Automatic Blade Slope Control System

• US 20120239258A1
• Filed: 07/21/2011
• Published: 09/20/2012
• Est. Priority Date: 03/16/2011
• Status: Active Grant

• Current Assignee: Topcon Positioning Systems Incorporated (Topcon Corporation)
• Original Assignee: Topcon Positioning Systems Incorporated (Topcon Corporation)
• Inventors: Brabec, Vernon Joseph, Konno, Hiroyuki, Graham, Renard Tomas
• Granted Patent: US 8,738,242 B2
• Time in Patent Office: Days
• US Class Current: 701/50
• CPC Class Codes: E01C 19/004 Devices for guiding or controlling the machines along a predetermined path for graders or bulldozers E02F3/841; for other soil-shifting machines E02F9/2045
• CPC Class Codes: E02F 3/845 using mechanical sensors to determine the blade position, e.g. inclinometers, gyroscopes, pendulums

Abstract

The slope angle of a blade on an earthmoving machine is automatically controlled based on measurements from a three-axis gyroscope, a blade slope angle tilt sensor, and a blade tip angle tilt sensor mounted on the blade. A three-axis gyroscope has high dynamic response and high resistance to mechanical disturbances but is subject to potentially unbounded errors. A tilt sensor has bounded errors but has a slow dynamic response and a high sensitivity to mechanical disturbances. The combination of a three-axis gyroscope and two tilt sensors provides an advantageous measurement system. Algorithms for performing proper fusion of the measurements account for the lack of synchronization between the three-axis gyroscope and the tilt sensors and also screen out invalid measurements from the tilt sensors. The blade slope angle is controlled based on a reference blade slope angle and an estimate of the blade slope angle computed from properly fused measurements.

Claims

1. A method for controlling a blade mounted on a vehicle, the method comprising the steps of:

receiving at a first time a first angular velocity measurement about a first axis, a second angular velocity measurement about a second axis, and a third angular velocity measurement about a third axis from a three-axis gyroscope mounted on the blade, wherein the first axis, the second axis, and the third axis are orthogonal;

receiving at a second time a blade slope angle measurement from a blade slope angle tilt sensor mounted on the blade;

receiving at a third time a blade tip angle measurement from a blade tip angle tilt sensor mounted on the blade;

determining whether the second time is greater than the first time;

upon determining that the second time is greater than the first time;

determining whether the received blade slope angle measurement is valid;

determining whether the third time is greater than the first time;

upon determining that the third time is greater than the first time;

determining whether the received blade tip angle measurement is valid; and

upon determining that the second time is greater than the first time, the received blade slope angle measurement is valid, the third time is greater than the first time, and the received blade tip angle measurement is valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, the received blade slope angle measurement, and the received blade tip angle measurement.

2. The method of claim 1, further comprising the steps of:

upon determining that the second time is not greater than the first time and the third time is not greater than the first time;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, and the received third angular velocity measurement;

upon determining that the second time is greater than the first time, the received blade slope angle measurement is not valid, and the third time is not greater than the first time;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, and the received third angular velocity measurement;

upon determining that the second time is not greater than the first time, the third time is greater than the first time, and the received blade tip angle is not valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, and the received third angular velocity measurement; and

upon determining that the second time is greater than the first time, the received blade slope angle measurement is not valid, the third time is greater than the first time, and the received blade tip angle is not valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, and the received third angular velocity measurement.

3. The method of claim 1, further comprising the steps of:

upon determining that the second time is greater than the first time, the received blade slope angle measurement is valid, and the third time is not greater than the first time;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, and the received blade slope angle measurement; and

upon determining that the second time is greater than the first time, the received blade slope angle measurement is valid, the third time is greater than the first time, and the received blade tip angle measurement is not valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, and the received blade slope angle measurement.

4. The method of claim 1, further comprising the steps of:

upon determining that the second time is not greater than the first time, the third time is greater than the first time, and the received blade tip angle is valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, and the received blade tip angle measurement; and

upon determining that the second time is greater than the first time, the received blade slope angle measurement is not valid, the third time is greater than the first time, and the received blade tip angle measurement is valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, and the received blade tip angle measurement.

5. The method of claim 1, further comprising the steps of:

receiving a reference blade slope angle; and

controlling the blade slope angle based on the received reference blade slope angle and the computed estimate of the blade slope angle.

6. The method of claim 1, further comprising the steps of:

receiving a reference blade slope angle;

computing an estimate of the first angular velocity based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, the received blade slope angle measurement, and the received blade tip angle measurement; and

controlling the blade slope angle based on the received reference blade slope angle, the computed estimate of the blade slope angle, and the computed estimate of the first angular velocity.

7. The method of claim 1, wherein the step of computing an estimate of the blade slope angle comprises the steps of:

determining a first estimate of a bias of the first angular velocity measurement;

determining a first estimate of a bias of the second angular velocity measurement;

computing a first estimate of a roll angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, the determined first estimate of the bias of the first angular velocity measurement, and the determined first estimate of the bias of the second angular velocity measurement; and

computing a first estimate of a pitch angle based on the received first angular velocity measurement, the received second angular velocity measurement, and the received third angular velocity measurement, the determined first estimate of the bias of the first angular velocity measurement, and the determined first estimate of the bias of the second angular velocity measurement.

8. The method of claim 7, further comprising the step of:

computing a corrected estimate of the roll angle, a corrected estimate of the pitch angle, a corrected estimate of the bias of the first angular velocity measurement, and a corrected estimate of the bias of the second angular velocity measurement based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, the received blade slope angle measurement, the received blade tip angle measurement, the determined first estimate of the bias of the first angular velocity measurement, and the determined first estimate of the bias of the second angular velocity measurement.

9. The method of claim 1, wherein the vehicle comprises an earthmoving machine.

10. The method of claim 9, wherein the earthmoving machine comprises a motor grader.

11. The method of claim 9, wherein the earthmoving machine comprises a bulldozer.

12. The method of claim 1, wherein the blade comprises a screed and the vehicle comprises a paver.

13. An apparatus for controlling a blade mounted on a vehicle, the apparatus comprising:

means for receiving at a first time a first angular velocity measurement about a first axis, a second angular velocity measurement about a second axis, and a third angular velocity measurement about a third axis from a three-axis gyroscope mounted on the blade, wherein the first axis, the second axis, and the third axis are orthogonal;

means for receiving at a second time a blade slope angle measurement from a blade slope angle tilt sensor mounted on the blade;

means for receiving at a third time a blade tip angle measurement from a blade tip angle tilt sensor mounted on the blade;

means for determining whether the second time is greater than the first time;

means for, upon determining that the second time is greater than the first time;

determining whether the received blade slope angle measurement is valid;

means for determining whether the third time is greater than the first time;

means for, upon determining that the third time is greater than the first time;

determining whether the received blade tip angle measurement is valid; and

means for, upon determining that the second time is greater than the first time, the received blade slope angle measurement is valid, the third time is greater than the first time, and the received blade tip angle measurement is valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, the received blade slope angle measurement, and the received blade tip angle measurement.

14. The apparatus of claim 13, further comprising:

means for, upon determining that the second time is not greater than the first time and the third time is not greater than the first time;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, and the received third angular velocity measurement;

means for, upon determining that the second time is greater than the first time, the received blade slope angle measurement is not valid, and the third time is not greater than the first time;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, and the received third angular velocity measurement;

means for, upon determining that the second time is not greater than the first time, the third time is greater than the first time, and the received blade tip angle is not valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, and the received third angular velocity measurement; and

means for, upon determining that the second time is greater than the first time, the received blade slope angle measurement is not valid, the third time is greater than the first time, and the received blade tip angle is not valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, and the received third angular velocity measurement.

15. The apparatus of claim 13, further comprising:

means for, upon determining that the second time is greater than the first time, the received blade slope angle measurement is valid, and the third time is not greater than the first time;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, and the received blade slope angle measurement; and

means for, upon determining that the second time is greater than the first time, the received blade slope angle measurement is valid, the third time is greater than the first time, and the received blade tip angle measurement is not valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, and the received blade slope angle measurement.

16. The apparatus of claim 13, further comprising:

means for, upon determining that the second time is not greater than the first time, the third time is greater than the first time, and the received blade tip angle is valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, and the received blade tip angle measurement; and

means for, upon determining that the second time is greater than the first time, the received blade slope angle measurement is not valid, the third time is greater than the first time, and the received blade tip angle measurement is valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, and the received blade tip angle measurement.

17. The apparatus of claim 13, further comprising:

means for receiving a reference blade slope angle; and

means for controlling the blade slope angle based on the received reference blade slope angle and the computed estimate of the blade slope angle.

18. The apparatus of claim 13, further comprising:

means for receiving a reference blade slope angle;

means for computing an estimate of the first angular velocity based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, the received blade slope angle measurement, and the received blade tip angle measurement; and

means for controlling the blade slope angle based on the received reference blade slope angle, the computed estimate of the blade slope angle, and the computed estimate of the first angular velocity.

19. The apparatus of claim 13, wherein the means for computing an estimate of the blade slope angle comprises:

means for determining a first estimate of a bias of the first angular velocity measurement;

means for determining a first estimate of a bias of the second angular velocity measurement;

means for computing a first estimate of a roll angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, the determined first estimate of the bias of the first angular velocity measurement, and the determined first estimate of the bias of the second angular velocity measurement; and

means for computing a first estimate of a pitch angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, the determined first estimate of the bias of the first angular velocity measurement, and the determined first estimate of the bias of the second angular velocity measurement.

20. The apparatus of claim 19, further comprising:

means for computing a corrected estimate of the roll angle, a corrected estimate of the pitch angle, a corrected estimate of the bias of the first angular velocity measurement, and a corrected estimate of the bias of the second angular velocity measurement based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, the received blade slope angle measurement, the received blade tip angle measurement, the determined first estimate of the bias of the first angular velocity measurement, and the determined first estimate of the bias of the second angular velocity measurement.

21. The apparatus of claim 13, wherein the vehicle comprises an earthmoving machine.

22. The apparatus of claim 21, wherein the earthmoving machine comprises a motor grader.

23. The apparatus of claim 21, wherein the earthmoving machine comprises a bulldozer.

24. The apparatus of claim 13, wherein the blade comprises a screed and the vehicle comprises a paver.

25. A computer readable medium for storing computer program instructions for controlling a blade mounted on a vehicle, the computer program instructions defining the steps of:

receiving at a first time a first angular velocity measurement about a first axis, a second angular velocity measurement about a second axis, and a third angular velocity measurement about a third axis from a three-axis gyroscope mounted on the blade, wherein the first axis, the second axis, and the third axis are orthogonal;

receiving at a second time a blade slope angle measurement from a blade slope angle tilt sensor mounted on the blade;

receiving at a third time a blade tip angle measurement from a blade tip angle tilt sensor mounted on the blade;

determining whether the second time is greater than the first time;

upon determining that the second time is greater than the first time;

determining whether the received blade slope angle measurement is valid;

determining whether the third time is greater than the first time;

upon determining that the third time is greater than the first time;

determining whether the received blade tip angle measurement is valid; and

upon determining that the second time is greater than the first time, the received blade slope angle measurement is valid, the third time is greater than the first time, and the received blade tip angle measurement is valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, the received blade slope angle measurement, and the received blade tip angle measurement.

26. The computer readable medium of claim 25, wherein the computer program instructions further comprise computer program instructions defining the steps of:

upon determining that the second time is not greater than the first time and the third time is not greater than the first time;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, and the received third angular velocity measurement;

upon determining that the second time is greater than the first time, the received blade slope angle measurement is not valid, and the third time is not greater than the first time;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, and the received third angular velocity measurement;

upon determining that the second time is not greater than the first time, the third time is greater than the first time, and the received blade tip angle is not valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, and the received third angular velocity measurement; and

upon determining that the second time is greater than the first time, the received blade slope angle measurement is not valid, the third time is greater than the first time, and the received blade tip angle is not valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, and the received third angular velocity measurement.

27. The computer readable medium of claim 25, wherein the computer program instructions further comprise computer program instructions defining the steps of:

upon determining that the second time is greater than the first time, the received blade slope angle measurement is valid, and the third time is not greater than the first time;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, and the received blade slope angle measurement; and

upon determining that the second time is greater than the first time, the received blade slope angle measurement is valid, the third time is greater than the first time, and the received blade tip angle measurement is not valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, and the received blade slope angle measurement.

28. The computer readable medium of claim 25, wherein the computer program instructions further comprise computer program instructions defining the steps of:

upon determining that the second time is not greater than the first time, the third time is greater than the first time, and the received blade tip angle is valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, and the received blade tip angle measurement; and

upon determining that the second time is greater than the first time, the received blade slope angle measurement is not valid, the third time is greater than the first time, and the received blade tip angle measurement is valid;

computing an estimate of the blade slope angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, and the received blade tip angle measurement.

29. The computer readable medium of claim 25, wherein the computer program instructions further comprise computer program instructions defining the steps of:

receiving a reference blade slope angle; and

controlling the blade slope angle based on the received reference blade slope angle and the computed estimate of the blade slope angle.

30. The computer readable medium of claim 25, wherein the computer program instructions further comprise computer program instructions defining the steps of:

receiving a reference blade slope angle;

computing an estimate of the first angular velocity based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, the received blade slope angle measurement, and the received blade tip angle measurement; and

controlling the blade slope angle based on the received reference blade slope angle, the computed estimate of the blade slope angle, and the computed estimate of the first angular velocity.

31. The computer readable medium of claim 25, wherein the computer program instructions defining the step of computing an estimate of the blade slope angle comprise computer program instructions defining the steps of:

determining a first estimate of a bias of the first angular velocity measurement;

determining a first estimate of a bias of the second angular velocity measurement;

computing a first estimate of a roll angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, the determined first estimate of the bias of the first angular velocity measurement, and the determined first estimate of the bias of the second angular velocity measurement; and

computing a first estimate of a pitch angle based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, the determined first estimate of the bias of the first angular velocity measurement, and the determined first estimate of the bias of the second angular velocity measurement.

32. The computer readable medium of claim 31, wherein the computer program instructions defining the step of computing an estimate of the blade slope angle further comprise computer program instructions defining the step of:

computing a corrected estimate of the roll angle, a corrected estimate of the pitch angle, a corrected estimate of the bias of the first angular velocity measurement, and a corrected estimate of the bias of the second angular velocity measurement based on the received first angular velocity measurement, the received second angular velocity measurement, the received third angular velocity measurement, the received blade slope angle measurement, the received blade tip angle measurement, the determined first estimate of the bias of the first angular velocity measurement, and the determined first estimate of the bias of the second angular velocity measurement.

33. The computer readable medium of claim 25, wherein the vehicle comprises an earthmoving machine.

34. The computer readable medium of claim 33, wherein the earthmoving machine comprises a motor grader.

35. The computer readable medium of claim 33, wherein the earthmoving machine comprises a bulldozer.

36. The computer readable medium of claim 25, wherein the blade comprises a screed and the vehicle comprises a paver.