POSITIONING DEVICE AND METHOD FOR DETECTING A LASER BEAM

• US 20110141488A1
• Filed: 06/19/2008
• Published: 06/16/2011
• Est. Priority Date: 06/19/2008
• Status: Active Grant

• Current Assignee: Spectra Precision Inc. (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Conner, Robert G., Schumacher, Lars
• Granted Patent: US 8,526,014 B2
• Time in Patent Office: Days
• US Class Current: 356/614
• CPC Class Codes: G01B 11/14 for measuring distance or clearance between spaced objects or spaced apertures G01B11/26 takes precedence; rangefinders G01C3/00
• CPC Class Codes: G01C 15/004 Reference lines, planes or sectors

Abstract

The present invention relates to a positioning device and method for detecting light of fan shaped laser beam, as well as to a positioning system comprising the device and to a light emitting device emitting the fan shaped laser beam, which enable to find a spot of a laser beam easier and quicker. The positioning device comprises a detector for detecting light of a fan shaped laser beam rotating around a propagation axis with a direction of rotation and having two detector elements arranged in a known spatial relation for outputting a detection signal when irradiated; and a position determining unit to obtain a first set of detection signals from the detector elements, determine a first time relation between the detection signals of the first set, and determine a positional relation between the detector and the propagation axis based on the first time relation.

Claims

1. A positioning device, comprising:

a detector for detecting light of a fan shaped laser beam rotating around a propagation axis with a direction of rotation and having at least two detector elements (A, B) arranged in a known spatial relation to one another for outputting a detection signal when irradiated by the fan shaped laser beam; and

a position determining unit to

obtain a first set of detection signals from the detector elements,

determine at least one first time relation between the detection signals of the first set, and

determine a positional relation between the detector and the propagation axis based on the first time relation.

2. The positioning device according to claim 1, wherein the first set of detection signals is obtained from detector elements arranged along a first line, and wherein

the position determining unit is adapted to

obtain a second set of detection signals from detector elements arranged along a second line, the first and second lines not being parallel with respect to one another;

and

determine at least one second time relation between the detection signals of the second set.

3. The positioning device according to claim 1, wherein the first time relation is a first time sequence of the detection signals of the first set and wherein the position determining unit is adapted to determine one of at least two segments of a plane intersecting the propagation axis, in which the detector is located.

4. The positioning device according to claim 3, wherein the second time relation is a second time sequence of the detection signals of the second set and wherein the position determining unit is adapted to determine one of at least four segments of the plane intersecting the propagation axis, in which the detector is located, based on the first time sequence and the second time sequence.

5. The positioning device according to claim 2, wherein the detector includes at least three detector elements (A, B, C), a first connecting line between a first one of the detector elements (A) and a second one of the detector elements (C) having a first predetermined length (a) not being parallel to a second connecting line between a third one of the detector elements (C) and the second detector element (B) having a second predetermined length (b);

and

wherein the first set of detection signals is obtained from the first and the second detector elements (A, B) and wherein the second set of detection signals is obtained from the second and the third detection elements (B, C).

6. The positioning device according to claim 2, wherein the position determining unit is adapted to obtain the first set of detection signals with the detector having a first orientation and to obtain the second set of detection signals with the detector having a second orientation rotated with respect to the first orientation.

7. The positioning device according to claim 2, wherein the position determining unit is adapted to determine a repetition time interval between two detection signals from the same detector element and to determine an angular velocity (ω

) of the fan shaped laser beam based thereon.

8. The positioning device according to claim 7, wherein the position determining unit is adapted to

determine a first time interval between the detection signals of the first set and a second time interval between the detection signals of the second set;

determine, based on the angular velocity of the fan shaped laser beam and the first and second time intervals of a plurality of detector elements, two angles between the detector elements; and

determine, based on the two detector element angles and the spatial relation of the detector elements, a distance of the detector to the propagation axis.

9. The positioning device according to claim 8, wherein the position determining unit is adapted to

obtain a third and fourth set of detection signals with the propagation axis of the fan shaped laser beam of a laser emitter tilted by an angle with respect to the orientation of the propagation axis for obtaining the first set and second set of detection signals;

determine a third time interval between the detection signals of the third set and a fourth time interval between the detection signals of the fourth set;

determine, based on the angular velocity of the fan shaped laser beam and the third and fourth time intervals of a plurality of detector elements, two other angles between the detector elements;

determine, based on the two other detector element angles and the spatial relation of the detector elements, a second distance of the detector to the tilted propagation axis; and

determine, based on the distance and the second distance, a position of the detector with respect to the laser emitter.

10. The positioning device according to claim 8, wherein the position determining unit is adapted to

determine a reference angle of one of the detector elements with respect to a reference orientation and

determine a position of the detector relative to the propagation axis and the reference orientation based on the reference angle and the distance of the detector to the propagation axis.

11. The positioning device according to claim 1, wherein the detector includes at least one level sensor for indicating at least one reference orientation of the detector in space.

12. The positioning device according to claim 1, further comprising

a laser emitter for emitting the fan shaped laser beam rotating around the propagation axis with the direction of rotation.

13. A positioning method, comprising:

detecting light of a fan shaped laser beam rotating around a propagation axis with a direction of rotation by a detector with at least two detector elements (A, B) arranged in a known spatial relation to one another and outputting a detection signal when irradiated by the fan shaped laser beam;

obtaining a first set of detection signals from the detector elements;

determining at least one first time relation between the detection signals of the first set; and

determining a positional relation between the detector and the propagation axis based on the first time relation.

14. The positioning method according to claim 13, further comprising

obtaining the first set of detection signals from detector elements arranged along a first line, and

obtaining a second set of detection signals from detector elements arranged along a second line, the first and second lines not being parallel with respect to one another;

and

determining at least one second time relation between the detection signals of the second set.

15. The positioning method according to claim 13, wherein the first time relation is a first time sequence of the detection signals of the first set, and the method further comprising

determining one of at least two segments of a plane intersecting the propagation axis, in which the detector is located.

16. The positioning method according to claim 15, wherein the second time relation is a second time sequence of the detection signals of the second set, and the method further comprising

determining one of at least four segments of the plane intersecting the propagation axis, in which the detector is located based on the first time sequence and the second time sequence.

17. The positioning method according to claim 14, wherein the detector includes at least three detector elements (A, B, C), a first connecting line between a first one of the detector elements (A) and a second one of the detector elements (C) having a first predetermined length (a) not being parallel to a second connecting line between a third one of the detector elements (C) and the second detector element (B) having a second predetermined length (b);

and the method further comprising

obtaining the first set of detection signals from the first and the second detector elements (A, B), and

obtaining the second set of detection signals from the second and the third detection elements (B, C).

18. The positioning method according to claim 14, further comprising

obtaining the first set of detection signals with the detector having a first orientation, and

obtaining the second set of detection signals with the detector having a second orientation rotated with respect to the first orientation.

19. The positioning method according to claim 14, further comprising

determining a repetition time interval between two detection signals from the same detector element, and

determining an angular velocity (ω

) of the fan shaped laser beam based thereon.

20. The positioning method according to claim 19, further comprising

determining a first time interval between the detection signals of the first set and a second time interval between the detection signals of the second set;

determining, based on the angular velocity of the fan shaped laser beam and the first and second time intervals of a plurality of detector elements, two angles between the detector elements; and

determining, based on the two detector element angles and the spatial relation of the detector elements, a distance of the detector to the propagation axis.

21. The positioning method according to claim 20, further comprising

obtaining a third and fourth set of detection signals with the propagation axis of the fan shaped laser beam of a laser emitter tilted by an angle with respect to the orientation of the propagation axis for obtaining the first set and second set of detection signals;

determining a third time interval between the detection signals of the third set and a fourth time interval between the detection signals of the fourth set;

determining, based on the angular velocity of the fan shaped laser beam and the third and fourth time intervals of a plurality of detector elements, two other angles between the detector elements;

determining, based on the two other detector element angles and the spatial relation of the detector elements, a second distance of the detector to the tilted propagation axis; and

determining, based on the distance and the second distance, a position of the detector with respect to the laser emitter.

22. The positioning method according to claim 20, further comprising

determining a reference angle of one of the detector elements with respect to a reference orientation, and

determining a position of the detector relative to the propagation axis and the reference orientation based on the reference angle and the distance of the detector to the propagation axis.

23. The positioning method according to claim 13, further comprising

indicating at least one reference orientation of the detector in space using at least one level sensor.

27. A program including instructions adapted to cause data processing means to carry out the method of claim 13.

28. A computer readable medium, in which a program is embodied, where the program is to make a computer execute the method of claim 13.

29. A computer program product comprising the computer readable medium according to claim 28.

24. A positioning system, comprising:

a laser emitter for emitting a fan shaped laser rotating around a propagation axis with a direction of rotation;

a detector having at least two detector elements (A, B) arranged in a known spatial relation to one another for outputting a detection signal when irradiated by the fan shaped laser beam;

a position determining unit to

obtain a first set of detection signals from the detector elements,

determine at least one first time relation between the detection signals of the first set, and

determine a positional relation between the detector and the propagation axis based on the first time relation.

25. A light emitting device, comprising

a laser emitter for emitting a fan shaped laser beam rotating around a propagation axis with a predetermined direction of rotation.

26. The light emitting device according to claim 25, comprising

a rotatable cylindrical lens or a rotatable diffraction structure for fanning the laser beam.