Patent Description:
As is described in <CIT>(the '<NUM> Patent), the height of a header of a combine harvester is capable of being adjusted.

Header height is typically adjusted depending upon the type of crop being harvested by the combine. The header height is also adjusted to conform to the changing contours of the ground. More particularly, combines typically include ground contact sensors to detect the distance between the header or cutter bar and the ground. The height of the header is adjusted based upon the input of the ground contact sensors. The header height (e.g., the distance from the cutterbar to the ground - see 'H' in <FIG>) can also be adjusted by changing the pitch of the header. More particularly, the pitch of the header can be adjusted by rotating the header in the fore-aft direction (i.e., about the longitudinal axis of the header and cutter bar).

It has been discovered that changing the pitch of the header produces a lower reaction force on the combine than does changing the height of the header. This occurs because the inertia of the fore-aft tilt degree of freedom is lower than the inertia of the height adjustment degree of freedom. Accordingly, the operator of the combine will physically feel adjustments to the height of the header to a greater degree than adjustments to the pitch of the header. Stated differently, adjustments to the pitch of the header result in a smoother ride than do adjustments to the height of the header.

Additionally, in most combines, changing the pitch of the header is a relatively speedy operation as compared with changing the height of the header.

In view of the foregoing, as a combine traverses uneven ground (e.g., terrace, hill or steep surface) it would be desirable to automatically adjust the height and/or pitch of a header in the interest of enhancing ride quality.

<CIT> describes an agricultural vehicle comprising a chassis, a header carried by the chassis, an actuator system including a plurality of actuators linked to a frame of the header and configured to adjust an orientation of the header, a GPS device configured to output a GPS position of the vehicle, and a controller.

According to the invention, a method of controlling a position of a header for a combine harvester according to claim <NUM> is provided.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates an embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention which is defined by the appended claims.

For convenience of reference and understanding in the following discussions, and with respect to the various drawings and their descriptions, the point of reference for the use of various terms that are hereafter employed, including "left", "right", "forward", "rearward", "front", "back", "top", and "bottom", should generally be considered to be taken from a point at the rear of the combine harvester machine facing in its normal direction of travel, unless it is clear from the discussion and context that a different point of reference is appropriate. Any use of such terms should therefore be considered exemplary and should not be construed as limiting or introducing limitations.

Moreover, inasmuch as various components and features of harvesters are of well-known design, construction, and operation to those skilled in the art, the details of such components and their operations will not generally be discussed in significant detail unless considered of pertinence to the present invention or desirable for purposes of better understanding.

In the drawings, like numerals refer to like items, certain elements and features may be labeled or marked on a representative basis without each like element or feature necessarily being individually shown, labeled, or marked, and certain elements are labeled and marked in only some, but not all, of the drawing figures.

Turning now to the drawings, wherein a preferred embodiment of the invention is shown, in <FIG> a front end of an agricultural combine <NUM> is shown including a conventional header <NUM> supported on a feeder <NUM>, for cutting or severing crops, and inducting the severed crops into feeder <NUM> for conveyance into combine <NUM> for threshing and cleaning as the combine <NUM> moves forwardly over a field. Header <NUM> includes a bottom or pan <NUM> which is supported in desired proximity to the ground surface of the field during the harvesting operation. An elongate, sidewardly extending cutter bar <NUM> supporting elongate, reciprocally movable sickle knives <NUM> (for example) is disposed along a forward edge of pan <NUM>. The cutter bar <NUM> severs the crop for induction into the header <NUM> for threshing by a rotor and concave (not shown, but described in <CIT>). An elongate, sidewardly extending reel <NUM> is disposed above pan <NUM> and is rotatable in a direction for facilitating induction of the severed crops into header <NUM>. An elongate, rotatable auger <NUM> extends in close proximity to a top surface of pan <NUM> and has spiral flights therearound (not shown) which convey the severed crops to feeder <NUM> for induction into combine <NUM>. The front wheels <NUM> (or tracks) of the combine <NUM> are shown in <FIG>.

Combine <NUM> includes a ground speed sensor <NUM> for sensing the ground speed of the combine <NUM> during operation. The ground speed sensor <NUM> may be a speedometer, GPS, or other speed sensing device of the combine <NUM>, as is known in the art.

Header <NUM> includes a ground height sensor <NUM> constructed and operable according to teachings of the present invention, for sensing or contacting the ground surface <NUM> of a field residing directly beneath the header <NUM>. The ground height sensor <NUM> is positioned either at or behind cutter bar <NUM>. The ground height sensor <NUM> is configured to provide information relating to (i) the contour of the ground <NUM> directly beneath the header, (ii) contact with the ground, and/or (iii) the height 'H' of the cutter bar <NUM> (or another point on the header <NUM>) with respect to the ground <NUM> at the current position of header <NUM>, for example. Ground height sensor <NUM> transmits that information to one or more controllers <NUM>. Ground height sensor <NUM> does not necessarily have to contact the ground, and, may be a non-contact sensor that may utilize LIDAR, RADAR, or SONAR, and/or ground sensor <NUM> may be ultrasonic sensor or camera. Further details of the ground sensor <NUM> are provided in the '<NUM> Patent.

A hydraulic motor <NUM> raises and lowers the feeder <NUM> via hydraulic pistons <NUM> (otherwise referred to as lift cylinders) in a vertical direction <NUM>, as is known in the art. Header <NUM>, which is connected to feeder <NUM>, moves along with feeder <NUM>. Alternatively, motor <NUM> could raise or lower the header <NUM> independently of the feeder <NUM>. It is noted that the vertical motion does not necessarily have to be absolutely vertical. For example, the vertical motion may follow an arc trajectory.

A hydraulic motor <NUM> is configured to adjust the pitch of the header <NUM>, i.e., rotate the header <NUM> in the fore-aft direction and about the longitudinal axis of header <NUM>. See the double head arrows <NUM> in <FIG> indicating pitch adjustment of header <NUM>.

An inclination sensor <NUM> (e.g., an inclinometer) is disposed on the combine. Alternatively, sensor <NUM> could be disposed on the housing of header <NUM>. Inclination sensor <NUM> senses the level of incline of the combine itself or the header <NUM> relative to the Earth's gravity. Inclinometers, also called tilt sensors, clinometers or slope sensors, are designed to measure the angle of an object (e.g., the combine or header) with respect to the force of gravity. The inclinometer determines the pitch and/or roll angle and outputs these values via an electrical interface. According to this embodiment, the inclination sensor <NUM> senses the pitch of the combine (or header), however, inclination sensor <NUM> could also sense the roll of the combine (or header).

Combine <NUM> also includes a controller <NUM> configured to receive signals from the above-described sensors for controlling the above-described motors. Further details concerning controller <NUM> will be described with reference to <FIG>.

<FIG> is a schematic block diagram of a header positioning system <NUM> for controlling the header position of the combine <NUM>. In the combine <NUM>, the header positioning system <NUM> comprises the controller <NUM>, that receives signals from the sensors <NUM>, <NUM> and <NUM>, and transmits instructions to actuate the motors <NUM> and <NUM> to raise, lower and/or adjust the pitch of the header <NUM> based upon the signals from the sensors <NUM>, <NUM> and <NUM>, as will be described in greater detail with reference to <FIG>. The controller <NUM> performs other function related to the operation of combine <NUM>, and accordingly may be associated with other systems of the combine <NUM>. The controller <NUM> includes a sub-controller <NUM> that is specifically responsible for changing the position (raise/lower/pitch movement) of the header <NUM> in an automatic mode. Sub-controller <NUM> may be either separate from or integrated with controller <NUM>. Alternatively, controller <NUM> may perform the functionality of sub-controller <NUM>, and sub-controller <NUM> may be omitted.

<FIG> depicts a method <NUM> for controlling a position of the header <NUM> of the combine <NUM>. At step <NUM>, the target ground height is input to the controller <NUM>. The target ground height may be either a value that is input by a user or a value that is automatically calculated by the combine. At step <NUM>, the current ground height, as measured by ground height sensors <NUM>, is also input to controller <NUM>. At step <NUM>, the controller <NUM> compares the measured ground height against the target ground height, and transmits the difference, in the form of an error signal, to the sub-controller <NUM>. At steps <NUM> and <NUM>, the output signals from ground-speed sensors <NUM> and inclination sensor <NUM>, respectively, are input to the sub-controller <NUM>.

At step <NUM>, sub-controller <NUM> performs a routine for controlling the height and pitch positions of the header <NUM> based upon the data received from steps <NUM>, <NUM> and <NUM>. The details in connection with the routine at step <NUM> will be described later. Based upon the output of the routine at step <NUM>, at step <NUM>, the sub-controller <NUM> transmits a first scaled error signal to motor <NUM> for adjusting the header height 'H. ' And, based upon the output of the routine at step <NUM>, at step <NUM>, the sub-controller <NUM> transmits a second scaled error signal to motor <NUM> for adjusting the header pitch. At step <NUM>, upon receiving the respective signal(s), motor <NUM> either raises or lowers the header <NUM>, and/or, motor <NUM> pivots the header <NUM>, as dictated by the first and second scaled error signals. The header <NUM> ultimately reaches the target ground height at step <NUM> either in one step or incrementally as part of a PID loop, for example. This method <NUM> is repeated as the ground height changes and/or the target ground height changes. In particular, at step <NUM>, the most current ground height, as measured by ground height sensors <NUM>, is input to controller <NUM>, as was described above, and the above-described process <NUM> is repeated. Reference numeral <NUM> represents a closed control loop.

Turning now to the details of step <NUM>, using the outputs at steps <NUM>, <NUM> and <NUM> as an input, controller <NUM> is configured to convert the error signal at step <NUM> into two scaled error signals and transmit those scaled error signals to the motors <NUM> and <NUM>, respectively, for adjusting the position of the header <NUM> by raising/lowering the header and/or pitching the header.

The scaling process is described hereinafter. Using the inclination sensor output (I) at step <NUM>, the sub-controller <NUM> calculates the derivative of inclination (dI/dt). For purposes of calculating the derivative, time can be supplied from a clock associated with controller <NUM>. The sub-controller <NUM> also receives the ground speed (dx/dt) at step <NUM>. Sub-controller <NUM> then calculates the quotient of the derivative of inclination (dI/dt) and the ground speed (dx/dt) to arrive at the quotient dI/dx. Quotient dI/dx is a measure of the change of inclination with respect to distance travelled.

The value of quotient dI/dx may be (i) at or near zero, (ii) a positive value, or (iii) a negative value. A zero value indicates that the inclination of the combine is not changing to a notable degree over a distance travelled. A positive value indicates that the combine is entering an upwardly sloped region in the direction of travel (e.g., terrace). A negative value indicates that the combine is entering a downwardly sloping region in the direction of travel.

As noted above, using the outputs at steps <NUM>, <NUM> and <NUM> as an input, controller <NUM> is configured to convert the error signal at step <NUM> into two scaled error signals, namely, 'pitch control scaled error signal' and 'height control scaled error signal. ' Controller <NUM> transmits 'pitch control scaled error signal' and 'height control scaled error signal' to the motors <NUM> and <NUM> at steps <NUM> and <NUM>, respectively, for adjusting the position of the header <NUM>.

The two scaled error signals could be computed by controller <NUM> in accordance with a look-up table stored in the memory of controller <NUM>, or as a function of an algorithm. An exemplary lookup table is shown below.

In the look-up table, the ground speed and indication derivatives are input calculated values. Calculated dI/dx is an input calculated value based upon the ground speed and the inclination derivative inputs. Once dI/dx is calculated, that value is assigned to the closest Factory Set dI/dx value (as shown in the table). The pitch and height control scaling factors, which are both factory set values, are assigned based upon the assigned Factory Set dI/dx value.

Also, it should be understood in viewing the Table that the 'pitch control scaled error signal' is the product of the 'pitch control scaling factor' and the 'height error signal'; and, the 'height control scaled signal' is the product of the 'height control scaling factor' and the 'height error signal. ' The sum of the pitch and height control scaling factors is equal to <NUM>%. The height error signal is set to a value of <NUM> in each row for the purpose of simplicity, however, the error signal can vary based upon step <NUM>. It is also noted that the sum of the 'pitch control scaled error signal' and the 'height error scaled error signal' equal the 'error signal.

In Example <NUM> in the Table, the combine is not encountering a change in inclination over a travelled distance. According to the Table, the position of the header <NUM> is adjusted using (only) pitch adjustment. The pitch control scaled error signal is '<NUM>' and the height control scaled error signal is '<NUM>. ' Thus, the pitch control scaled error signal transmitted at step <NUM> results in pitching of the header. And, the height control scaled error signal transmitted at step <NUM> does not result in raising or lowering of the header. As noted above, adjustments to the pitch of the header result in a smoother ride as compared with raising the header using the motor <NUM> at step <NUM>.

In Examples <NUM> and <NUM> in the Table, the combine is entering an upwardly sloped region. Upon entering the upwardly sloped region, there is a minimal risk of undesirably lodging the knives of the header into the ground. For that reason, the position of the header <NUM> is adjusted using (primarily) pitch adjustment by scaling the 'error signal' accordingly. According to Example <NUM> of the Table, the position of the header <NUM> is adjusted using pitch and raise/lower adjustment, with pitching of the header at step <NUM> being weighted more heavily than raising/lowering of the header at step <NUM>. The pitch control scaled error signal is '<NUM>' and the height control scaled error signal is '<NUM>. ' Thus, the ground height position at step <NUM> is reached to a greater degree by pitching of the header at step <NUM> than by raising/lowering of the header at step <NUM>. Specifically, the pitch of the header <NUM> is changed such that knives <NUM> move further from the ground. It is noted that changing the pitch of the header <NUM> moves header <NUM> closer toward a "protection position" in which the sharp ends of the knives <NUM> are rotated away from the ground.

In Example <NUM> in the Table, the combine is nearing the top of the sloped region, as evidenced by the comparatively large value of dI/dx. At that point, the ground height sensors <NUM> detect a large distance between the ground and the header. To compensate for the large distance, the position of the header <NUM> is adjusted downward toward the ground using height adjustment by scaling the 'error signal' accordingly. But, because there is also a risk of undesirably lodging the knives of the header into the ground while the combine is travelling along an upward slope, the header is pitched away from the ground by scaling the 'error signal' accordingly.

In Examples <NUM> and <NUM> in the Table, the combine is entering an downwardly sloped region. In contrast to travelling uphill, there is a higher risk of undesirably lodging the knives of the header into the ground once the downwardly sloped region shifts to a flat region or an upwardly sloped region. For that reason, once the combine enters a downwardly sloping region, the position of the header <NUM> is adjusted using (primarily) height adjustment by scaling the 'error signal' accordingly. According to Example <NUM> of the Table, the position of the header <NUM> is adjusted using pitch and raise/lower adjustment, with raising/lowering of the header at step <NUM> being weighted more heavily than pitching of the header at step <NUM>. The pitch control scaled error signal is '<NUM>' and the height control scaled error signal is '<NUM>. ' Thus, the ground height position at step <NUM> is reached to a greater degree by raising/lowering of the header at step <NUM> than by pitching of the header at step <NUM>. It is also noted that at step <NUM>, the header <NUM> is pitched to the "protection position" in which the knives are rotated away from the ground.

Although some of the above steps were carried out by controller <NUM> and other steps were carried out by sub-controller <NUM>, it should be understood that either one of those controllers could perform all of the above-described steps, if so desired. Also, the method <NUM> is not limited to any step or sequence of steps.

It is to be understood that the above-described operating steps are performed by the controller <NUM>/<NUM> upon loading and executing software code or instructions which are tangibly stored on a tangible computer readable medium, such as on a magnetic medium, e.g., a computer hard drive, an optical medium, e.g., an optical disc, solid-state memory, e.g., flash memory, or other storage media known in the art. Thus, any of the functionality performed by the controller <NUM>/<NUM> described herein, such as the aforementioned method of operation, is implemented in software code or instructions which are tangibly stored on the tangible computer readable medium. Upon loading and executing such software code or instructions by the controller, the controller may perform any of the functionality of the controller described herein, including any steps of the aforementioned method described herein.

Claim 1:
A method of controlling a position of a header (<NUM>) for a combine harvester (<NUM>), said method comprising:
measuring an inclination of either the header (<NUM>) or the combine;
measuring a height of the header (<NUM>) with respect to ground;
measuring a ground speed of the header (<NUM>) or the combine;
adjusting both a vertical height and a pitch of the header (<NUM>) as a function of the measured inclination, the measured ground speed and the measured height; and
generating a ground height error signal as a function of the measured height and a
predefined target height value for the header (<NUM>);
characterized in that the method further comprises generating a pitch control scaled error signal for adjusting the pitch of the header
as a function of the ground height error signal, the measured ground speed and the measured inclination, wherein the pitch control scaled error signal is the product of the ground height error signal and a pitch control scaling factor, and wherein the pitch control scaling factor is a factory set value that is assigned based upon the measured ground speed and the measured inclination.