Abstract:
The invention provides a guidance system for guiding a towed agricultural implement such as seeders, planters, sprayers and the like, along a preferred path between rows of growing crop or standing stubble by sensing the rows of growing crop or standing stubble with a uniquely designed paddle-like sensor means which does not engage the ground.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a guidance system for guiding a towed agricultural implement such as seeders, planters, sprayers and the like, along a preferred path. More particularly, the present invention relates to a guidance system that senses rows of growing crops or previous crop stubble with a uniquely designed paddle-like sensor. 
       BACKGROUND OF THE INVENTION 
       [0002]    No-till farming practices, also known as conservation tillage or zero tillage, have become common for both row crops and solid seeded crops. No-till farming allows for the growing of crops from year to year without disturbing the soil through tillage. In no-till farming, the soil is left intact and crop residue and standing stubble from the previous year&#39;s crop are left to aid in moisture retention, to prevent soil erosion, etc. 
         [0003]    In no-till farming it is often desirable to guide seeders, planters, sprayers and the like that are being towed by a work vehicle such as a tractor between the rows standing stubble of the previous year crop. For example, when seeding, it is desirable to plant the seeds between the rows of standing stubble. Thus, specialized equipment has been developed to ensure seeding between rows of standing stubble (see, for example, U.S. Pat. No. 4,624,197, U.S. Pat. No. 4,616,712 and U.S. Pat. No. 6,553,925). As pointed out in U.S. Pat. No. 4,624,197, the advantages of seeding between previous years stubble rows in a no-till cropping system is that it reduces clogging or build up of trash from the previous crop, and reduces wind and water erosion by leaving the old stubble standing. 
         [0004]    Many different devices have been used for sensing the stubble or growing plants to send a signal to the towing hitch, allowing it to move left or right so that the towed implement follows the desired path. Ground engaging sensors, such as disclosed in U.S. Pat. No. 6,553,925 and U.S. Pat. No. 4,616,712, sense the furrows or base of the plant stalks. Other sensors, such as wand sensors as disclosed by U.S. Pat. No. 4,930,581, U.S. Pat. No. 5,156,219 and U.S. Pat. No. 4,821,807 sense the side of the plants or stalks without engaging the ground. However, there are drawbacks with both ground engaging sensors and wand sensors. 
         [0005]    There are also times where it is desirable to guide an agricultural implement towed by a work vehicle between rows of growing crops. For example, a guidance system may be beneficial when towing a cultivator to remove weeds, etc. growing between rows of growing crops. Thus, it is important that the cultivator tools are towed through the field of field such that the tools do not engage the crop. 
         [0006]    There are several problems that may arise when using ground engaging sensors, in particular in no-till farming. For example, the furrows left by the previous year&#39;s seeding operation are often distorted by the weather, i.e., the rains filling them in, or traffic on the field from harvest equipment or spraying equipment. Thus, if the ground engaging sensor is designed to sense the furrows, an uneven furrow may give false readings. Also, ground engaging sensors can be affected stones, clumps of dirt or lumps of straw left by harvesters, etc. so the sensors riding on the ground often give false readings. Thus, often it is necessary to implement a second sensor to give the operator an option as to which sensor is working properly because stubble rows have been trampled by previous field operations (see, for example, U.S. Pat. No. 6,553,925). 
         [0007]    Ground engaging sensors are more complex and expensive than a sensor that only engages the crop, as they need to be able to follow the contours of the ground and to be lifted into and out of transport position. They are also subject to damage from rocks and wear. Another disadvantage of ground engaging sensors is that with narrow row spacing cereal crops, it is often desirable to harrow the field after harvest to further spread and break up straw left by the harvesters in order to provide a better seed bed when seeding into wet spring conditions. However, such a harrowing operation fills in the furrows, hence, furrow sensors would not work in a harrowed field. 
         [0008]    There are also several problems associated with using wand sensors in no-till conditions. Wand sensors are most often used in growing crops where damage to the plants is a concern. Each of the wand sensors shown in U.S. Pat. No. 4,930,581, U.S. Pat. No. 5,156,219 and U.S. Pat. No. 4,821,807 are wishbone shaped whereby the outer edges are rods designed to engage the crop plants or the previous crop stalks. However, for example, in no-till cereal stubble, the stalks are often 6 to 14 inches high, the row width generally about 2 to 6 inches wide and the space between the rows of stalks generally about 6 to 12 inches. Thus, if the wand gets caught in the middle of the row instead of between the rows it will have a tendency to stay there instead of moving to the desired position between the rows. 
         [0009]    Another drawback associated with many of the row sensor devices taught in the prior art arises when these devices are used in narrow row spacing small grains such as Wheat, Barley, or Canola stubble. Because of the narrow row spacing there is potential for the sensor device to get off track for several reasons; rows are knocked down from previous operations, areas of the stubble is lodged and flat on the ground or the moving hitch has moved as far as it can in one direction and cannot go any further. It would be desirable for a sensor device to also provide the operator with the ability to reset the device by centering the towed implement relative to the towing vehicle and starting the guidance system over again. 
         [0010]    Thus, it is desirable to have a sensor device that is generally not affected by the contour of the ground or debris on the ground such as stones, straw, etc. and that generally does not get caught in the middle of the stubble row. 
       SUMMARY OF THE INVENTION 
       [0011]    In one aspect of the present invention, a guidance system for positioning an agricultural implement having a hitch and towed by a work vehicle on a preferred path for operating between rows of growing crops or standing stalks or stubble, said hitch being pivotally attached to the distal end of a hitch plate and the work vehicle being pivotally attached to the proximal end of the hitch plate, comprising:
   (a) a paddle-like sensor means having a right edge and a left edge operably mounted on the implement such that the sensor means does not engage the ground;   (b) a sensing means for sensing when a force is being applied to one of the right edge or left edge of the sensor by one or the other of the rows and producing a corresponding signal; and   (c) means for receiving the signal and for effecting the lateral rotation of the hitch plate thereby laterally moving the towed implement either to the right or left relative to the work vehicle so that the force is no longer being applied to either the right edge or left edge of the sensor means.   
 
         [0015]    The present guidance system is particularly useful in guiding a seeder between rows of standing stalks of stubble left in a field during no-till farming. However, it is understood that the guidance system could be used to guide any towed implement such as a cultivator, fertilizing implement, etc. between rows of either standing stubble or growing crops rows. 
         [0016]    Preferably, the width of the sensor means at its widest point is only slightly narrower than the gap between the rows of standing stalks or growing crops that are being sensed. 
         [0017]    In one embodiment, the paddle-like sensor means is a substantially solid paddle being narrower at the front end and wider at the back end, the width at the back end being slightly narrower than the gap between the crops or stalks that are being sensed. In another embodiment, a portion of the back end of the paddle-like sensor means is essentially concave such that in the event that the sensor begins to ride on top of a row of crops or stalks, a force will be applied to the right or left sloped surface of the concave portion of the sensor. The sensing means can also sense this force being applied to either sloped surface and will produce a corresponding signal. The signal receiving means will receive the signal and effect the lateral rotation of the hitch plate. Thus, the lateral rotation of the hitch plate will laterally move the towed implement either to the right or left relative to the work vehicle so that the force is no longer being applied to either the right or left sloped surface of the sensor means. Thus, the concave back end of the paddle-like sensor means will reduce the chances and the length of time the sensor means tends to stay on top of the row. The paddle-like sensor means is preferably made from a durable resin such as a plastic resin, a light-weight metal or other durable materials known in the art. 
         [0018]    In operation, the paddle-like sensor means is preferably positioned about 3 to about 12 inches above the ground so that the sensor does not encounter obstacles on the ground. Of course, it is understood that the position of the sensor will depend on a number of factors such as the type of growing crop; the height of the growing crop or standing stubble; the condition of the soil, i.e., how rocky the soil is, and the like. By having the sensor means work above the ground level and only engage the standing stalks crop, the farmer can conduct field operations after harvest and prior to seeding such as spraying or harrowing without causing a negative affect on the sensor&#39;s ability to operate properly. 
         [0019]    When the guidance system is first put into operation, i.e., switched on, the sensor means is preferably positioned between the rows of crops or stalks such that neither the right or left edge is touching either row. However, if either the right or left edge of the paddle-like sensor means engages the growing crops or standing stalks, this will cause a slight lateral movement of the sensor means, which in turn will activate the sensing means to produce a corresponding signal. 
         [0020]    In one embodiment, the sensing means comprises a pair of steering sensor switches, which produce an electrical signal corresponding to the force applied to the sensor means. The electrical signal then activates or opens at least one electric over hydraulic solenoid valve. The activated hydraulic solenoid valve in turn causes the release of hydraulic fluid to at least one hydraulic cylinder operably connected at one end to the hitch plate and at the other end to the hitch of the towed implement, thereby causing the hitch plate to laterally rotate either to the left or the right which in turn causes the towed implement to move laterally either to the right or left and reposition the sensor means back into the middle of the gap between the rows of crops or stalks. 
         [0021]    In one embodiment, a double acting hydraulic solenoid valve and a double acting hydraulic cylinder are used. In another embodiment, a pair of hydraulic solenoid valves and a pair of corresponding hydraulic cylinders are used. 
         [0022]    In another aspect of the present invention, the guidance system further comprises a centering system which provides the operator with the option of centering the towed implement relative to the towing vehicle by temporarily overriding the guidance system. This may be desirable in situations where the sensor means is no longer sensing the rows of crops or stubble, for example, when the sensor means encounters trampled or lodged crop or a patch of weeds, when the sensor means is riding on top of a row, when the operator first starts the farming operation or when starting a new row of seeding, etc. In these circumstances it may be desirable to turn off the guidance system and turn on the centering system to center the towed implement relative to the towing vehicle so that the towed implement and towing vehicle are now aligned. The operator can then position the sensor means of the guidance system between the rows again and re-engage the guidance system. Thus, the centering system operates to realign the towed implement prior to engaging the guidance system. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The features and advantages of the invention will become more apparent from the following detailed description of the embodiment with reference to the attached diagrams wherein: 
           [0024]      FIG. 1   a  is a top view of a hitch with an embodiment of the guidance system of the present invention attached thereto. 
           [0025]      FIG. 1   b  is an enlarged top view of an embodiment of the sensor means, which is shown contacting a row of growing crops or standing stubble, and an embodiment of the sensing means for sensing said contact. 
           [0026]      FIG. 1   c  is a cross-section along lines B-B of the embodiment of the sensor means shown in  FIG. 1   b.    
           [0027]      FIG. 1   d  is an enlarged top view of an embodiment of the hitch plate with the hydraulic cylinders attached thereto. 
           [0028]      FIG. 1   e  is a side view of an embodiment of the sensor means and sensor mounting arm which mounts the sensor means to the hitch of the towed implement such that the sensor means does not contact the ground. 
           [0029]      FIG. 2  shows the hydraulics of an embodiment of the guidance system and centering system of the present invention. 
           [0030]      FIG. 3  shows the electrical circuitry of an embodiment of the guidance system and centering system of the present invention. 
           [0031]      FIG. 4   a  is a top view of a hitch with an embodiment of the centering system of the present invention attached thereto. 
           [0032]      FIG. 4   b  is an enlarged top view of the hitch plate and centering system. 
           [0033]      FIG. 4   c  is a side view of an embodiment of the centering system. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0034]    The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments contemplated by the inventors. The detailed description includes specific details for the purpose of providing a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details. 
         [0035]    With reference first to  FIGS. 1   a  to  1   e,  one embodiment of the present invention will be described.  FIG. 1   a  is a top view of a guidance system  10  of the present invention that has been operably attached to hitch  28  of the towed implement (not shown). Hitch  28  is pivotally attached to the distal end of hitch plate  30  by means of pivot pin  34 . The proximal end of hitch plate  30 , in turn, is attached to a towing vehicle such as a tractor (not shown) by means of hitch pin  32 . 
         [0036]    The guidance system  10  comprises sensor means  14 . As can be seen more clearly in the expanded top view of sensor means  14  in  FIG. 1   b,  in this embodiment sensor means  14  is shaped like a paddle having a wider end  18  and a narrower tapered end  20 . The narrow end  20  of sensor means  14  is pivotally attached to sensor mount arm  24  by means of pivot pin  21 . Sensor mount arm  24  is mounted to hitch  28  of the towed implement by means of hitch mount arm  26  such that sensor mount arm extends downwardly from hitch  28  towards the ground and sensor means  14  extends from sensor mount arm  24  so as to be substantially parallel to the ground. This can be seen more clearly in  FIG. 1   e,  a side view of the sensor means  14  mounted on hitch  28 .  FIG. 1   e  shows the sensor means  14  mounted substantially parallel to and raised a few inches above ground  31 . Height adjustment bolt  29  allows for sensor mount arm  24  to be raised or lowered, depending on crop or stubble being sensed. Routinely, sensor means will be between about 3 to about 12 inches off the ground. 
         [0037]    As can be seen in the expanded view of sensor means  14  in  FIG. 1   b,  sensor means  14  has left and right edges,  16  and  16 ′, respectively, which edges sense the rows of growing crops or standing stubble. As shown in  FIGS. 1   a  and  1   b,  the sensor means is positioned between left and right rows of crop or stubble,  12  and  12 ′, respectively. However, as shown in  FIG. 1   a,  there may be times when the towed implement and hitch  28  are not centered, i.e., in this instance, path  13  is slightly to the right of center. Because of the misaligned path of the towed implement and hitch  28 , as shown in  FIG. 1   a,  the right edge  16 ′ of sensor means  14  is now touching right row  12 ′. Thus, a force is now being applied to right edge  16 ′, which force causes the sensor means  14  to pivot towards the left. The pivotal movement of sensor means  14  (either to the right or left) causes the narrow tapered end  20  of sensor means  14  to activate one or the other of steering sensor switches  22 ,  22 ′. In the instance shown in  FIGS. 1   a  and  1   b,  narrow tapered end  20  is activating steering sensor switch  22 ′. 
         [0038]    When turned on, steering sensor switches  22 ,  22 ′ will provide an electrical signal to a corresponding hydraulic solenoid valve, which valve in turn causes the release of hydraulic fluid to one or the other of a pair of hydraulic cylinders  36 ,  36 ′. The hydraulic cylinders  36 ,  36 ′ are connected at one end to hitch plate  30  and at the other end to hitch  28 , such that when one or the other of the hydraulic cylinders is activated the hitch plate  30  will pivotally rotate either to the right or the left, thereby causing the towed implement and hitch  28  to laterally move to the right or left and hence centering the senor means  14  in between the rows of growing crop or standing stubble once again. 
         [0039]    The hydraulics and the electrical circuitry of the present invention are shown in more detail in  FIGS. 2 and 3 , respectively. As can be seen in  FIG. 3 , control box  50 , which is preferably situated in the cab of the towing vehicle, supplies power to the guidance system when the guidance system (GS) switch is switched on. When either steering sensor switches  22 ,  22 ′ of the guidance system are subsequently switched on, which will occur when the sensor means is off-center, the turned-on steering sensor switch will send an electrical current to respective hydraulic solenoid valves  52 ,  52 ′. With reference now to  FIG. 2 , when either hydraulic solenoid valve  52 ,  52 ′ is activated, it will send hydraulic fluid to corresponding hydraulic cylinder  36 ,  36 ′. 
         [0040]    The operation of the hydraulics and electrical system will be further described using the example shown in  FIGS. 1   a  to  1   b.  In  FIGS. 1   a  and  1   b,  the narrower tapered end  20  of sensor means  14  is being pushed into steering sensor switch  22 ′ as a result of the force being applied to right edge  16 ′ by the crop or stubble row  12 ′, which force allows the senor means  14  to pivot about pivot pin  21 . The force applied to steering sensor switch  22 ′ turns on the steering sensor switch  22 ′, which then sends an electrical signal (current) to hydraulic solenoid valve  52 ′. Hydraulic solenoid valve  52 ′ effects the release of hydraulic fluid to hydraulic cylinder  36 ′, which cylinder expands so that the hitch plate  30  pivots or rotates to the left and in turn towed implement and hitch  28  moves to the left until there no longer is any force being applied to either left edge  16  or right edge  16 ′. It is understood that a pneumatic solenoid valve system coupled with pneumatic cylinders could also be used. 
         [0041]      FIG. 1   c  is the cross section of the wider end  18  of sensor means  14  along line B-B as shown in  FIG. 1   b.  In this embodiment, a portion of the wider section  18  is concave or bow-shaped to facilitate the guidance of the sensor means off the top of a row of crops or stubble in the event sensor means  14  wanders on top of same. As can be seen in  FIG. 1   c,  sensor means  14  further comprises left sloped surface  17  and right sloped surface  17 ′. Under normal operating conditions, left and right edges  16 ,  16 ′ are sufficient to guide the sensor means  14  and hence the tools of the towed implement between the rows. However, if sensor means  14  wanders onto the top of a row, a force will be applied to either left sloped surface  17  or right sloped surface  17 ′ when either of these surfaces contacts the row. These forces will also cause the sensor means to pivot either to the right or the left around pivot point  21 , thereby causing the narrower tapered end  20  of sensor means  14  to be pushed into either steering sensor switch  22  or  22 ′ and ultimately activating the corresponding hydraulic cylinder. Thus, the guidance system will be activated and the sensor means  14  will ultimately be move to the left or right allowing it to slide off the crop or stubble row. It is understood, however, that the sensor means being concave is a preferred feature and that a substantially planar sensor means will also successfully guide the tools of a towed implement between the rows. 
         [0042]      FIG. 1   d  is an expanded view of a portion of hitch  28  and hitch plate  30 . Hitch  28  further comprises a centering system  40 , which will be described in more detail with reference now to  FIGS. 4   a  and  4   b.  There are instances where it may be advantageous for an operator to be able to center the towed implement relative to the work vehicle by a separate system from the guidance system. For example, there may be times where the towed implement encounters an area where the crops or stubble have been trampled or where there is a patch of weeds and it may be necessary to re-center the towed implement relative to the work vehicle and starting the guidance system once again. Hence, the guidance system of the present invention may further comprise centering system  40 . Thus, the operator has the option of overriding the guidance system by switching off the GS switch and instead switching on the CTR (centering) switch, which is also found in control box  50  (see  FIG. 3 ). Now, the electrical current is being supplied to centering system  40  instead of guidance system  10 . 
         [0043]      FIGS. 4   a  to  4   c  illustrates centering system  40 , which operates to align the towed implement with the work vehicle by aligning pivot point  34  with pivot point  32 . As previously mentioned, there may be situations where the sensor means of the guidance system is no longer sensing the rows of crops or stubble. Thus, it may be desirable for the operator to turn off the guidance system and turn on the centering system and center or align the towed implement relative to the work vehicle and start all over again. 
         [0044]    Centering system  40  is positioned on hitch  28  so as to be operably associated with hitch plate  30  as follows. Centering system  40  comprises a pair of centering electric switches  60 ,  60 ′, each having corresponding activating levers  62 ,  62 ′. Hitch plate  30  comprises flat bar  64 , which is welded on to hitch plate  30  so that it extends upwardly between activating levers  62 ,  62 ′. This is seen most clearly in  FIG. 4   c.  Thus, when the center line of the towed implement is not aligned with the center line of hitch  30 , flat bar  64  will exert a force on either activating levers  62 ,  62 ′, depending upon whether the towed implement is off center to the left or right of the center line of the hitch. For example, as shown in  FIGS. 4   a  and  4   b,  hydraulic cylinder  36 ′ is extended so that hitch plate  30  is pivoted to the left. Thus, in order to center the towed implement, hydraulic cylinder  36  must be activated to pivotally rotate the hitch plate  30  to the right. 
         [0045]    Hydraulic cylinder  36  is activated as follows. Because hitch plate  30  is pivotally rotated to the left, this causes flat bar  64  to exert a force onto activating lever  62 , as shown in  FIGS. 4   a  and  4   b.  Activating lever  62  in turn activates centering electric switch  60 . With reference to  FIG. 3 , it can be seen that when centering electric switch  60  is switched on it sends an electrical signal to hydraulic solenoid valve  52 . With reference now to  FIG. 2 , hydraulic solenoid valve  52  effects the release of hydraulic fluid to hydraulic cylinder  36 , which cylinder expands so that the hitch plate  30  rotates to the right until there no longer is any force being applied to either activating levers  62 ,  62 ′ by flat bar  64 . At this time, the towed implement will be aligned with the work vehicle. 
         [0046]    While the invention has been described in conjunction with the disclosed embodiments, it will be understood that the invention is not intended to be limited to these embodiments. On the contrary, the current protection is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention. Various modifications will remain readily apparent to those skilled in the art.