Hydraulic motor having controlled output based on machine slippage model

1. A programmed controller-implemented method of managing excessive slippage at a physical interface between a machine and a traveled surface, the method comprising:

determining a track force, the track force being indicative of a propulsive force exerted by the machine on the traveled surface;

determining a modeled slippage based, at least in part, upon the track force and a slippage model; and

conditionally causing, by a programmed controller, a reduction of power output to propulsive drive components, by a motor, based upon a comparison, by the programmed controller, between the modeled slippage and a slippage limit.

2. The method of claim 1 , further comprising:

receiving a signal indicative of a normal force upon the traveled surface; and

calculating a ratio of the track force and the normal force,

wherein the modeled slippage is determined by applying the ratio to the slippage model.

3. The method of claim 2 , wherein the slippage model relates the ratio to the modeled slippage, and

wherein a slippage value for the modeled slippage is defined, at least in part by, a ratio between:

(1) a slip velocity, consisting of a difference between a non-slip velocity and an actual velocity of the machine; and

(2) the non-slip velocity of the machine.

4. The method of claim 3 wherein the slippage is defined as a slip percentage.

5. The method of claim 1 wherein the motor is a hydraulic motor, and the conditionally causing a reduction of power output to drive components comprises reducing a speed of the hydraulic motor.

6. The method of claim 2 wherein the normal force upon the traveled surface is determined according to the expression: (machine weight)×cosine(traveled slope).

7. The method claim 1 wherein the motor is a hydraulic motor, and wherein the track force is determined according to the expression:

Ft=[Dm ×(delta) P ×GRFD/ Rs ]−[machine mass× a]

where:

Dm is the hydraulic motor displacement;

delta P is the differential pressure across the hydraulic motor;

GRFD is the gear ratio of the final drive;

Rs is the radius of the sprockets driving the continuous track; and

“machine mass×a” is the force due to instantaneous acceleration of the machine.

8. The method of claim 1 further comprising:

determining an actual velocity of the machine in a forward direction;

determining a non-slip velocity of the machine based upon a speed of a propulsive drive component of the machine;

calculating a current slippage, wherein the current slippage is defined, at least in part, by a current slip ratio between:

(1) a difference between the non-slip velocity and the actual velocity of the machine; and

(2) the non-slip velocity of the machine; and

updating the slippage model based, at least in part, upon the current slippage and the track force.

9. The method of claim 8 further comprising the step of:

processing a stream of accelerometer signal values to render the actual velocity of the machine.

10. The method of claim 9 wherein the processing step comprises applying a filter to the stream of accelerometer signal values.

11. The method of claim 8 wherein updating the slippage model comprises applying a filter to the current slippage when incorporating the current slippage into the slippage model.

12. A non-transitory computer-readable medium including computer executable instructions for managing excessive slippage at a physical interface between a machine and a traveled surface, the computer-executable instructions, when executed by a programmed controller, facilitating performing the steps of:

determining a track force, the track force being indicative of the propulsive force exerted by the machine on the traveled surface;

determining a modeled slippage based, at least in part, upon the track force and a slippage model; and

conditionally causing a reduction of power output to propulsive drive components, by a motor, based upon a comparison between the modeled slippage and a slippage limit.

13. The non-transitory computer-readable medium of claim 12 , further comprising computer-executable instructions for:

receiving a signal indicative of a normal force upon the traveled surface; and

calculating a ratio of the track force and the normal force,

wherein the modeled slippage is determined by applying the ratio to the slippage model.

14. The non-transitory computer-readable medium of claim 13 , wherein the slippage model relates the ratio to the modeled slippage, and

wherein a slippage value for the modeled slippage is defined, at least in part by, a ratio between:

(1) a slip velocity, consisting of a difference between a non-slip velocity and an actual velocity of the machine; and

(2) the non-slip velocity of the machine.

15. The non-transitory computer-readable medium of claim 12 wherein the motor is a hydraulic motor, and wherein the track force is determined according to the expression:

Ft=[Dm ×(delta) P ×GRFD/ Rs ]−[machine mass× a]

where:

Dm is the hydraulic motor displacement;

delta P is the differential pressure across the hydraulic motor;

GRFD is the gear ratio of the final drive;

Rs is the radius of the sprockets driving the continuous track; and

“machine mass×a” is the force due to instantaneous acceleration of the machine.

16. The non-transitory computer-readable medium of claim 12 further comprising computer-executable instructions for:

determining an actual velocity of the machine in a forward direction;

determining a non-slip velocity of the machine based upon a speed of a propulsive drive component of the machine;

calculating a current slippage, wherein the current slippage is defined, at least in part, by a current slip ratio between:

(1) a difference between the non-slip velocity and the actual velocity of the machine; and

(2) the non-slip velocity of the machine; and

updating the slippage model based, at least in part, upon the current slippage and the track force.

17. A machine including:

a propulsive force source for driving the machine on a traveled surface; and

a programmed controller including a slippage control module including computer-executable instructions for managing excessive slippage at a physical interface between a machine and a traveled surface, the computer-executable instructions, when executed by the programmed controller, facilitating performing the steps of:

determining a track force, the track force being indicative of the propulsive force exerted by the machine on the traveled surface;

determining a modeled slippage based, at least in part, upon the track force and a slippage model; and

conditionally causing a reduction of power output to propulsive drive components, by a motor, based upon a comparison, by the programmed controller, between the modeled slippage and a slippage limit.

18. The machine according to claim 17 wherein the propulsive force source is a hydraulic motor.

19. The machine according to claim 18 further comprising a continuous track driven by the hydraulic motor.

20. The machine according to claim 17 wherein the slippage control module further comprises computer-executable instructions for:

determining an actual velocity of the machine in a forward direction;

determining a non-slip velocity of the machine based upon a speed of a propulsive drive component of the machine;

calculating a current slippage, wherein the current slippage is defined, at least in part, by a current slip ratio between:

(1) a difference between the non-slip velocity and the actual velocity of the machine; and

(2) the non-slip velocity of the machine; and

updating the slippage model based, at least in part, upon the current slippage and the track force.