Laser reference system and method of determining grade rake

• US 6,693,706 B2
• Filed: 01/08/2002
• Issued: 02/17/2004
• Est. Priority Date: 01/08/2002
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Zalusky, James T., Kahle, Kent W., Green, Francisco R.
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US10/041,190
• Publication Number:
  US 20030128357A1
• Time in Patent Office: 770 Days
• Field of Search: 356/4.08, 356/141.3, 356/141.4
• US Class Current: 356/141.3
• CPC Class Codes: G01C 15/004 Reference lines, planes or sectors

Abstract

A laser reference system orients a reference plane of laser light generated by a transmitter so compensation is made for a rake angle between the first and second axes of the transmitter and an alignment axis and an axis perpendicular thereto. The transmitter includes an optical system arranged to generate a laser beam, the optical system projecting said laser beam radially along a rotational arc defined about a central rotational axis, thereby substantially defining a reference plane of laser light, and a positioning arrangement, coupled to said optical system, for adjusting the angular orientation of the optical system with respect to a first transmitter axis and with respect to a second transmitter axis. A detector is arranged to detect reception of the laser beam. The detector includes a generally vertically arranged row of detector elements. The detector further includes a transmitter for transmitting information regarding the location of said laser beam, as detected by said detector elements. The system further includes a processor adapted to receive said transmitted information from said detector regarding the location of the laser beam. The processor calculates the rake angle between the first transmitter axis and the alignment direction.

Claims

1. A laser reference system, comprising:

a laser transmitter including

an optical system arranged to generate a laser beam, said optical system projecting said laser beam radially along a rotational arc defined about a central rotational axis, thereby substantially defining a reference plane of laser light; and

a positioning arrangement, coupled to said optical system, for adjusting an angular orientation of said optical system with respect to a first transmitter axis and with respect to a second transmitter axis;

a detector arranged to detect reception of said laser beam, said detector including a generally vertically arranged row of detector elements, said detector further including a transmitter for transmitting information regarding the location of said laser beam, as detected by said detector elements; and

a processor adapted to receive said transmitted information from said detector regarding the location of the laser beam, and arranged to;

determine the distance in an alignment direction between said transmitter and said detector,

determine the distance from said detector to said first transmitter axis in a direction generally perpendicular to said alignment direction, and

calculate a rake angle between said first transmitter axis and the alignment direction.

2. The laser reference system of claim 1, in which said transmitter includes an input for inputting a first desired slope for said reference plane of laser light in said alignment direction and a second desired slope in a direction perpendicular thereto, and in which said processor is further adapted to calculate a first calculated slope and a second calculated slope based on the calculated rake angle, so that said plane through which said laser beam has projected is said first desired slope in said alignment direction and said second desired slope in a direction perpendicular thereto.

3. The laser reference system of claim 1, in which said processor is adapted to determine the distance in an alignment direction between said transmitter and said detector by:

directing said beam in succession to illuminate two detector elements spaced vertically along said row,

determining the included vertical angle of the reference plane as it shifts from illuminating one of said two detector elements to illuminating the other of said two detector elements, and

computing the distance between said transmitter and said detector based on the height difference between said two detector elements and said included vertical angle.

4. The laser reference system of claim 1, in which said processor is adapted to determine the distance from said detector to said first transmitter axis in a direction generally perpendicular to said alignment direction by:

illuminating the center of the row of elements with the reference plane horizontal in the direction of said second transmitter axis,

tilting the reference plane in the direction of said second transmitter axis until a detector element, vertically displaced from the center of the row of elements, is illuminated,

determining the angle by which the reference plane is tilted in the direction of said second transmitter axis, and

computing the distance from said detector to said first transmitter axis in a direction generally perpendicular to said alignment direction based on the height difference between the center of the row of elements and detector element that is vertically displaced from the center of the row of elements, and on said angle by which the reference plane is tilted.

5. The laser reference system of claim 1 in which said rake angle is calculated as the arctangent of the ratio of said distance from said detector to said first transmitter axis in a direction generally perpendicular to said alignment direction to said distance in an alignment direction from said transmitter to said detector.

6. A laser reference system, comprising:

a laser transmitter including an optical system for generating a reference plane of laser light; and

a positioning arrangement, coupled to said optical system, for adjusting the angular orientation of said optical system with respect to a first transmitter axis and with respect to a second transmitter axis such that the angular orientation of the reference plane of laser light is adjusted with respect to said first and second transmitter axes;

a detector for detecting reception of said plane of laser light along a generally vertical detector line, said detector further including a transmitter for transmitting information regarding the location of said laser light; and

a processor, adapted to receive said transmitted information from said detector regarding the location of the laser light, and arranged to determine the distance in an alignment direction between said transmitter and said detector, to determine the distance from said detector to said first transmitter axis in a direction generally perpendicular to said alignment direction, and to calculate a rake angle between said first transmitter axis and the alignment direction.

7. The laser reference system of claim 6, in which said transmitter includes means for inputting a first desired slope for said reference plane of laser light in said alignment direction and a second desired slope in a direction perpendicular thereto, and in which said processor is further adapted to calculate a first calculated slope and a second calculated slope based on the calculated rake angle, such that said plane through which said laser light is projected has said first desired slope in said alignment direction and said second desired slope in a direction perpendicular thereto.

8. The laser reference system of claim 6, in which said processor is adapted to determine the distance in an alignment direction between said transmitter and said detector by:

directing said light in succession to illuminate two points spaced vertically along said detector line,

determining the included vertical angle of the reference plane as it shifts from illuminating one of said two points to illuminating the other of said two points, and

computing the distance from said transmitter to said detector based on the height difference between said two points and said included vertical angle.

9. The laser reference system of claim 6, in which said processor is adapted to determine the distance from said detector to said first transmitter axis in a direction generally perpendicular to said alignment direction by:

illuminating the center of the detector line with the reference plane horizontal in the direction of said second transmitter axis,

tilting the reference plane in the direction of said second transmitter axis until a point on the detector line, vertically displaced from the center of the detector line, is illuminated,

determining the angle by which the reference plane is tilted in the direction of said second transmitter axis, and

computing the distance from said detector to said first transmitter axis in a direction generally perpendicular to said alignment direction based on the height difference between the center of the detector line and the point on the detector line that is vertically displaced from the center of the detector line, and on said angle by which the reference plane is tilted.

10. The laser reference system of claim 6 in which said rake angle is calculated as the arctangent of the ratio of said distance between said detector and said first transmitter axis in a direction generally perpendicular to said alignment direction to said distance in an alignment direction from said transmitter to said detector.

11. A method of orienting a reference plane of laser light generated by a transmitter, the transmitter including a positioning arrangement that adjusts the angular orientation of the reference plane with respect to a first transmitter axis and with respect to a second transmitter axis perpendicular thereto, the laser light being detected along a generally vertical detector line defined by a detector, with the detector also including a transmitter that transmits information regarding the location of said laser light, comprising the steps of:

determining the distance in an alignment direction between said transmitter and said detector,

determining the distance from said detector to said first transmitter axis in a direction generally perpendicular to said alignment direction, and

calculating a rake angle between said first transmitter axis and the alignment direction.

12. The method of orienting a reference plane of laser light of claim 11 in which the step of determining the distance in an alignment direction between said transmitter and said detector comprises the steps of

directing said light in succession to illuminate two points spaced vertically along said detector line,

determining the included vertical angle of the reference plane as it shifts from illuminating one of said two points to illuminating the other of said two points, and

computing the distance from said transmitter to said detector based on the height difference between said two points and said included vertical angle.

13. The method of orienting a reference plane of laser light of claim 11 in which the step of determining the distance from said detector to said first transmitter axis in a direction generally perpendicular to said alignment direction comprises the steps of:

illuminating the center of the detector line with the reference plane horizontal in the direction of said second transmitter axis,

tilting the reference plane in the direction of said second transmitter axis until a point on the detector line, vertically displaced from the center of the detector line, is illuminated,

determining the angle by which the reference plane is tilted in the direction of said second transmitter axis, and

computing the distance from said detector to said first transmitter axis in a direction generally perpendicular to said alignment direction based on the height difference between the center of the detector line and the point on the detector line that is vertically displaced from the center of the detector line, and on said angle by which the reference plane is tilted.

14. The method of orienting a reference plane of laser light of claim 11 in which the step of calculating the rake angle between said first transmitter axis and the alignment direction comprises the step determining the arctangent of the ratio of said distance from said detector to said first transmitter axis in a direction generally perpendicular to said alignment direction to said distance in an alignment direction between said transmitter and said detector.

15. The method of orienting a reference plane of laser light according to claim 11, in which the step of orienting said reference plane with respect to said first and second transmitter axes such that a desired orientation with respect to said alignment direction and a direction perpendicular thereto is achieved, comprises the step of orienting said reference plane with respect to said first and second transmitter axes according to the equations:

16. A method of orienting a reference plane of laser light generated by a transmitter, the transmitter including a positioning arrangement that adjusts the angular orientation of the reference plane with respect to a first transmitter axis and with respect to a second transmitter axis perpendicular thereto, the laser light being detected along a generally vertical detector line defined by a detector, with the detector also including a transmitter that transmits information regarding the location of said laser light, comprising the steps of:

defining an alignment direction from said transmitter by positioning a detector in said alignment direction for illumination with said plane of laser light;

tilting said reference plane in a direction of said first transmitter axis while keeping said plane horizontal in a direction of said second transmitter axis;

effectively rotating said plane of laser light such that a predetermined point on said detector line is illuminated at two effective angular positions of rotation of said plane;

determining a mid-point between said two effective angular positions as said first transmitter axis, and determining an angular position at ninety degrees thereto as said second transmitter axis;

determining the angular difference between said alignment direction and said first transmitter axis as a rake angle; and

orienting said reference plane with respect to said first and second transmitter axes such that a desired orientation with respect to said alignment direction and a direction perpendicular thereto is achieved.

17. The method of orienting a reference plane of laser light according to claim 16, in which the step of orienting said reference plane with respect to said first and second transmitter axes such that a desired orientation with respect to said alignment direction and a direction perpendicular thereto is achieved, comprises the step of orienting said reference plane with respect to said first and second transmitter axes according to the equations:

18. A method of orienting a reference plane of laser light generated by a transmitter, the transmitter including a positioning arrangement that adjusts the angular orientation of the reference plane with respect to a first transmitter axis and with respect to a second transmitter axis perpendicular thereto, the laser light being detected along a generally vertical detector line defined by a detector, with the detector also including a transmitter that transmits information regarding the location of said laser light, comprising the steps of:

defining an alignment direction from said transmitter by positioning a detector in said alignment direction for illumination with said plane of laser light;

tilting said reference plane and determining a grade x₁ in a direction of said first transmitter axis and a grade y₁ in a direction of said second transmitter axis which cause specific point on said generally vertical detector line to be illuminated;

tilting said reference plane and determining a grade x₂ in a direction of said first transmitter axis and a grade y₂ in a direction of said second transmitter axis which cause said specific point on said generally vertical detector line to be illuminated;

calculating a rake angle between said first transmitter axis and the alignment direction; and

orienting said reference plane with respect to said first and second transmitter axes such that a desired orientation with respect to said alignment direction and a direction perpendicular thereto is achieved.

19. The method of orienting a reference plane of laser light according to claim 18, in which the step of calculating the rake angle θ

between said first transmitter axis and said alignment direction includes the step of calculating the rake angle according to the equation;

20. The method of orienting a reference plane of laser light according to claim 18, in which the step of calculating the rake angle θ

between said first transmitter axis and said alignment direction includes the step of calculating the rake angle according to the equation;

21. The method of orienting a reference plane of laser light according to claim 18, in which the step of orienting said reference plane with respect to said first and second transmitter axes such that a desired orientation with respect to said alignment direction and a direction perpendicular thereto is achieved, comprises the step of orienting said reference plane with respect to said first and second transmitter axes according to the equations:

22. A method of orienting a reference plane of laser light generated by a transmitter, the transmitter including a positioning arrangement that adjusts the angular orientation of the reference plane with respect to a first transmitter axis and with respect to a second transmitter axis perpendicular thereto, the laser light being directed at a target that extends generally vertically along a target line, comprising the steps of:

determining the distance in an alignment direction between said transmitter and said target,

determining the distance from said target to said first transmitter axis in a direction generally perpendicular to said alignment direction, and

calculating a rake angle between said first transmitter axis and the alignment direction.

23. The method of orienting a reference plane of laser light of claim 22 in which the step of determining the distance in an alignment direction between said transmitter and said target comprises the steps of

directing said light in succession to illuminate two points spaced vertically along said target line,

determining the included vertical angle of the reference plane as it shifts from illuminating one of said two points to illuminating the other of said two points, and

computing the distance from said transmitter to said target based on the height difference between said two points and said included vertical angle.

24. The method of orienting a reference plane of laser light of claim 22 in which the step of determining the distance from said target to said first transmitter axis in a direction generally perpendicular to said alignment direction comprises the steps of:

illuminating the center of the target line with the reference plane horizontal in the direction of said second transmitter axis,

tilting the reference plane in the direction of said second transmitter axis until a point on the target line, vertically displaced from the center of the target line, is illuminated,

determining the angle by which the reference plane is tilted in the direction of said second transmitter axis, and

computing the distance from said target to said first transmitter axis in a direction generally perpendicular to said alignment direction based on the height difference between the center of the target line and the point on the target line that is vertically displaced from the center of the target line, and on said angle by which the reference plane is tilted.

25. The method of orienting a reference plane of laser light of claim 22 in which the step of calculating the rake angle between said first transmitter axis and the alignment direction comprises the step determining the arctangent of the ratio of said distance from said target to said first transmitter axis in a direction generally perpendicular to said alignment direction to said distance in an alignment direction between said transmitter and said target.

26. The method of orienting a reference plane of laser light according to claim 22, in which the step of orienting said reference plane with respect to said first and second transmitter axes such that a desired orientation with respect to said alignment direction and a direction perpendicular thereto is achieved, comprises the step of orienting said reference plane with respect to said first and second transmitter axes according to the equations:

27. A method of orienting a reference plane of laser light generated by a transmitter, the transmitter including a positioning arrangement that adjusts the angular orientation of the reference plane with respect to a first transmitter axis and with respect to a second transmitter axis perpendicular thereto, the laser light being detected along a generally vertical target line defined by a target, comprising the steps of:

defining an alignment direction from said transmitter by positioning a target in said alignment direction for illumination with said plane of laser light;

tilting said reference plane in a direction of said first transmitter axis while keeping said plane horizontal in a direction of said second transmitter axis;

effectively rotating said plane of laser light such that a predetermined point on said target line is illuminated at two effective angular positions of rotation of said plane;

determining a mid-point between said two effective angular positions as said first transmitter axis, and determining an angular position at ninety degrees thereto as said second transmitter axis;

determining the angular difference between said alignment direction and said first transmitter axis as a rake angle; and

orienting said reference plane with respect to said first and second transmitter axes such that a desired orientation with respect to said alignment direction and a direction perpendicular thereto is achieved.

28. The method of orienting a reference plane of laser light according to claim 27, in which the step of orienting said reference plane with respect to said first and second transmitter axes such that a desired orientation with respect to said alignment direction and a direction perpendicular thereto is achieved, comprises the step of orienting said reference plane with respect to said first and second transmitter axes according to the equations:

29. A method of orienting a reference plane of laser light generated by a transmitter, the transmitter including a positioning arrangement that adjusts the angular orientation of the reference plane with respect to a first transmitter axis and with respect to a second transmitter axis perpendicular thereto, the laser light being detected along a generally vertical target line defined by a target, with the target also including a transmitter that transmits information regarding the location of said laser light, comprising the steps of:

defining an alignment direction from said transmitter by positioning a target in said alignment direction for illumination with said plane of laser light;

tilting said reference plane and determining a grade x₁ in a direction of said first transmitter axis and a grade y₁ in a direction of said second transmitter axis which cause specific point on said generally vertical target line to be illuminated;

tilting said reference plane and determining a grade x₂ in a direction of said first transmitter axis and a grade y₂ in a direction of said second transmitter axis which cause said specific point on said generally vertical target line to be illuminated;

calculating a rake angle between said first transmitter axis and the alignment direction; and

orienting said reference plane with respect to said first and second transmitter axes such that a desired orientation with respect to said alignment direction and a direction perpendicular thereto is achieved.

30. The method of orienting a reference plane of laser light according to claim 29, in which the step of calculating the rake angle θ

between said first transmitter axis and said alignment direction includes the step of calculating the rake angle according to the equation;

31. The method of orienting a reference plane of laser light according to claim 29, in which the step of calculating the rake angle θ

between said first transmitter axis and said alignment direction includes the step of calculating the rake angle according to the equation;

32. The method of orienting a reference plane of laser light according to claim 29, in which the step of orienting said reference plane with respect to said first and second transmitter axes such that a desired orientation with respect to said alignment direction and a direction perpendicular thereto is achieved, comprises the step of orienting said reference plane with respect to said first and second transmitter axes according to the equations: