Abstract:
A method and system for automatically correcting a steering command from an auto guidance system to adjust for misalignments between the crop rows and the header due to errors which may include, but are not limited to a stack up of errors from the remote positioning system information translation, planter and harvester machine centerline differences, harvesting and planting pattern differences, and the like, that integrates row sensor information into the auto guidance system.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to automatic steering control of an agricultural harvester, such as a combine, and more particularly to a method for automatically responding to misalignment between the header and rows of crops such as corn, cotton and the like, with a steering correction based on integration of harvester row sensor information into the harvester auto guidance system. 
       BACKGROUND ART 
       [0002]    An agricultural harvesting machine for harvesting corn or maize includes a specialized header assembly for separating and guiding crops during harvesting. This header assembly typically uses row separators which create an opening to guide the stalks of the crops into stalkways containing snapping rolls that separate the crop from the stalk. Accurate positioning of the crop prior to reaching the snap rolls is important to prevent excessive crop waste due to corn head loss and the like. 
         [0003]    Modern work machines, such as tractors and agricultural combine harvesters are often equipped with remote positioning systems such as a Differential Global Positioning System (DGPS) for use with auto guidance systems. These positioning systems are limited in their ability to accurately function in crops requiring increased steering accuracy, such as corn and the like, due to “stack up” of errors. Although the DGPS may provide relatively precise accuracy as to the position of the DGPS sensor, mathematical translation of that position to the position of the planter may introduce approximation and rounding errors, and the like, which may be further compounded when translating the position of the DGPS sensor on the combine to the position of the header during harvesting. These errors may be further compounded by uneven terrain such as hills and depressions and the like. Errors may be introduced, in part, due to approximations in the height of the DGPS sensor as compared to the ground and/or header height, as well as approximations of the distance fore or aft of the DGPS sensor of the planter and/or header. 
         [0004]    In addition, the harvesting machine will likely travel a different swath order based on a different centerline than the planting machine. For example, it is not unusual to use a 24 row planter and an 8 row harvester in a particular field. The row map created using the 24 row planter uses a different reference line or machine centerline than that of the 8 row harvester. It is also beneficial to have the capability to skip passes when harvesting a field allowing the harvester to operate in a control traffic scheme that can reduce compaction and increase yield as well as allowing traditional and high value or specialized crops to be harvested from a single field. 
         [0005]    It is also desirable to unload on the go with a cart driving alongside the harvester on the left or unloading side of the machine. Thus the harvesting machine may follow a swath pattern that skips passes to always provide a previously harvested swath or road on its unloading side. 
         [0006]    These planting and harvesting variations and other sources of error may degrade the accuracy of the information used by the auto guidance system. Thus the auto guidance system may not achieve the +/−4 inch accuracy at the corn head row unit required for harvesting corn. Undesirable harvesting conditions, including excessive head loss may result if the crop is more than +/−4 inches from the centerline of the snapping rolls of the harvester. 
         [0007]    The specialized headers used for harvesting corn, and the like, include sensors on the row separators extending into the opening through which the crops pass, which sensors are sensitive to physical contact with the crops. When the sensors detect the presence of crops that are not centered between the row separators, misalignment between the header and the crop row may exist. Many combines include a “nudging” capability to supplement the auto guidance system and improve header and crop alignment. The auto guidance system uses a reference line that extends between the ends of a swath of a field called an a-b line. When the operator notices that the header and the crop row are out of alignment, the operator implements one or more nudge commands. Each command shifts the auto guidance system a-b line by a small increment, for example, 10 centimeters, to realign the header with the crop row. Inattention or operator fatigue may result in a delay in implementing the nudge command and/or undercorrection or overcorrection thus leading to undesirable harvesting characteristics and even crop loss. 
         [0008]    Reference in the above regard, Day, V et al., U.S. Pat. No. 4,726,175, which discloses a guidance control system that links the row sensors directly to one steerable wheel actuator. As the row sensors detect misalignment between the crop and the header, a valve is opened allowing hydraulic fluid flow to the steerable wheel&#39;s actuator to turn the wheel in a direction for realigning the header and the crop row. However, it is foreseen that use of a system such as this could be problematic when used with an auto guidance steering system. For instance, it is foreseen that the actuation of the steerable wheel in response to the row sensor could be interpreted by the auto guidance system as a steering error that needs to be corrected. Thus, the row sensor correction and the auto guidance system commands may conflict, causing a series of commands or inputs resulting in an oscillation of the steerable wheel. 
         [0009]    Accordingly, what is sought is an auto guidance system which includes automatic steering correction in response to header and crop row misalignment that can be adapted for use in row crop environments that can overcome and/or correct header and crop row misalignment errors due to various factors, which can include, but are not limited to, stack up of errors from the remote positioning system, uneven terrain, variations in planting and harvesting path order, and the like, and which overcomes one or more of the problems and shortcomings set forth above. 
       SUMMARY OF THE INVENTION 
       [0010]    It is an object of the present invention to provide a method and a system for automatically providing a steering correction to a steering command of an agricultural harvesting machine auto guidance system in response to a misalignment between a row of crops and a header row. In this method, crops, such as corn or cotton, are planted in rows, and remote positioning system information is used to generate a map of information representative of locations of the rows of crops. This map is used to create a harvesting swath pattern which is used by the harvesting machine auto guidance system, along with remote position sensing information, to align row units of the machine with rows of crops and produce steering commands to steer the harvesting machine along the rows. An apparatus, such a pair of row sensors is provided in association with the row units for sensing an amount of misalignment between the row units and the rows of crops and outputting information representative thereof to the auto guidance system. If the amount of misalignment is beyond a predetermined range and the steering command will maintain the amount of misalignment, the steering command is corrected as a function of the amount of misalignment between the row unit and the row of crops. For example, if the row sensors indicate the rows of crops are too far to the left within the row units, and the steering command steers the harvesting machine straight or to the right, the steering command is corrected to steer the harvesting machine to the left to realign the row units and the rows of crops. 
         [0011]    As an alternative, the auto guidance system may execute the steering command prior to checking the row sensors for misalignment. If the row sensors indicate misalignment between the row unit and the row of crops, than a steering correction command is executed. 
         [0012]    It is another object to provide a system which automatically provides a steering correction to the steering command of an agricultural harvesting machine, in response to misalignment between rows of crops and the cutting element of the machine. A header on the harvesting machine includes row dividers that define an aperture operable to isolate a crop in a row of crops and guide the crop along the aperture towards a cutting element. Row sensors located on the row dividers provide an indication of a location of the crops relative to the cutting element within the aperture. The automatic guidance system of the harvesting machine is operable to receive machine position information from a remote position sensing system, such as a differential global positioning system, and to determine a steering command to control the machine to follow a predetermined path along the rows of crops. When the row sensors indicate that the location of the crop is beyond a predetermined range of locations in the aperture the steering command is automatically adjusted to align the crops with the cutting element of the harvester 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    These and other advantages of the present invention are best understood with reference to the drawings, in which: 
           [0014]      FIG. 1  is a side view of a front portion of an agricultural combine including a specialized header for harvesting corn that may be used with the method and system of this invention; 
           [0015]      FIG. 2  is a partial top view of the header of the combine of  FIG. 1 ; 
           [0016]      FIG. 3  is a simplified top view of the combine of  FIG. 1  depicting use of a 6 row header; 
           [0017]      FIG. 3A  is a simplified top view of a tractor equipped with a 24 row planter and the combine of  FIG. 1  equipped with an 8 row header depicting one possible variation between the planter centerline used during planting and the combine centerline used during harvesting; 
           [0018]      FIG. 4  is a block diagram representation of the system of the invention; 
           [0019]      FIG. 5  is a top level logic flow diagram depicting steps of one embodiment of the method of the invention; and 
           [0020]      FIG. 6  is a top level logic flow diagram depicting steps of another embodiment of the method of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    Referring now to the drawings,  FIG. 1  shows a front portion of a combine  10  with a specialized header  14  for harvesting rows of crops such as corn. An operator cab  12  is equipped with a remote positioning system sensor  16 , such as a differential global positioning system (DGPS) sensor, for receiving information representative of the combine  10  position in a field.  FIG. 2  shows a partial top view of header  14  including row dividers  18  and row sensors  20 . A pair of row dividers creates a row unit  22  defining an aperture  24 . As combine  10  harvests a swath of a field, row dividers  18  separate stalks of the crops within the rows and guide the stalks towards snapping rolls  26  in stalkways  28  of header  14 . Row sensors  20  may be equipped with fingers  21  which physically detect crops within aperture  24  and provide an indication of crop position or alignment with a centerline  23  of row unit  22 . 
         [0022]    As shown in  FIGS. 3 and 4 , combine  10  is equipped with an automatic guidance system  30  that determines and provides steering commands for a steering system  34  of combine  10  when harvesting crops. Automatic guidance system  30  uses a previously generated map  32 , typically created while planting, that includes information representative of locations of rows of crops as well as information from DGPS sensor  16  which is representative of combine  10  location. During harvesting, it is desirable to align the stalks with stalkways  28  along centerline  23  to minimize crop damage or loss at snapping rolls  26  (see  FIG. 2 ). 
         [0023]    Errors that may contribute to misalignment between the stalks and stalkways  28  may be introduced from calculations translating DGPS sensor  16  position to header row unit  22  position based on the geometry of combine  10 . Variations or approximations in distances denoted x, y and z on combine  10  shown in  FIGS. 1 and 3  may impact the auto guidance system  30  steering commands, which in turn, may affect the alignment of rows of crops and header row unit  22 , which may ultimately affect the alignment of the stalks with snapping rolls  26  in stalkways  28 . In addition, similar errors may be inherent in map  32  generated during planting due to analogous variations or approximations in distances denoted X and Z (Y coming out of the page) in the geometry of planter  29  shown in  FIG. 3A . 
         [0024]    An additional source of error may be introduced during initial alignment of combine  10  with the rows of crops at the beginning of a swath. It is not unusual to use a 24 row planter  29  during planting and a 6 or 8 row header  14  on combine  10  during harvesting. As shown in  FIG. 3A , these vehicles may have auto guidance system  30  reference lines, such as vehicle centerlines denoted CL 1  and CL 2 , at different locations. This variation in reference lines and the likelihood that the field will be harvested in a different swath pattern than it was planted, may also impact the steering commands generated by auto guidance system  30  and therefore the alignment of the rows of crops and header row unit  22 . 
         [0025]    Variations in terrain over a field such as ruts, holes, hills, and the like, may also ultimately contribute to alignment errors. For example, combine  10  will likely encounter a change in terrain, such as a dip or a rut  31 , during harvesting the swath shown in  FIG. 3A . Planter  29 , having different centerline CL 1  and wheel locations, would not likely have encountered rut  31 . It is therefore possible that no indication of the terrain change, or any resulting variation in crop location resulting therefrom, is represented in map  32 . Errors such as those listed herein may stack up and the steering commands provided by auto guidance system  30  may produce some misalignment between row units  22  and crop rows. 
         [0026]    According to the invention, auto guidance system  30  integrates alignment information from row sensors  20  to correct or adjust the steering command to steering system  34  as shown in  FIGS. 3 and 4 .  FIG. 3  shows a top view of combine  10  with interconnections between DGPS sensor  16 , header row sensors  20  and auto guidance system  30 . Auto guidance system  30  provides steering commands to steering system  34  which provides commands to actuate steerable wheels  35  of combine  10 . 
         [0027]      FIG. 5  illustrates an embodiment of the method of this invention. Using map  32  generated during planting, a harvesting swath pattern will be implemented. At block  40  auto guidance system  30  is verified as operational, and at block  42  DGPS information is received by auto guidance system  30 . Based on DGPS information and information from map  32 , a steering command is determined by auto guidance system  30  and executed by steering system  34  at blocks  44  and  46  respectively. At block  48  auto guidance system  30  monitors information from row sensor  20 . If row sensor  20  indicates misalignment of crops relative to centerline  23  of row unit  22  at decision block  50 , control is directed to block  52  where auto guidance system  30  determines a steering correction and steering system  34  executes that steering correction at blocks  52  and  54  respectively. 
         [0028]    Another embodiment of the method of the invention is shown in  FIG. 6 . Again using map  32  generated during planting, a harvesting swath pattern will be implemented. At block  60  auto guidance system  30  is verified as operational, and at block  62  DGPS information is received by auto guidance system  30 . Based on DGPS information and information from map  32 , a steering command is determined by auto guidance system  30  at block  64 . Next, auto guidance system  30  receives information from row sensors  20 . If row sensors  20  indicate misalignment of crops relative to centerline  23  of row unit  22  at decision block  68 , auto guidance system  30  determines if the steering command will re-align the crops relative to centerline  23  at decision block  70 . If the steering command will not re-align the crops relative to centerline  23 , auto guidance system  30  computes a correction to, or modification of, the steering command at block  72 . Finally, steering system  34  executes the steering command at block  74 . 
         [0029]    It will be understood that changes in the details, materials, steps, and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention. Accordingly, the following claims are intended to protect the invention broadly as well as in the specific form shown.