Patent Publication Number: US-2021185919-A1

Title: Calibration System for an Agricultural Header

Description:
BACKGROUND 
     The present disclosure relates generally to a calibration system for an agricultural header. 
     A harvester may be used to harvest crops, such as barley, beans, beets, carrots, corn, cotton, flax, oats, potatoes, rye, soybeans, wheat, or other plant crops. During operation of the harvester, the harvesting process may begin by removing a portion of a plant from a field using a header of the harvester. The header may cut the plant and transport the cut crops to a processing system of the harvester. 
     Certain headers include a cutter bar assembly configured to cut a portion of each crop (e.g., a stalk), thereby separating the cut crop from the soil. The cutter bar assembly may extend along a substantial portion of the width of the header at a forward end of the header. The header may also include one or more belts positioned behind the cutter bar assembly relative to the direction of travel of the harvester. The belt(s) are configured to transport the cut crops to an inlet of the processing system. 
     Certain headers may also include a reel assembly, which may include a reel having multiple fingers extending from a central framework. The central framework is driven to rotate, such that the fingers move in a circular pattern. The fingers are configured to engage the crops, thereby preparing the crops to be cut by the cutter bar assembly and/or urging the cut crops to move toward the belt(s). The reel is typically supported by multiple arms extending from a frame of the header. The reel assembly may include one or more actuators configured to drive the arms to rotate, thereby adjusting the position of the reel relative to the frame of the header. 
     BRIEF DESCRIPTION 
     In one embodiment, a calibration system for an agricultural header includes a controller having a memory and a processor. The processor is configured to receive a first position signal indicative of a first position of a reel arm of the agricultural header, receive a first distance signal indicative of a first distance between the reel arm and a terrain feature, receive a second position signal indicative of a second position of the reel arm, receive a second distance signal indicative of a second distance between the reel arm and the terrain feature, determine a calibration curve having a plurality of offset distances of the reel arm based on the first position, the first distance, the second position, and the second distance, and select an offset distance of the plurality of offset distances based on an operational position of the reel arm and the calibration curve. 
     In one embodiment, a method of calibrating a monitoring system of an agricultural header includes receiving a first position of a reel arm of the agricultural header relative to a frame of the agricultural header, receiving a first distance between the reel arm and a terrain feature, receiving a second position of the reel arm of the agricultural header relative to the frame of the agricultural header, and receiving a second distance between the reel arm and the terrain feature. Additionally, the method includes determining a calibration curve indicative of a plurality of offset distances of the reel arm based on the first position of the reel arm, the first distance between the reel arm and the terrain feature, the second position of the reel arm, and the second distance between the reel arm and the terrain feature. Further, the method includes selecting an offset distance of the plurality of offset distances based on an operational position of the reel arm and the calibration curve. 
     In one embodiment, a non-transitory computer readable storage medium for an agricultural header includes instructions that, when executed by a processor, cause the processor to receive a first position signal indicative of a first position of a reel arm of the agricultural header, receive a first distance signal indicative of a first distance between the reel arm and a terrain feature, receive a second position signal indicative of a second position of the reel arm, and receive a second distance signal indicative of a second distance between the reel arm and the terrain feature. The storage medium also includes instructions that, when executed by the processor, cause the processor to determine a calibration curve indicative of a plurality of offset distances of the reel arm based on the first position of the reel arm, the first distance between the reel arm and the terrain feature, the second position of the reel arm, and the second distance between the reel arm and the terrain feature and select an offset distance of the plurality of offset distances based on an operational position of the reel arm and the calibration curve. 
    
    
     
       DRAWINGS 
       These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
         FIG. 1  is a side view of an embodiment of a harvester, in accordance with embodiments of the present disclosure; 
         FIG. 2  is a perspective view of an embodiment of a header that may be employed within the harvester of  FIG. 1 , in accordance with embodiments of the present disclosure; 
         FIG. 3  is a side view of an embodiment of a portion of the header of  FIG. 2 , in which a reel arm having a device is in a first position relative to a frame of the header, in accordance with embodiments of the present disclosure; 
         FIG. 4  is a side view of the portion of the header of  FIG. 3 , in which the reel arm having the device is in a second position relative to the frame of the header, in accordance with embodiments of the present disclosure; 
         FIG. 5  is an embodiment of a calibration curve that may be determined by a calibration system based on the first position of the reel arm of  FIG. 3  and the second position of the reel arm of  FIG. 4 , in accordance with embodiments of the present disclosure; 
         FIG. 6  is an embodiment of an offset distance that may be selected based on the calibration curve of  FIG. 5  and an operational position of the reel arm of the header of  FIG. 2 , in accordance with embodiments of the present disclosure; 
         FIG. 7  is a flow diagram of an embodiment of a method of determining a calibration curve using a calibration system for an agricultural header, in accordance with embodiments of the present disclosure; and 
         FIG. 8  is a flow diagram of an embodiment of a method of selecting an offset distance of a reel arm of an agricultural header based on a calibration curve and an operational position of the reel arm, in accordance with embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Any examples of operating parameters and/or environmental conditions are not exclusive of other parameters/conditions of the disclosed embodiments. 
     Turning to the drawings,  FIG. 1  is a side view of an embodiment of a harvester  100  (e.g., agricultural harvester) having a header  200  (e.g., agricultural header). The harvester  100  includes a chassis  110  configured to support the header  200  and an agricultural crop processing system  120 . As described in greater detail below, the header  200  is configured to cut crops and to transport the cut crops toward an inlet  121  of the agricultural crop processing system  120  for further processing of the cut crops. The agricultural crop processing system  120  receives cut crops from the header  200  and separates desired crop material from crop residue. For example, the agricultural crop processing system  120  may include a thresher  122  having a cylindrical threshing rotor that transports the crops in a helical flow path through the harvester  100 . In addition to transporting the crops, the thresher  122  may separate certain desired crop material (e.g., grain) from the crop residue (e.g., husks and pods) and may enable the desired crop material to flow into a cleaning system located beneath the thresher  122 . The cleaning system may remove debris from the desired crop material and transport the desired crop material to a storage compartment within the harvester  100 . The crop residue may be transported from the thresher  122  to a crop residue handling system  130 , which may remove the crop residue from the harvester  100  via a crop residue spreading system  131  positioned at the aft end of the harvester  100 . To facilitate discussion, the harvester  100  and/or its components may be described with reference to a lateral axis or direction  140 , a longitudinal axis or direction  142 , and a vertical axis or direction  144 . The harvester  100  and/or its components may also be described with reference to a direction of travel  146 . 
     As discussed in detail below, the header  200  includes a cutter bar assembly  210  configured to cut the crops within the field. The header  200  also includes a reel assembly  220  configured to engage the crops to prepare the crops to be cut by the cutter bar assembly  210  and/or to urge crops cut by the cutter bar assembly  210  onto belts that convey the cut crops toward the inlet  121  of the agricultural crop processing system  120 . As discussed in detail below, the reel assembly  220  includes a reel having multiple fingers extending from a central framework. The central framework is driven to rotate, such that the fingers engage the crops and urge the crops toward the cutter bar assembly  210  and the belts. Additionally, the reel may be supported by multiple arms (e.g., reel arms) that are coupled to a frame  201  of the header  200 . Each arm of the multiple arms may be coupled to the frame  201  via a respective pivot joint. For example, one pivot joint is configured to enable a first arm of the multiple arms to pivot (e.g., about the lateral axis  140 ) relative to the frame  201  of to the header  200 , and another pivot joint is configured to enable a second arm of the multiple arms to pivot (e.g., about the lateral axis  140 ) relative to the frame  201  of the header  200 . 
     The reel assembly  220  may include a device configured to facilitate detection of terrain features (e.g., a ground  150 ) as the harvester  100  travels through the field. For example, the device may be a sensor that is configured to detect the terrain features and to send a signal indicative of the terrain features to an electronic controller for processing. In some embodiments, the reel assembly  220  may include any number of devices (e.g., 1, 2, 3, 4, 5 or more) and any of a variety of devices, such as any of a variety of devices that emit electromagnetic waves (e.g., sensors), coupled to the device mounting structure. 
     As described above, the arm of the reel assembly  220  may pivot (e.g., rotate) relative to a frame of the header  200 . As such, the device coupled to the arm may move generally vertically relative to the ground  150  on which the header  200  and the harvester  100  are disposed. The device may monitor the terrain features at different/varying positions relative to ground  150 . For example, the device may detect a distance between the arm of the reel assembly  220  and the terrain feature of the ground  150  at the different positions of the arm relative to the ground  150 . Movement (e.g., pivoting) of the arm relative to the frame of the header  200  may affect (e.g., increase or decrease) the distance between the arm of the reel assembly  220  and the terrain feature, as detected by the device. 
     In the disclosed embodiments, an agricultural system (e.g., the header  200  and/or the harvester  100 ), may include a calibration system configured to compensate for movement of the arm of the reel assembly  220  relative to the frame of the header  200 . For example, the device may detect the distance between the arm and the terrain feature of the ground  150  at different positions of the arm, and the calibration system may determine a calibration curve based on the positions of the arm and the detected distances between the arm and the terrain feature. In the disclosed embodiments, the calibration system, and/or a controller of the agricultural system, may select an offset distance of the arm based on the calibration curve and a position of the arm during operation of the header  200  (e.g., an operational position). The offset distance may be provided as an input to a header height control system configured to adjust a height of the header  200  relative to the ground  150  (e.g., a distance between the header  200  and the ground  150  along the vertical axis  144 ). Accordingly, the calibration system disclosed herein may enable the header height control system to control the height of the header  200  based on the distance between the arm and the ground  150 , as detected by the device, and by compensating for movement of the arm of the reel assembly  220  relative to the frame of the header  200 . 
     The calibration curve for the header  200  may be determined periodically (e.g., once per year, once per month, once per day, once per harvesting season), after or in response to maintenance and/or repair of the harvester  100 , prior to entering a field, after transitioning from a roadway to a field, or at other suitable times. Additionally, an operator, a dealer, and/or a manufacturer may control the calibration system of the header  200  to determine the calibration curve (e.g., provide an operator input to cause the calibration system to determine the calibration curve). 
       FIG. 2  is a perspective view of an embodiment of the header  200  that may be employed within the harvester  100  of  FIG. 1 . In the illustrated embodiment, the header  200  includes the cutter bar assembly  210  configured to cut a portion of each crop (e.g., a stalk), thereby separating the crop from the soil. The cutter bar assembly  210  is positioned at a forward end of the header  200  relative to the longitudinal axis  142  of the header  200 . As illustrated, the cutter bar assembly  210  extends along a substantial portion of the width of the header  200  (e.g., the extent of the header  200  along the lateral axis  140 ). The cutter bar assembly  210  includes a blade support, a stationary guard assembly, and a moving blade assembly. The moving blade assembly is fixed to the blade support (e.g., above the blade support along the vertical axis  144  of the header  200 ), and the blade support/moving blade assembly is driven to oscillate relative to the stationary guard assembly. In the illustrated embodiment, the blade support/moving blade assembly is driven to oscillate by a driving mechanism  211  positioned at the lateral center of the header  200 . However, in other embodiments, the blade support/moving blade assembly may be driven by another suitable mechanism (e.g., located at any suitable position on the header  200 ). As the harvester  100  is driven through the field, the cutter bar assembly  210  engages crops within the field, and the moving blade assembly cuts the crops (e.g., the stalks of the crops) in response to engagement of the cutter bar assembly  210  with the crops. 
     In the illustrated embodiment, the header  200  includes a first lateral belt  202  on a first lateral side of the header  200  and a second lateral belt  203  on a second lateral side of the header  200 , opposite the first lateral side. Each belt is driven to rotate by a suitable drive mechanism, such as an electric motor or a hydraulic motor. The first lateral belt  202  and the second lateral belt  203  are driven such that the top surface of each belt moves laterally inward. In addition, the header  200  includes a longitudinal belt  204  positioned between the first lateral belt  202  and the second lateral belt  203  along the lateral axis  140 . The longitudinal belt  204  is driven to rotate by a suitable drive mechanism, such as an electric motor or a hydraulic motor. The longitudinal belt  204  is driven such that the top surface of the longitudinal belt  204  moves rearwardly relative to the direction of travel  146 . 
     In the illustrated embodiment, the crops cut by the cutter bar assembly  210  are directed toward the belts at least in part by the reel assembly  220 , thereby substantially reducing the possibility of the cut crops falling onto the surface of the field. The reel assembly  220  includes a reel  221  having multiple fingers  222  extending from a central framework  223 . The central framework  223  is driven to rotate such that the fingers  222  move (e.g., in a circular pattern). The fingers  222  are configured to engage the crops and urge the cut crops toward the belts. The cut crops that contact the top surface of the lateral belts  202 ,  203  are driven laterally inwardly to the longitudinal belt  204  due to the movement of the lateral belts  202 ,  203 . In addition, cut crops that contact the longitudinal belt  204  and the cut crops provided to the longitudinal belt  204  by the lateral belts  202 ,  203  are driven rearwardly relative to the direction of travel  146  due to the movement of the longitudinal belt  204 . Accordingly, the belts move the cut agricultural crops through an opening  206  in the header  200  to the inlet  121  of the agricultural crop processing system  120  ( FIG. 1 ). 
     In the illustrated embodiment, the reel  221  includes multiple sections coupled to one another. In particular, the reel  221  includes a center section  224  (e.g., positioned forward of a center section  205  of the frame  201  of the header  200  relative to the direction of travel  146 ), a first wing section  225 , and a second wing section  226 . In the illustrated embodiment, each section of the reel  221  is supported by one or more arms  227  (e.g., reel arms) that are coupled to the frame  201  of the header  200 . While the reel  221  includes three sections  224 ,  225 ,  226  coupled to the frame  201  of the header  200  via four arms  227 , it should be appreciated that the reel  221  may include any number of sections coupled to the frame  201  of the header  200  via any number of arms (e.g., one section coupled to the frame  201  of the header  200  via two arms; two sections coupled to the frame  201  of the header  200  via three arms; four sections coupled to the frame  201  of the header  200  via five arms). 
     As discussed in detail below, regardless of the number of arms  227 , each arm  227  is pivotally coupled to the frame  201  of the header  200  via a respective pivot joint. The pivot joints are configured to enable the arms  227  to pivot (e.g., about the lateral axis  140 ) relative to the frame  201  of the header  200 . An actuator may be coupled to each arm  227  and configured to drive the respective arm  227  to rotate, thereby controlling a position of the reel  221  relative to the frame  201  of the header  200  along the vertical axis  144 . Such a configuration may enable the reel  221  to be positioned at an appropriate position along the vertical axis  144  to engage the crops to prepare the crops to be cut by the cutter bar assembly  210  and/or to urge the cut crops toward the belts  202 ,  203 ,  204 , for example. In some embodiments, each section of the reel  221  may also be configured to slide along its respective arm(s) to enable the reel  221  to move along the longitudinal axis  142  relative to the frame  201  of the header  200 . Such a configuration may enable at least a portion of the reel assembly  220  to be positioned forward of the cutter bar assembly  210  relative to the direction of travel  146  to enable the reel assembly  220  to engage the crop to prepare the crop to be cut by the cutter bar assembly  210 , for example. 
     As noted above, the reel assembly  220  may include one or more devices  252  (e.g., sensors) configured to facilitate detection of terrain features, such as a distance to the ground  150 , as the harvester  100  travels through the field. Additionally, the reel assembly  220  may include one or more support structures  251  (e.g., brackets, reel arm extensions) coupled to and configured to support the devices  252 . In the illustrated embodiment, each of the arms  227  is coupled to a respective support structure  251  that supports a respective device  252 . However, only some of the arms  227  may be coupled to a respective support structure  251  that supports a respective device  252 . For example, only the laterally-outer arms  227  may be coupled to a respective support structure  251  and a respective device  252 , only the laterally-inner arm(s)  227  may be coupled to a respective support structure  251  and a respective device  252 , and/or every other arm  227  (e.g., non-adjacent or alternating arms) may be coupled to a respective support structure  251  and a respective device  252 . 
     As discussed in more detail below, regardless of the number of support structures  251  and devices  252  included in the reel assembly, the header  200  and/or the harvester  100  may include a calibration system configured to compensate for movement of the arm  227  relative to the frame  201  of the header  200 . For example, the device may detect a distance between the arm  227  and the terrain feature of the ground  150  at different positions of the arm  227  relative to the frame  201 , and the calibration system may determine a calibration curve based on the positions of the arm  227  and the detected distances between the arm  227  and the terrain feature. Thereafter, the calibration curve and an operational position of the arm  227  may be used to select an offset distance of the arm  227 . The offset distance may be provided as an input to a header height control system configured to adjust a height of the header  200  relative to the ground  150  (e.g., generally along the vertical axis  144 ), thereby compensating for movement of the arm  227  while controlling the height of the header  200 . 
       FIG. 3  is a side view of a portion of the header  200  with the arm  227  in a first position  230  relative to the frame  201  of the header  200 , and  FIG. 4  is a side view of the portion of the header  200  with the arm  227  in a second position  231  relative to the frame  201  of the header  200 . The arm  227  includes a first arm portion  232  and a second arm portion  233  that are coupled together (e.g., in a fixed position relative to one another). In the illustrated embodiment, the first arm portion  232  and the second arm portion  233  are coupled together another via one or more plates  234  (e.g., on opposite lateral sides of the arm portions  232 ,  233 ), although the first arm portion  232  and the second arm portion  233  may be coupled together via any suitable fasteners (e.g., bolts, pins, welds). In certain embodiments, the first position  230  may be a lowest position (e.g., a minimum position) of the arm  227  along the vertical axis  144  that the header  200  may achieve, and/or the second position  231  may be a highest position (e.g., a maximum position) of the arm  227  along the vertical axis  144  that the header  200  may achieve. For example, the first position  230  may be a lowermost position of the arm  227  during operation (e.g., a field/harvesting operation) and/or transport of the header  200 , and/or the second position  231  may be an uppermost position of the arm  227  during operation (e.g., a field/harvesting operation) and/or transport of the header  200 . 
     It should be appreciated that the arm  227  may have any of a variety of shapes or configurations. For example, the first arm portion  232  and the second arm portion  233  may be physically separate structures that are coupled together, or the first arm portion  232  and the second arm portion  233  may be formed as a one-piece structure. Furthermore, the arm  227  may be formed from any number of portions (e.g., 1, 2, 3, 4, 5, or more) having any of a variety of dimensions (e.g., lengths). Moreover, the arm  227  may have any number (e.g., 1, 2, 3, 4, 5, or more) of bends and/or the arm portions may be positioned at any of a variety of angles relative to one another. The reel  221  ( FIG. 2 ) may be coupled to the arm  227  via a slide  235  (e.g., carriage) that enables the reel  221  to slide along the second arm portion  233  to move along the longitudinal axis  142  relative to the frame  201  of the header  200 . To facilitate discussion and for image clarity, the reel  221  and the other associated components that couple the reel  221  to the arm  227  are omitted in  FIGS. 3 and 4 . 
     The header  200  includes an actuator  236  that may be controlled (e.g., via an electronic controller and/or manually via an operator) to adjust the arm  227  between the first position  230  and the second position  231 . As shown, the actuator  236  extends between the frame  201  of the header  200  and the one or more plates  234 , although the actuator  236  may be positioned at any suitable location and may be coupled to any suitable structures (e.g., the first arm portion  232 , the second arm portion  233 ) to drive the arm  227  between the first position  230  and the second position  231 . An end  237  (e.g., proximal end) of the arm  227  is also pivotally coupled to the frame  201  of the header  200  via a pivot joint  238  (e.g., arm-to-frame pivot joint). The arm  227  is configured to rotate relative to the frame  201  at the pivot joint  238 , as indicated by arrows  242 . 
     As described above, a calibration system  300  is configured to compensate for movement of the arm  227  relative to the frame  201  of the header  200  (e.g., about the pivot joint  238 ). For example, the calibration system  300  includes the device  252  configured to detect a first distance  302  (e.g., a compensated distance, a baseline distance, a minimum distance) between the arm  227  (e.g., the second arm portion  233 ) and a surface  240  of the ground  150  while the arm  227  is in the first position  230 . In certain embodiments, the device  252  may be a sensor configured to emit electromagnetic waves  304  to detect terrain feature(s) of the surface  240  and the ground  150 . In some embodiments, the device may include an ultrasonic sensor configured to emit sound waves, a Radio Detection and Ranging (radar) sensor, a Light Detecting and Ranging (lidar) sensor, an ultraviolet sensor configured to emit ultraviolet light, an infrared sensor configured to emit infrared light, and/or a camera sensor. 
     Additionally, the calibration system  300  includes a device  310  (e.g., a reel sensor) configured to detect a position (e.g., a rotational position including the first position  230  and the second position  231 ) of the arm  227  relative to the frame  201 , such as at the pivot joint  238 . For example, the device  310  may be a position sensor configured to detect the position of the arm  227 , such as based on an amount of an output voltage. In other embodiments, the device  310  may be another suitable sensor configured to detect the position of the arm  227  relative to the frame  201 . 
     As shown, the calibration system  300  includes a controller  312  having a processor  314  and a memory  316 . The controller  312  is configured to receive signals from the device  252 , such as distance signals indicative of distances between the arm  227  and the ground  150 . For example, the controller  312  may receive a first distance signal from the device  252  indicative of the first distance  302  of  FIG. 3  and a second distance signal from the device  252  indicative of a second distance  320  of  FIG. 4  (e.g., a second distance between the arm  227  and the ground  150  while the arm  227  is disposed in the second position  231 ). Additionally, the controller  312  is configured to receive position signals from the device  310 , such as position signals indicative of positions of the arm  227  relative to the frame  201  of the header  200 . For example, the controller  312  may receive a first position signal from the device  310  indicative of the first position  230  of the arm  227  of  FIG. 3  and a second position signal from the device  310  indicative of the second position  231  of the arm  227  of  FIG. 4 . 
     As described in greater detail below in reference to  FIG. 5 , the controller  312  may receive additional signals from the device  252  indicative of additional distance(s) between the arm  227  and the ground  150 , such as additional distances greater than the first distance  302  of  FIG. 3  and less than the second distance  320  of  FIG. 4 . Additionally, the controller  312  may receive additional signals from the device  310  indicative of additional position(s) of the arm  227  relative to the frame  201 , such as additional rotational positions between the first position  230  and the second position  231 . Each additional position of the arm  227  may correspond to an additional distance between the arm  227  and the ground  150 . In certain embodiments, the controller  312  may be communicatively coupled to and configured to control the actuator  236  to drive rotation of the arm  227 , such as to the first position  230 , the second position  231 , and positions between the first position  230  and the second position  231  to facilitate collection of data (e.g., the additional distances). 
     Based on the detected positions of the arm  227  relative to the frame  201 , including the first position  230 , the second position  231 , additional detected position(s), or a combination thereof, and detected distances between the arm  227  and the ground  150 , such as the first distance  302 , the second distance  320 , additional detected distance(s), or a combination thereof, the controller  312  may determine or generate a calibration curve including offset distances of the arm  227 . Each offset distance may be a distance to be subtracted from a measured distance detected by the device  252 . 
     By way of example, in  FIG. 4 , the header  200  may be operating with the arm  227  in the second position  231 . The device  310  may detect that the arm  227  is disposed at the second position  231 . Based on the arm  227  being disposed at the second position  231  and by referencing the calibration curve, the controller  312  may select an offset distance  322 . As illustrated, the offset distance  322  is a difference between the second distance  320  and the first distance  302 . Accordingly, the offset distance  322  may account for movement of the arm  227  from the first position  230  to the second position  231  to enable the measured distance (e.g., the second distance  320 ) to be used as an input for controlling the height of the header  200  relative to the ground  150 . As may be appreciated, the offset distance  322  selected by the controller  312  may change as the arm  227  changes position (e.g., rotates) relative to the frame  201 . 
     The processor  314  (e.g., a microprocessor) may be used to execute software, such as software stored in the memory  316  for controlling the calibration system  300  (e.g., for determining the calibration curve and/or for selecting the offset distance  322 ). Moreover, the processor  314  may include multiple microprocessors, one or more “general-purpose” microprocessors, one or more special-purpose microprocessors, and/or one or more application specific integrated circuits (ASICS), or some combination thereof. For example, the processor  314  may include one or more reduced instruction set (RISC) or complex instruction set (CISC) processors. 
     The memory device  316  may include a volatile memory, such as random access memory (RAM), and/or a nonvolatile memory, such as read-only memory (ROM). The memory device  316  may store a variety of information and may be used for various purposes. For example, the memory device  316  may store processor-executable instructions (e.g., firmware or software) for the processor  314  to execute, such as instructions for controlling the calibration system  300 . In certain embodiments, the controller  312  may also include one or more storage devices and/or other suitable components. The storage device(s) (e.g., nonvolatile storage) may include ROM, flash memory, a hard drive, or any other suitable optical, magnetic, or solid-state storage medium, or a combination thereof. The storage device(s) may store data (e.g., the calibration curve), instructions (e.g., software or firmware for controlling the calibration system  300 ), and any other suitable data. The processor  314  and/or the memory device  316 , and/or an additional processor and/or memory device, may be located in any suitable portion of the system. For example, a memory device for storing instructions (e.g., software or firmware for controlling portions of the calibration system  300 ) may be located in or associated with the calibration system  300 . The processor  314  may be any suitable type of computer processor or microprocessor capable of executing computer-executable code. The processor  314  may also include multiple processors that may perform the operations described herein. The memory  316  may represent non-transitory computer-readable media (e.g., any suitable form of memory or storage) that may store the processor-executable code used by the processor  314  to perform various techniques described herein. It should be noted that non-transitory merely indicates that the media is tangible and not a signal. 
     It should also be appreciated that any of the devices disclosed herein (e.g., the device  252 , the device  310 , and any other device) may include a power source (e.g., battery) and/or may be coupled to a power source (e.g., via a power cable). Furthermore, the controller  312  may control operation of the device(s) and/or process signals received from the devices. For example, the controller  312  may control operation of the devices and may also receive signals from the devices. The controller  312  may process the signals to determine the terrain features, including the distance to the ground  150 , and then may provide control signals to adjust the header  200  to an appropriate position (e.g., vertical position) based on the terrain features (e.g., header height control), for example. 
     In some embodiments, the calibration system  300  may include a user interface communicatively coupled to the controller  312 . The user interface may be configured to inform an operator of the position of the arm  227 , the selected offset distance  322 , to enable the operator to initiate a process (e.g., method  700  of  FIG. 7 ) of determining the calibration curve and/or selecting the offset distance  322 , and to enable other operator interactions. For example, the user interface may include a display and/or other user interaction devices (e.g., buttons) configured to enable operator interactions. 
       FIG. 5  is an embodiment of a calibration curve  500  that may be determined by the calibration system  300  of  FIGS. 3 and 4  to facilitate controlling a height of the header  200  based on the distance between the arm  227  and the ground  150  (e.g., as detected by the device  252 ). The controller  312  may determine the calibration curve  500  based on the first position  230  of the arm  227  of  FIG. 3 , the first distance  302  of  FIG. 3 , the second position  231  of the arm  227  of  FIG. 4 , the second distance  320  of  FIG. 4 , and additional positions of the arm  227  relative to the frame  201  and corresponding distances between the arm  227  and the ground  150 . 
     For example, the calibration curve  500  is plotted along a graph  502  having an x-axis  504  identified as a reel position axis and a y-axis  506  identified as a distance measurement. A first data point  510  at a first end of the calibration curve  500  represents the first position  230  of the arm  227  relative to the frame  201  and the first distance  302  between the arm  227  and the ground  150 . A second data point  512  at a second end of calibration curve  500  (e.g., opposite of the first end having the first data point  510 ) represents the second position  231  and the second distance  320 . As such, the calibration curve  500  extends along the x-axis  504  from the first data point  510  representing the minimum position  230  to the second data point  512  representing the maximum position  231 . Additionally, the calibration curve  500  extends along the y-axis  506  from the first data point  510  representing the minimum distance  302  to the second data point  512  representing the maximum distance  320 . 
     In certain embodiments, the calibration curve  500  may be a straight line extending between the first data point  510  and the second data point  512 . To enhance an accuracy of the offset distance  322  selected by the controller  312  during operation of the header  200  (e.g., during harvesting operations), additional data points  522  may be plotted on the graph  502  along a middle portion  520  between the first data point  510  and the second data point  512 , such that the calibration curve  500  is connected to or adjusted based on each additional data point  522 . The additional data points  522  may be obtained by the calibration system  300  by incrementally moving the arm  227  from the first position  230  to the second position  231 , or vice versa. For example, the controller  312  or another controller of the header  200  may control the actuator  236  configured to drive rotation of the arm  227  to move incrementally from the first position  230  to the second position  231 . At each increment, the controller  312  may receive a distance signal from the device  310  indicative of the distance between the arm  227  and the terrain feature of the ground  150  (e.g., the same terrain feature detected at  FIG. 3  to determine the distance  302  and at  FIG. 4  to determine the distance  320 ). Each additional data point  522  is plotted along the x-axis  504  at the detected/controlled position and along the y-axis  506  at the detected distance. Thereafter, the calibration curve  500  is determined or adjusted, such that the calibration curve  500  intersects the first data point  510 , each additional data point  522 , and the second data point  512 , thereby forming a piecewise linear function. In certain embodiments, the calibration curve  500  may be a best fit line extending generally along the first data point  510 , the additional data points  522 , and the second data point  512  or another suitable line/curve. 
     As illustrated, the x-axis  504  may include percentage increments, such that the first position  230  corresponds to a position of the arm  227  at 0 percent and the second position  231  corresponds to a position of the arm  227  at 100 percent. Each additional data point  522  is measured at increments of 10 percent (e.g., 20 percent, 30 percent). In certain embodiments, other percentage increments may be used, such as 20 percent, 5 percent, 1 percent, or the increments may be an angular rotation measurement of the arm  227  relative to the frame (e.g., 1 degree, 2 degrees, 5 degrees). As illustrated, the y-axis  506  is illustrated in millimeter units. In certain embodiments, the y-axis  506  may be in centimeters, meters, or in imperial units. The calibration curve  500  may be generated while the frame  201  of the header  200  is stationary relative to the ground  150  during a calibration process (e.g., prior to traveling in the direction of travel over the ground  150 ; prior to harvesting operations). 
       FIG. 6  is an embodiment of an offset distance  322 ′ that may be selected by the controller  312  based on the calibration curve  500  of  FIG. 5  and an operational position  602  of the arm  227  of the header  200 . For example, during operation of the header  200  (e.g., a harvesting operation) and/or during transport of the header  200 , the arm  227  may be disposed at the operational position  602  relative to the frame  201  (e.g., at about 60 percent along the x-axis  504 ). The operational position  602  is disposed along the calibration curve  500  adjacent to one of the additional data points  522  and corresponds to a distance measurement  604  along the y-axis. The distance measurement  604  may represent a distance that would exist between the arm  227  and the ground  150  at the same portion of the ground  150  where the first position  230 , the second position  231 , the first distance  302 , the second distance  320 , and additional positions/distances were measured. Accordingly, the offset distance  322 ′ is a difference between the distance measurement  604  and the first position  230  (e.g., the baseline/minimum position). In other words, the offset distance  322 ′ compensates for movement of the arm  227  to the operational position  602  and while the device  252  is detecting the distance between the arm  227  and the ground  150  at the operational position  602 . As such, the calibration curve  500  is indicative of offset distances that may be selected based on the operational position of the arm  227 . The offset distance  322 ′ may be provided as an input to a control system configured to adjust the height of the header  200  relative to the ground  150 , such as the controller  312  or another suitable control system. Thereafter, the control system may adjust the height of the header  200  based on the offset distance  322 ′, among other inputs and/or factors. 
       FIG. 7  is a flow diagram of an embodiment of a method  700  of determining the calibration curve  500  using the calibration system  300  of the header  200 . The method  700 , or portions thereof, may be performed by the controller  312  of the calibration system  300 . The method  700  begins at block  702 , where a minimum position of a reel arm and a first distance between a terrain feature and the reel arm are received. For example, the minimum position of the reel arm may be the first position  230  of the arm  227  relative to the frame  201 , and the first distance may be the first distance  302  between the arm  227  and the terrain feature of the ground  150 . In certain embodiments, block  702  may be separate steps, in which the minimum position of the reel arm is received as one step and the first distance between the terrain feature and the reel arm is received as another step. 
     At block  704 , a maximum position of the reel arm and a second distance between a terrain feature and the reel arm are received. For example, the maximum position of the reel arm may be the second position  231  of the arm  227  relative to the frame  201 , and the second distance may be the second distance  320  between the arm  227  and the terrain feature of the ground  150 . In certain embodiments, block  702  may be separate steps, in which the maximum position of the reel arm is received as one step and the second distance between the terrain feature and the reel arm is received as another step. 
     At block  706 , additional position(s) of the reel arm and additional distance(s) between the terrain feature and the reel arm are received. For example, the controller  312  may receive additional position(s) of the arm  227  relative to the frame  201  and additional distance(s) between the arm  227  and the ground  150 , such as the positions and distances of the additional data points  522  of  FIGS. 5 and 6 . Each additional position of the arm  227  may correspond to an additional distance between the arm  227  and the ground  150 . In certain embodiments, block  706  may be omitted. 
     At block  708 , a calibration curve indicative of offset distances of the reel arm is determined based on the positions of the reel arm relative to the distances between the reel arm and the terrain feature. For example, as described in reference to  FIGS. 5 and 6 , the calibration curve  500  may be a piecewise linear function, a best fit line, or another suitable function determined based on the positions of the arm  227  relative to the frame  201  of the header  200  and the corresponding distances between the arm  227  and the ground  150 . Points along the calibration curve  500  may correspond to a given operational position of the arm  227  and a distance measurement of the arm  227 . The offset distance may be determined based on the distance measurement, such that the calibration curve is indicative of various offset distances of the arm  227 . The method  700  may be carried out while the frame  201  of the header  200  is stationary relative to the ground  150  (e.g., prior to traveling in the direction of travel over the ground  150 ; prior to harvesting operations). 
       FIG. 8  is a flow diagram of an embodiment of a method  800  of selecting the offset distance  522 ,  522 ′ of the arm  227  based on the calibration curve  500  and the operational position of the arm  227 . The method  800 , or portions thereof, may be performed by the controller  312  of the calibration system  300 . The method  800  begins at block  802 , where a position of a reel arm is received. For example, the controller  312  may receive the operational position  602  of the arm  227 . 
     At block  804 , an offset distance of the reel arm is selected based on the position of the reel arm and a calibration curve indicative of offset distances of the reel arm. For example, the controller  312  may select the offset distance by comparing the received operational position of the arm to the calibration curve determined via method  700 . In reference to  FIG. 6 , the offset distance  322 ′ may be selected based on the operational position  602  and the calibration curve  500 . 
     At block  806 , the selected offset distance of the reel arm is provided as an input to a control system of the agricultural system, such as a header height control system that is configured to control a position of the header (e.g., a vertical position of the header). The header height control system, such as the controller  312 , another controller of the header  200 , or a controller of the harvester  100  generally, may control the height of the header  200  (e.g., the frame  201  of the header  200 ) based on the selected offset distance, such as by raising or lowering the header  200  based on the selected offset distance. The method  800  may be carried out while the frame  201  of the header  200  is travels in the direction of travel over the ground  150  (e.g., during harvesting operations). 
     Accordingly, the calibration system described herein may facilitate controlling the height of the header based on a distance between a reel arm of the header and a ground on which the header is disposed, as detected by a device (e.g., a sensor) coupled to the reel arm. The calibration system may select an offset distance based on an operational position of the reel arm relative to a frame of the header and use the selected offset distance to control the height of the header. It should be appreciated that the disclosed embodiments may be adapted for use while the device is positioned on any movable portion (e.g., vertically movable portion; movable relative to the frame of the header) of the agricultural system (e.g., to compensate for changes in vertical position of the device relative to the frame of the header). Furthermore, while certain figures illustrate the device maintaining an orientation relative to the frame of the header and/or relative to the ground, it should be appreciated that the device may maintain an orientation relative to the arm  227  or may have any of a variety of other configurations and/or orientations that enable the device to monitor the terrain features as disclosed herein. 
     While only certain features have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure. The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function] . . . ” or “step for [perform]ing [a function] . . . ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).