METHOD OF DETERMINING WHEEL SLIPPAGE AND ENGAGING A DIFFERENTIAL LOCK IN A WORK VEHICLE

• US 20080208428A1
• Filed: 02/23/2007
• Published: 08/28/2008
• Est. Priority Date: 02/23/2007
• Status: Active Grant

• Current Assignee: Deere & Company
• Original Assignee: Deere & Company
• Inventors: Anderson, Eric, Thompson, Isaac W., Gratton, Michael R.
• Granted Patent: US 7,856,303 B2
• Time in Patent Office: Days
• US Class Current: 701/82
• CPC Class Codes: B60K 23/04 for differential gearing
• CPC Class Codes: B60K 28/165 acting on elements of the vehicle drive train other than the propulsion unit and brakes, e.g. transmission, clutch, differential acting on brakes B60T8/17
• CPC Class Codes: B60W 2510/104 Output speed
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60Y 2200/221 Tractors
• CPC Class Codes: B60Y 2200/411 Bulldozers, Graders

Abstract

A method of determining wheel slippage in a work vehicle includes the steps of: sensing an absolute ground speed of the work vehicle; calculating a ground speed of the work vehicle using at least one drive train component; comparing the absolute ground speed with the calculated ground speed; generating a scaling factor based upon the comparison; and adjusting the calculated ground speed using the scaling factor. The method may also include the steps of scaling the absolute ground speed to a threshold value; comparing the calculated ground speed with the threshold value; and engaging a differential lock if the calculated ground speed is greater than the threshold value.

Claims

1. A method of determining wheel slippage in a work vehicle, comprising the steps of:

sensing an absolute ground speed of the work vehicle;

calculating a ground speed of the work vehicle using at least one drive train component;

comparing said absolute ground speed with said calculated ground speed;

generating a scaling factor based upon said comparison; and

adjusting said calculated ground speed using said scaling factor.

2. The method of determining wheel slippage in a work vehicle of claim 1, including the step of feeding back said adjusted calculated ground speed to said comparing step in a closed loop fashion.

3. The method of determining wheel slippage in a work vehicle of claim 1, wherein said comparing step results in a speed error signal, and said generating step is carried out by integrating said speed error signal over time to generate said scaling factor.

4. The method of determining wheel slippage in a work vehicle of claim 3, wherein said integration can be used to detect an abrupt change in said error signal over time.

5. The method of determining wheel slippage in a work vehicle of claim 1, including the step of outputting a scaled calculated ground speed based upon said adjusted calculated ground speed.

6. The method of determining wheel slippage in a work vehicle of claim 1, wherein said calculating step comprises calculating a ground speed of the work vehicle using a transmission output speed.

7. The method of determining wheel slippage in a work vehicle of claim 1, wherein said absolute ground speed is sensed using a radar.

8. The method of determining wheel slippage in a work vehicle of claim 1, including the step of scaling said absolute ground speed to a threshold value at which a differential lock is engaged.

9. The method of determining wheel slippage in a work vehicle of claim 8, including the step of comparing said scaled absolute ground speed with said scaled calculated ground speed.

10. The method of determining wheel slippage in a work vehicle of claim 9, including the step of engaging a differential lock if said scaled calculated ground speed is greater than said scaled absolute ground speed.

11. The method of determining wheel slippage in a work vehicle of claim 10, wherein said absolute ground speed is sensed using a radar, and including the step of not engaging said differential lock if said radar has a signal fallout from a reflective ground surface.

12. The method of determining wheel slippage in a work vehicle of claim 11, wherein said radar has two sensing horns, and said signal fallout is determined when one said sensing horn ceases providing an output while an other said sensing horn continues providing an output.

13. A method of determining wheel slippage in a work vehicle, comprising the steps of:

sensing an absolute ground speed of the work vehicle;

calculating a ground speed of the work vehicle using at least one drive train component;

scaling said absolute ground speed to a threshold value;

comparing said calculated ground speed with said threshold value; and

engaging a differential lock if said calculated ground speed is greater than said threshold value.

14. The method of determining wheel slippage in a work vehicle of claim 13, wherein said absolute ground speed is sensed using a radar.

15. The method of determining wheel slippage in a work vehicle of claim 13, wherein said threshold value comprises one of a plurality of threshold values stored in a memory, each said threshold value corresponding to a different said sensed absolute ground speed of the work vehicle.

16. The method of determining wheel slippage in a work vehicle of claim 15, wherein said memory includes a lookup table with said plurality of threshold values.

17. The method of determining wheel slippage in a work vehicle of claim 13, wherein said absolute ground speed is sensed using a radar, and including the step of not engaging said differential lock if said radar has a signal fallout from a reflective ground surface.

18. The method of determining wheel slippage in a work vehicle of claim 17, wherein said radar has two sensing horns, and said signal fallout is determined when one said sensing horn ceases providing an output while an other said sensing horn continues providing an output.

19. The method of determining wheel slippage in a work vehicle of claim 13, wherein said calculating step comprises calculating a ground speed of the work vehicle using a transmission output speed.