed is:

1. An optoelectronic sensor ( 10 ) for detecting objects in a monitoring area ( 20 ), the sensor ( 10 ) comprising
a light transmitter ( 12 ) for transmitting a light beam ( 16 ),
a rotatable deflection unit ( 18 ) for periodically deflecting the light beam ( 16 ) in the monitoring area ( 20 ),
an angle measuring unit ( 30 ) for determining an angular position of the deflection unit ( 18 ),
a light receiver ( 26 ) for generating a reception signal from a reflected light beam ( 22 ) being remitted or reflected by the objects,
and an evaluation unit ( 40 ) configured to evaluate the reception signal for detecting the objects,
wherein the angle measuring unit ( 30 ) comprises an integrated system comprising:
an image sensor ( 32 ) moving with the deflection unit and arranged in the direction of a stationary part ( 44 , 46 ) of the sensor ( 10 ),
or a stationary image sensor ( 32 ) arranged in the direction of the deflection unit ( 18 ),

and wherein the integrated system further comprises a computing unit ( 36 ) configured to determine a relative movement of the deflection unit ( 18 ) with respect to the sensor ( 10 ) from a signal of the image sensor ( 32 ), the relative movement is determined from the signal of the image sensor ( 32 ) and the computing unit ( 36 ) with an optical flow method.

2. The sensor ( 10 ) according to claim 1 ,
the sensor ( 10 ) being configured as a laser scanner.

3. The sensor ( 10 ) according to claim 1 ,
wherein the angle measuring unit ( 30 ) comprises an illumination unit ( 34 ).

4. The sensor ( 10 ) according to claim 1 ,
wherein at least one reference marking ( 48 ) is arranged at the stationary part ( 44 , 46 ) or at the deflection unit ( 18 ) in a known angular position.

5. The sensor ( 10 ) according to claim 1 ,
wherein the deflection unit ( 18 ) comprises a rotary mirror, and wherein the image sensor ( 32 ) is arranged at the rear side of the rotary mirror.

6. The sensor ( 10 ) according to claim 1 ,
wherein the deflection unit ( 18 ) is configured as a rotating scanning unit which comprises the light transmitter ( 12 ) and the light receiver ( 26 ), and wherein the image sensor ( 32 ) is arranged on the scanning unit at an angular offset with respect to the light transmitter ( 12 ) and the light receiver ( 26 ).

7. The sensor ( 10 ) according to claim 1 ,
the sensor ( 10 ) comprising a front screen ( 46 ), with the image sensor ( 32 ) being arranged in the direction of the front screen ( 46 ), wherein the computing unit ( 36 ) is configured to detect a contamination of the front screen ( 46 ) from the signal of the image sensor ( 32 ).

8. The sensor ( 10 ) according to claim 7 ,
wherein a reference signal for a front screen ( 46 ) without contamination is stored in the computing unit ( 36 ).

9. The sensor ( 10 ) according to claim 1 ,
the sensor ( 10 ) being configured as a safety sensor and comprising a safe output ( 42 ), wherein the evaluation unit ( 40 ) is configured to determine whether there is an object in a protected field within the monitoring area ( 20 ) and to then output a safety-related stop signal via the safe output ( 42 ).

10. The sensor ( 10 ) according to claim 9 ,
wherein the evaluation unit ( 40 ) is configured to output a safety-related stop signal when there is a contamination of the front screen ( 46 ) in connection with a protected field.

11. The sensor ( 10 ) according to claim 1 ,
wherein the computing unit ( 36 ) is configured to also detect a relative movement of the deflection unit ( 18 ) with respect to the stationary part ( 44 , 46 ) in a direction transverse to the rotary movement of the deflection unit ( 18 ).

12. A method for detecting objects in a monitoring area ( 20 ), the method comprising the steps of
transmitting a light beam ( 16 ),
periodically deflecting the light beam ( 16 ) in the monitoring area ( 20 ) by means of a deflection unit ( 18 ),
generating a reception signal from a reflected light beam ( 22 ) remitted or reflected by the objects, and
evaluating the reception signal for detecting the objects,
wherein a respective angular position of the light beam ( 16 ) transmission is determined,
wherein for measuring the angular position an integrated system comprising a computing unit ( 36 ) and either:
an image sensor ( 32 ) which is arranged in the direction of a stationary part ( 44 , 46 ) is moved with the deflection unit ( 18 ),
or a stationary image sensor ( 32 ) is arranged in the direction of the deflection unit ( 18 ),

and wherein a relative movement of the deflection unit ( 18 ) with respect to the stationary part ( 44 , 46 ) is determined from the signal of the image sensor ( 32 ), the relative movement is determined from the signal of the image sensor ( 32 ) and the computing unit ( 36 ) with an optical flow method.

13. The method according to claim 12 ,
wherein the image sensor ( 32 ) is arranged in the direction of a front screen ( 46 ), and wherein additionally a contamination of the front screen ( 46 ) is detected from the signal of the image sensor ( 32 ).

14. The method according to claim 13 ,
wherein the contamination is detected by comparison with a reference signal for a front screen ( 46 ) without contamination.

15. An optoelectronic sensor ( 10 ) for detecting objects in a monitoring area ( 20 ), the sensor ( 10 ) comprising
a light transmitter ( 12 ) for transmitting a light beam ( 16 ),
a rotatable deflection unit ( 18 ) for periodically deflecting the light beam ( 16 ) in the monitoring area ( 20 ),
an angle measuring unit ( 30 ) for determining an angular position of the deflection unit ( 18 ),
a light receiver ( 26 ) for generating a reception signal from a reflected light beam ( 22 ) being remitted or reflected by the objects,
and an evaluation unit ( 40 ) configured to evaluate the reception signal for detecting the objects,
wherein the angle measuring unit ( 30 ) comprises an integrated system comprising an image sensor ( 32 ) moving with the deflection unit and arranged in the direction of a stationary part ( 44 , 46 ) of the sensor ( 10 ),
and wherein the integrated system further comprises a computing unit ( 36 ) configured to determine a relative movement of the deflection unit ( 18 ) with respect to the sensor ( 10 ) from a signal of the image sensor ( 32 ), the relative movement is determined from the signal of the image sensor ( 32 ) and the computing unit ( 36 ) with an optical flow method.

Assignees

• Sick Ag

Inventors

• Albert Magnus
• Baldischweiler Boris
• Engler Michael
• Krämer Joachim
• Sigmund Jörg

Classifications

• G01C15/002

  Active optical surveying means (optical plumbing G01C15/105) · CPC title

• G01B11/26

  for measuring angles or tapers; for testing the alignment of axes · CPC title

• G01S7/4817

  relating to scanning · CPC title

• G02B26/0816

  by means of one or more reflecting elements · CPC title

• G02B27/48

  Laser speckle optics · CPC title