Distance determination

• US 6,781,705 B2
• Filed: 11/29/2001
• Issued: 08/24/2004
• Est. Priority Date: 11/29/2000
• Status: Expired due to Term

• Current Assignee: Sick AG (Sick)
• Original Assignee: Sick AG (Sick)
• Inventors: Merettig, Gerhard, Waslowski, Kai, Ringwald, Siegfried
• Primary Examiner(s): Pham, Hoa Q.
• Application Number:
  US09/997,417
• Publication Number:
  US 20020097404A1
• Time in Patent Office: 999 Days
• Field of Search: 356/601-623, 356/3.08, 356/3.13, 356/3.04
• US Class Current: 356/614
• CPC Class Codes: G01B 11/026 by measuring distance between sensor and object G01B11/0608 takes precedence
• CPC Class Codes: G01C 3/06 Use of electric means to obtain final indication
• CPC Class Codes: G01S 17/48 Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 7/4814 of transmitters alone
• CPC Class Codes: G01S 7/4912 Receivers

Abstract

The invention relates to a method for the determination of the object distance between an opto-electronic sensor working according to the principle of triangulation and an object,

wherein the sensor has at least one measuring channel between a transmission unit for the emission of electromagnetic sensing rays into the measuring region and a reception unit for the detection of sensing rays reflected and/or remitted from the measuring region;

wherein the sensor has at least one additional channel which has a further transmission unit and/or a further reception unit in addition to the transmission unit and the reception unit; and

wherein the received signals of the measuring channel and of the additional channel are jointly evaluated for the determination of the object distance.

The invention further relates to an apparatus for the carrying out of this method.

Claims

1. A method for the determination of an object distance between an opto-electronic sensor working according to the principle of triangulation and a sensed object, comprising

providing the sensor with at least one measuring channel between a transmission unit for emitting first electromagnetic sensing rays into the measuring region and a reception unit for detecting sensing rays coming from the measuring region;

providing the sensor with at least one additional channel which has at least one of a further transmission unit for transmitting second electromagnetic sensing rays into the measuring region and a further reception unit;

expanding the second sensing rays and directing the expanded second sensing rays onto the measuring region to form an expanded sensing zone; and

jointly evaluating the received signals of the measuring channel and of the additional channel in order to determine the object distance by forming a difference between the received signals of the measuring channel and of the additional channel.

2. A method in accordance with claim 1 wherein the measuring channel and the additional channel are operated at least substantially simultaneously for each object distance.

3. A method in accordance with claim 1 wherein the received signals of both the measuring channel and of the additional channel are used to determine a distance value serving as the measure for the object distance.

4. A method in accordance with claim 1 wherein in at least one of the measuring channel and in the additional channel the respective intensity distribution of the received signal on the reception unit is used for determining the distance.

5. A method in accordance with claim 4 wherein one of the position of a center of the intensity distribution and of a characteristic region of the intensity distribution is used in at least one of the measuring channel and the additional channel for determining the distance.

6. A method in accordance with claim 1 wherein jointly evaluating comprises deducting the received signal of the additional channel from the received signal of the measuring channel, setting negative difference values resulting from the deduction at zero, and using positive difference signals resulting from deducting for determining the object distance.

7. A method in accordance with claim 1 including selecting an intensity of the sensing rays such that the received signal is larger in the additional channel than in the measuring channel in a characteristic region which is caused by an interfering object having one of a high reflection and remittance capability in comparison to the sensed object.

8. A method in accordance with claim 1 wherein expanding comprises expanding the second sensing rays in at least one of an unfocused, scattered, expanded and diffused manner.

9. A method according to claim 1 wherein the sensing zone covers at least a substantial part of a half-space of the sensor on the sensed object side.

10. A method for the determination of an object distance between an opto-electronic sensor working according to the principle of triangulation and a sensed object, comprising

providing the sensor with at least one measuring channel between a transmission unit for emitting first electromagnetic sensing rays into the measuring region and a reception unit for detecting sensing rays coming from the measuring region;

providing the sensor with at least one additional channel which has at least one of a further transmission unit for transmitting second electromagnetic sensing rays into the measuring region and a further reception unit for receiving signals;

evaluating the received signals of at least one of the measuring channel and the additional channel to determine a distance value for the object distance;

determining from the signals received by the further reception unit whether the signals fulfill at least one additional criterion; and

using the distance value as the measure of the object distance if the additional criterion is fulfilled.

11. A method in accordance with claim 10 including providing a separate transmission unit for each of the measuring channel and the additional channel.

12. A method in accordance with claim 11 including emitting the sensing rays of the measuring channel and of the additional channel in different directions.

13. A method in accordance with claim 12 wherein, when mutually corresponding characteristic regions of the received signals of the measuring channel and of the additional channel are jointly evaluated, an investigation is being made in each case whether they arc mutually displaced by an expected amount.

14. A method in accordance with claim 11 including focusing the sensing rays of the measuring channel and of the additional channel at different distances.

15. A method in accordance with claim 14 wherein, when mutually corresponding regions of the received signals of the measuring channel and of the additional channel are jointly evaluated, an investigation is being made in each case whether the emitted sensing rays are imaged with different degrees of sharpness.

16. A method in accordance with claim 10 including focusing the sensing rays of both the measuring channel and the additional channel.

17. A method in accordance with claim 10 wherein the measuring channel and the additional channel are operated at least substantially simultaneously for each object distance.

18. A method in accordance with claim 10 wherein the received signals of both the measuring channel and of the additional channel are used to determine a distance value serving as the measure for the object distance.

19. A method in accordance with claim 10 wherein in at least one of the measuring channel and in the additional channel the respective intensity distribution of the received signal on the reception unit is used for determining the distance.

20. A method for the determination of an object distance between an opto-electronic sensor working according to the principle of triangulation and a sensed object, comprising

providing the sensor with at least first and second measuring channels and a transmission unit emitting electromagnetic sensing rays into a measuring region, each channel including one of a reception unit and an optical reception system for detecting sensing rays coming from the measuring region;

and

arranging the transmission unit between the at least one of the reception unit and the optical reception system, and

jointly evaluating the received signals of the first and second channels to determine the object distance by

respectively determining for the received signals a center of an intensity distribution of the detected sensing rays coming from the measuring region and a distance of the center from a position of the transmission unit, and

using a mean value of the center distances as a measure for the object distance.

21. A method for the determination of an object distance between an opto-electronic sensor working according to the principle of triangulation and a sensed object, comprising

providing the sensor with at least first and second measuring channels and a transmission unit emitting electromagnetic sensing rays into the measuring region, each channel including one of a reception unit and an optical reception system for detecting sensing rays coming from the measuring region;

arranging the at least one of the reception units and the optical reception system at the sane side of the transmission unit; and

jointly evaluating the received signals of the first and second channels to determine the object distance by

respectively determining for the received signals a center of an intensity distribution of the detected sensing rays coming from the measuring region and a distance of the center from a position of the transmission unit, and

using a distance between mutually corresponding characteristic regions of the received signals of the first and second channels as a measure for the object distance.

22. Apparatus for the determination of an object distance between an opto-electronic sensor working according to the principle of triangulation and a sensed object, comprising

at least one measuring channel between a transmission unit for emitting first electromagnetic sensing rays into a measuring region and a reception unit for detecting sensing rays coming from the measuring region;

at least one additional channel which has at least one of a further transmission unit for transmitting second electromagnetic sensing rays into the measuring region and a further reception unit;

a device expanding the second sensing rays and directing the expanded second sensing rays onto the measuring region to form an expanded sensing zone; and

a processor which jointly evaluates the received signals of the measuring channel and of the additional channel in order to determine the object distance by forming a difference between the received signals of the measuring channel and of the additional channel.

23. Apparatus for the determination of an object distance between an opto-electronic sensor working according to the principle of triangulation and a sensed object comprising

at least one measuring channel between a transmission unit for emitting first electromagnetic sensing rays into the measuring region and a reception unit for detecting sensing rays coming from the measuring region;

at least one additional channel which has at least one of a further transmission unit for transmitting second electromagnetic sensing rays into the measuring region and a further reception unit for receiving signals;

a device evaluating the received signals of at least one of the measuring channel and the additional channel to determine a distance value for the object distance;

a further device determining from the signals received by the further reception unit whether the signals fulfill at least one additional criterion; and

a processor for using the distance value as the measure of the object distance if the additional criterion is fulfilled.