Method and apparatus for accurately positioning a tool on a mobile machine using on-board laser and positioning system

• US 6,108,076 A
• Filed: 12/21/1998
• Issued: 08/22/2000
• Est. Priority Date: 12/21/1998
• Status: Expired due to Term

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Hanseder, Anthony
• Primary Examiner(s): Buczinski, Stephen C.
• Time in patent office: 610 Days
• Field of Search: 356/141.1, 356/4.08, 356/4.01, 172/4.5, 702/152, 702/167
• US Class Current: 356/141.1
• CPC Class Codes: E02F 3/847 using electromagnetic, optical or acoustic beams to determine the blade position, e.g. laser beams
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105
• CPC Class Codes: G01S 17/06 Systems determining position data of a target
• CPC Class Codes: G01S 17/86 Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders

Abstract

A method and apparatus for accurately positioning a tool on a mobile machine are provided. The machine is equipped with a satellite positioning system (SPS) receiver, a robotic total station with an integrated scanning laser and a storage facility storing a digital terrain model (DTM) of a work area. The machine operates within the work area and a number of stationary reflectors are positioned at various locations about the work area. The SPS receiver determines the current location of the machine. A system controller then references the DTM to determine the closest stationary reflector to the current location of the machine. Location data of the closest reflector is then provided to the robotic total station, which locates the closest reflector. The scanning laser then locks on to the reflector and the system controller determines the angle between the laser and the reflector. Based upon a computed angle, a displacement between the actual elevation of the machine and the design elevation for the current location of the machine is computed. The position of the tool is then adjusted based upon the computed displacement. If the closest reflector is out of range or obstructed by another object, the onboard system automatically determines the next closest reflector.

Claims

1. A method of positioning a tool on a mobile unit, the method comprising:

storing on-board the mobile unit data representing the locations of a plurality of stationary reference points;

using a positioning system on-board the mobile unit to determine the location of the mobile unit;

selecting one of the stationary reference points based on the location of the mobile unit and the data representing the locations of the stationary reference points;

transmitting a laser beam from a laser on-board the mobile unit to the selected stationary reference point; and

determining a positional adjustment for the tool based on the location of the mobile unit and a parameter associated with the laser beam.

2. A method as recited in claim 1, wherein said selecting comprises automatically selecting the stationary reference point.

3. A method as recited in claim 2, wherein said using a positioning system comprises using a satellite positioning system receiver on-board the mobile unit.

4. A method as recited in claim 2, wherein said determining a positional adjustment for the tool comprises using a digital terrain model stored on-board the mobile unit.

5. A method as recited in claim 4, wherein the digital terrain model includes the data representing the locations of the plurality of selectable reference points.

6. A method of positioning a tool on a mobile unit during operation of the mobile unit within a work area, the method comprising:

storing on-board the mobile unit a terrain model of the work area, the terrain model including data on the locations of each of a plurality of selectable reference points;

using a positioning system on-board the mobile unit to determine the location of the mobile unit; and

using one of the plurality of selectable stationary reference points and the location of the mobile unit to determine a positional adjustment for the tool.

7. A method as recited in claim 6, wherein said using one of the plurality of stationary reference points to determine the positional adjustment for the tool comprises:

transmitting a laser beam from a laser on-board the mobile unit at said one of the plurality of stationary reference points; and

determining the positional adjustment of the tool based on a measurement associated with said transmitting.

8. A method as recited in claim 7, wherein said using a positioning system comprises using a satellite positioning system receiver on-board the mobile unit.

9. A method of accurately positioning a tool on a mobile unit, the method comprising:

storing on-board the mobile unit a terrain model of an area including data indicating the locations of each of a plurality of fixed reference points;

using an on-board positioning system to determine the location of the mobile unit;

selecting one of the plurality of fixed reference points based on the terrain model and the location of the mobile unit;

aiming a laser beam generated by an on-board laser at the selected reference point;

computing a displacement based on a parameter associated with the laser beam and the selected reference point; and

determining a positional adjustment for the tool based on the computed displacement.

10. A method as recited in claim 9, further comprising automatically repositioning the tool based on the computed displacement.

11. A method as recited in claim 9, further comprising generating a visual indication of the computed displacement to an operator of the tool.

12. A method as recited in claim 9, further comprising storing design elevations for a plurality of locations within the area, and wherein said computing the displacement comprises computing the displacement based on the measured parameter and a design elevation associated with the location of the mobile unit.

13. A method as recited in claim 11, wherein the parameter comprises a measured angle between the laser beam and the selected reference point.

14. A method as recited in claim 9, wherein said aiming comprises aiming the laser beam at the selected reference point based on data in the terrain map indicating the location of the selected reference point.

15. A method as recited in claim 9, wherein said using a precise positioning system comprises using a satellite positioning system receiver.

16. A method as recited in claim 9, further comprising using a survey measurement unit to locate the selected reference point.

17. A method as recited in claim 16, wherein said using the survey measurement unit comprises using a robotic total station.

18. A method of automatically positioning a tool on a mobile machine operating within an area, the method comprising:

using an on-board satellite positioning system location device to determine a horizontal location of the machine;

providing an on-board digital terrain model (DTM), the DTM indicating the locations of each of a plurality of stationary reflectors located about the area and design elevations for a plurality of locations within the area;

selecting and determining the location of one of the plurality of stationary reflectors based on the horizontal location of the machine and the DTM, including determining an approximate elevation of the selected reflector;

using an on-board total station to locate the selected reflector based on the determined location;

using an on-board scanning laser to lock onto the selected reflector based on the approximate elevation;

computing an angle between the laser and the selected reflector;

computing an adjustment for the tool based on the angle and a design elevation from the DTM corresponding to the location of the machine; and

adjusting the position of the tool based on the computed adjustment.

19. An on-board system for enabling positioning of an adjustable tool in a mobile unit, the on-board system comprising:

storage means for storing data representing the locations of a plurality of stationary reference points;

a positioning system to determine the location of the mobile unit;

a laser unit to generate a laser beam;

selection means for selecting a stationary reference point of the plurality of stationary reference points, based on said data and the location of the mobile unit;

aiming means for aiming the laser beam at the selected stationary reference point;

means for determining a parameter associated with the laser beam and the selected stationary reference point; and

means for determining a displacement of the tool based on the parameter.

20. A system as recited in claim 19, wherein the positioning system comprises a satellite positioning system receiver.

21. A system as recited in claim 19, further comprising a survey measurement unit to locate the selected stationary reference point.

22. A system as recited in claim 21, wherein the survey measurement unit comprises a robotic total station.

23. A system as recited in claim 19, further comprising means for automatically repositioning the tool based on the displacement.

24. A system as recited in claim 19, further comprising means for generating an indication of the displacement to an operator of the tool.

25. A system as recited in claim 19, wherein the storage means comprises means for storing a terrain model of an area in which the mobile unit is to operate.

26. A system as recited in claim 25, wherein the positioning system comprises a satellite positioning system receiver, and wherein the terrain model is stored within the satellite positioning system receiver.

27. A system as recited in claim 25, wherein the storage means comprises means for storing design coordinates for a plurality of locations within the area, and wherein the means for computing the displacement comprises means for computing the displacement based on the measured parameter and a design coordinate associated with the location of the mobile unit.

28. A system as recited in claim 25, wherein the terrain map includes the data representing the locations of the plurality of stationary reference points.

29. A system as recited in claim 19, wherein the parameter comprises an angle between the laser beam and the stationary reference point.

30. A system as recited in claim 19, wherein the means for computing a displacement comprises means for computing a vertical displacement based on the design coordinate associated with the location of the mobile unit.

31. A system as recited in claim 19, wherein the laser unit comprises a scanning laser;

and wherein each of the stationary reference points comprises an optical reflector.

32. In a mobile unit having a tool, an on-board system for enabling accurate positioning of the tool, the on-board system comprising:

a precise positioning system configured to determine the location of the mobile unit;

a laser unit configured to generate a laser beam;

storage means for storing a terrain model of an area including data indicating the locations of each of a plurality of fixed reference points;

selection means for selecting one of the plurality of fixed reference points;

aiming means for directing the laser beam to the selected reference point;

means for computing a displacement based on a measured parameter associated with the laser beam and the selected reference point; and

means for determining a positional adjustment for the tool based on the computed displacement.

33. A system as recited in claim 32, wherein the precise positioning system includes the terrain model.

34. A system as recited in claim 32, wherein the selection means comprises means for selecting said one of the plurality of reference points based on the terrain model and the location of the mobile unit.

35. A system as recited in claim 32, wherein the storage means comprises means for storing design coordinates for a plurality of locations within the area, and wherein the means for computing the displacement comprises means for computing the displacement based on the measured parameter and a design coordinate associated with the location of the mobile unit.

36. A system as recited in claim 32, wherein the measured parameter comprises an angle between the laser beam and the selected reference point.

37. A system as recited in claim 32, wherein the means for computing a displacement comprises means for computing a vertical displacement.

38. A system as recited in claim 32, wherein the aiming means comprises means for aiming the laser beam at the selected reference point based on data in the terrain map indicating the location of the selected reference point.

40. A system as recited in claim 32, wherein the precise positioning system comprises a satellite positioning system receiver.

41. A system as recited in claim 32, wherein the aiming means comprises a survey measurement unit.

42. A system as recited in claim 41, wherein the survey measurement unit comprises a total station.

43. An on-board system in a mobile unit having a tool, the system for enabling accurate positioning of the tool, the system comprising:

a satellite positioning system unit configured to determine a horizontal location of the mobile unit;

a survey measurement unit;

a laser unit;

a storage unit having stored therein a terrain model, including data indicating the locations of each of a plurality of reflectors positioned about an area; and

a processor configured to select and determine the location of one of the plurality of reflectors based on the terrain model;

wherein the survey measurement unit is configured to locate the selected reflector; and

wherein the processor is further configured to;

compute an angle between the selected reflector and a laser beam generated by the laser unit;

compute a positional adjustment for the tool based on the computed angle; and

output signals for enabling repositioning of the tool based on the computed adjustment.

39. A system as recited in claim 48, wherein the laser unit comprises a scanning laser, and wherein each of the fixed reference points comprises an optical reflector.

44. A system as recited in claim 43, wherein the storage unit storing the terrain model is an integral component of the satellite positioning system unit.

45. A system as recited in claim 43, wherein the survey measurement unit comprises a total station.

46. A system as recited in claim 43, wherein the laser unit is an integral component of the total station.

47. A system as recited in claim 43, wherein the processor is configured to select and determine the location of said one of the plurality of reflectors based on the terrain model and the horizontal location of the mobile unit.

48. A system as recited in claim 43, wherein the storage unit further has stored therein design elevations for a plurality of locations within the area, and wherein the processor is configured to compute the positional adjustment for the tool based on the computed angle and a design elevation corresponding to the location of the mobile unit.

49. An on-board system for automatically positioning a tool on a mobile machine operating within an area, the system comprising:

positioning means for determining a precise horizontal location of the machine;

storage means for storing an on-board digital terrain model (DTM), the DTM indicating the locations of each of a plurality of stationary reflectors located about the area and design elevations for a plurality of locations within the area;

means for selecting one of the plurality of stationary reflectors based on the DTM;

means for determining coordinates of the selected stationary reflector, including means for determining an approximate elevation of the selected reflector;

locating means for locating the selected reflector based on the coordinates;

light-emitting means for optically acquiring the selected reflector based on the approximate elevation based on a transmitted light beam;

means for computing an adjustment for the tool based on an angle between the light beam and the selected reflector and a design elevation from the DTM corresponding to the location of the machine; and

means for adjusting the position of the tool based on the computed adjustment.

50. A system as recited in claim 49, wherein the locating means comprises a total station.

51. A system as recited in claim 49, wherein the positioning means comprises a satellite positioning system receiver.

52. A system as recited in claim 49, wherein the light-emitting means comprises a laser.

53. A system as recited in claim 49, wherein the means for computing an adjustment for the tool comprises means for computing the adjustment for the tool based on the angle and a design elevation from the DTM corresponding to the location of the machine.

54. An on-board system in a mobile machine having a tool, for enabling accurate positioning of the tool, the system comprising:

a satellite positioning system receiver configured to determine a horizontal location of the machine;

a robotic total station with an integrated a scanning laser;

a storage device having stored therein a digital terrain model (DTM), including data indicating the locations of each of a plurality of stationary reflectors positioned at various locations about an area and design elevations for a plurality of locations within the area;

a tool controller configured to control the position of the tool; and

a processor configured to;

select and determine the location of one of the plurality of stationary reflectors based on the horizontal location of the machine and the DTM, including determining an approximate elevation of the selected reflector; and

generate a first control signal including an indication of the location and approximate elevation of the selected reflector;

wherein the total station is configured to;

locate the selected reflector in response to the first control signal; and

acquire the selected reflector using the scanning laser;

wherein the processor is further configured to;

compute an angle between the laser and the selected reflector;

compute an adjustment for the tool based on the angle and a design elevation from the DTM corresponding to the location of the machine; and

provide the first control signals to the tool controller to cause the tool controller to alter the position of the tool based on the computed adjustment.