Patent Publication Number: US-2021185918-A1

Title: Systems and methods for controlling a position of a reel of an agricultural header

Description:
BACKGROUND 
     The present disclosure relates generally to a reel assembly of 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 certain embodiments, a header system for an agricultural harvester includes a first reel section, a second reel section, and a sensor configured to generate data indicative of a parameter related to a crop within a field. The header system also includes a controller configured to receive the data and to control a first actuator to adjust the first reel section independently from the second reel section based on the data as the agricultural harvester travels through the field. 
     In certain embodiments, a control system for an agricultural header includes a controller comprising a processor configured to receive an input of a desired height of a first reel section, receive an indication of a crop attribute, determine a desired adjustment of the first reel section based on the input and the indication, and adjust the first reel section by the desired adjustment and independent from a second reel section. 
     In certain embodiments, a method of independently controlling a section of a reel of an agricultural header includes receiving a first signal indicative of a current position of the section of the reel at one or more processors. The method also includes receiving a second signal indicative of a crop parameter at the one or more processors. The method further includes determining an adjustment for the section of the reel based on the first signal and the second signal using the one or more processors. The method further includes instructing an actuator to adjust the section of the reel independently from another section of the reel of the agricultural header using the one or more processors. 
    
    
     
       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 an agricultural harvester; 
         FIG. 2  is a perspective view 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 block diagram of a control system that may be used to control a reel assembly of the header of  FIG. 2 , in accordance with embodiments of the present disclosure; 
         FIG. 4  is a rear view of a portion of the reel assembly that may be employed within the header of  FIG. 2 , in accordance with embodiments of the present disclosure; 
         FIG. 5  is a rear view of the portion of the reel assembly of  FIG. 4 , wherein a section of the reel assembly is in a raised position; 
         FIG. 6  is a side view of a portion of the reel assembly that may be employed within the header of  FIG. 2 , in accordance with embodiments of the present disclosure; 
         FIG. 7  is a side view of the portion of the reel assembly of  FIG. 6 , wherein a section of the reel assembly is in a rearward position; and 
         FIG. 8  is a flow chart of an embodiment of a method for controlling a position of the reel assembly that may be employed within the header of  FIG. 2 . 
     
    
    
     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) with a reel assembly  220 . 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 crops to an inlet  121  of the agricultural crop processing system  120  for further processing of the cut crops. The agricultural crop processing system  120  receives 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 crops, the thresher  122  may separate certain desired crop material (e.g., grain) from the crop residue, such as 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 . 
     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 . 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 reel arms that are coupled to a frame  201  of the header  200 . Each reel arm of the multiple reel 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 . 
     In the disclosed embodiments, the reel assembly  220  may include a sensor assembly (e.g., reel arm sensor assembly) having one or more sensors. In particular, at least one of the multiple reel arms may be coupled to a bracket (e.g., reel arm extension member) that supports a sensor. The sensor may be configured to facilitate detection of terrain features (e.g., a height, position, and/or density of the crops and/or surface features of the ground) as the harvester  100  travels through the field. For example, the sensor may be configured to detect the terrain features and to send a signal indicative of the terrain features to a controller (e.g., electronic controller) for processing. 
     In some embodiments, the reel assembly  220  may include actuators coupled to the header  200  and/or the reel arms. The actuators may be configured to move the reel arms (e.g., relative to the frame  201  of the header; via rotation at the pivot joints), and thus, the reel assembly  220 , along the vertical axis  144  and/or the longitudinal axis  142  relative to the frame  201 . In some embodiments, the reel assembly  220  may include multiple reel sections that move independently from one another. In such cases, the actuators may be configured to move the reel arms to thereby move the reel sections independently from one another. For example, each actuator may be a hydraulic cylinder that retracts a piston rod to raise one reel section relative to another reel section. Similarly, the hydraulic cylinder may extend the piston rod to lower the one reel section relative to another reel section. Also, the actuators may be configured to move the reel sections forward and aft relative to one another. 
     By independently adjusting the height (e.g., along the vertical axis  40 ) and position (e.g., forward and aft position; along the longitudinal axis  42 ) of the reel sections, each of the reel sections may be positioned at an appropriate position relative to the crop canopy and/or relative to the ground as the harvester  100  travels through the field. For example, an operator may provide an input (e.g., via a user interface in a cab of the harvester  100 ) to set a desired reel position relative to the crop canopy (e.g., desired reel height; set reel position; a distance below the crop canopy) for the reel sections of the reel assembly  220 . However, as the harvester  100  travels through the field, the height of the crop canopy may change at a portion of the reel, such as at one reel section (e.g., forward of one reel section, at the portion of the field over which the one reel section may travel). In such cases, the sensor  252  may detect the height of the crop canopy at the one reel section and provide the signal indicative of the height of the crop canopy at the one reel section to the controller. Then, the controller may instruct the actuators to adjust the position of the one reel section to maintain the one reel section at the desired reel position (e.g., to maintain the one reel section at the distance below the crop canopy). In this way, the disclosed embodiments may maintain a substantially constant distance between each section of the reel assembly  220  and the crop canopy as the harvester  100  moves through the field. Various other features related to control of the reel sections of the reel assembly  220  are described in more detail below. 
       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 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 reel arms  227  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 reel 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 reel arms (e.g., one section coupled to the frame  201  of the header  200  via two or more reel arms; two sections coupled to the frame  201  of the header  200  via three or more reel arms; four sections coupled to the frame  201  of the header  200  via five or more reel arms). 
     Regardless of the number of reel arms  227 , each reel arm  227  may be movably coupled to the frame  201  of the header  200 . For example, in the illustrated embodiment, each reel arm  227  is pivotally coupled to the frame  201  of the header  200  via a respective pivot joint  229 . The pivot joints  229  are configured to enable the reel arms  227  to pivot (e.g., about the lateral axis  140 ) relative to the frame  201  of the header  200 . An actuator  228  may be coupled to each reel arm  227  and configured to drive the respective reel arm  227  to move (e.g., rotate about the pivot joint  229 ), thereby controlling a position of the reel  221  (e.g., including independently controlling respective positions of the reel sections  224 ,  225 ,  226  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 (e.g., to maintain a substantially constant distance between each reel section  224 ,  225 ,  226  of the reel  221  and the crop canopy) along the vertical axis  144 , and to thereby 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  224 ,  225 ,  226  of the reel  221  may also be configured to slide along its respective reel arm(s)  227  to move along the longitudinal axis  142  relative to the frame  201  of the header  200 . In this way, each section  224 ,  225 ,  226  may be adjusted to be appropriately 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 the sensor assembly  250 . The sensor assembly  250  may include one or more brackets  251  (e.g., reel arm extension) and one or more sensors  252 . The one or more sensors  252  may be configured to facilitate detection of terrain features, such as a height, a position, and/or a density of the crops and/or surface features of the ground, as the harvester  100  travels through the field. In the illustrated embodiment, each of the reel arms  227  is coupled to a respective bracket  251  that supports a respective sensor  252 . However, only some of the reel arms  227  may be coupled to a respective bracket  251  that supports a respective sensor  252 . For example, only the laterally-outer reel arms  227  may be coupled to a respective bracket  251  and a respective sensor  252 , only the laterally-inner reel arm(s)  227  may be coupled to a respective bracket  251  and a respective sensor  252 , and/or every other reel arm  227  (e.g., non-adjacent or alternating arms) may be coupled to a respective bracket  251  and a respective sensor  252 . As discussed in more detail below, regardless of the number of brackets  251  and sensors  252  included in the sensor assembly  250 , the sensors  252  may monitor the terrain features forward of the header  200  as the harvester  100  travels through the field. It should be appreciated that the sensors  252  may additionally or alternatively be coupled to the frame  201  of the header  200  (e.g., the brackets  251  may be fastened to the frame  201  of the header  200 ) and/or may be coupled to the harvester  100 . 
     As the header  200  travels through the field, the sensors  252  of the sensor assembly  250  may monitor the terrain features forward of the header  200 . As noted above, the terrain features may include a height of the crops (e.g., a crop canopy height; a height of the crops relative to the ground), a position of the crops (e.g., an orientation or angle of the crops relative to the ground, such as whether the crops are leaning toward or away from the header  200 ), and/or a density of the crops (e.g., a density of the crop canopy). As discussed below, the sensors  252  may provide sensor signals indicative of the terrain features to a control system (e.g., electronic control system), which may process the sensor signals to determine the appropriate position for each reel arm  227  and may output control signals to the actuators  228  to adjust each reel arm  227  to the appropriate position. In this way, the reel sections  224 ,  225 ,  226  may be adjusted based on (e.g., in response to) the terrain features as the header  200  travels through the field. 
       FIG. 3  is a diagram of an embodiment of a control system  300  (e.g., electronic control system) configured to control each actuator  228  coupled to the reel arms  227  of the reel assembly  220 . In the illustrated embodiment, the control system  300  includes a controller  302  having a memory  304  and a processor  306 . The memory  304  may be any type of non-transitory machine readable medium for storing data and executable instructions, such as random-access memory, read-only memory, rewritable flash memory, hard drives, optical discs, and the like. The processor  306  may execute instructions stored on the memory  304 . For example, the memory  304  may contain machine readable code, such as instructions, that may be executed by the processor  84 . In some embodiments, the memory  304  and processor  306  may enable automatic (e.g., processor/memory controlled) operation of the header  200 , including automatic adjustment of the reel assembly  220  based on the terrain features. As will be described below, the controller  302  is configured to control a hydraulic control system  310  to adjust the height and/or the position of the reel sections  224 ,  225 ,  226  based on operator inputs, data from the sensors  252 , pre-loaded design conditions, and the like. 
     As mentioned above, in the illustrated embodiment, the actuators  228  are hydraulic cylinders. The hydraulic control system  310  is configured to control the flow of hydraulic fluid to and from the actuators  228 . For instance, the hydraulic control system  310  may include tanks, pumps, and/or valves configured to regulate the flow of hydraulic fluid to the actuators  228 . In the illustrated embodiment, the hydraulic control system  88  regulates the flow of the hydraulic fluid to the actuators  228  to adjust the position of the actuators  228 , and thus, the position of the reel arms  227  (and the independent reel sections coupled thereto) based on control signals received from the controller  302 . 
     As mentioned above, the sensors  252  are communicatively coupled to the controller  302 . In the illustrated embodiment, the sensors  252  are ultrasonic transducers configured to send and receive acoustic energy to/from the agricultural field  12 . However, any other suitable type of sensor that is capable of detecting the terrain features may be utilized. The sensors  252  may act as a height sensor configured to obtain data indicative of the height of a crop canopy. Additionally or alternatively, the sensors  252  may be configured to obtain data indicative of the position of the crop canopy and/or the density of the crop canopy. Additionally or alternatively, the sensors  252  may act as an obstacle sensor and/or ground contour sensor configured to determine the ground contour of the field. 
     The control system  300  is configured to receive the data (e.g., signals) from the sensors  252 , process the data, determine an appropriate position for each reel arm  227  of the reel assembly  220  (e.g., that achieves an appropriate position for each section  224 ,  225 ,  226  of the reel assembly  220 , such as to maintain the desired reel position at the set distance below the crop canopy), and to provide control signals to the hydraulic control system  310  to adjust the position of the actuators  228  to drive each reel arm  227  to the respective appropriate position as the harvester  100  travels through the field of crops based on the received data. 
     To carry out these techniques, the controller  302  may also be configured to receive data (e.g., signals) from reel sensors  230  that is indicative of respective current positions of the reel arms  227  (e.g., and each reel section  224 ,  225 ,  226  coupled thereto, relative to the ground and/or relative to the crop canopy). The respective current positions of the reel arms  227  may be used to determine how (e.g., up, down, forward, rearward) to adjust the reel arms  227  to reach the respective appropriate positions of the reel arms  227  and/or to provide feedback (e.g., as part of a feedback loop) to confirm that the reel arms  227  have reached their respective appropriate positions. For example, the controller  302  may compare the current position with the appropriate position and direct the hydraulic control system  310  to adjust the actuators  228  to drive each reel arm  227  to the respective appropriate position. As mentioned above, the control system  300  may continuously or periodically monitor the current position of the reel assembly  220  and continuously or periodically change the position of the reel sections  224 ,  225 ,  226 , such as to maintain the desired reel position relative to the crop canopy. 
     The control system  300  may adjust the reel assembly  220  in various ways. For example, in some embodiments, an operator may provide an input (e.g., via a user interface  312 ) to set a desired reel position relative to the crop canopy (e.g., desired reel height; set reel position; a set distance below the crop canopy) for the reel sections of the reel assembly  220 . It should be appreciated that the controller  302  may establish or receive the desired reel position relative to the crop canopy in other ways, such as via a programmed or manufacturer setting, for example. Regardless of the manner in which the desired reel position is obtained, the sensor  252  may detect the height of the crop canopy at the one or more reel sections (e.g., forward of the one or more reel section, at the area of the field over which the one or more reel sections may travel) and may provide the signal indicative of the height of the crop canopy at the one or more reel sections to the controller  302 . Then, the controller  302  may instruct the actuators  228  to adjust the position of the one or more reel arms  227  to maintain the one or more reel sections at the desired reel position (e.g., to maintain the one or more reel sections at the set distance below the crop canopy). In this way, the disclosed embodiments may maintain a substantially constant distance between each section of the reel assembly  220  and the crop canopy as the harvester  100  moves through the field. 
     In some embodiments, an operator may provide an input (e.g., via the user interface  312 ) to set a desired reel position relative to the ground for the reel sections of the reel assembly  220  (e.g., desired reel height; set reel position; a set distance above the ground). It should be appreciated that the controller  302  may establish or receive the desired reel position relative to the ground in other ways, such as via a programmed or manufacturer setting, for example. Regardless of the manner in which the desired reel position is obtained, the sensor  252  may detect the ground contour at the one or more reel sections (e.g., forward of the one or more reel section, at the area of the field over which the one or more reel sections may travel) and may provide the signal indicative of the ground contour at the one or more reel sections to the controller  302 . Then, the controller  302  may instruct the actuators  228  to adjust the position of the one or more reel arms  227  to maintain the one or more reel sections at the desired reel position (e.g., to maintain the one or more reel sections at the set distance above the ground). In this way, the disclosed embodiments may maintain a substantially constant distance between each section of the reel assembly  220  and the ground as the harvester  100  moves through the field. 
     In some such embodiments, the controller  302  may control the one or more reel arms  227  to maintain the one or more reel sections at the desired reel position at the set distance above the ground, as long as (e.g., only as long as) the desired reel position would also result in the one or more reel sections being below the crop canopy and/or at an appropriate position relative to another parameter (e.g., above a center of gravity of the crops, as determined by the controller  302  based on data from the sensors  252 ). For example, the operator may provide the input to set the desired reel position relative to the ground. The sensors  252  may monitor the ground contour and the height of the crop canopy, and the sensors  252  may provide the data indicative of the ground contour and the height of the crop canopy to the controller  302 . The reel sensors  230  may also provide data indicative of the current positions of the reel arms  227  to the controller  302 . As the harvester  100  travels through the field, the controller  302  may then adjust the actuators  228  to position each reel section at its respective desired reel position relative to the ground. However, if the desired reel position relative to the ground would result in the reel section being above the crop canopy, the controller  302  may block and/or limit adjustment of the actuator  228  to maintain the reel section between the ground and the crop canopy along the vertical axis  40 . 
     In some embodiments, the operator may provide an input to instruct the controller  302  to control the actuators  228  to operator in different modes, such as a “crop canopy mode” in which the controller  302  controls the actuators  228  so that each reel section tracks the crop canopy (e.g., maintain the set distance below the crop canopy) or a “ground contour mode” in which the controller  302  controls the actuators  228  so that each reel section tracks the ground contours (e.g., maintain the set distance above the ground). Further, the controller  302  may be configured to automatically switch between these modes. For example, the controller  302  may be configured to switch from the ground contour mode to the crop canopy mode if the desired reel position relative to the ground would place (or result in) the reel section being above the crop canopy. The controller  302  may be configured to automatically switch modes based on various other factors, including the density of the crop, the position of the crop, a degree of variation (e.g., as determined by the controller  302  based on the data from the sensors  252 ) of the height of the crop canopy across the width of the header  200  and/or as the harvester  100  travels through the field, a degree of variation (e.g., as determined by the controller  302  based on the data from the sensors  252 ) of the ground contour across the width of the header  200  and/or as the harvester  100  travels through the field. For example, if the degree of variation in the height of the crop canopy is higher than the degree of variation in the ground contour, the controller  302  may operate in the ground contour mode to reduce adjustments. Alternatively, in such cases, the controller  302  may operate in the crop canopy mode to more closely account and match the variations. 
     The controller  302  may determine and/or take into account other factors to control the reel assembly  220 . In some embodiments, the controller  302  may process the data from the sensors  252  to determine the density of the crop (e.g., at the crop canopy). The controller  302  may then adjust each reel section based on the density of the crop. For example, the operator may set the desired reel position relative to the crop canopy. However, the controller  302  may adjust the desired reel position relative to the crop canopy (e.g., adjust the set distance input by the operator; adjust to an adjusted desired reel position) for each reel section to account for the density, and then the controller  302  may maintain each reel sections at the respective adjusted desired reel position as the harvester  100  travels through field (e.g., through the portion of the field having the density). Thus, the controller  302  may determine the respective appropriate position for each reel section by taking into account the operator input (or other input of the desired position), the height of the crop canopy, the ground contour, and/or the density of the crop. Advantageously, this may enable each reel section to engage the crop at the respective appropriate position relative to the center of gravity of the crops (e.g., slightly above the center of gravity) to block the crops from flipping and/or to effectively urge the crops onto the cutter bar assembly  210 . 
     Similarly, in some embodiments, the controller  302  may process the data from the sensors  252  to determine the position of the crops (e.g., the orientation relative to the ground). The controller  302  may then adjust each reel section based on the position of the crops. For example, the operator may set the desired reel position relative to the crop canopy. However, the controller  302  may adjust the desired reel position relative to the crop canopy and/or relative to the frame  201  of the header  200  (e.g., adjust the set distance input by the operator; adjust to an adjusted desired reel position; adjust up, down, forward, and/or aft) for each reel section to account for the position of the crops, and then the controller  302  may maintain the each reel sections at the respective adjusted desired reel position as the harvester  100  travels through field (e.g., through the portion of the field having the density). Thus, the controller  302  may determine the respective appropriate position for each reel section by taking into account the operator input (or other input of the desired position), the height of the crop canopy, the ground contour, the density of the crop, and/or the position of the crop. Advantageously, this may enable each reel section to engage the crop at the respective appropriate position relative to the center of gravity of the crops (e.g., slightly above the center of gravity) and/or relative to the cutter bar assembly  210  to block the crops from flipping and/or to effectively urge the crops onto the cutter bar assembly  210 . 
     It should be appreciated that the controller  302  may also be configured to independently adjust the position of each reel section to avoid contact between the reel sections and the cutter bar assembly  210 . For example, the header  200  may operate in a “flex mode” in which the cutter bar flexes as the harvester  100  travels through the field. In such cases, cutter bar sensors may monitor the position of the cutter bar assembly  210 . The controller  302  may receive data (e.g., signals) indicative of the position of the cutter bar assembly  210  from the cutter bar sensors and may adjust the reel sections accordingly. 
       FIGS. 4-6  provide examples to facilitate understanding of the operation of the header  200 , including operation of the sensor assembly  250  and adjustment of the reel sections  224 ,  225 ,  226 , of the reel assembly  220 .  FIG. 4  is a rear view of an embodiment of a portion of the reel assembly  220  that includes the reel sections  224 ,  225 ,  226 . The reel sections  224 ,  225 ,  226  may be in a first configuration (e.g., level configuration; the respective central axes of the sections may be aligned with one another and/or may be aligned with the lateral axis  140 ) while the reel assembly  220  travels over and/or interacts with a generally level field of crops  206 . As shown, the reel sections  224 ,  225 ,  226  of the reel assembly  220  may be coupled together by pivot joints  229 , which enable the reel sections  224 ,  225 ,  226  to rotate independently from one another to adjust to terrain features (e.g., a height, position, and/or density of the crops and/or surface features of the ground). However, the reel sections  224 ,  225 ,  226  of the reel assembly  220  may be coupled together and/or coupled to the frame  201  of the header  200  in other ways (e.g., via a sliding connection and/or another connection) that enable the reel sections  224 ,  225 ,  226  to move (e.g., slide and/or rotate) independently from one another. 
       FIG. 5  is a rear view of an embodiment of a portion of the reel assembly  220  that includes the reel sections  224 ,  225 ,  226 . The reel sections  224 ,  225 ,  226  may be in a second configuration (e.g., non-level configuration; the respective central axes of the sections are not aligned with one another and/or are not aligned with the lateral axis  140 ) while the reel assembly  220  travels over and/or interacts with a generally uneven crop canopy  240 . In particular, one reel section  226  is raised (e.g., via rotation at the pivot joint  229 ) relative to the other sections  224 ,  225  due to the height of the crop canopy  240  at the one reel section  226  being greater than the height of the crop canopy  240  at the other sections  224 ,  225  to enable the reel section  226  to effectively engage the crops. While the illustrated embodiment shows the distance between the crop canopy and the reel section  226  being approximately equal across the width of the reel section  226  to facilitate discussion, it should be appreciated that the distance may not be substantially equal across the width of the reel section  226 . Instead, the reel section  226  may be positioned so that at least some percentage of the reel section  226  is at the desired reel position or close to the desired reel position (e.g., approximately equal to or greater than 25, 30, 40, 50, 60, 70, 80, or 90 percent), for example. Generally, the controller  302  may determine the appropriate position to be the position at which the reel section  226  will effectively engage the crops, taking into account the operator input, the height of the crop canopy, the position of the crops, the density of the crops, and/or other factors. 
       FIG. 6  is a side view of an embodiment of a header  200  having the reel assembly  220 , the cutter bar assembly  210 , and the sensors  252 . In the illustrated embodiment, the crops  206  are positioned to lean away from the header  200 . In operation, the controller  302  may process the data from the sensors  252  to determine the position of the crops  206  and to determine the appropriate position for each reel section of the reel assembly  220 . For example, with the illustrated position of the crops  206 , the controller  302  may be configured to control the actuators  228  to move the reel assembly  220  to a first position relative to the frame  201  of the header  200  (e.g., away from the frame  201  of the header  200  along the longitudinal axis  142 ) to effectively engage the crops and/or to urge the crops toward the cutter bar assembly  210 . 
       FIG. 7  is a side view of an embodiment of a header  200  having the reel assembly  220 , the cutter bar assembly  210 , and the sensors  252 . In the illustrated embodiment, the crops  206  are positioned to lean toward from the header  200 . In operation, the controller  302  may process the data from the sensors  252  to determine the position of the crops  206  and to determine the appropriate position for each reel section of the reel assembly  220 . For example, with the illustrated position of the crops  206 , the controller  302  may be configured to control the actuators  228  to move the reel assembly  220  to a second position relative to the frame  201  of the header  200  (e.g., toward the the frame  201  of the header  200  along the longitudinal axis  142 ; closer to the frame  201  of the header  200  as compared to the first position of  FIG. 5 ) to effectively engage the crops and/or to urge the crops toward the cutter bar assembly  210 . For example, if the operator set the desired reel position relative to the crop canopy, the controller  302  may control each reel section to generally maintain the desired reel position relative to the crop canopy as the harvester  100  travels through the field. However, the controller  302  may adjust the desired reel position and/or determine the appropriate reel position based on the position of the crops (e.g., given the same desired reel position set by the operator, the controller  302  may adjust the desired reel position forward to the first position relative to the frame  201  of the header  200  while the crops  206  are positioned to lean away from the frame  201  of the header  200  and may adjust the desired reel position rearward to the second position relative to the frame  201  of the header  200  while the crops  206  are positioned to lean toward the frame  201  of the header  200 ), thereby enabling each reel section to more effectively engage the crops. Similar adjustments to the desired reel position may be made based on the density of the crops. 
     It should be appreciated that the bracket  251  may contact and/or be fastened (e.g., via one or more bolts or welds) to the frame  201  of the header  200 . For example, at least a portion of the bracket  251  may be non-rotatably coupled or fixed to the frame  201  of the header  200 , and the bracket  251  may extend up and over (e.g., forward) the reel assembly  220  to enable the sensor  252  to detect the terrain features forward of the header  200 . It should be appreciated that any of the sensors  252  coupled to the reel arms  227  as shown in  FIGS. 1-7  may be coupled to the frame  201  of the header  200 . Furthermore, any of the features disclosed herein may be combined in any suitable manner. 
       FIG. 8  is a flow chart of an embodiment of method  800  for independently adjusting the position of the reel sections. In the illustrated embodiment, the controller  302  receives a first signal indicative of a first height of a first section  224  relative to the ground of a field of crops  206  and/or relative to the crop canopy at block  802 . The controller  302  may receive the first signal from the sensor  252 . The controller  302  receives a second signal indicative of a second height of the first section  224  relative to the ground of the field of crops  206  and/or relative to the crop canopy at block  804 . In certain embodiments, the controller  302  receives a third signal indicative of the density of the crops at block  806 . The controller  302  may receive the third signal from the sensor  252 . As discussed above, the controller  302  may additionally or alternatively receive other parameters or attributes, such as the position of the crops (e.g., the orientation). In some embodiments, the controller  302  is configured to receive an operator input indicative of desired cutting parameters, such as the desired reel position relative to the ground and/or relative to the crop canopy at block  808 . 
     In some embodiments, the controller  302  is configured to determine a desired adjustment of the first section  224  based on the first signal, the second signal, the third signal, and/or the operator input of the desired cutting parameter at block  810 . The controller  302  may then instruct the actuator  228  to adjust the first section  224  by the desired adjustment at block  812  (e.g., to maintain the desired cutting parameter as the harvester  100  travels through the field and/or to maintain the desired cutting parameter in a manner that also accounts for various other factors, such as changes in density of the crop). For example, the controller  302  may send a signal to the actuator  228  to raise the height of the first section  224  of the reel assembly  220  relative to the second section  225  such that a desired cut crop length is achieved. 
     While only certain features of the invention 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 invention