ARTICULATION CONTROL SYSTEM HAVING STEERING PATH TRACKING

• US 20130192919A1
• Filed: 01/31/2012
• Published: 08/01/2013
• Est. Priority Date: 01/31/2012
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Michael C. Subrt, Owen C. Kolstad, Yongliang Zhu
• Inventors: SUBRT, Michael C., ZHU, Yongliang, KOLSTAD, Owen C.
• Granted Patent: US 8,807,261 B2
• Time in Patent Office: Days
• US Class Current: 180/400
• CPC Class Codes: B62D 12/00 Steering specially adapted for vehicles operating in tandem or having pivotally connected frames steering endless tracks or the like B62D11/00; steering specially adapted for trailers B62D13/00
• CPC Class Codes: B62D 6/002 computing target steering angles for front or rear wheels B62D7/159 takes precedence
• CPC Class Codes: B62D 9/00 Steering deflectable wheels not otherwise provided for steering positon indicators B62D15/02

Abstract

An articulation control system is disclosed for use with a mobile machine having a traction device. The articulation control system may have a speed sensor configured to generate a first signal indicative of a travel speed of the mobile machine, a steering angle sensor configured to generate a second signal indicative of a steering angle of the traction device, and an articulation actuator configured to articulate a front frame of the mobile machine relative to a rear frame of the mobile machine. The articulation control system may also have a controller in communication with the speed sensor, the steering angle sensor, and the articulation actuator. The controller may be configured to track a travel path of the front frame based on the first and second signals, and to regulate operation of the articulation actuator to cause the rear frame to follow the travel path of the front frame.

Claims

1. An articulation control system for a mobile machine having a traction device, the articulation control system comprising:

a speed sensor configured to generate a first signal indicative of a travel speed of the mobile machine;

a steering angle sensor configured to generate a second signal indicative of a steering angle of the traction device;

an articulation actuator configured to articulate a front frame of the mobile machine relative to a rear frame of the mobile machine; and

a controller in communication with the speed sensor, the steering angle sensor, and the articulation actuator, the controller being configured to;

track a travel path of the front frame based on the first and second signals; and

regulate operation of the articulation actuator to cause the rear frame to follow the travel path of the front frame.

2. The articulation control system of claim 1, wherein the controller is configured to calculate sequential points of the travel path at equally timed intervals.

3. The articulation control system of claim 2, wherein the sequential points are spaced apart by about 20 milliseconds.

4. The articulation control system of claim 1, wherein:

the traction device is one of a pair of front traction devices supported at opposing ends of a front axle; and

the travel path of the front frame corresponds with a travel path of a point on the front axle located about equidistant between the front traction devices.

5. The articulation control system of claim 4, wherein:

the rear frame includes tandem axles supporting opposing rear traction devices; and

the controller is configured to regulate operation of the articulation actuator to cause a point located about equidistant between the tandem axles and about equidistant between the opposing rear traction devices to follow the travel path of the front frame.

6. The articulation control system of claim 1, further including an articulation angle sensor configured to generate a third signal indicative of an articulation angle of the front frame relative to the rear frame, wherein the travel path of the front frame is tracked based further on the third signal.

7. The articulation control system of claim 6, wherein the controller is configured to regulate operation of the articulation actuator based on the travel path of the front frame and on the third signal.

8. The articulation control system of claim 1, wherein the controller is configured to:

calculate discrete sequential points of the travel path of the front frame; and

selectively shift and rotate the discrete sequential points of the travel path relative to a machine frame of reference as the mobile machine moves.

9. The articulation control system of claim 8, wherein:

the controller is configured to select one of the discrete sequential points of the travel path as a desired path point; and

regulate operation of the articulation actuator based on a location of the desired path point.

10. The articulation control system of claim 9, wherein the desired path point is at a location between a front axle of the mobile machine and a position about midway between rear tandem axles of the mobile machine.

11. The articulation control system of claim 10, wherein the location is about 90-95% of a distance from a center of the front axle to the position about midway between the rear tandem axles.

12. The articulation control system of claim 1, further including a mode selector configured to indicate operator selection of an automated articulation control mode and a manual articulation control mode, wherein the controller is in communication with the mode selector and configured to automatically track the travel path of the front frame and automatically regulate operation of the articulation actuator only when the mode selector indicates that the automated articulation control mode has been selected by an operator of the mobile machine.

13. The articulation control system of claim 12, wherein the controller is further configured to exit the automated articulation control mode when at least one of the travel speed, the steering angle, and an articulation angle of the mobile machine deviates from an acceptable range.

14. A method of controlling articulation of a mobile machine having a traction device, the method comprising:

detecting a travel speed of the mobile machine;

detecting a steering angle of the traction device;

tracking a travel path of a front frame of the mobile machine based on the travel speed and the steering angle; and

articulating the front frame relative to a rear frame of the mobile machine to cause the rear frame to follow the travel path of the front frame.

15. The method of claim 14, wherein tracking the travel path of the front frame includes calculating discrete sequential points of the travel path at equally timed intervals.

16. The method of claim 15, further including selectively shifting and rotating the discrete sequential points of the travel path relative to a machine frame of reference as the mobile machine moves.

17. The method of claim 16, further including:

selecting one of the discrete sequential points of the travel path as a desired path point; and

articulating the front frame relative to a rear frame based on a location of the desired path point.

18. The method of claim 14, wherein:

the traction device is one of a pair of front traction devices supported at opposing ends of a front axle;

the travel path of the front frame corresponds with a travel path of a point on the front axle located about equidistant between the front traction devices;

the rear frame includes tandem axles supporting opposing rear traction devices;

and articulating the front frame relative to the rear frame of the mobile machine to cause the rear frame to follow the travel path of the front frame includes articulating the front frame to cause a point located about equidistant between the tandem axles and about equidistant between the opposing rear traction devices to follow the travel path of the front frame.

19. The method of claim 14, further including:

receiving an operator selection of an automated articulation control mode and a manual articulation control mode, wherein the method includes articulating the front frame relative to a rear frame of the mobile machine to cause the rear frame to follow the travel path of the front frame only when the operator selection is the automated articulation control mode; and

exiting the automated articulation control mode when at least one of the travel speed, the steering angle, and an articulation angle of the mobile machine deviates from an acceptable range.

20. An articulated machine, comprising:

a front axle connecting opposing front traction devices;

a front frame supported by the front axle;

an operator station mounted to the front frame;

tandem rear axles each supporting opposing rear traction devices;

a rear frame supported by the tandem rear axles;

an engine mounted to the rear frame and configured to drive the rear traction devices;

an articulation joint pivotally connecting the front and rear frames;

an articulation actuator configured pivot the front frame relative to the rear frame about the articulation joint;

a speed sensor configured to generate a first signal indicative of a travel speed of the articulated machine;

a steering sensor configured to generate a second signal indicative of a steering angle of the front traction devices;

an articulation sensor configured to generate a third signal indicative of an actual articulation angle of the front frame relative to the rear frame; and

a controller in communication with the articulation actuator, the speed sensor, the steering sensor, and the articulation sensor, the controller being configured to;

track a travel path of the front frame based on the first, second, and third signals;

determine a desired articulation angle that should cause the rear frame to follow the travel path of the front frame; and

regulate operation of the articulation actuator based on the desired and actual articulation angles.