Abstract:
An agricultural implement with ground-engaging implements tracks in a direction down slope when pulled by a traction vehicle over uneven, or sloped, terrain. The implement&#39;s path from the track of the vehicle depends upon, among other things, the slope of the terrain. To compensate for this tendency to drift down slope away from the pulling vehicle&#39;s track, the implement frame is provide with controllable forward and aft pivoting wing sections to which the ground engaging implements are attached. Using a GPS receiver, precise positioning information is used to position the wing sections so that the ground engaging members are directed up slope to move the implement&#39;s track upwardly in correcting its track, with the wing sections then automatically re-positioned when the implements are on the proper track.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to strip tillage of the soil, and is particularly directed to strip tillage on sloped terrain, such as encountered on hillsides and in gullies. 
     BACKGROUND OF THE INVENTION 
     Strip tillage is a farming practice which has evolved primarily out of no-till farming. In no-till farming, the field is generally plowed under after harvest, but is left in an untilled state with crop residue covering the field. The crop residue is effective in limiting soil erosion. Strip tillage involves the tilling of a narrow strip of soil, rather than the entire field which is followed by a planter row unit directly in each of the strips. Thus, only the elongated strips, or zones, of ground will be planted with the upcoming season&#39;s row crop. In strip tillage and no-till, the farmer typically uses a less aggressive tilling method and does not completely plow or turn the soil under. Over time, farmers increase the fracture of the ground and the air pore space within the soil to enhance root growth area to support more productive plants. 
     Strip tillage requires precise positioning of the agricultural implements with each pass through the field. End strips of adjacent passes should optimally be positioned as closely as possible to ensure the development of highly productive plants. Too large a space results in a waste of soil area, while too close spacing restricts development of the plants in adjacent rows. Accurate positioning of the soil working implements becomes increasingly difficult with irregularities in the surface of the soil. When operating on a slope, the pulled implements tend to drift down slope and below the track of the traction vehicle pulling the implements, resulting in non-uniform spacing between adjacent rows. The extent of down slope drift increases with the change in elevation of the soil surface. 
     The present invention addresses these challenges in strip tillage by providing for the automatic positioning of agricultural implements in precisely placed strips for each field pass using a global positioning system (GPS) for precisely controlling inter-strip spacing during on-the-go operations. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a method and apparatus for improved strip tillage operations. 
     It is another object of the present invention to provide highly accurate positioning of an agricultural implement for each successive pass relative to a narrow strip of soil previously tilled when operating on uneven terrain. 
     A further object of the present invention to provide precise positioning of an agricultural implement to sub-inch accuracies for soil working operations on sloped terrain. 
     A still further object of the present invention is to provide automatic correction of the position of a tillage machine to provide properly spaced tillage passes relative to previously tilled strips when traversing sloped fields. 
     Yet another object of the present invention is to provide a flexible tillage frame with a satellite-based automatic positioning feature which ensures highly accurate implement positioning for strip tillage particularly on sloped fields. 
     Still another object of the present invention is to provide for the precise positioning of ground engaging agricultural implements relative to previously planted strips on sloped terrain without reference to the position of the traction vehicle pulling the implements. 
     The present invention contemplates a method and apparatus for strip tilling a field having an uneven surface, the method comprising the steps of: establishing a straight line extending the length of the field using satellite-based positioning information; determining a pre-determined offset distance from the straight line corresponding to the distance between adjacent tillage strips; traversing the field along or parallel to the straight line while pulling a draw bar having plural ground engaging implements attached thereto, the drawbar having a center section and left and right wing sections, each coupled to a respective opposed end of the center section and capable of forward and aft pivoting movement relative to the center section; comparing the position of the drawbar during a pass of the field with the pre-determined offset distance from the straight line; pivoting the left and right wing sections in first and second opposed directions relative to the center section when the position of the drawbar and the pre-determined offset distance do not coincide to correct for down slope drift of the drawbar caused by the uneven surface of the field; and pivoting the left and right wing sections in third and fourth opposed directions relative to the center section when the position of the drawbar coincides with the pre-determined offset distance to traverse the field parallel to and at the pre-determined offset distance relative to the straight line. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The appended claims set forth those novel features which characterize the invention. However, the invention itself, as well as further objects and advantages thereof, will best be understood by reference to the following detailed description of a preferred embodiment taken in conjunction with the accompanying drawings, where like reference characters identify like elements throughout the various figures, in which: 
         FIG. 1  is a top plan view of an agricultural implement having an automatic guidance system in accordance with the principles of the present invention; 
         FIG. 2  is a top plan view of the inventive agricultural implement of  FIG. 1  showing the implement making a change in its direction of travel in a first direction in accordance with the present invention; 
         FIG. 3  is a top plan view of the inventive agricultural implement of  FIG. 1  showing the implement making a change in its direction of travel in a second, opposed direction from that shown in  FIG. 2 ; 
         FIG. 4  is an upper perspective view of a typical ground engaging implement capable of use with the present invention; and 
         FIG. 5  is a simplified block diagram showing the series of steps involved in carrying out the automatic guidance method for a pull-type agricultural implement in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , there is shown a top plan view of an agricultural implement with an automatic guidance system  10  in accordance with the principles of the present invention. The agricultural implement with an automatic guidance system  10  includes an agricultural implement  12  adapted to be pulled by a traction vehicle, which is not shown in the figures for simplicity. Agricultural implement  12  includes an elongated frame member typically tubular in form  10  having a hitch  16  mechanism on its forward end for secure attachment to a traction vehicle. 
     In operation, agricultural implement  12  generally travels in the direction of arrow  11 . The longitudinal axis of elongated frame member  14  is thus aligned with arrow  11  as the agricultural implement is pulled by a traction vehicle. 
     Attached to an aft end of elongated frame member  14  is a carrier frame  18 . Carrier frame  18  includes an axle aligned generally transverse to the direction of travel of the agricultural implement  12 . Attached to opposed ends of axle  20  are first and second ground engaging wheels  22   a  and  22   b.    
     Attached to an aft end of carrier frame  18  is an aft transverse structural member  52  also aligned generally perpendicular to the direction of travel of the agricultural implement  12 . Attached to and disposed aft of the aft transverse structural member  52  is a drawbar  53 . 
     Pivotally attached to the left end of the aft transverse structural member  52 , as viewed in  FIG. 1 , by means of left pivot pin  54   a  is a left wing section  24 . Pivotally coupled to the right end of the aft transverse structural member  52  by means of a right pivot pin  54   b  is a right wing section  26 . Mounted to the left wing section  24  and to the right wing section  26  are left and right ground engaging wheels  28  and  30 , respectively. Just as the first and second wheels  22   a  and  22   b  provide support and allow for motion of the carrier frame  18 , the left and right ground engaging wheels  28 ,  30  respectively support and allow for motion of left and right wing sections  24  and  26 . 
     Mounted to an aft portion of elongated frame member  14  is a pivot mechanism  36 . Pivot mechanism  36  includes a generally flat plate  41 . Attached to flat plate  41  are first, second and third pivot pins,  42 ,  44  and  48 . First pivot pin  42  is coupled to a first end of a left draft link  32 . Second pivot pin  44  is connected to a first end of a right draft link  34 . Plate  41  is pivotally coupled to elongated frame member  14  by means of the third pivot pin  48 . 
     A second opposed end of the left draft link  32  is pivotally coupled to left wing section  24  by means of a first coupling bracket and pivot pin  38 . Similarly, a second opposed end of the right draft link  34  is pivotally coupled to the right wing section  26  by means of a second coupling bracket and pivot pin  40 . Thus, left draft link  32  is freely movable relative to first pivot pin  42  and to the first coupling bracket and pivot pin  38 , while right draft link  34  is freely movable relative to second pivot pin  44  and second coupling bracket and pivot pin  40 . 
     Pivotally attached to elongated frame member  14  and the flat plate  41  of the pivot mechanism  36  is a hydraulic cylinder  50 . Hydraulic cylinder  50  is of the dual acting type capable of both extension and retraction under the control of a hydraulic control system  66  which also typically would be mounted to agricultural implement  12 . Also shown in  FIG. 1  is the combination of GPS receiver  62  with antenna  64  coupled to a computer  63 . Computer  63  is coupled to hydraulic controller  66  for controlling its operation and is programmed to carry out the series of steps of the inventive method described in detail below. 
     As shown in  FIG. 2 , extension of hydraulic cylinder  50  causes a downward pivoting displacement of left wing section  24  and an upward pivoting displacement of right wing section  26 . Similarly, as shown in  FIG. 3 , retraction of hydraulic cylinder  50  causes upward pivoting displacement of left wing section  24  and downward pivoting displacement of right wing section  26 . It is in this manner that the left and right wing sections  24 ,  26  may be pivotally displaced in a coordinated manner about aft transverse structural member  52  in either forward or aft directions. 
     Attached to respective forward portions of the left and right wing sections  24 ,  26  are left and right slide brackets  72  and  74 . Left slide bracket  72  is in sliding engagement with first coupling bracket and pivot pin  38 , while right slide bracket  74  is in sliding engagement with second coupling bracket and pivot pin  40 . This sliding arrangement allows the left and right wing sections  24 ,  26  to be pivotally displaced in a full forward position for transport and storage of the agricultural implement with the automatic guidance system  10 . A cross member  17  is attached fixedly to elongated frame member  14  and is adapted to engage and provide support for the left and right wing sections  24 ,  26  when in the stored position. In the stored position, the left and right wing sections  24 ,  26  are positioned adjacent and generally parallel to the agricultural implement&#39;s elongate frame member  14 . 
     Attached respectively to left and right wing sections  24 ,  26  are first and second ground engaging implements such as coulters  56  and  57 . A third ground engaging implement such as a coulter  58  is attached to drawbar  53 . Each of these coulters is rigidly attached to either one of the pivoting wing sections or to the drawbar. During normal operation, additional ground engaging implements would typically be attached to the first and second wing sections  24 ,  26  and to drawbar  53 , but only three such ground engaging implements are shown in the various figures for simplicity. These grounding engaging implements may take various forms, in addition to that of coulters, such as planter units, soil working implements or fertilizer units. Typically, one ground engaging implement is provided for each row formed in strip tillage. 
     Referring to  FIG. 4 , there is shown an upper perspective view of a ground engaging implement  80  typical of the implements with which the inventive agricultural implement with automatic guidance system is intended for use. Ground engaging implement  80  is shown fixedly attached to a pivoting wing section  82  as previously described. Ground engaging implement includes a smooth front coulter  84  and a pair of gauge wheels disposed on opposed sides of the coulter, where one gauge wheel is shown as element  86 . The gauge wheels  86  set the depth of the front coulter  84  through the soil. Trailing the front coulter  84  is a soil engaging knife fertilizer  88  which forms a shallow furrow, or groove, in the soil into which fertilizer is deposited. The furrow is then covered by means of first and second disc sealers  90  and  92  to ensure that the fertilizer remains in the soil for subsequent planting operations. 
     In  FIG. 4 , the field traversed by the grounding engaging implement  80  is shown as having a lower area on the right side of the grounding engaging implement as it traverses the field in the direction of arrow  100 . A higher area of the field is shown on the left side of the grounding engaging implement  80  as it traverses the field. The tendency of the ground engaging implement  80 , and any other grounding engaging implement attached to the same pivoting wing section to which grounding engaging implement is attached, is also to drift from left to right from the higher area to the lower area of the field as shown by the direction of arrow  114 . 
     The present invention corrects for this drift caused by the uneven contour of the field by changing the orientation of the ground engaging implement  80  so that it is turned toward the higher area in the direction of the first turning direction arrow  108  shown in  FIG. 4 . Turning the grounding engaging implement  80  in the direction of the first turning direction arrow  108  causes the soil to exert a sideways pressure on the implement in the direction of arrow  110  toward the area of higher elevation in the field. The ground engaging implement&#39;s coulter  84  functions in the soil as does a boat&#39;s rudder in water by steering the ground engaging implement  90  on a desired course, or track, through the soil. This causes the grounding engaging implement  80  to travel upslope toward the higher area in initiating a correction to its course through the field. 
     When it is determined that this change in course has caused the ground engaging implement  80  to be re-positioned on the desired course for the next strip tillage row, the ground engaging implement  80  undergoes a second turn in the direction of turning arrow  112  so as to transit the field on a pre-determined course which is parallel to and offset a pre-determined distance from the previous tilled strip. Similarly, if the higher area were to the right of the ground engaging implement  80  as shown in  FIG. 4 , first turning the ground engaging implement in the direction of a second turning direction arrow  112  would cause pressure to be applied to the coulter  96  by the soil in the direction of arrow  114 . This would allow the ground engaging implement  80  to change its course in the field in a rightward direction as shown in  FIG. 4 , which correction would be maintained upslope until it was determined that the ground engaging implement  80  had reached the desired track through the field relative to the previous pass through the field. A second correction would then be introduced in the direction of the first turning direction arrow  108  to allow the ground engaging implement to remain on the desired track through the field which is parallel to and spaced a pre-determined distance from the previously formed tilled strip. 
     The operation of the present invention as just described in terms of  FIG. 4  can also be explained in terms of  FIGS. 2 and 3  for the case of the entire agricultural implement  12  having plural spaced coulters  56  and  57  respectively mounted to its left and right pivoting wing sections  24  and  26 . For example, with reference to  FIG. 2 , rearward pivoting displacement of left wing section  24  and forward pivoting displacement of right wing section  26  as shown in  FIG. 2 , results in the application of leftward pressure on first and second coulters  56 ,  58  in the direction of arrow  21  causing the agricultural implement  12  to alter its track through a field in a leftward direction. 
     Similarly, forward pivoting displacement of left wing section  24  and rearward pivoting displacement of right wing section  26  as shown in  FIG. 3 , will result in the application of increased pressure by the soil on the first and second coulters  56  and  57 . This increased pressure would be in the direction of arrow  23  in  FIG. 3  causing agricultural implement  12  to turn in a rightward direction to alter its course through the field. The change in course of the agricultural implement  12  discussed in terms of  FIG. 2 or 3  will be maintained until the position of the agricultural implement coincides with the desired track relative to the reference line through the field discussed above. A second correction is then implemented in terms of the pivoting displacement of the left and right wing sections  24 ,  26  so that the agricultural implement  12  tracks through the field on the desired course which is parallel to and displaced a pre-determined distance from the aforementioned reference line through the field. 
     Referring to  FIG. 5 , there is shown a flow chart illustrating the series of steps involved in carrying out the method of providing automatic guidance for a pull-type agricultural implement in accordance with an embodiment of the present invention. Each block in  FIG. 5  represents a step, or plural steps, in carrying out the method of the present invention. The inventive method starts at step  120  with the establishment of a referenced line in a field using two points defined by a global positioning satellite (“GPS”) system. The line will be defined typically as one side of the field to be stripped tilled. After defining a reference line in the field and storing this information in computer  63 , the user then enters a pre-determined spacing parameter between adjacent strip tillage passes over the field at step  122 . This pre-determined spacing will be dependent upon various parameters such as the type of crops to be planted and characteristics of the soil. The program stored in the computer  63  then at step  124  determines the present position of the ground engaging implement using the GPS system. The program then at step  126  determines the difference between the present position of the ground engaging implement and the pre-determined spacing between adjacent passes in the strip tillage operation at step  126 . At step  126 , the program also provides a correction signal to the hydraulic controller  66  for controlling the angle of attack of the ground engaging implement such as coulters  56  and  57 . A first correction signal is then provided to hydraulic cylinder  68  for the purpose of changing the course, or track, of the ground engaging implement through the field at step  128 . 
     The program stored in computer  63  then at step  130  compares the actual position of the ground engaging implement with the pre-determined position at step  130  during the course correction made by the ground engaging implement. When the actual and pre-determined positions of the ground engaging implement coincide, a second correction signal is provided to the hydraulic cylinder  50  for changing the track of the ground engaging implement so as to be parallel with the original reference line and located at a pre-determined distance from that reference line. 
     While particular embodiments of the present invention has been shown and described, it will be apparent to those skilled in the yard that changes and modifications may be made without departing from the invention and its broader aspects. Therefore, the aim in the appended claims is to cover all such changes and modifications that fall within the true spirit and scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as imitation. The actual scope of the invention is intended to be defined in the following claims when viewed in theirs perspective based on the prior art.