Motor Grader Cross Slope Control With Articulation Compensation

• US 20140326471A1
• Filed: 05/03/2013
• Published: 11/06/2014
• Est. Priority Date: 05/03/2013
• Status: Abandoned Application

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Zhu, Yongliang, Perschbacher, Jessica
• Application Number:
  US13/886,894
• Publication Number:
  US 20140326471A1
• Time in Patent Office: Days
• US Class Current: 172/4.5
• CPC Class Codes: E02F 3/764 with the scraper blade being pivotable about a vertical axis
• CPC Class Codes: E02F 3/7645 with the scraper blade being pivotable about a horizontal axis disposed parallel to the blade
• CPC Class Codes: E02F 3/765 with the scraper blade being pivotable about a horizontal axis disposed perpendicular to the blade
• CPC Class Codes: E02F 3/7654 with the scraper blade being horizontally movable into a position near the chassis
• CPC Class Codes: E02F 3/845 using mechanical sensors to determine the blade position, e.g. inclinometers, gyroscopes, pendulums
• CPC Class Codes: E02F 9/0841 Articulated frame, i.e. having at least one pivot point between two travelling gear units tractor-trailer combinations B62D53/00

Abstract

A motor grader is provided having cross slope cut angle control for providing accurate cuts generally, and particularly while the machine is travelling in other than a straight and level fashion. A controller is configured to adjust the cross slope angle of the blade, so that the cross slope cut angle corresponds to a desired cross slope cut angle. The controller receives a signal indicative of the desired cross slope cut angle and executing a pure pursuit procedure to identify a blade cross slope angle to yield the desired cross slope cut angle. The pure pursuit procedure includes identifying a blade travel direction, and identifying a horizontal component thereof. The blade edge is projected onto a plane perpendicular to the horizontal component of the blade travel direction, generating a slope function specifying the cross slope cut angle as a function of blade cross slope angle.

Claims

1. A method for controlling a blade of a motor grader to provide a desired cross slope cut angle, the motor grader including a frame having a front frame portion and a rear frame portion, the blade, wherein the blade has an edge and a center point, one or more blade slope actuators, and a plurality of machine sensors, the method comprising:

receiving a signal indicative of the desired cross slope cut angle;

receiving one or more sensor signals from the plurality of sensors;

executing a pure pursuit procedure to identify a blade slope to yield the desired cross slope cut angle based on the one or more sensor signals, the pure pursuit procedure comprising;

identifying a direction of travel of the blade based on at least one of the sensor signals, the direction of travel of the blade having a horizontal component, and

identifying an angle between the horizontal component and the front frame portion;

identifying a machine travel direction at the blade center point;

generating a projection of the blade edge onto a plane perpendicular to the horizontal component of the direction of travel of the blade; and

based on the projection of the blade edge onto the perpendicular plane, generating a slope function specifying the cross slope cut angle as a function of blade cross slope angle.

2. The method for controlling a blade of a motor grader in accordance with claim 1, further comprising outputting a blade slope command to the one or more blade slope actuators, the blade slope command representing a blade slope angle that will yield the desired cross slope cut angle in keeping with the slope function.

3. The method for controlling a blade of a motor grader in accordance with claim 1, wherein the plurality of sensors include a blade slope sensor for sensing the slope of the blade relative to the front frame portion and a blade rotation sensor for sensing a rotation of the blade relative to the front frame portion.

4. The method for controlling a blade of a motor grader in accordance with claim 3, wherein the plurality of sensors include a mainfall sensor for sensing a pitch angle of the motor grader and a roll angle of the motor grader.

5. The method for controlling a blade of a motor grader in accordance with claim 4, wherein the plurality of sensors further include a steering sensor for sensing a steering angle of the motor grader and an articulation sensor for sensing an articulation angle between the front frame portion and the rear frame portion.

6. The method for controlling a blade of a motor grader in accordance with claim 5, wherein the articulation angle is non-zero.

7. The method for controlling a blade of a motor grader in accordance with claim 1, wherein the signal indicative of the desired cross slope cut angle is generated based on an operator command.

8. A motor grader having improved cross slope cut angle control, the motor grader comprising:

a frame having a front frame portion and a rear frame portion,

a blade movably attached to the front frame portion, wherein the blade has an edge and a center point;

one or more blade slope actuators to adjust the cross slope angle of the blade;

a plurality of machine sensors; and

a controller configured to adjust the cross slope angle of the blade, so that the cross slope cut angle corresponds to a desired cross slope cut angle, by receiving a signal indicative of the desired cross slope cut angle, receiving one or more sensor signals from the plurality of sensors, and executing a pure pursuit procedure to identify a blade cross slope angle to yield the desired cross slope cut angle based on the one or more sensor signals, the pure pursuit procedure comprising;

identifying a direction of the blade cutting edge based on at least one of the sensor signals;

identifying a machine travel direction at the blade center point;

generating a normal direction of the plane formed by the blade cutting edge and the travel direction; and

based on the normal direction of the plane formed by the blade cutting edge and the travel direction, generating a slope function specifying the cross slope cut angle as a function of blade cross slope angle.

9. The motor grader in accordance with claim 8, wherein the controller is further configured to output a blade slope command to the one or more blade slope actuators, the blade slope command representing a blade slope angle that will yield the desired cross slope cut angle in keeping with the slope function.

10. The motor grader in accordance with claim 8, wherein the plurality of sensors include a blade slope sensor for sensing the slope of the blade relative to the front frame portion and a blade rotation sensor for sensing a rotation of the blade relative to the front frame portion.

11. The motor grader in accordance with claim 10, wherein the plurality of sensors include a mainfall sensor for sensing a pitch angle of the motor grader and a roll angle of the motor grader.

12. The motor grader in accordance with claim 11, wherein the plurality of sensors further include a steering sensor for sensing a steering angle of the motor grader and an articulation sensor for sensing an articulation angle between the front frame portion and the rear frame portion.

13. The motor grader in accordance with claim 8, wherein the controller is further configured to generate the signal indicative of the desired cross slope cut angle based on receipt of an operator command.

14. A method for controlling a blade of a motor grader to provide a desired cross slope cut angle via one or more blade slope actuators the method comprising:

measuring a blade cross slope angle;

generating a blade travel vector representing a direction of travel of the blade;

projecting the blade travel vector onto a horizontal surface to define a blade travel projection, and generating a plane perpendicular to the blade travel projection;

projecting a cutting edge of the blade onto the plane perpendicular to the projection to generate a cut projection as a function of blade cross slope angle; and

adjusting a cross slope angle of the blade such that an angle of the cut projection matches the desired cross slope cut angle.

15. The method for controlling a blade of a motor grader in accordance with claim 14, wherein measuring the blade cross slope angle includes receiving a slope signal from a blade slope sensor.

16. The method for controlling a blade of a motor grader in accordance with claim 14, wherein generating a blade travel vector representing a direction of travel of the blade includes sensing a pitch angle and roll angle of the motor grader and sensing a steering angle and articulation angle of the motor grader.

17. The method for controlling a blade of a motor grader in accordance with claim 16, wherein sensing a pitch angle and roll angle of the motor grader includes receiving a signal from a mainfall sensor.

18. The method for controlling a blade of a motor grader in accordance with claim 17, wherein the mainfall sensor is a gravitational sensor.

19. The method for controlling a blade of a motor grader in accordance with claim 17, wherein the mainfall sensor is a gyroscopic sensor.

20. The method for controlling a blade of a motor grader in accordance with claim 14, wherein adjusting a cross slope angle of the blade such that an angle of the cut projection matches the desired cross slope cut angle includes sending a slope command to one or more blade slope actuators.