Patent Description:
Crop yields are affected by a variety of factors, such as seed placement, soil quality, weather, irrigation, and nutrient applications. Soil compaction affects how seeds are placed, as well as how water and fertilizer permeates the soil. Thus, tests have been developed to measure soil compaction in agricultural fields. As used herein, the term "soil compaction" is a measure of the volume of solid material within a given volume of soil as compared to the volume of liquid or gases (e.g., in pores between particles of solid material). Soil compaction is proportional to soil density of dry soil. Information about soil compaction is valuable because it assists farmers with determining how deep to plant seeds, how much water and fertilizer to apply, etc. Furthermore, soil compaction is related to the force required to break through soil so that seeds can be planted below the surface. Crop yield can also be affected by soil compaction. Significant changes in soil compaction or soil density in the soil profile of the root zone of a plant can adversely affect crop yield. For example, a large change in soil compaction may cause roots to change direction when they reach the soil with high compaction. Soil compaction typically varies throughout a field and with depth beneath the surface. A no-till field could have a higher soil density or soil compaction compared to tilled field, all other variables being equal, but the density and compaction of the no-till field could still be within acceptable ranges. Therefore, the no-till field may still produce similar or better crop yield than the tilled field if rapid and significant soil density changes are minimized. Information about the density and compaction can help farmers make decisions about whether tilling is required or if tillage depth should increase or decrease.

Methods of measuring soil compaction are described in <CIT>.

<NPL>, discloses a soil compaction profile sensor (SCPS) using five customized octagonal ring load-sensing units instrumented with four strain gauges each for force sensing.

The present invention provides an apparatus according to claim <NUM> and a method according to claim <NUM>. Further aspects of the invention are defined in the dependent claims.

In some embodiments, an apparatus for measuring a soil condition includes a shank configured to engage with a drawbar, an array of movable pads carried by the shank, and a plurality of sensors. Each of the movable pads are spaced at different distances from a point at which the shank is configured to engage the drawbar. Each sensor is coupled to at least one movable pad of the array of movable pads and configured to measure deflection of the at least one movable pad relative to the shank as the shank is dragged through soil by the drawbar.

A method of measuring a property of soil includes dragging a shank through soil. A lateral surface of the shank carries an array of movable pads, and each of the movable pads are spaced at different distances from a drawbar engaging the shank. Deflection of the movable pads is measured relative to the shank as the shank is dragged through soil using a plurality of sensors coupled to the movable pads.

While the specification concludes with claims particularly pointing out and distinctly claiming what are regarded as embodiments of the present disclosure, various features and advantages of embodiments of the disclosure may be more readily ascertained from the following description of example embodiments when read in conjunction with the accompanying drawings, in which:.

The illustrations presented herein are not actual views of any machine, sensor, or portion thereof, but are merely idealized representations that are employed to describe example embodiments of the present disclosure. Additionally, elements common between figures may retain the same numerical designation.

The drawings accompanying the application are for illustrative purposes only, and are thus not drawn to scale.

<FIG> is a simplified top view illustrating a tractor <NUM> drawing an agricultural implement <NUM>, e.g., a tillage implement, comprising a drawbar <NUM> supporting tilling assemblies <NUM> or other tools. An implement monitor <NUM>, which may include a central processing unit ("CPU"), memory, and graphical user interface ("GUI") (e.g., a touch-screen interface), is typically located in the cab of the tractor <NUM>, but may be located elsewhere. A global positioning system ("GPS") receiver <NUM> may be mounted to the tractor <NUM> and connected to communicate with the monitor <NUM>.

The tractor <NUM> or the implement <NUM> may carry one or more apparatus <NUM> for measuring soil conditions. For example, the apparatus <NUM> may be coupled to the drawbar <NUM>. In some embodiments, the apparatus <NUM> may be coupled directly to a hitch of the tractor <NUM>, or to another part of the implement <NUM>. In <FIG>, the implement <NUM> is shown carrying four of the apparatus <NUM>, but may carry any number of the apparatus <NUM> (e.g., one, two, three, etc.).

<FIG> is a simplified perspective view of the apparatus <NUM>, which includes a shank <NUM> configured to engage with the drawbar <NUM> (<FIG>). For example, the shank <NUM> may include mounting holes <NUM> for bolts or other fasteners to connect to the drawbar <NUM>. The mounting holes <NUM> may optionally be used to connect to any other selected tool, or to another mount point. For example, the shank <NUM> may be mounted to a set of parallel arms and a gauge wheel to set the depth of the shank <NUM> in the soil. The shank <NUM> may have generally parallel lateral surfaces <NUM> and tapered leading surfaces <NUM> (only one of each surface <NUM>, <NUM> is depicted in <FIG>). In use, the shank <NUM> may typically travel through the soil in a travel direction T parallel to the lateral surfaces <NUM>.

The shank <NUM> may carry an array of movable pads <NUM> on one or both lateral surfaces <NUM>. Each of the movable pads <NUM> may be spaced along the shank <NUM> at different distances from the end of the shank <NUM> or from the engagement point of the shank <NUM> with the drawbar. If the shank <NUM> has movable pads <NUM> on both lateral surfaces <NUM>, the movable pads <NUM> on one side may be offset from the movable pads <NUM> on the opposite side of the shank <NUM> so that each movable pad <NUM> is a different distance from the end of the shank <NUM>, which distances correspond to different depths in the soil. The shank <NUM> may also carry a strain gauge <NUM> or load cell configured to measure a total draft force acting on the shank <NUM>. Though depicted on one lateral surface <NUM>, the strain gauge <NUM> may be located anywhere on the apparatus <NUM>.

<FIG> is a simplified cross-sectional view of the shank <NUM> along line <NUM>-<NUM> of <FIG>, and which shows movable pads <NUM> spaced on both sides of the shank <NUM>. For example, if the movable pads <NUM> are spaced one inch (<NUM>) apart from one another on each lateral surface <NUM> of the shank <NUM>, the vertical distance between adjacent movable pads <NUM> on opposite lateral surfaces <NUM> may be one-half inch (<NUM>). The movable pads <NUM> may be formed of a hard, wear-resistant material, such as a polymer, a metal, a composite, etc..

The shank <NUM> may also carry a plurality of sensors <NUM>, each coupled to one of the movable pads <NUM>, and configured to detect the deflection of the movable pads <NUM>. Typically, the sensors <NUM> may be located behind the movable pads <NUM>, such that the movable pads <NUM> protect the sensors <NUM> from contact with dirt and debris. Each sensor <NUM> may be configured to generate a signal corresponding to the deflection of a respective movable pad <NUM>. The sensors <NUM> may be load cells, strain gauges, pressure sensors, or any other selected sensors.

<FIG> is a simplified bottom view of the shank <NUM>, and depicts the movable pads <NUM> extending outward past the lateral surfaces <NUM> thereof. The movable pads <NUM> may have curved or tapered front surfaces to enable the shank <NUM> to travel through the soil without binding the movable pads <NUM> on the soil. <FIG> is a simplified perspective view of a portion of the shank <NUM> with one of the movable pads <NUM> removed. As shown, elastic pads <NUM> may be disposed within pockets <NUM> in the shank <NUM>. The elastic pads <NUM> may enable the movable pads <NUM> and the sensors <NUM> to move within the pockets <NUM>. The elastic pads <NUM> may optionally transfer loads from the soil to the sensors <NUM>. In other embodiments, the elastic pads <NUM> may simply allow movement of the movable pads <NUM>, and another mechanism may transfer loads to the elastic pads <NUM>. The movable pads <NUM> may be retained in the pockets <NUM> by flange bolts <NUM> (<FIG>) or other fasteners.

<FIG> is a simplified side cross section of the shank <NUM> showing one movable pad <NUM>, one sensor <NUM>, and two elastic pads <NUM> within a pocket <NUM> of the shank <NUM>. The movable pads <NUM> may be slidingly coupled to the shank <NUM> with the flange bolts <NUM> to enable the movable pads <NUM> to move inward and outward relative to the lateral surface <NUM>. Seals <NUM> may be disposed between the movable pads <NUM> and the shank <NUM> to keep dirt and debris out of the space between the movable pads <NUM> and the shank <NUM>. For example, the seals <NUM> may include an O-ring, a gasket, or another seal. The seals <NUM> may be formed of an elastomeric material (e.g., natural or synthetic rubber), a hard polymer, etc. The movable pad <NUM> may directly contact the sensor <NUM>, such that a force applied by the soil to the movable pad <NUM> may be transferred to the sensor <NUM>. The elastic pads <NUM> may urge the movable pad <NUM> outward when the force of the soil decreases (e.g., when the shank <NUM> is removed from the soil, or when softer soil is encountered).

<FIG> is a simplified side cross section of a portion of the shank <NUM> illustrating another way the movable pad <NUM> may be coupled to the sensor <NUM>. In particular, the movable pad <NUM> may press directly on the elastic pads <NUM>. This force deforms the elastic pads <NUM>, which therefore apply a force on the sensor <NUM>. That is, the movable pad <NUM> may apply a compressive strain to the elastic pads <NUM>, and the elastic pads <NUM> exert a stress in response, which stress pushes on the sensor <NUM>.

<FIG> is a simplified side cross section illustrating another way the movable pad <NUM> may be coupled to the sensor <NUM>. The movable pad <NUM> may pivot about a hinged joint <NUM>, and one end of the movable pad <NUM> may press on an elastic pad <NUM> (as shown in <FIG>) or directly on the sensor <NUM> (e.g., as shown in <FIG>).

<FIG> illustrates an embodiment in which a movable pad <NUM> is coupled to a base plate <NUM> by a seal <NUM>. The base plate <NUM> may have mounting holes <NUM> to enable each base plate <NUM> to be individually secured to the shank <NUM> (and thus, individually replaced, in the event one movable pad <NUM> becomes damaged).

<FIG> illustrates a view of the opposite side of the base plate <NUM> and the movable pad <NUM>. The seal <NUM> may be bonded to the movable pad <NUM> and/or the base plate <NUM> to provide structure and a fluid-tight seal. The seal <NUM> may flex enough to enable the movable pad <NUM> to move freely inward and outward, yet may still prevent soil from entering between the base plate <NUM> and the movable pad <NUM>. The movable pad <NUM> may a void <NUM> shaped to receive the sensor <NUM> (see, e.g., <FIG>). The movable pad <NUM> may also define one or more holes <NUM> shaped to receive alignment pins protruding from the shank <NUM>, which may enable the movable pad <NUM> to move inward toward and outward from the shank <NUM>, while preventing fore-and-aft, vertical, and twisting movement. Thus, the holes <NUM> and alignment pins may help isolate movement other than movement inward and outward.

The implement monitor <NUM> of the tractor <NUM> (<FIG>) may include a receiver (e.g., wired or wireless) configured to receive signals from the sensors <NUM>. The implement monitor <NUM> may calculate a property of the soil, such as soil hardness. The implement monitor <NUM> may also include a transmitter configured to transmit the property of the soil, such as to a controller, another vehicle, a network (e.g., the internet), etc..

<FIG> is a simplified cross-sectional view of the shank <NUM> traveling through soil. A portion of the shank <NUM> is below a surface <NUM> of the soil, including at least some of the movable pads <NUM>. The sensors <NUM> (<FIG>) measure deflection of the movable pads <NUM> and calculate forces on the movable pads <NUM>. Because the movable pads <NUM> are arranged in an array with known locations, the implement monitor <NUM> (<FIG>) may correlate the force on the movable pads <NUM> to a depth in the soil, visualized in the graph <NUM> shown in <FIG>. The soil density generally increases with depth, and a point <NUM> at which the slope of the graph <NUM> changes may identify a depth of a compaction layer <NUM> or hard pan. Identification of the compaction layer <NUM> may enable a farmer to change tillage, seeding, fertilizing, watering, or other parameters, at the time of the measurement or at any later time. For example, the implement monitor <NUM> may generate a map of a field with depth of the compaction layer <NUM>, which may be used to identify portions of the field for additional tilling, different seed populations, different seed depths, etc..

<FIG> is a simplified perspective view of another apparatus <NUM>, which includes a shank <NUM> configured to engage with the drawbar <NUM> (<FIG>) via mounting holes <NUM>. The mounting holes <NUM> may optionally be used to connect to any other selected tool, or to another mount point. The shank <NUM> may have generally parallel lateral surfaces <NUM> and tapered leading surfaces <NUM> (only one of each surface <NUM>, <NUM> is depicted in <FIG>).

The shank <NUM> may carry an array of movable pads <NUM> along the rear of the shank <NUM>, rearward of the lateral surfaces <NUM>. The shank <NUM> may also carry a strain gauge <NUM> or load cell configured to measure a total draft force acting on the shank <NUM>.

<FIG> is a simplified cross-sectional view of the shank <NUM> along line <NUM>-<NUM> of <FIG>, and which shows that the movable pad <NUM> along the rear of the shank <NUM> may be flared outward past the lateral surfaces <NUM>, such as in a generally trapezoidal shape. The movable pads <NUM> in this embodiment may measure draft forces (i.e., the force required to drag the movable pads <NUM> through the soil), rather than compressive forces, which may be measured by the apparatus <NUM> shown in <FIG>. As soil density increases, draft force also increases. The angle and length of the surfaces of the movable pads <NUM> may affect the draft force applied to the movable pads <NUM>. The movable pads <NUM> may be connected to the shank <NUM> by a load cell <NUM>, which is in tension when the shank <NUM> is dragged through soil.

<FIG> is a simplified flow chart illustrating a method <NUM> of measuring a property of soil. Block <NUM> represents dragging a shank through soil, such as the shank <NUM> shown and described above. Block <NUM> represents measuring deflection of movable pads relative to the shank as the shank is dragged through the soil using sensors coupled to the movable pads. In block <NUM>, signals related to the deflection of the movable pads are generated with the sensors. In block <NUM>, the draft force on each movable pad is calculated. Alternatively, a compressive force on each movable pad may be calculated. In block <NUM>, the sum of the draft forces on each movable pad is compared to the total draft force on the shank. This may be used to calibrate the apparatus or verify proper operation of the apparatus. In block <NUM>, soil compaction is calculated as a function of depth in the soil. In block <NUM>, a depth of a compaction layer of the soil is calculated.

Claim 1:
An apparatus (<NUM>) for measuring a soil condition, the apparatus (<NUM>) comprising:
a shank (<NUM>) configured to engage with a drawbar (<NUM>);
an array of movable pads (<NUM>) carried by the shank (<NUM>), each of the movable pads (<NUM>) spaced at different distances from a point at which the shank (<NUM>) is configured to engage the drawbar (<NUM>); and
a plurality of sensors (<NUM>), each sensor coupled to at least one movable pad of the array of movable pads (<NUM>) and configured to measure deflection of the at least one movable pad relative to the shank (<NUM>) as the shank (<NUM>) is dragged through soil by the drawbar (<NUM>);
characterized in that
the movable pads (<NUM>) of the array are disposed on or over a lateral surface of the shank (<NUM>).