Abstract:
Systems, methods and apparatus are provided for monitoring and controlling an agricultural implement, including seed planting implements. Systems, methods and apparatus are provided for detecting seeds being conveyed by seed conveyor.

Description:
BACKGROUND 
       [0001]    As growers in recent years have increasingly incorporated additional sensors and controllers on agricultural implements such as row crop planters, the control and monitoring systems for such implements have grown increasingly complex. Installation and maintenance of such systems have become increasingly difficult. Thus there is a need in the art for effective control and monitoring of such systems. In planting implements incorporating seed conveyors, special control and monitoring challenges arise; thus there is also a particular need for effective seed counting and effective incorporation of the seed conveyor into the implement control and monitoring system. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0002]      FIG. 1  schematically illustrates an embodiment of an electrical control system for controlling and monitoring an agricultural implement having a plurality of rows. 
           [0003]      FIG. 2  schematically illustrates an embodiment of a multi-row control module. 
           [0004]      FIG. 3  schematically illustrates an embodiment of a drive module. 
           [0005]      FIG. 4  schematically illustrates an embodiment of a conveyor module. 
           [0006]      FIG. 5A  is a side elevation view of a planter row unit including a seed tube and incorporating an embodiment of an electronic control system. 
           [0007]      FIG. 5B  is a side elevation view of a planter row unit including a seed conveyor and incorporating another embodiment of an electronic control system. 
           [0008]      FIG. 6A  schematically illustrates another embodiment of an electrical control system including a modular extension at each row. 
           [0009]      FIG. 6B  schematically illustrates the electrical control system of  FIG. 6A  with a conveyor module installed at each row. 
           [0010]      FIG. 7  illustrates an embodiment of a process for transmitting identification and configuration data to a multi-row control module and to a row control module. 
           [0011]      FIG. 8  illustrates an embodiment of a process for controlling a drive module. 
           [0012]      FIG. 9  illustrates an embodiment of a process for controlling a conveyor module. 
           [0013]      FIG. 10A  is a perspective view of an embodiment of a seed meter incorporating an embodiment of a drive module. 
           [0014]      FIG. 10B  is a perspective view of the seed meter and drive module of  FIG. 10A  with several covers removed for clarity. 
           [0015]      FIG. 11A  is a bottom view of the drive module of  FIG. 10A . 
           [0016]      FIG. 11B  is a side elevation view of the drive module of  FIG. 10A . 
           [0017]      FIG. 12A  is a bottom view of the drive module of  FIG. 10A  with two covers and a housing removed for clarity. 
           [0018]      FIG. 12B  is a side elevation view of the drive module of  FIG. 10A  with two covers and a housing removed for clarity. 
           [0019]      FIG. 13A  is a front view of the drive module of  FIG. 10A . 
           [0020]      FIG. 13B  is a rear view of the drive module of  FIG. 10A . 
           [0021]      FIG. 14A  is a front view of the drive module of  FIG. 10A  with two covers and a housing removed for clarity. 
           [0022]      FIG. 14B  is a rear view of the drive module of  FIG. 10A  with two covers and a housing removed for clarity. 
           [0023]      FIG. 15  is a perspective view of the drive module of  FIG. 10A  with two covers and a housing removed for clarity. 
           [0024]      FIG. 16  schematically illustrates another embodiment of an electrical control system for controlling and monitoring an agricultural implement having a plurality of rows. 
           [0025]      FIG. 17  illustrates an embodiment of a process for counting seeds using two optical sensors associated with a seed conveyor. 
           [0026]      FIG. 18  illustrates exemplary signals generated by optical sensors associated with a seed conveyor. 
           [0027]      FIG. 19  illustrates an embodiment of a single-row network. 
       
    
    
     DESCRIPTION 
       [0028]    Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views,  FIG. 1  schematically illustrates an agricultural implement, e.g., a planter, comprising a toolbar  14  operatively supporting six row units  500 . The toolbar  14  is supported by left and right implement wheels  520   a , 520   b  and drawn by a tractor  5 . A control system  100  includes a monitor  110  preferably mounted in the tractor  5 , an implement network  135 , and two row networks  130   a ,  130   b.    
         [0029]    The monitor  110  preferably includes a graphical user interface (“GUI”)  112 , a memory  114 , a central processing unit (“CPU”)  116 , and a bus node  118 . The bus node  118  preferably comprises a controller area network (“CAN”) node including a CAN transceiver, a controller, and a processor. The monitor  110  is preferably in electrical communication with a speed sensor  168  (e.g., a radar speed sensor mounted to the tractor  5 ) and a global positioning receiver (“GPS”) receiver  166  mounted to the tractor  5  (or in some embodiments to the toolbar  14 ). 
         [0030]    The implement network  135  preferably includes an implement bus  150  and a central processor  120 . The central processor  120  is preferably mounted to the toolbar  14 . Each bus described herein is preferably a CAN bus included within a harness which connects each module on the bus to power, ground, and bus signal lines (e.g., CAN-Hi and CAN-Lo). 
         [0031]    The central processor  120  preferably includes a memory  124 , a CPU  126 , and a bus node  128  (preferably a CAN node including a CAN transceiver, a controller, and a processor). The implement bus  150  preferably comprises a CAN bus. The monitor  110  is preferably in electrical communication with the implement bus  150 . The central processor  120  is preferably in electrical communication with wheel speed sensors  164   a , 164   b  (e.g., Hall-effect speed sensors) mounted to the left and right implement wheels  520   a ,  520   b , respectively. The central processor  120  is preferably in electrical communication with a gyroscope  162  mounted to the toolbar  14 . 
       Row Networks—Overview 
       [0032]    Each row network  130  preferably includes a multi-row control module  200  mounted to one of the row units  500 , a row bus  250 , three drive modules  300  individually mounted to three row units  500 , and three conveyor modules  400  individually mounted to three row units  500  respectively. Each row unit  500  having at least a drive module  300  in a particular row unit network  130  is described herein as being “within” that row network. 
       Row Networks—Multi-Row Control Module 
       [0033]    Turning to  FIG. 2 , the multi-row control module  200  preferably includes a bus node  202  (preferably a CAN node including a CAN transceiver, a controller, and a processor). The CAN node, specifically the CAN transceiver, is preferably in electrical communication with the row bus  250  and the implement bus  150 . The multi-row control module  200  further includes a memory  214  and a processor  204  in electrical communication with a downforce signal conditioning chip  206 , a seed sensor auxiliary input  208 , a downforce solenoid pulse-width modulation (“PWM”) driver  210 , and generic auxiliary inputs  212 . The auxiliary inputs  212  are preferably configured for electrical communication with sensors including a pressure sensor and a lift switch. The downforce signal conditioning chip  206  is preferably in electrical communication with a downforce sensor  506  on each row unit  500  within the implement network  135 . The downforce solenoid PWM driver  210  is preferably in electrical communication with a downforce solenoid  510  on each row unit within the row network  130 . In embodiments including a seed tube (described in more detail herein with respect to  FIG. 5A ), the seed sensor auxiliary input  208  is preferably in electrical communication with a seed sensor  508  (e.g., an optical sensor) on each row unit  500  within the row network  130 . 
       Row Networks—Drive Module 
       [0034]    Turning to  FIG. 3 , the drive module  300  preferably includes circuit board  301 , a motor encoder  576 , and a meter drive motor  578 . The circuit board  301  preferably includes a bus node  302  (preferably a CAN node including a CAN transceiver, a controller, and a processor). The CAN node, specifically the CAN transceiver, is preferably in electrical communication with the row bus  250 . The drive module  300  preferably further includes a memory  306  and a processor  304  in electrical communication with a motor encoder signal conditioning chip  316 , a motor PWM driver  318 , and a motor current signal conditioning chip  314 . The motor PWM driver  318  is preferably in electrical communication with a motor  578  for controlling an output speed of the motor  578 . The motor encoder signal conditioning chip  316  is preferably in electrical communication with the motor encoder  576 , which is preferably configured to generate a signal indicative of driving speed of the motor  570 , e.g., by generating a defined number of encoder pulses per motor shaft rotation. The motor current signal conditioning chip  314  is preferably in electrical communication with the motor PWM driver  318  far sampling the actual current driving the motor  578 . 
         [0035]    Referring to  FIGS. 10A and 10B , the drive module  300  comprises an electrical assembly  340  and motor  578  shielded by a cover  304  and a gearbox  320  shielded by a cover  302 . The drive module  300  is mounted to a seed meter  530 . The seed meter is preferably of the type disclosed in Applicant&#39;s co-pending international patent application no. PCT/US2012/030192, the disclosure of which is hereby incorporated herein in its entirety by reference. Specifically, the drive module  300  is preferably mounted to a cover  532  shielding a seed disc  534  housed within the meter  530 . The gearbox  320  includes an output gear  312  adapted to drive the seed disc  534  by sequential engagement with gear teeth arranged circumferentially around a perimeter of the seed disc  534 . 
         [0036]    Turning to  FIGS. 11A and 11B , the drive module  300  further includes a housing  308  to which the covers  302 , 304  are mounted. The cover  302  preferably includes rubber grommet  305  for introducing electrical leads into the cover  302 . 
         [0037]    Turning to  FIGS. 12A ,  12 B,  14 A,  14 B, and  15 , the gearbox  320  includes an input shaft  325  and input gear  324  driven by the motor  578 . The input gear drives a first step-down gear  326  and a second step-down gear  328 . The second step-down gear  328  preferably has a smaller diameter than the first step-down gear  326 . The second step-down gear  328  is preferably mounted coaxially to the first step-down gear  326 , e.g., by press fitting. The second step-down gear  328  preferably drives an intermediate gear  322 . The intermediate gear  322  drives the output gear  312  via a shaft  321 . 
         [0038]    Continuing to refer to  FIGS. 12A ,  12 B,  14 A,  14 B, and  15 , the electrical assembly  340  includes the circuit board  301 , the motor encoder  576  (preferably including a magnetic encoder disc), and two leads  344   a , 344   b  in electrical communication with the motor  578  for driving the motor. 
         [0039]    Referring to  FIGS. 13A and 13B , the drive module  300  preferably includes mounting tabs  382 , 384 , 386 , 388  for mounting the drive module  300  to the seed meter  530  (e.g., by screws adapted to mate with threaded apertures in the cover  532 ). 
       Row Networks—Conveyor Module 
       [0040]    Turning to  FIG. 4 , the conveyor module  400  preferably includes a bus node  402  (preferably a CAN node including a CAN transceiver, a controller, and a processor). The CAN node, specifically the CAN transceiver, is preferably in electrical communication with the row bus  250 . The conveyor module  400  preferably further includes a memory  406  and a processor  404  in electrical communication with a motor encoder signal conditioning chip  422 , a motor PWM driver  448 , and signal conditioning chips  432 , 434 . The motor PWM driver  448  is in electrical communication with a conveyor motor  590  mounted to a conveyor  580 . In some embodiments, the motor encoder signal conditioning chip  422  is in electrical communication with a motor encoder  597  disposed to measure an operating speed of the conveyor motor  590 . The signal conditioning chips  432 , 434  are preferably in electrical communication with optical sensors  582 , 584 , respectively. 
       Implementation on Planter Row Units 
       [0041]    Referring to  FIG. 5A , a planter row unit  500  is illustrated with components of the control system  100  installed. The row unit  500  illustrated in  FIG. 5A  is one of the row units to which a multi-row control module  200  is mounted. 
         [0042]    In the row unit  500 , a downforce actuator  510  (preferably a hydraulic cylinder) is mounted to the toolbar  14 . The downforce actuator  510  is pivotally connected at a lower end to a parallel linkage  516 . The parallel linkage  516  supports the row unit  500  from the toolbar  14 , permitting each row unit to move vertically independently of the toolbar and the other spaced row units in order to accommodate changes in terrain or upon the row unit encountering a rock or other obstruction as the planter is drawn through the field. Each row unit  500  further includes a mounting bracket  520  to which is mounted a hopper support beam  522  and a subframe  524 . The hopper support beam  522  supports a seed hopper  526  and a fertilizer hopper  528  as well as operably supporting a seed meter  530  and a seed tube  532 . The subframe  524  operably supports a furrow opening assembly  534  and a furrow closing assembly  536 . 
         [0043]    In operation of the row unit  500 , the furrow opening assembly  534  cuts a furrow  38  into the soil surface  40  as the planter is drawn through the field. The seed hopper  526 , which holds the seeds to be planted, communicates a constant supply of seeds  42  to the seed meter  530 . The drive module  300  is preferably mounted to the seed meter  530  as described elsewhere herein. As the drive module  300  drives the seed meter  530 , individual seeds  42  are metered and discharged into the seed tube  532  at regularly spaced intervals based on the seed population desired and the speed at which the planter is drawn through the field. The seed sensor  508 , preferably an optical sensor, is supported by the seed tube  532  and disposed to detect the presence of seeds  42  as they pass. The seed  42  drops from the end of the seed tube  532  into the furrow  38  and the seeds  42  are covered with soil by the closing wheel assembly  536 . 
         [0044]    The furrow opening assembly  534  preferably includes a pair of furrow opening disk blades  544  and a pair of gauge wheels  548  selectively vertically adjustable relative to the disk blades  544  by a depth adjusting mechanism  568 . The depth adjusting mechanism  568  preferably pivots about a downforce sensor  506 , which preferably comprises a pin instrumented with strain gauges for measuring the force exerted on the gauge wheels  548  by the soil  40 . The downforce sensor  506  is preferably of the type disclosed in Applicant&#39;s co-pending U.S. patent application Ser. No. 12/522,253, the disclosure of which is hereby incorporated herein in its entirety by reference. In other embodiments, the downforce sensor is of the types disclosed in U.S. Pat. No. 6,389,999, the disclosure of which is hereby incorporated herein in its entirety by reference. The disk blades  544  are rotatably supported on a shank  554  depending from the subframe  524 . Gauge wheel arms  560  pivotally support the gauge wheels  548  from the subframe  524 . The gauge wheels  548  are rotatably mounted to the forwardly extending gauge wheel arms  560 . 
         [0045]    It should be appreciated that the row unit illustrated in  FIG. 5A  does not include a conveyor  580  such that a conveyor module  400  is not required. Turning to  FIG. 5B , a planter row unit  500 ′ including a conveyor  580  is illustrated with components of the control system  100  installed. 
         [0046]    The row unit  500 ′ is similar to the row unit  500  described above, except that the seed tube  532  has been removed and replaced with a conveyor  580  configured to convey seeds at a controlled rate from the meter  530  to the furrow  42 . The conveyor motor  590  is preferably mounted to the conveyor  580  and is configured to selectively drive the conveyor  580 . The conveyor  580  is preferably one of the types disclosed in Applicant&#39;s U.S. patent application No. 61/539,786 and Applicant&#39;s co-pending international patent application no. PCT/US2012/057327, the disclosures of which are hereby incorporated herein in their entirety by reference. As disclosed in that application, the conveyor  580  preferably includes a belt  587  including flights  588  configured to convey seeds received from the seed meter  530  to a lower end of the conveyor. On the view of  FIG. 5B , the seed conveyor  580  is preferably configured to drive the belt  587  in a clockwise direction. On the view of  FIG. 5B , the seed conveyor  580  is preferably configured to guide seeds from an upper end of the conveyor down a forward side of the conveyor, such that seeds descend with flights  588  of the belt  587  on forward side of the conveyor  580  and are deposited from the lower end of the conveyor such that no seeds are present on flights  588  ascending the rearward side of the conveyor during normal operation. The optical sensor  582  is preferably mounted to the forward side of the conveyor  580  and disposed to detect seeds and descending conveyor flights  588  as they pass. The optical sensor  584  is preferably mounted to the rearward side of the conveyor  580  and disposed to detect ascending conveyor flights  588  as they return to the meter  530 . In other embodiments the optical sensor  582  and/or the optical sensor  584  may be replaced with other object sensors configured to detect the presence of seeds and/or flights, such as an electromagnetic sensor as disclosed in Applicant&#39;s co-pending U.S. patent application Ser. No. 12/984,263 (Pub. No. US2012/0169353). 
       Addition of Modular Components 
       [0047]    Comparing the embodiments of  FIGS. 5A and 5B , it should be appreciated that some embodiments of control system  100  require a conveyor module  400  while some do not. Thus row buses  250  are preferably configured to allow the user to install one or more additional CAN modules without replacing or modifying the row buses  250 . 
         [0048]    Referring to  FIG. 6A , a modified control system  100 ′ includes modified row buses  250 ′ having a modular extension  600  at each row. Each modular extension  600  preferably includes a first drop  610  and a second drop  620 . Each drop  610 ,  620  preferably includes connections to power, ground and the bus signal lines (e.g., CAN Hi and CAN Lo). 
         [0049]    Turning to  FIG. 6B , a modified control system  100 ″ differs from control system  100 ′ in that a conveyor module  400  has been connected to the first drop  610  of each modular extension  600 . It should be appreciated that the second drop  620  is still available to add further modules to the row networks  130 . 
       Operation—Configuration Phase 
       [0050]    In order to effectively operate the control system  100  of  FIG. 1 , each module is preferably configured to determine its identity (e.g., the row unit or row units  500  with which it is associated) and certain configuration data such as the relative location of its associated row unit. Thus in operation of the control system  100 , a configuration process  700  ( FIG. 7 ) is preferably carried out to identify the modules and transmit configuration data to each module. At step  705 , the monitor  110  preferably sends a first identification signal to the multi-row control module  200   a  via a point-to-point connection  160 . The multi-row control module  200   a  preferably stores identification data (e.g., indicating its status as the leftmost multi-row control module) in memory. Continuing to refer to step  705 , the multi-row control module  200   a  preferably sends a second identification signal to the multi-row control module  200   b  via a point-to-point electrical connection  161 . The multi-row control module  200   b  preferably stores identification data (e.g., indicating its status as the rightmost multi-row control module) in memory. 
         [0051]    At step  710 , each row module (e.g., each drive module  300  and each conveyor module  400 ) preferably determines the row unit  500  with which it is associated based on the voltage on an identification line (not shown) connecting the row module to the row bus  150 . For example, three identification lines leading to the drive modules  300 - 1 , 300 - 2 , 300 - 3  are preferably connected to ground, a midrange voltage, and a high voltage, respectively. 
         [0052]    At step  715 , the monitor  110  preferably transmits row-network-specific configuration data to each multi-row control module  200  via the implement bus  150 . For example, the configuration data preferably includes transverse and travel-direction distances from each row unit  500  to the GPS receiver  166  and to the center of the toolbar  14  (“GPS offsets”); the row-network-specific GPS offsets sent to multi-row control module  200   a  at step  715  preferably corresponds to the row units  500 - 1 ,  500 - 2 ,  500 - 3  within the row network  130   a . At step  720 , each multi-row control module  200  preferably transmits row-unit-specific configuration data to each row control module (e.g, the drive modules  300 ) via the row buses  250 . For example, the multi-row control module  200   a  preferably sends GPS offsets corresponding to row unit  500 - 1  to the drive module  300 - 1 . 
       Operation—Drive Module Control 
       [0053]    Turning to  FIG. 8 , the control system  100  preferably controls each drive module  300  according to a process  800 . At step  805 , the monitor  110  preferably transmits an input prescription (e.g., a number of seeds per acre to be planted) to each multi-row control module  200  via the implement bus  150  of the implement network  135 . At step  810 , the various kinematic sensors in the control system  100  transmit kinematic signals to the central processor  120 . For example, wheel speed sensors  164  and gyro  162  send speed signals and angular velocity signals, respectively, to the central processor  120  via point-to-point electrical connections. In some embodiments the monitor  110  also sends the speed reported by the speed sensor  168  to the central processor  120  via the implement bus  150 , which speed is sent to the central processor  120  via the implement bus  150 . 
         [0054]    At step  815 , the central processor  120  preferably calculates the speed of the center of the toolbar  14  and the angular velocity of the toolbar  14 . The speed Sc of the center of the toolbar may be calculated by averaging the wheel speeds Swa,Swb reported by the wheel speed sensors  164   a ,  164   b , respectively or using the tractor speed reported by the speed sensor  168 . The angular velocity w of the toolbar  14  may be determined from an angular velocity signal generated by the gyroscope  162  or by using the equation: 
         [0000]    
       
         
           
             w 
             = 
             
               
                 
                   S 
                   wa 
                 
                 - 
                 
                   S 
                   wb 
                 
               
               
                 
                   D 
                   wa 
                 
                 + 
                 
                   D 
                   wb 
                 
               
             
           
         
       
       
         
           
             Where: Dwa=The lateral offset between the center of the toolbar and the left implement wheel  520   a , and
           Dwb=The lateral offset between the center of the toolbar and the right implement wheel  520   b.      
         
           
         
       
     
         [0057]    At step  820 , the central processor  120  preferably transmits the planter speed and angular velocity to each multi-row control module  200  via the implement bus  150  of the implement network  135 . 
         [0058]    At step  825 , each multi-row control module  200  preferably determines a meter speed command (e.g., a desired number of meter rotations per second) for each drive module within its row network  130 . The meter speed command for each row unit  500  is preferably calculated based on a row-specific speed Sr of the row unit. The row-specific speed Sr is preferably calculated using the speed Sc of the center of the toolbar, the angular velocity w and the transverse distance Dr between the seed tube (or conveyor) of the row unit from the center of the planter (preferably included in the configuration data discussed in  FIG. 7 ) using the relation: 
         [0000]    
       
      
       S 
       r 
       =S 
       c 
       +w×D 
       r  
      
     
         [0059]    The meter speed command R may be calculated based on the individual row speed using the following equation: 
         [0000]    
       
         
           
             
               R 
                
               
                 ( 
                 
                   rotations 
                   second 
                 
                 ) 
               
             
             = 
             
               
                 Population 
                  
                 
                     
                 
                  
                 
                   ( 
                   
                     seeds 
                     acre 
                   
                   ) 
                 
                 × 
                 Row 
                  
                 
                     
                 
                  
                 
                   Spacing 
                    
                   
                     ( 
                     ft 
                     ) 
                   
                 
                 × 
                 
                   
                     S 
                     r 
                   
                    
                   
                     ( 
                     
                       ft 
                       s 
                     
                     ) 
                   
                 
               
               
                 Meter 
                  
                 
                     
                 
                  
                 Ratio 
                  
                 
                     
                 
                  
                 
                   ( 
                   
                     seeds 
                     rotation 
                   
                   ) 
                 
                 × 
                 43 
                 , 
                 500 
                  
                 
                   ( 
                   
                     
                       ft 
                       2 
                     
                     acre 
                   
                   ) 
                 
               
             
           
         
       
       
         
           
             Where: Meter Ratio=The number of seed holes in the seed disc  534 , and
           Row Spacing=The transverse spacing between row units  500 .   
         
           
         
       
     
         [0062]    At step  830 , the multi-row control module  200  preferably transmits the meter speed command determined for each drive module  300  to the respective drive module via the row bus  250  of the row network  130 . In embodiments in which the row bus  250  comprises a CAN bus, the multi-row control module  200  preferably transmits a frame to the row bus having an identifier field specifying a drive module  300  (e.g., module  300 - 2 ) and a data field including the meter speed command for the specified drive module. 
         [0063]    At step  835 , the drive module  300  preferably compares the meter speed command R to a measured meter speed. The drive module  300  preferably calculates the measured meter speed using the time between encoder pulses received from the motor encoder  576 . At step  840 , the drive module  300  preferably adjusts a voltage used to drive the meter  530  in order to adjust the measured meter speed closer to the meter speed command R. 
         [0064]    At step  845 , each seed sensor sends seed pulses to the associated multi-row control module  200 . In embodiments including a seed tube  532 , each seed sensor  508  preferably sends seed pulses to the associated multi-row control module  200  via point-to-point electrical connections. In embodiments including a seed tube  532 , seed pulses preferably comprise signal pulses having maximum values exceeding a predetermined threshold. In some embodiments including a seed conveyor  580 , each seed sensor  582  preferably sends seed pulses to the associated multi-row control module  200  via the implement bus  250  of the row network  130 . In embodiments including a seed conveyor  580 , the seed pulses comprise signal pulses that differ by a predetermined threshold from signal pulses caused by passing flights of the conveyor. Alternative methods of detecting seeds in a seed conveyor  580  are described later herein. 
         [0065]    At step  850 , the multi-row control module  200  preferably calculates the population, singulation and seed spacing at each row unit  500  within the row network  130  using the row speed Sr and the seed pulses transmitted from each row unit within the row network. At step  855 , the multi-row module  200  transmits the population, singulation and spacing values to the central processor  120  via the implement bus  150  of the implement network  130 . At step  860 , the central processor  120  preferably transmits the population, singulation and spacing values to the monitor  110  via the implement bus  150  of the implement network  135 . 
       Operation—Conveyor Module Control 
       [0066]    Turning to  FIG. 9 , the control system  100  preferably controls each conveyor module  400  according to a process  900 . At steps  910  through  920 , control system  100  preferably performs the same steps described with respect to steps  810  through  820  of process  800 . At step  925 , each multi-row control module  200  preferably determines a conveyor speed command for each conveyor module  400  within the row network  130 . The conveyor speed command is preferably selected such that a linear speed of flights traveling down the conveyor is approximately equal to the row-specific speed Sr; e.g., the conveyor motor speed command is preferably equal to the row-specific speed Sr multiplied by a predetermined constant. At step  930 , the multi-row control module  200  preferably transmits individual conveyor speed commands to each corresponding conveyor module  400  via the row bus  250  of the row network  130 . 
         [0067]    At step  935 , the conveyor module  400  preferably compares the conveyor speed command to a measured conveyor speed. In some embodiments, the conveyor speed is measured using the time between flight pulses resulting from conveyor flights passing the optical sensor  584 . In other embodiments, the conveyor speed is measured using the time between encoder pulses received from the conveyor motor encoder  597 . At step  940 , the conveyor module  400  preferably adjusts a voltage used to drive the conveyor motor  590  in order to adjust the measured meter speed closer to the conveyor speed command. 
         [0068]    At steps  945  through  960 , the conveyor module  400  preferably performs the same steps  845  through  860  described herein with respect to process  800 , specifically as those steps are described for embodiments including a conveyor  580 . 
       Seed Sensing Methods 
       [0069]    In embodiments including a seed conveyor  580 , the control system  100  is preferably configured to count seeds, time-stamp seeds, and determine a seeding rate based on the signals generated by the first and second optical sensors  582 ,  584 . It should be appreciated that in normal operation, the first optical sensor  582  detects both seeds and conveyor flights as the seeds from the meter  530  descend the conveyor  580 , while the second optical sensor  584  detects only conveyor flights as they return to the top of the conveyor after seeds are deposited. The shape and size of flights in the conveyor  580  are preferably substantially consistent. 
         [0070]    Referring to  FIG. 17 , the monitor  110  (or in some embodiments the central processor  120 ) is preferably configured to carry out a process  1700  for detecting seeds. At step  1710 , the monitor  110  preferably receives signals from both the first optical sensor  582  and the second optical sensor  584  over a measuring period. A first optical sensor signal  1810  (in which amplitude increases when either flights or seeds pass) and a second optical sensor signal  1820  (in which amplitude increases when flights pass) are illustrated on an exemplary multi-signal graph  1800  in  FIG. 18 . At step  1715 , the control system  100  preferably changes the conveyor speed during the measuring period such that the length of signal pulses resulting from belts having the same length (as best illustrated by viewing the varying-width pulses in the sensor signal  1820 ). At step  1720 , the monitor  110  preferably applies a time shift Ts (e.g., the time shift Ts illustrated in  FIG. 18 ) to the second optical sensor signal  1820 , resulting in a time-shifted sensor signal  1820 ′. The time shift Ts is related to the conveyor speed and is preferably calculated as follows: 
         [0000]    
       
      
       Ts=k×Tf  
      
       
         
           
             Where: Tf=Average time between flights detected by the second optical sensor  258 
           k=A constant value preferably determined as described below.   
         
           
         
       
     
         [0073]    The value of k is related to the conveyor and optical sensor geometry and in some embodiments is determined as follows: 
         [0000]    
       
         
           
             k 
             = 
             
               Tf 
               × 
               D 
                
               
                   
               
                
               E 
                
               
                   
               
                
               
                 C 
                  
                 
                   ( 
                   
                     Ds 
                     Df 
                   
                   ) 
                 
               
             
           
         
       
     
         [0074]    Where: Ds=Linear flight distance between the first and second optical sensors
       Df=Distance between flights   DEC(x) returns the decimal portion of x (e.g., DEC(105.2)=0.2).       
 
         [0077]    In other embodiments, the monitor  110  preferably calculates k empirically in a setup stage while seeds are not being planted by running the conveyor  580  at a constant speed and determining the values of Tf and Ts; with no seeds on the belt, the value of Ts may be determined by measuring the time between a flight pulse at the first optical sensor  582  and the next subsequent flight pulse at the second optical sensor  584 . In still other embodiments, the sensors  582 ,  584  are positioned at a relative distance Ds equal to an integer multiple of Df such that no time shift or a near-zero time shift is required. 
         [0078]    Continuing to refer to the process  1700  of  FIG. 17 , at step  1725  the monitor  110  preferably subtracts the time-shifted second optical sensor signal  1820 ′ from the first optical sensor signal  1810 , resulting in a flight-corrected signal  1830  (see  FIG. 18 ) which correlates to the signal from the first optical sensor signal with signal pulses resulting from conveyor flights substantially eliminated. At step  1730  the monitor  110  preferably compares pulses  1832  in the flight-corrected signal  1830  to one or more seed pulse validity thresholds (e.g., a minimum amplitude threshold and a minimum period threshold); the monitor preferably identifies each pulse exceeding the seed pulse validity thresholds as valid seed event. At step  1735 , the monitor  110  preferably adds the identified seed event to a seed count. At step  1740 , the monitor  110  preferably stores the seed count; seeding rate (e.g., the seed count over a predetermined time period); a time associated with the seed event, seed count, or seeding rate; and a GPS associated with the seed event, seed count, or seeding rate to memory for mapping, display and data storage. 
       Alternative Embodiments 
     Single Row Networks 
       [0079]    In an alternative control system  100 ′″ illustrated in  FIG. 16 , each of a plurality of row networks  132  includes a single-row control module  202  mounted to one of the row units  500 , a row bus  250 , a drive module  300  individually mounted to the same row unit  500 , and a conveyor module  400  individually mounted to the same row unit  500 . The single-row control module  202  preferably includes equivalent components to the multi-row control module  200 , except that the downforce signal conditioning chip  206 , seed sensor auxiliary input  208 , and the downforce solenoid PWM driver  210  are only in electrical communication with one of the corresponding devices mounted to the same row unit  500 . Additionally, in the alternative control system  100 ′″ the row bus  250  is in electrical communication with a single drive module  300  and a single conveyor module  400  as well as the single-row control module  202 . 
         [0080]    In still other embodiments, two seed meters  530  are mounted to a single row unit  500  as described in U.S. Provisional Patent Application No. 61/838,141. In such embodiments, a drive module  300  is operably coupled to each seed meter  530 . A row network  132 ′ having two drive modules  300  is illustrated in  FIG. 19 . The row network  132 ′ preferably includes a single-row control module  202 , a row bus  250 , a first drive module  300   a  (preferably mounted to the row unit  500 ), a second drive module  300   b  (preferably mounted to the row unit  500 ), a conveyor module  400 , an input controller  307  and an identification power source  309 . The first drive module  300   a  and the second drive module  300   b , including the hardware and software components, are preferably substantially identical. The single-row control module  202 , the first drive module  300   a , the second drive module  300   b , and the conveyor module  250  are preferably in electrical communication with the row bus  250 . The single-row control module  202  is preferably in electrical communication with an implement bus  150  of one of the control system embodiments described herein. The first drive module  300   a  is preferably in electrical communication with the identification power source  309  and the input controller  307 . The first drive module  300   a  is preferably in electrical communication with the input controller  307  via an electrical line  311 . The identification power source  309  preferably supplies a low-voltage signal to the first drive module  300   a , and may comprise a point-to-point connection to a power source including a relatively large resistor. The input controller  307  is preferably a swath and/or rate controller configured to shut off and/or modify an application rate of a crop input such as (without limitation) liquid fertilizer, dry fertilizer, liquid insecticide, or dry insecticide. 
         [0081]    During a setup phase of operation of the row network  132 ′, the first drive module  300   a  receives a signal from the identification power source  309  and sends a corresponding identification signal to the monitor  110  (and/or the central processor  120 ) identifying itself as the first drive module  300   a . Subsequently, the monitor  110  (and/or the central processor  120 ) preferably sends commands to the first drive module  300   a  and stores data received from the first drive module  300   a  based on the identification signal. 
         [0082]    During field operation of the row network  132 ′, the monitor  110  determines which seed meter  530  should be seeding by comparing position information received from the GPS receiver  166  to an application map. The monitor  110  then preferably commands the single-row control module  202  to send a desired seeding rate to the drive module associated with the meter  530  that should be seeding, e.g., the first drive module  300   a.    
         [0083]    In embodiments in which the input controller  307  comprises a swath controller configured to turn a dry or liquid crop input on or off, the first drive module  300   a  preferably sends a command signal to the input controller commanding the input controller to turn off the associated input, e.g., by closing a valve. In embodiments including only a single seed meter  530  and a single drive module  300  associated with each row unit, the drive module  300  transmits a first signal (e.g., a high signal) via the line  311  to the input controller  307  when the drive module is commanding the seed meter to plant, and transmits a second signal (e.g., a low signal) or no signal when the drive module is not commanding the seed meter to plant. The line  311  is preferably configured for electrical communication with any one of a plurality of input controllers, e.g. by incorporating a standard electrical connector. The first and second signal are preferably selected to correspond to swath commands recognized by any one of a plurality of input controllers such that the input controller  307  turns off the crop input when the seed meter  530  is not planting and turns on the crop input when the seed meter  530  is planting. 
         [0084]    In embodiments in which the input controller  307  comprises a swath controller and in which each row unit includes two seed meters  530  and associated drive modules  300   a ,  300   b , the first drive module  300   a  preferably receives a signal from the row bus  250  (preferably generated either by the single-row control module  202  or the second drive module  300   b ) indicating whether the second drive module is commanding its associated seed meter  530  to plant. The first drive module  300   a  then determines whether either the first drive module  300   a  or  300   b  is commanding either of the seed meters  530  to plant. If neither of the drive modules  300   a ,  300   b  are commanding either seed meter to plant, the first drive module  300   a  preferably sends a first signal to the input controller  307  via the line  311 . The input controller  307  is preferably configured to turn off the crop input (e.g., by closing a valve) upon receiving the first signal. If either of the drive modules  300   a ,  300   b  are commanding either seed meter to plant the first drive module  300   a  preferably sends a second signal (or in some embodiments no signal) to the input controller  307  such that the input controller does not turn off the crop input. 
         [0085]    In embodiments in which the input controller  307  comprises a rate controller configured to modify the application rate of a dry or liquid crop input, the monitor  110  (and/or the central processor  120 ) preferably determines a desired crop input application rate and transmits a corresponding signal to the input controller. 
         [0086]    Components described herein as being in electrical communication may be in data communication (e.g., enabled to communicate information including analog and/or digital signals) by any suitable device or devices including wireless communication devices (e.g., radio transmitters and receivers). 
         [0087]    The foregoing description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiment of the apparatus, and the general principles and features of the system and methods described herein will be readily apparent to those of skill in the art. Thus, the present invention is not to be limited to the embodiments of the apparatus, system and methods described above and illustrated in the drawing figures, but is to be accorded the widest scope consistent with the spirit and scope of the appended claims.