# Patent

## Title
Auto-steerable farming system

## Abstract

A steering system for a towable implement includes a steering sensor, an implement steering controller, a steering control valve, a steering cylinder, and an implement steering mechanism that steers the implement. The steering sensor measures, directly or indirectly, the angular position of the steerable wheels of the implement. The implement steering controller processes feedback from the steering sensor and with a desired steering angle, outputs a steering control signal that is input to the steering control valve. The steering control valve controls the flow of hydraulic fluid to the steering cylinder, which, in turn, powers the implement steering mechanism to turn the wheels of the implement. The steering system may be operated in various control modes, such as, a transportation steering mode, a corner and 180 turn steering mode, a swath tracking steering mode, crab steering mode, and a manual steering mode, which allows manual control of the steering system.

## Background
BACKGROUND OF THE INVENTION
The present invention relates generally to agricultural implements and, more particularly, to a steering system for an agricultural implement, such as a towed planter, that can automatically steer the implement during field operations or road transport.
Conventional agricultural implements are designed to follow the motion of a towing vehicle, such as a tractor. In this regard, most agricultural implements are passively steered principally by the tractor rather than have their own steering mechanisms. However, increasingly, there is a desire for implements that are capable of limited self-steering. That is, in some situations, it may be desirable for the implement to be steered so as to maintain alignment with the tractor when the tractor is moving across a sloped area or avoiding an obstruction, such as a mailbox.
A number of steering systems have been developed as an aftermarket add-on to make a non-steerable implement steerable. One such system is GPS-based that is mounted to the toolbar of the non-steerable implement. Such add-on systems generally have two subsystems: the steering subsystem that mechanically causes steering of the implement and the auto-guidance subsystem (GPS, for example) that controls the steering subsystem. These subsystems can be quite costly and ultimately cost prohibitive. For example, it is not uncommon for the steering subsystem alone to cost several thousands of dollars with additional costly expense for the auto-guidance subsystem. Also, after market systems are designed to provide implement steering during field operation and do not provide steering function while transporting. Additionally, for many aftermarket add-on systems, the implement must be mechanically modified, which may not be practical for some types of implements, such as folding planters, or negate warranties for the implement.
Moreover, steerable implements have been limited heretofore in the type of available movements. For example, many steerable implements have systems that are designed to maintain alignment of the implement with the tractor. While there is a need in some circumstances to maintain such alignment, a steerable implement that can be steered intentionally along an offset track may be desirable in other circumstances, such as during transport. Additionally, it is desirable to have an implement that can be automatically controlled to turn or otherwise corner during field operations. Automatic implement swath tracking during field operation would also be desirable.
SUMMARY OF THE INVENTION
In one aspect of the invention, a steering system for a towable implement includes a steering sensor, an implement steering controller, a steering control valve, a steering cylinder, and an implement steering mechanism that steers the implement. The steering sensor, which may be a rotary position sensor or linear position sensor, measures, directly or indirectly, the angular position of the steerable wheels of the implement. The implement steering controller processes feedback from the steering sensor and with a desired steering angle, outputs a steering control signal that is input to the steering control valve. The steering control valve controls the flow of hydraulic fluid to the steering cylinder, which, in turn, “powers” the implement steering mechanism to turn the wheels of the implement. The steering system may be operated in various control modes, operator selectable or automatic based upon criteria, such as, a transportation steering mode, a corner and 180 turn steering mode, a swath tracking steering mode, crab steering mode, and a manual steering mode, which allows manual control of the steering system. Preferably, the implement is towed by a tractor or other prime mover having a GPS system, such as an auto-guidance tractor. Information as to the position of the tractor as provided by the GPS system of the tractor is provided to and processed by the implement steering controller to provide a suitable steering control signal. The implement may be auto-steered in both forward and reverse directions.
It is therefore an object of the invention to provide a towable and steerable implement.
It is another object of the invention to provide an automatic steering system for a towable implement.
It is yet a further object of the invention to provide an automatic steering system that can be selectively operated in various modes.
Other objects, features, aspects, and advantages of the invention will become apparent to those skilled in the art from the following detailed description and accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.



BRIEF DESCRIPTION OF THE FIGURES
Preferred exemplary embodiments of the invention are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout.
In the drawings:
FIG. 1 is a pictorial view of an agricultural system comprising a steerable agricultural implement shown hitched to a towing vehicle according to the invention;
FIG. 2 is a schematic representation of the agricultural system of FIG. 1 according to a first embodiment of the invention;
FIG. 2A is a schematic representation of an implement control system for use with the agricultural system shown in FIG. 2;
FIG. 3 is a schematic representation of the agricultural system of FIG. 1 according to a second embodiment of the invention;
FIG. 3A is a schematic representation of an implement control system for use with the agricultural system shown in FIG. 3;
FIG. 4 is a schematic representation of the agricultural system of FIG. 1 according to a third embodiment of the invention;
FIG. 4A is a schematic representation of an implement control system for use with the agricultural system shown in FIG. 4;
FIG. 5 is a schematic representation of the agricultural system of FIG. 1 according to a fourth embodiment of the invention;
FIG. 5A is a schematic representation of an implement control system for use with the agricultural system shown in FIG. 5;
FIG. 6 is a schematic representation of the agricultural system of FIG. 1 according to a fifth embodiment of the invention; and
FIG. 6A is a schematic representation of an implement control system for use with the agricultural system shown in FIG. 6.



DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings, and more particularly to FIG. 1, an exemplary agricultural system 10 includes an agricultural implement, such as a planter 12, hitched in a conventional manner to a prime mover, such as tractor 14. The planter 12 includes a frame 16 supporting a plurality of spaced apart row units 18 that deposit granular material, such as seed, onto a planting surface. Preferably, two bulk fill tanks 20, 22 are supported by the frame 16 and may be filled with seed or other granular material for subsequent passage to the individual row units 18, which may have individual row hoppers 24, in a conventional manner. The implement frame 16 is supported above the farm field by two pairs of outer wheels 26 and two pairs of inner wheels 28. As will be described in greater detail below, the inner wheels 28 may be auto-steered so that the implement is not only towed by the tractor 14 but is steered according to one of a number of operating modes, e.g., transportation steering mode, cornering steering mode, swath tracking mode, and crab steering mode. While a planter 12 is shown, it is understood that the invention is applicable with other types of agricultural implements in which it is desirable to provide auto-steering of the implement.
FIG. 2 schematically illustrates one embodiment of the present invention for auto-steering a towable implement, such as planter 12, by a prime mover, e.g., tractor 14. In this first illustrated embodiment, auto-steering of the planter 12 is controlled by an implement steering controller 30 that receives information from a rotary steering sensor 32, a towing angle sensor 34, and a tractor GPS receiver 36, as well as operator input controls 38, which are preferably contained within the operator cab (not numbered) of the tractor 14. From the information provided by the aforementioned sensors 32 and 34, the receiver 36, and the operator controls, the implement steering controller 30 provides an input signal to a steering control valve 40 which in turn controls the flow of hydraulic fluid to and from a steering cylinder 42 that is operably associated with a steering mechanism 44 that responds to changes in the position of the steering cylinder and, more particularly, a rod (not shown) that is extended or retracted as pressure across the cylinder 42 to turn the wheels 28. It is understood that the steering mechanism 44 could be of any conventional or to-be-developed design. The control system for implement steering control is further illustrated in FIG. 2A. The implement steering controller 30 could be a microprocessor-based electronic control unit. The operator input controls 38 could be a multi-position switch which is wired to the implement steering controller 30. The operator input controls 38 also could be any type of operator interface, such as a touch-screen display, which relays operator inputs to the implement steering controller 30 by means of electronic communication such as CAN bus communication.
In a preferred implementation, the rotary steering sensor 32 is mounted at the pivot axle 46 of the steerable wheels 28. In one preferred embodiment, a single rotary steering sensor 32 is used to measure the angular position of a single pair of inner wheels 28; however, it is understood that two such sensors could be used to measure the angular position of both pairs of inner wheels 28. As referenced above, and further illustrated in FIG. 2A, the rotary sensing sensor 32 provides a feedback signal to the implement steering controller 30, which in turn uses the information embodied in the feedback signal to develop a control signal for the steering control valve 40. It will be appreciated that the steering sensor 32, which may be a rotary position sensor, an inertial sensor, or other type of sensor is capable of providing a direct measurement of the angular position of the pivot axle 46.
The towing angle sensor 34 is preferably mounted to or approximate the hitch point of the implement frame 16 to the tractor 14, and like the rotary position sensor 32 provides a feedback signal to the implement steering controller 30. The signal transmitted by the towing angle sensor 34 is embodied with information containing a direct measurement of the angle of the implement frame 16 to the tractor 14, which is used by the implement steering controller 30 to develop the control signal for the steering control valve 40. It will be appreciated that the towing angle sensor 34 may directly or indirectly measure the angular position of the implement frame 16. Additionally, it will be appreciated that the towing angle sensor 34 may be a rotary position sensor, an inertial sensor, or other type of sensor capable of providing a direct or indirect measurement of the angular displacement of the implement frame 16.
GPS receiver 36 is mounted to the tractor 14 in a known manner and provides a feedback signal to the implement steering controller containing information regarding the position of the tractor 14, which can be used to determine the position of the tractor 14 in a field, along a road, and the like. In one preferred embodiment, the tractor 14 is an auto-guidance tractor using GPS technology as known in the art.
FIG. 3 illustrates another embodiment of the present invention, and the corresponding control system for the implement steering control is shown in FIG. 3A. In this embodiment, a cylinder steering sensor 48 rather than the aforedescribed rotary steering sensor 32 is used to measure the angular position of the inner wheels 28. More particularly, the cylinder steering sensor 48 is either mounted inside or integral with the external surface of the steering cylinder 42 and measures the displacement of the cylinder rod (not shown). The angular position of the wheels 28 can then be computed by the implement steering controller 30 from the measured cylinder rod displacement together with information regarding the operating parameters of the steering mechanism 44. While in one embodiment the cylinder steering sensor 48 is used instead of a rotary position sensor 32, it is contemplated that both sensors could be used to provide two separate measurements regarding the angular position of the inner wheels 28.
FIG. 4 illustrates yet another embodiment of the present invention. The control system for the implement steering control of this embodiment is shown in FIG. 4A. In the embodiment illustrated in FIGS. 4 and 4A, an implement GPS receiver 50 is used to measure the field position of the implement 12 rather than a towing angle sensor. In this regard, the GPS receiver 50, which includes an antenna and GPS receiver circuitry, provides a feedback signal to the implement steering controller 30 regarding the field position of the implement 12 and the controller 30 uses the field position information together with feedback from the rotary steering sensor 32, the tractor GPS receiver 36, and operator input controls to develop a control signal for the steering control valve 40.
FIGS. 5 and 5A illustrate an embodiment similar to FIGS. 4 and 4A, except that the cylinder steering sensor 48, described above as being used to indirectly measure angular displacement of the inner wheels 28, is used rather than the rotary position sensor 32. In this regard, the embodiment illustrated in FIGS. 5 and 5A is a combination of the embodiment of FIGS. 3 and 4.
FIGS. 6 and 6A illustrate another embodiment of the present invention that is suited for use with a prime mover 14 having a steering circuit 52 that auto-steers the prime mover based on steering commands provided thereto by a prime mover navigation controller 54. The navigation controller 54 receives field position information of the tractor 14 from a GPS receiver 36 mounted to the tractor 14 and receives feedback from various implement mounted sensors, such as an implement steering sensor 32, an implement GPS receiver 50, and operator input controls 38. Additionally, the prime mover 14 also has a steering sensor 56 that measures the angular position of at least one wheel 58 of the prime mover 14 and provides corresponding feedback to the navigation controller 54. In this embodiment it will thus be appreciated the navigation controller 54 of the prime mover 14 provides auto-steering commands to the prime mover steering circuit 52 as well as the steering control valve 40.
The invention may also be embodied in a process, executed by a suitable processing equipment of the implement and/or the prime mover. For example, the position of the prime mover and the agricultural implement may be determined using GPS or other technology, such as field position sensors. The position of the implement and the prime mover may then be compared to respective desired positions, such as those of a predefined field course. From the comparison, appropriate course correction signals can be provided to the steering mechanisms of the prime mover and the implement to reduce the deviations between the real-time position of the prime mover and the implement from their respective desired positions.
It is contemplated that the implement may be controlled in various operating modes, such as a transportation steering mode in which implement is auto-steered to generally follow the prime mover, a cornering steering mode in which the implement is auto-steered to turn, such as at the end of a planting row, a swath tracking steering mode in which the implement is auto-steered to track predefined swaths in a field, and a crab steering mode in which the implement is auto-steered based on command signals provided by the steering controller of the prime mover.
Many changes and modifications could be made to the invention without departing from the spirit thereof. The scope of these changes will become apparent from the appended claims.

## Claims

1. An agricultural system comprising:
a prime mover;
an implement coupled to the prime mover and adapted to be towed by the prime mover, the implement having:
a frame supported by a pair of steering wheels between a pair of outer wheels;
a steering sensor generating a wheel orientation feedback signal in response to a measured angular position of at least one of the steering wheels; and
a steering device operative to turn the steering wheels according to a steering control signal;

a hitch point pivotably connecting the implement to the prime mover;
a towing angle sensor mounted to the hitch point, the towing angle sensor generating a prime mover steering angle signal embodied with a direct measurement of an angle between the implement and the prime mover;
a steering control including a microprocessor operatively connected to the steering sensor and the towing angle sensor for receiving the wheel orientation feedback signal and the prime mover steering angle signal,
the steering control is configured to process the wheel orientation feedback signal with respect to the prime mover steering angle signal, compare the wheel orientation feedback signal to a desired steering angle, determine a corrected steering angle, and transmit the corrected steering angle to the steering device in the steering control signal.

2. The system of claim 1 wherein the steering device includes a hydraulically controlled steering cylinder operative to receive hydraulic fluid and a steering control valve operative to control hydraulic fluid flow to the steering cylinder according to the steering control signal.

3. The system of claim 2 wherein the steering cylinder includes a rod that is displaced as a function of pressure across the steering cylinder, and wherein the steering sensor includes a cylinder steering sensor associated with the steering cylinder to measure displacement of the rod.

4. The system of claim 1 wherein the implement frame includes a steering wheel axle to which the pair of steering wheels are mounted, and wherein the steering sensor includes a rotary steering sensor mounted to measure the angular position of the wheels.

5. The system of claim 1 further comprising a first GPS device carried by the prime mover and a second GPS device carried by the implement, wherein each GPS receiver provides respective positioning signals to the steering control, and wherein the steering control processes the positioning signals to determine any variance between actual positions of the prime mover and the implement and desired positions for the prime mover and the implement and uses the variance as a factor in determining the corrected steering angle.

6. The system of claim 1 wherein the steering sensor is one of a rotary position sensor, a linear position sensor, and an inertial sensor.

7. The system of claim 1 wherein the steering control includes programming that when executed causes the steering control to control movement of the implement in at least one of a forward direction and a reverse direction according to one of a plurality of operating modes, wherein the plurality of operating modes include:
a transportation steering mode wherein the steering control provides control signals to the steering device to cause the steering device to turn the steering wheels so as to follow the prime mover;
a cornering steering mode wherein the steering control provides control signals to the steering device to cause the steering device to turn the steering wheels in a cornering maneuver at a predefined field position;
a swath tracking steering mode wherein the steering control provides control signals to the steering device to cause the steering device to turn the steering wheels so as to track predetermined swaths in a farm field; and
a crab steering mode wherein the steering control provides control signals to the steering device based on steering command signals received from a steering controller of the prime mover.

8. The system of claim 1 further comprising an operator input control for providing manual control signals to the steering control.

9. The system of claim 1 wherein the prime mover is a tractor and the implement is a planter.

10. An agricultural system comprising:
a prime mover having an auto-steering device;
a steerable implement including a frame adapted to be hitched to the prime mover, the implement further having an axle supporting a pair of steering wheels between a pair of outer wheels and a steering device operative to steer the steering wheels;
a first steering sensor that measures angular position of the steering wheels relative to their respective pivot axes and a second steering sensor that measures angular position of at least one wheel of the prime mover relative to its pivot axis;
a hitch point pivotably connecting the implement to the prime mover;
a towing angle sensor mounted to the hitch point, the towing angle sensor generating a prime mover steering angle signal embodied with a direct measurement of an angle between the implement and the prime mover; and
a navigation controller including a microprocessor operatively connected to the first steering sensor, the second steering sensor and the towing angle sensor for receiving the measurements of the first and second steering sensors and the prime mover steering angle signal, the navigation controller being configured to provide command signals to the auto-steering device to steer the prime mover and to provide command signals to the steering device of the steerable implement for steering the steerable implement
in response to the prime mover steering angle and the measurements from the first and second steering sensors.

11. The system of claim 10 wherein the navigation controller is further operative to provide control signals to the steering device to steer the steerable wheels selectively according to one of a plurality of operating modes, wherein the operating modes include:
a transportation steering mode wherein the navigation controller provides control signals to the steering device to cause the steering device to turn the steering wheels so as to follow the prime mover;
a cornering steering mode wherein the navigation controller provides control signals to the steering device to cause the steering device to turn the steering wheels in a cornering maneuver at a predefined field position; and
a swath tracking steering mode wherein the navigation controller provides control signals to the steering device to cause the steering device to turn the steering wheels so as to track predetermined swaths in a field.

12. The system of claim 11 wherein the steering device for the implement includes a hydraulically controlled steering cylinder operative to receive hydraulic fluid and a steering control valve operative to control hydraulic fluid flow to the steering cylinder according to the steering control signal.

13. The system of claim 12 wherein the steering cylinder includes a rod that is displaced as a function of pressure across the steering cylinder, and wherein the steering sensor includes a cylinder steering sensor associated with the steering cylinder to measure displacement of the rod.

14. The system of claim 10 wherein the implement frame includes a steering wheel axle to which the pair of steering wheels are mounted, and wherein the first steering sensor includes a rotary steering sensor mounted to measure the angular position of the steering wheels.

15. The system of claim 10 wherein the prime mover has a GPS receiver that provides a prime mover field position feedback signal to the navigation controller.

16. The system of claim 15 wherein the implement has a GPS receiver that provides an implement field position feedback signal to the navigation controller.

17. A method of planting a field, comprising:
pivotably connecting the implement to the prime mover with a hitch point;
mounting a towing angle sensor to the hitch point;
determining a position of the prime mover and the agricultural implement being towed by the prime mover, the agricultural implement including a pair of steering wheels between a pair of outer wheels;
generating a prime mover steering angle signal embodied with a direct measurement of an angle between the implement and the prime mover by the towing angle sensor;
generating a wheel orientation feedback signal embodied with a direct measurement of an angular position of at least one of the steering wheels;
comparing the position of the prime mover to a desired prime mover position;
comparing the position of the agricultural implement to a desired implement position;
providing a course correction signal to a steering mechanism for the prime mover to reduce a deviation of the position of the prime mover from the desired prime mover position;
providing a course correction signal to a steering mechanism for the agricultural implement to reduce a deviation of the position of the agricultural implement from the desired implement position, the course correction signal dependent on the prime mover steering angle and the wheel orientation feedback signal; and

wherein:
the course correction signals are provided by an on-board navigation controller of the prime mover; and
the course correction signal to the agricultural implement causes the steering mechanism for the agricultural implement to steer the steering wheels such that the agricultural implement travels along a path that is parallel to and offset from a path of the prime mover.

18. The method of claim 17 further comprising operating the agricultural implement in one of a number of operating modes, wherein the operating modes includes:
a transportation steering mode;
a cornering steering mode;
a swath tracking steering mode; and
a crab steering mode.