Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Construction or agricultural-type vehicle
Reexamination Certificate
1999-11-23
2001-04-10
Nguyen, Tan (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Construction or agricultural-type vehicle
C180S197000, C172S010000
Reexamination Certificate
active
06216072
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a hitch control system, and in particular to a hitch control system which is responsive to wheel slip.
There are two basic types of known hitch control systems which respond to sensed wheel slip. A system of the first type is described in U.S. Pat. No. 4,518,044, issued May 21, 1985 to Wiegardt et al., and assigned to the assignee of this application. In this system the hitch control signal includes an offset which is proportional to the amount of slip error (defined by difference between desired slip and actual slip)—the hitch control signal is an arithmetic combination of wheel slip error with other error signals such as draft force error and/or position error. The system described in the '044 patent includes an activity control for adjusting a gain value which multiplies not only slip error, but the combination of slip error, draft force error, engine speed error and position error. The system described in the '044 patent also includes an operator-controlled, rate-selecting switch for selecting slow and rapid rates of implement movement.
A system of the second type is described in U.S. Pat. No. 5,911,769, issued Jun. 15, 1999 to Orbach et al. The system of the '769 patent generates a slip signal based upon the apparent speed and the ground speed, and has a first operational mode which is operative when the slip signal is below a slip limit and second operational mode which is operational when the slip signal is above the slip limit. In the first mode, the system generates a hitch actuator control signal based upon the difference between the first or second operating parameter (draft force or position) and a reference value. In the second mode, the system can override control based on this difference by using a control signal based upon the difference between the slip signal and a slip reference value. The '769 system also includes a three-position rocker switch movable between OFF, ON and SET positions and which is used for turning a slip control function on and off and for setting a slip limit value.
Both types of system operate satisfactorily in high slip conditions, or when minimum depth variation is desired. However, when operating in light soils in rolling terrain, such systems may not control depth with sufficient accuracy, and they may operate too aggressively and cause overshoot of the hitch. Neither of these systems has an operator control solely for adjustment of the slip response of the system.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a slip-responsive hitch control system which functions properly when operating in light soils in rolling terrain.
Another object of the present invention is to provide such a slip-responsive hitch control system which accurately controls depth.
Another object of the present invention is to provide such a hitch control system which does not operate too aggressively and which does not cause overshoot of the hitch.
Another object of the present invention is to provide such a hitch control system which includes an operator control for adjusting only the slip response of the system, apart from the responsiveness of other parameters.
These and other objects are achieved by the present invention wherein a hitch control system provides the operator with the ability to select the type of slip control function based on field conditions and implement type. When operating in light soils in rolling terrain the operator can select a slow acting slip integration control mode wherein the slip responsiveness of the hitch control system is purely a function of an integrated wheel slip signal. A slip response control permits the operator to adjust the control system from a pure integration control mode, though a mix mode to a proportional control mode. As the slip response control is adjusted toward the proportional end of its range, the slip responsiveness of the hitch control system is a function of both an integral of sensed wheel slip, together with a term which is proportional to sensed wheel slip. When the slip response control is adjusted fully to the proportional end of its range, the slip responsiveness of the hitch control system is a function only of the term which is proportional to sensed wheel slip, and is not a function of integrated wheel slip. This slip responsive hitch control system does not require an operator control for setting an adjustable slip set point, and thus, a desired slip responsiveness can be achieved with only the operator adjustable slip response control.
REFERENCES:
patent: 3913680 (1975-10-01), Carlson
patent: 4465142 (1984-08-01), Van Der Lely et al.
patent: 4508176 (1985-04-01), Wiegardt et al.
patent: 4518044 (1985-05-01), Wiegardt et al.
patent: 4809785 (1989-03-01), Arnold et al.
patent: 4886123 (1989-12-01), Arnold et al.
patent: 4969527 (1990-11-01), Boe et al.
patent: 4979092 (1990-12-01), Bergene et al.
patent: 5190111 (1993-03-01), Young et al.
patent: 5320186 (1994-06-01), Strosser et al.
patent: 5443307 (1995-08-01), Maier
patent: 5560431 (1996-10-01), Stratton
patent: 5755291 (1998-05-01), Orbach et al.
patent: 5911769 (1999-06-01), Orbach et al.
patent: 6058342 (2000-05-01), Orbach et al.
Case IH, “Operator's Manual Tractors Models 8910-8920”, Published Date Unknown, pp. 112-123.
John Deere, “Operator's Manual 8100, 8200, 8300 And 8400 Tractors”, 1995, pp. 45-1 Through 45-5.
Ford New Holland, “66 To 106 PTO Hp PowerStar Tractors”, 1991, pp. 10-17, 20-21.
Bergene Mark Allen
Boe Thomas Eugene
Livdahl Richard James
Deere & Company
Nguyen Tan
Tran Dalena
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