Ripper autodig system implementing machine acceleration control

• US 8,083,004 B2
• Filed: 03/29/2007
• Issued: 12/27/2011
• Est. Priority Date: 03/29/2007
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Knight, Robert Paul Jr.
• Primary Examiner(s): Pezzuto, Robert
• Assistant Examiner(s): MCGOWAN, JAMIE LOUISE
• Application Number:
  US11/730,083
• Publication Number:
  US 20080243345A1
• Time in Patent Office: 1,734 Days
• Field of Search: 172/2, 172/3, 172/4, 172/7, 172/8, 172/699, 373/48, 56/102.G, 56/102.H, 56/102.R, 56D/IG.15, 701/50
• US Class Current: 172/7
• CPC Class Codes: E02F 3/84 Drives or control devices therefor , e.g. hydraulic drive systems
• CPC Class Codes: E02F 5/32 Rippers E02F5/106 takes precedence, ripper or scarifying teeth mounted on blades E02F3/8152; ripper tips E02F9/2875
• CPC Class Codes: E02F 9/2029 Controlling the position of implements in function of its load, e.g. modifying the attitude of implements in accordance to vehicle speed control for hydraulic or pneumatic drives E02F9/2203, E02F9/2221 and E02F9/2253 take precedence

Abstract

A control system for a machine having a power source, a traction device, and a ripping tool is disclosed. The control system may have a slip sensor configured to generate at least one signal indicative of machine slippage, and at least one actuator operable to position the ripping tool. The control system may also have a controller in communication with the slip sensor, the at least one actuator, and the power source. The controller may be configured to receive at least one operator input indicative of an acceptable slip value, and determine actual machine slippage based on the at least one signal. The controller may also be configured to directly and separately regulate a speed of the machine and a position of the ripping tool during an excavation process based on the acceptable slip value and actual machine slippage.

Claims

1. A control system for a machine having a power source, a traction device, and a ripping tool, comprising:

a slip sensor configured to generate at least one signal indicative of machine slippage;

at least one actuator operable to move the ripping tool; and

a controller in communication with the slip sensor, the at least one actuator, and the power source, the controller being configured to;

receive at least one operator input indicative of an acceptable slip value;

determine an actual machine slippage based on the at least one signal;

directly and separately regulate a fueling of the power source and a movement of the ripping tool during an excavation process based on the acceptable slip value and the actual machine slippage, including lowering the ripping tool into a work surface until the actual machine slippage is within a desired value;

reduce fueling to decrease a machine travel speed in response to the actual machine slippage exceeding the acceptable slip value; and

raise the ripping tool away from the work surface in response to machine slippage only if progressive reduction of the fueling decreases the machine travel speed to a reference value without reducing the actual machine slippage below the acceptable slip value.

2. The control system of claim 1, wherein the slip sensor includes a travel speed sensor and a traction device speed sensor, the actual machine slippage being determined based on a difference between a travel speed of the machine and a speed of the traction device.

3. The control system of claim 1, wherein:

the controller regulates a movement of the ripping tool by activating the at least one actuator; and

regulating a movement of the ripping tool includes regulating both a height and an angle of the ripping tool.

4. The control system of claim 3, wherein the ripping tool has a plurality of available settings and the controller is further configured to regulate the angle of the ripping tool based on a current one of the plurality of settings.

5. The control system of claim 4, wherein the controller is further configured to detect the current one of the plurality of settings.

6. The control system of claim 4, wherein the controller is configured to regulate the angle of the ripping tool based further on a task currently being performed by the machine.

7. The control system of claim 1, wherein the controller is further configured to decelerate travel of the machine to a first speed before lowering the ripping tool into the work surface.

8. The control system of claim 7, wherein the controller is further configured to accelerate the machine to a second speed after the ripping tool is lowered into the work surface.

9. The control system of claim 8, wherein the controller accelerates the machine to the second speed after activating the actuator to move the ripping tool from a penetration angle to a ripping angle while the ripping tool is lowered in the work surface.

10. The control system of claim 9, wherein reducing fueling to decrease a machine travel speed in response to the actual machine slippage exceeding the acceptable slip value includes doing so after movement of the ripping tool to the ripping angle and after the acceleration of machine travel speed to the second speed, if the actual machine slippage exceeds the acceptable slip value by a predetermined amount.

11. The control system of claim 10, wherein reducing fueling to decrease a machine travel speed in response to the actual machine slippage exceeding the acceptable slip value includes continuing decelerating the travel speed of the machine to a limit of about 40% of the second speed when the actual machine slippage exceeds the acceptable slip value by the predetermined amount.

12. The control system of claim 11, wherein raising the ripping tool away from the work surface in response to machine slippage only if progressive reduction of the fueling decreases the machine travel speed to a reference value without reducing the actual machine slippage below the acceptable slip value includes raising the ripping tool away from the work surface after the travel speed of the machine has been decelerated to about 40% of the second speed if the actual machine slippage still exceeds the acceptable slip value by the predetermined amount.

13. A method of autonomously controlling a ripping tool of a mobile machine, comprising:

receiving a threshold machine slip value;

adjusting a current travel speed to a first threshold speed less than a maximum excavation travel speed;

determining a first actual machine slippage;

lowering the ripping tool into a work surface while determining the first actual machine slippage until the first actual machine slippage is within a desired value;

adjusting an angle of the ripping tool after the ripping tool has been lowered into the work surface;

increasing the current travel speed after the angle of the ripping tool has been adjusted;

determining a second actual machine slippage after increasing the current travel speed;

reducing the current travel speed while determining the second actual machine slippage until the second actual machine slippage is within a desired amount of the threshold machine slip value or until the current travel speed is within a desired amount of a second threshold speed greater than a minimum excavation travel speed; and

raising the ripping tool away from the work surface in response to machine slippage only if the second actual machine slippage still exceeds the threshold slip value after the current travel speed has been reduced to the second threshold speed.

14. The method of claim 13, wherein adjusting the angle of the ripping tool includes moving a tip of the ripping tool toward the machine.

15. The method of claim 14, further including regulating the angle of the ripping tool based on at least one of a ripping tool configuration and a task currently being performed by the ripping tool.

16. The method of claim 13, wherein the first threshold speed is about 50% of a maximum excavation travel speed.

17. The method of claim 16, wherein the travel speed is adjusted by changing a fueling of an engine.

18. The method of claim 14, further including determining a configuration of the ripping tool, and limiting the angle of the ripping tool based on the configuration such that the tip of the ripping tool is kept from a location under the mobile machine.

19. The method of claim 13, wherein the second threshold speed is about 80% of the first threshold speed.

20. A machine, comprising:

a power source configured to generate a power output;

a traction device driven by the power output to propel the machine;

a ripping tool movable to disrupt a work surface;

an actuator coupled to move the ripping tool;

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

a traction device speed sensor configured to generate a second signal indicative of a traction device speed; and

a controller in communication with the power source, the actuator, the travel speed sensor, and the traction device speed sensor, the controller being configured to;

receive at least one operator input indicative of a threshold slip value;

determine an actual machine slippage based on the first and second signals; and

directly and separately regulate a fueling of the power source and a movement of the ripping tool during an excavation process based on the threshold slip value and the actual machine slippage, including raising the ripping tool away from the work surface in response to slippage only if the actual machine slippage exceeds the threshold slip value by the predetermined amount after reduction of the fueling of the power source to decrease the machine travel speed to a reference value.

21. The machine of claim 20, wherein the controller is further configured to:

decelerate current travel speed of the machine to about 50% of a maximum excavation travel speed;

lower the ripping tool into a work surface after decelerating the current travel speed of the machine and while determining the actual machine slippage until the actual machine slippage is about equal to the threshold slip value;

adjust an angle of the ripping tool after the ripping tool has been lowered into the work surface;

return the current travel speed of the machine to the maximum excavation travel speed after the angle of the ripping tool has been adjusted; and

adjust the machine travel speed and the movement of the ripping tool, if the actual machine slippage deviates from the threshold slip value after return of the machine to the maximum excavation speed.

22. The control system of claim 21, wherein the threshold slip value defines a range having an upper slip threshold and a lower slip threshold.