System and method for controlling slip

• US 8,600,621 B2
• Filed: 12/20/2011
• Issued: 12/03/2013
• Est. Priority Date: 12/20/2011
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Callaway, Joshua, Farmer, Todd R.
• Primary Examiner(s): Tarcza, Thomas
• Assistant Examiner(s): Dunn, Alex C
• Application Number:
  US13/332,005
• Publication Number:
  US 20130158804A1
• Time in Patent Office: 714 Days
• Field of Search: 701/41
• US Class Current: 701/41
• CPC Class Codes: B60T 8/1701 Braking or traction control means specially adapted for particular types of vehicles for vehicles having more than one drive axle B60T8/1769
• CPC Class Codes: B60T 8/175 Brake regulation specially adapted to prevent excessive wheel spin during vehicle acceleration, e.g. for traction control safety devices for propulsion unit control responsive to, or preventing, skidding of wheels B60K28/16

Abstract

A system for automated control of a ground-engaging traction device includes sensors to indicate a speed of the ground-engaging traction device, an acceleration of the machine, and a pitch rate of the machine. A controller determines a drive acceleration based upon the speed, and a ground acceleration based upon the acceleration and the pitch rate. The controller determines a command signal at least in part based upon an operator input command signal and a difference between the drive acceleration and the ground acceleration. A method is also provided.

Claims

1. A system for automated control of a ground-engaging traction device of a machine having a drive system, the traction device engaging a ground surface, the system comprising:

a drive sensor configured to provide a drive signal indicative of a speed of the ground-engaging traction device;

a first sensor configured to provide an acceleration signal indicative of a measured acceleration of the machine;

a second sensor configured to provide a pitch rate signal indicative of a measured pitch rate of the machine; and

a controller configured to;

determine a drive acceleration based upon the drive signal;

determine a ground acceleration based upon the acceleration signal and the pitch rate signal, the ground acceleration being parallel to the ground surface;

compare the drive acceleration to the ground acceleration;

determine a command signal at least in part based upon an operator input command signal and a difference between the drive acceleration and the ground acceleration; and

transmit the command signal to the drive system to control the ground-engaging traction device.

2. The system for automated control of a ground-engaging traction device of claim 1, wherein the drive acceleration is determined by differentiating the drive signal.

3. The system for automated control of a ground-engaging traction device of claim 1, wherein the command signal is equal to the operator input command signal if an operator issues a predetermined steering command.

4. The system for automated control of a ground-engaging traction device of claim 1, wherein the command signal is equal to the operator input command signal if a prime mover is operating above a predetermined speed.

5. The system for automated control of a ground-engaging traction device of claim 1, wherein the command signal is equal to the operator input command signal if a load on a prime mover is less than a predetermined level.

6. The system for automated control of a ground-engaging traction device of claim 1, wherein the command signal is determined at least in part based upon data including the speed of the ground-engaging traction device when the drive acceleration is greater than the ground acceleration.

7. The system for automated control of a ground-engaging traction device of claim 1, wherein the drive sensor measures a speed of a motor operatively associated with the ground-engaging traction device.

8. The system for automated control of a ground-engaging traction device of claim 1, wherein the command signal is equal to the operator input command signal if the speed of the ground-engaging traction device is greater than a predetermined maximum activation speed, the maximum activation speed being at least as high as a predetermined slip speed.

9. The system for automated control of a ground-engaging traction device of claim 8, wherein the predetermined slip speed is averaged with the speed of the ground-engaging traction device when the drive acceleration is approximately equal to the ground acceleration.

10. The system for automated control of a ground-engaging traction device of claim 1, wherein the ground acceleration is determined in part by integrating the pitch rate signal.

11. The system for automated control of a ground-engaging traction device of claim 1, wherein the command signal is less than the operator input command signal if the drive acceleration is greater than the ground acceleration.

12. A system for automated control of a ground-engaging traction device of a machine having a drive system, the traction device engaging a ground surface, the system comprising:

a drive sensor configured to provide a drive signal indicative of a speed of the ground-engaging traction device;

a first sensor configured to provide an acceleration signal indicative of a measured acceleration of the machine;

a second sensor configured to provide a pitch rate signal indicative of a measured pitch rate of the machine; and

a controller configured to;

determine a drive acceleration based upon the drive signal;

determine a ground acceleration based upon the acceleration signal and the pitch rate signal, the ground acceleration being parallel to the ground surface;

compare the drive acceleration to the ground acceleration;

generate a slip factor based upon a difference between the drive acceleration and the ground acceleration;

determine a command signal at least in part based upon an operator input command signal, the slip factor, and a difference between the drive acceleration and the ground acceleration; and

transmit the command signal to the drive system to control the ground-engaging traction device.

13. The system for automated control of a ground-engaging traction device of claim 12, wherein the slip factor is increased if the drive acceleration is approximately equal to the ground acceleration.

14. A method for controlling a ground-engaging traction device of a machine having a drive system, the traction device engaging a ground surface, the method comprising:

receiving a drive signal at a controller indicative of a speed of the ground-engaging traction device;

receiving an acceleration signal at the controller indicative of a measured acceleration of the machine;

receiving a pitch rate signal at the controller indicative of a measured pitch rate of the machine;

determining a drive acceleration based upon the drive signal;

determining a ground acceleration based upon the acceleration signal and the pitch rate signal, the ground acceleration being parallel to the ground surface;

comparing the drive acceleration to the ground acceleration;

determining a command signal at least in part based upon an operator input command signal and a difference between the drive acceleration and the ground acceleration; and

transmitting the command signal from the controller to the drive system to control the ground-engaging traction device.

15. The method for controlling a ground-engaging traction device of a machine of claim 14, further including receiving at the controller a predetermined steering command and setting the command signal equal to the operator input command signal.

16. The method for controlling a ground-engaging traction device of a machine of claim 14, further including receiving at the controller a signal that a prime mover is operating above a predetermined speed and setting the command signal equal to the operator input command signal.

17. The method for controlling a ground-engaging traction device of a machine of claim 14, further including receiving at the controller a signal that a load on a prime mover is less than a predetermined level and setting the command signal equal to the operator input command signal.

18. The method for controlling a ground-engaging traction device of a machine of claim 14, further including differentiating the drive signal to determine the drive acceleration.

19. The method for controlling a ground-engaging traction device of a machine of claim 14, further including measuring a speed of a motor operatively associated with the ground-engaging traction device.

20. The method for controlling a ground-engaging traction device of a machine of claim 14, further including receiving at the controller a signal that the speed of the ground-engaging traction device is greater than a predetermined maximum activation speed and setting the command signal equal to the operator input command signal.