Abstract:
A control system and method of operation of a product distribution apparatus or machine that uses map based information to disengage the dynamic down force control for certain designated areas of the field. These areas can be roadways or waterways that are not planted with seed but through which the machine does operate. The control system disengages the down force dynamic control when the designated areas are reached and leaves the down force applied by the actuator at the magnitude immediately prior to entering the area or at some other desired level. This magnitude of down force will typically be much closer to the magnitude needed when the roadway, waterway or other designated area has been crossed.

Description:
FIELD 
     This disclosure relates to a control system for and method of operating a product distribution machine and is described in the context of an agricultural seeding machine. 
     BACKGROUND 
     Modern agricultural implements for sowing seed or distributing other products such as fertilizers and chemicals typically have one or more row units for distributing product in rows in a field as the implement is moved over the field. Various types of implements are known, including, but not limited to planters, drills, air seeders and nutrient applicators. Such machines are referred to herein generally as a product distribution apparatus or machine. When the distributed product is placed under the soil surface, a furrow opener is used to open a furrow into which the product is deposited. The furrow is then closed, covering the product. A typically opener is a single or double disc opener having one or two discs oriented at a slight angle to the forward direction of travel. A depth regulation member is positioned near the opener to limit the penetration of the opener into the soil to produce a furrow of the desired depth. 
     A downward force is needed for the opener to penetrate the soil to the desire depth. When the opener is fully penetrating the soil, the depth regulating member, often in the form of a “gauge wheel,” contacts the soil surface. The physical weight of the row unit together with the weight of any product stored on the row unit provides a downward force to help the opener penetrate the soil. However, this weight is often insufficient to ensure full penetration of the opener. It has long been the practice to provide supplemental down force to the row unit in the form of a mechanical spring arrangement. Such spring arrangements are adjustable so the operator can select a desired amount of supplemental down force before operating the implement. Changes in the amount of down force during operation is not possible. 
     More recently, the mechanical springs have been replaced with hydraulic or pneumatic actuators that allow the operator to make changes to the down force during machine operation. Changes are made through a control system that adjusts the hydraulic or pneumatic pressure delivered to each actuator. Even more recently, active or dynamic control of the down force is accomplished with a load sensor to measure to the soil reaction force on the depth regulation member. With dynamic control of the down force, a control system automatically operates the down force actuators by changing the system pressure in response to changing soil conditions in the field as the machine is moved over a field to achieve a desired soil reaction force on the depth regulation member. 
     Such active control systems can produce wide variations in the hydraulic or pneumatic pressures of the down force system as the machine moves through a field. A high capacity air compressor or hydraulic pump is needed to achieve the variation in a reasonable time. A high capacity system adds considerably to the overall cost. Large variations in the system pressures can be reduced by turning off the dynamic control of the down force for certain areas the field. 
     SUMMARY 
     A control system and method of operation of a product distribution apparatus is provided that uses map based field information to disengage the dynamic down force control for certain designated areas of the field. These areas can be roadways or waterways that are not planted with seed but through which the machine is operated. The harder soil in these areas causes the down force system to compensate by significantly increasing the pressure and thus the down force on the row unit. Once the area is crossed, and the machine returns to soil to be seeded, the down force is now much higher than needed, resulting in excessive soil compaction caused by the depth regulation member adjacent the furrow. The excessive soil compaction reduces crop yield. It may require several meters of travel before the down force can be reduced to the appropriate level. 
     The control system described below disengages the down force dynamic control when the designated areas are reached and leaves the down force applied by the actuator at the magnitude immediately prior to entering the area or at some other desired magnitude. This magnitude of down force will typically be much closer to the magnitude needed when the roadway, waterway or other designated area is crossed. By maintaining the down force in the designated area at the level prior to entering the area, upon exiting the area, the down force will be at a magnitude close to the desired amount. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a common row unit of a row crop planter; 
         FIG. 2  is a schematic view of a control system for the dynamic down force system; and 
         FIG. 3  is a plan view of a field map. 
     
    
    
     DETAILED DESCRIPTION 
     With Reference to  FIG. 1 , a portion of a seeding machine  10  is shown. Seeding machine  10  is in the form of a row crop planter but may also be other forms of machines.  FIG. 1  illustrates a single row unit  12  of a multi-row planter, with each row unit  12  being substantially identical and connected to a machine frame shown as a tool bar  14 . Only a single row unit  12  is shown and described below for simplicity sake. 
     Row unit  12  includes a row unit frame  16  which is attached to the tool bar  14  by parallel linkage  18 . Tool bar  14  in turn is coupled to a traction unit (not shown), such as an agricultural tractor. For example, the tool bar may be coupled to an agricultural tractor using a draw bar or 3-point hitch assembly. Tool bar  14  may be coupled with transport wheel assemblies, marker arms, etc. which may be of conventional design and not shown for simplicity. 
     Row unit frame  16  carries a double disc furrow opener  20  for forming a seed furrow  26  in soil  27 . A pair of gauge wheels  24  are provided which function as furrow depth regulation members and are respectively associated with the pair of discs of double disc furrow opener  20 . More particularly, each gauge wheel  24  is positioned generally in line with and immediately adjacent to the outside of each respective disc of double disc furrow opener  20 . The gauge wheels  24  may be vertically adjusted relative to the opener discs to adjust the depth of the furrow which is cut into the soil by the double disc furrow opener  20 . 
     A seed meter  32  is also carried by row unit frame  16 . Seed meter  32  receives seed from a seed hopper  28  carried above the seed meter on the frame  16 . The seed meter drive is not shown but may be of the type shown in U.S. Pat. No. 7,571,688 having a flexible cable drive with a clutch mechanism that enables the seed meter drive to be selectively disengaged to turn off the seed meter. Seed meter  32  delivers seed sequentially to a seed tube  36  through which the seed falls by gravity to the furrow  26 . The seed meter  32  and seed tube  36  form a product dispenser to dispense product to the furrow  26 . In this illustration, the product is seed but other meters can be used to dispense fertilizer, herbicides, insecticides or other chemicals. 
     A pair of closing wheels  38  follow behind the gauge wheels and are positioned generally in line with double disc furrow opener  20 . Closing wheels  38  are preferably biased in a downward direction and have a peripheral edge with a shape which may vary, depending upon the application. Closing wheels  38  push soil back into the furrow  26  upon the product deposited therein. 
     The row unit  12  is equipped with a row unit down force actuator  40  in the form of an adjustable pneumatic down force cylinder  44 . The row unit down force actuator  40  acts between the toll bar  14  and the lower links of the linkage  18  to apply down force on the row unit and the row unit components engaging the soil. The down force applied by the cylinder  44  ensures that the double disc furrow opener  20  is forming the furrow  26  to the desired depth. The down force applied to the row unit by the actuator  40  is shown by the arrow F D . The row unit weight also produces a down force shown by the arrow F G  acting through the center of gravity of the row unit. The force F G  varies over time as the level of product in the seed hopper  28  and chemical hopper  30  changes during operation of the machine  10 . These two downward acting forces, F D  and F G  are counter-acted by upward forces acting on the row unit. The opener penetrates the soil and has a force F O  acting upward on the opener. When the opener  20  is fully penetrating, the gauge wheels  24  will be in contact with the soil and a soil reaction force F R  acts upward on the gauge wheels. An additional upward force on the row unit includes the force F C  acting on the closing wheels  38 . 
     A minimum soil reaction force F R  is desired to ensure that the opener is fully penetrating the soil to the desired depth. If the opener is not fully penetrating, the gauge wheels will not touch the soil and F R  will be zero. Thus, some level of force F R  greater than zero is desired to ensure there is full penetration. The magnitude of the force F R  can be measured by a sensor or load cell in a variety of locations on the row unit. One example is a load sensing pin  46  in the gauge wheel depth adjustment link  48 . Adjustment link  48  bears against and resists upward movement of the pivot arm  50  supporting the gauge wheels  24 . A suitable load sensing pin is shown in WO2008/086283 A2. A controller  52  of a control system  54  receives a sensor output signal from the load sensing pin  46  and controls the pressure in the cylinder  44  accordingly to achieve the desired soil reaction force F R  on the gauge wheels. 
     As the machine  10  is moved through a field, the soil conditions will not be constant. In some areas of the field, the soil will be harder than in other areas. When the soil is harder, the force F O  required for full opener penetration will increase. If the down force F D  applied to the row unit remains constant, the soil reaction force F R  and the closing wheel force F C  will decrease and possibly go to zero. To avoid this, the controller  52  dynamically or actively monitors the output of the sensor  46 . As the force F R  decreases, with harder soil, the controller will operate the actuator  40  to increase the down force E D  acting on the row unit to maintain the desired force F R  on the gauge wheels. Likewise, if the force F R  increases, with softer soil, the controller  52  will operate the actuator  40  to reduce the down force F D . Operation of the actuator  40  is accomplished by commanding a change in the air pressure for the pneumatic down force cylinder  44 . The associated air compressor and valves are not shown but are well known. Hydraulic or electrical actuators could also be used to apply the down force F D  and are actuated to very the down force F D . 
     While the row unit  12  is shown with the sensor  46 , it is possible to use one sensor  46  on one row unit to measure the force F R  on the gauge wheels of that row unit while the controller receiving the sensor  46  output signal then controls the actuators  40  of multiple row units. This reduces the control system complexity and cost. Some machines may be configured with multiple row units carried as a gang on a movable frame. With such an arrangement, a single actuator  40  can apply down force to multiple row units. All such variations in the configuration of the machine  10  are contemplated in the following claims. 
     Large fluctuations in the soil hardness will require a longer time for the control system to adjust and change the down force F D . The length of time is a function of the system capacity, such as the air compressor used to supply pneumatic pressure to the cylinder  44 . One way to reduce the adjustment time is to increase the system capacity. This also increases the system cost. Some fluctuations in the down force can be anticipated and planned for based on an electronic field map. With reference to  FIG. 3 , a map  60  of a portion of a field  62  is shown. The field includes first areas  64  that are to be seeded or have other products applied thereto. Cutting through the field is a second field area shown as a waterway  66 . Waterway  66  is typically covered in a perennial grass to avoid or reduce erosion from the field. The soil in the waterway is typically much harder than the soil in the first field areas  64 . When a row unit enters the waterway, the force, F O , on the opener to achieve full penetration will dramatically increase, and the soil reaction force F R  on the gauge wheels will decrease. This results in the controller commanding an increase in the down force F D  to return the soil reaction force F R  to the desired magnitude. When the row unit then returns to the first area  64 , the down force F D  is much higher than needed, resulting in undesirable compaction of the soil adjacent the furrow  26 . The machine may have to travel several meters before the system reaches the desired lower down force F D . Since the waterway is not used to produce a crop, proper penetration of the opener  20  is not required in the waterway  66 . 
     To avoid the large fluctuations in the down force F D , the control system is programmed to not operate the actuator  40  while the row unit is in the waterway. By not operating the actuator, it is meant that the system pressure is not changed and a constant magnitude of down force is maintained. This is accomplished by including in the control system  54  a memory with an electronic field map  60  ( FIG. 3 ) with the location of the first field areas  64  and second field area  66  identified. The memory with the field map is accessible by the controller  52 . In addition, the control system  54  includes a machine locating system  68  such as a satellite based global positioning system or a local positioning system. The locating system provides an output to the controller indicative of the machine location to enable the controller to determine the location of the machine in the field. In  FIG. 3 , the machine  10  shown by the tool bar  14  and row units  12  is about to move from the first field area  64  into the second field area  66 . When the row unit exits the first field area  64  and enters the second field area  66 , the controller no longer operates the actuator  40  and instead leaves the actuator at the pressure and down force F D  that existed immediately prior to exiting the first area  64 . Then, when the row unit returns to the first field area  64  after crossing the waterway  66 , the dynamic control of the down force F D  resumes at a pressure likely close to the needed pressure to produce the desired soil reaction force F R  on the gauge wheels  24 . Switching on and off of the dynamic control of the down force can be done on individual row units at a time, a section of row units at a time or on all row units of the machine at a time. 
     As an alternative, the control system may be programmed to produce a different desired soil reaction force F R1  while in the second field area. The desired and thus commanded force F R1  in the waterway may be a lesser force than F R  to reduce wear on the row unit while traveling through the waterway. As a further alternative, the control system can be programmed such that, while in the waterway, as the row unit approaches the first field area  64 , the system pressure changes from that needed to produce a soil reaction force of F R1  in the waterway to the pressure previously needed to produce a soil reaction force of F R  in the first field area. Then, upon returning to the first field area, the pressure the pneumatic system is close to the needed pressure to produce the desired reaction force F R . This results in a relatively short time and travel distance needed to achieve the desired soil reaction force F R  once the row unit returns to the first field area and dynamic control of the down force is resumed. 
     Returning once again to  FIG. 1 , the seed meter  32  and the seed tube  36  constitute a produce dispenser  70  as that term is used in the following claims. The controller  52  also controls operation of the dispenser  70 , by controlling the operation of the seed meter through the clutch mechanism previously described. (In some machines, operation of the dispenser is controlled through valves or gates to stop the flow of product rather than by stopping the meter drive mechanism.) In many instances, it will be desired to cease operating the dispenser  70  when the row unit is in the second field area. In such a case, the controller  52  may cease operating the dispenser  70  and cease the dynamic control of the actuator  40  simultaneously when entering the second field area. Operation of the dispenser is then resumed simultaneously with resuming dynamic control of the down force actuator upon return to the first field area. 
     In some machine forms, such as an air seeder, the seed meter is located remotely from the row unit and furrow opener. A lengthy pneumatic distribution system delivers seed from the meter to the furrow. In such a machine, the seed meter and distribution system form the product dispenser, which still terminates in a tube delivering product to the furrow. With such a machine, the control system  54  will still operate both the product dispenser and the down force actuator  40 . But when approaching waterway  66 , the dispenser will be shut-off before the waterway is entered allowing the product in the pneumatic distribution system to be dispensed prior to reaching the waterway. When the waterway is reached, the dynamic control of the actuator  40  is ceased. Prior to return to the first field area, the product dispenser is activated to fill the distribution system by the time the row unit reaches the first field area. The dynamic control of the down force actuator resumes upon returning to the first field area. 
     Depending on the farming practice, the dispensers may or may not be operated in the waterway. Paths or roadways cutting across the field are other types of field areas for which it may be desirable to stop the dynamic operation of the down force actuator  40 . 
     Having described the control system and method, it will become apparent that various modifications can be made without departing from the scope of the accompanying claims.