Patent Publication Number: US-2010116974-A1

Title: Seed Sensor System And Method For Improved Seed Count And Seed Spacing

Description:
FIELD OF THE INVENTION 
     The invention pertains to agricultural planters and in particular to an improved sensor system for determining seed count and seed spacing. 
     BACKGROUND OF THE INVENTION 
     It is well known in the agriculture to use a monitor on planters to monitor the seed at each row unit. When first employed, monitors were used to alert the operator of a plugged row unit or a unit without any seed to avoid continued operation of the planter without actually planting seed. More recently, studies have quantified the importance of accurate seed spacing in producing enhanced crop yields. As a result, monitor technology has advanced in efforts to determine seed spacing. Current monitors use the time interval between seeds to determine skips or multiples of seed. These monitors also predict seed spacing in the furrow based on the timing of seed passing the monitor in the seed tube. 
     A paper entitled Opto-electronic Sensor System for Rapid Evaluation of Planter Seed Spacing Uniformity, Transactions of the ASAE 41(1):237-245 describes using the seed trajectory, speed of the planter and timing of seed release events to determine seed spacing. The goal of the study was to evaluate a sensor located just above the soil surface at the seed drop zone in measuring the seed location relative to the planter. The sensor was then used to determine seed spacing instead of dropping seed onto a grease belt and manually evaluating seed spacing. The sensor had two arrays of 12 pairs of LEDs and photo-transistors to sense and locate the seed along one axis. 
     SUMMARY OF THE INVENTION 
     The present invention provides a sensor system with higher sensitivity to seed counting, reduced errors for skips, doubles (intentional double, triples or unintentional); better dust immunity that enables the sensor to be moved closer to the ground, which is desired for closer to true in ground information; improved capability for higher rate seed monitoring, etc. The present invention provides a sensor system that uses the seed location relative to the planter as the seed passes through the seed tube, along with other parameters, to determine the seed spacing in the furrow. The sensor system of the present invention uses a sensor that not only counts the seed but determines the position of the seed relative to the seed tube in the direction of travel of the planter. From the position information, a trajectory is determined of the seed falling through the seed tube. Travel speed of the planter and the timing of the seed passing the monitor are other necessary factors in determining the seed trajectory. The trajectory then enables the seed spacing to be predicted with a higher degree of accuracy then is possible with sensors that only determine the interval of time between seed drop events. 
     Other parameters that further improve the accuracy of determining the seed spacing include acceleration of the planter row unit and the down force applied to the row unit. The acceleration of the row unit effects the initial direction of travel of the seed as the seed is released from the meter. The down force on the row unit effects the location of the seed tube exit relative to the furrow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a planting unit; 
         FIG. 2  is a side view of the seed tube of the planting unit show in  FIG. 1 ; 
         FIG. 3  is a sectional view of the seed tube as seen from substantially the line  3 - 3  of  FIG. 2 ; 
         FIG. 4  is another a sectional view of the seed tube as seen from substantially the line  3 - 3  of  FIG. 2 ; 
         FIG. 5A  is an example of the output signal from prior sensor showing background dust noise; 
         FIG. 5B  is an example of the output signal from prior sensor showing, like  FIG. 5A  with a seed passing the sensor; 
         FIG. 6A  is an example of the output signal form the current sensor showing background dust noise; 
         FIG. 6B  is an example of the output signal from the current sensor showing, like  FIG. 6A  with a seeds passing the sensor; 
         FIG. 7  is an example of the output signal from the current sensor showing a seed passing and being detected in both the X and Y directions; 
         FIG. 8  is similar to  FIG. 7  with two seeds being detected in both the X and Y directions; 
         FIG. 9  is an example of the output signal from the current sensor showing a seed passing and being detected by two adjacent radiation detectors in the X direction; 
         FIG. 10  is similar to  FIG. 9  showing a seed passing and being detected by two adjacent radiation detectors in the X direction and a second seed being detected solely by a third radiation detector in the X direction; 
         FIG. 11A  is similar to  FIG. 9  showing a seed passing and being detected by two adjacent radiation detectors in the Y direction; 
         FIG. 11B  is like  FIG. 11A  but shows two seeds passing in the same position in the Y direction; 
         FIG. 12  is a plan view of a tractor and a planter with multiple planting units of  FIG. 1 ; 
         FIG. 13  is a side view of the planter as seen along the line  13 - 13  of  FIG. 12 ; and 
         FIG. 14  is a side view of an alternative seed tube of the planting unit with two vertically spaced seed sensors of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  is a side view of a planting unit  10  equipped with the sensor system of the present invention. The planting unit  10  is mounted to rectangular toolbar  12  by U-bolts  14 . The planting unit  10  is provided with a frame  16  having a parallelogram linkage  18  for coupling the planting unit  10  to the toolbar  12  to allow up and down relative movement between the unit  10  and toolbar  12 . Seed is stored in seed hopper  20  and provided to seed meter  22 . From the seed meter  22  the seed is dropped through the seed tube  24  into a planting furrow formed in the soil by furrow openers  26 . Gauge wheels  28  control the depth of the furrow and closing wheels  29  close the furrow over the seed. The gauge wheels  28  are mounted to the frame  16  by arms  31 . A down force sensor  33  is coupled to one arm  31  and includes a strain gage for measuring the amount of force applied to the gauge wheel by the ground. An accelerometer  35  is mounted to the frame  16  and can be placed at any convenient location thereon. The toolbar and planting unit are designed to be move over the ground in a forward working direction X identified by the arrow  27 . 
     Pesticides can be stored in a chemical hopper  30  which is mounted to the planting unit frame  16 . This particular planting unit is provided at the front with a row cleaner attachment  34 . A mechanical down force generator  48  is attached to the toolbar  12  and includes springs  50  to generate a down force applied to the linkage  18 . The particular down force generator  48  shown is adjustable. Any type of down force generator can be used, fixed force, adjustable force, mechanical, hydraulic, pneumatic, etc. The planting unit  10  is shown as an example of the environment in which the present invention is used. The present invention can be used in any of a variety of planting units. 
     The seed tube  24 , shown in  FIGS. 1 and 2 , is provided with a curved forward wall  36 , a curved rear wall  38  and two sidewalls  40  joining the front and rear walls  36  and  38 . The forward and rear walls are curved rearwardly and downwardly. The tube has an open top  42  and an open bottom  44 . The exterior of front wall is also provided with tangs  45  for mounting the seed tube to the planting unit frame  16 . 
     With reference to  FIG. 2-4 , seed tube  24  is equipped with a first sensor assembly  56  mounted to the side walls  40  of the seed tube at apertures therein. The sensor assembly  56  includes a radiation emitter  58 , shown as an array of light emitting diodes (LEDs)  60  on one side wall  40  of the seed tube. The LEDs are mounted to a PC board  62  with conductive strips forming electrical connections with the LEDs  60  mounted thereon. 
     Positioned in front of the LEDs and preferably flush with the inner edge of the seed tube side wall is a lens  64  which directs the light emitted by the LEDs into parallel beams substantially in the Y-direction as shown by the arrows  66 . One type of lens can be a privacy filter such as that made by the 3M Company and of the type described in US Pat. No. 6,398,370. Any number of LEDs can be used in the emitter  58  as long as the emitters and lens  64 , in combination, produce beams of radiation in the Y direction across substantially the entire width of the side wall  40 . The sensor assembly  56  further includes a radiation detector  68  mounted to the opposite side wall  40  of the seed tube. A lens  69  is flush with the inside surface of the seed tube side wall  40  and will transmit radiation substantially in the Y-direction as shown by arrows  70 . Radiation detecting elements  72   a - g  are arranged in an array  76 . Elements  72  can be photo-diodes or photo-transistors or other detector capable of detecting the radiation from the radiation emitter  58 . The detecting elements  72  are also mounted on a PC board  78  with conductive strips forming electrical connections. The lens  69  ensures that radiation received by the radiation detecting elements  72  are traveling substantially in the Y-direction. Radiation not traveling in the Y-direction, such as shown by arrow  74 , is blocked or reflected by the lens  69 . Each of the detecting elements  72  are separated from one another by divider walls  80  extending between the lens  69  and the detector elements  72 . The divider walls further help to ensure that the detecting elements  72  receive radiation traveling substantially in the Y-direction. 
     When a seed  82  falls through the seed tube between the radiation emitter  58  and the array of radiation detecting elements  72 , there will be an interruption in the radiation incident upon one or more of the detectors  72 . In other words, the seed will momentarily block the radiation traveling across the seed tube. As shown in  FIG. 3  with the seed  82 , only the detector  72   e  will experience the interruption in radiation incident thereon as shown by the arrows  84 . This not only indicates that a seed has passed, but also indicates the location of the seed in the X-direction relative to the front and rear walls of the seed tube. The output from the detecting elements  72  is transmitted from the array to a processing unit  86  ( FIG. 12 ) through wires (not shown). Wireless communication is also possible. 
     A second sensor assembly  90  is mounted to the seed tube front and rear walls  36 ,  38 . The second sensor assembly  90  is of substantially the same construction as the first sensor assembly  56 . Second sensor assembly  90  includes a radiation emitter  92  mounted to the front wall  36  of the seed tube  24 . The emitter  92  is in the form of an array  94  of LEDs  96  mounted to a PC board  98 . LEDs  96  are covered by a lens  100  to direct radiation in substantially the X-direction. The lens  100  is flush with the interior surface of the front wall  36 . Sensor assembly  90  further includes a radiation detector  102  in the form of an array  103  of radiation detecting elements  104   a - d  on the rear wall  38 , opposite the radiation emitter  92 . The detecting elements  104   a - d  are similarly mounted on a PC board  106  with conductive strips forming electrical connections. The detecting elements are positioned behind a lens  108  that limits radiation passing therethrough to travel in substantially the X-direction as shown by the arrows  112 . Each of the detecting elements  104  are separated from one another by divider walls  110  extending between the lens  108  and the detector elements  104 . The divider walls further help to ensure that the detecting elements  72  receive radiation traveling in the X-direction. While the radiation emitter  92  is shown mounted on the front wall of the seed tube and the detector  102  is shown mounted on the rear wall, they can be reversed without effecting the functioning of the second sensor assembly  90 . The second sensor assembly provides the location in the Y-direction of the seed passing through the tube. Ideally, the second sensor assembly  90  is positioned to sense along the same plane as the first sensor assembly  56 . However, the two sensor assemblies  56 ,  90  can be located in different planes and the difference accounted for in the processing algorithm. 
     As shown in  FIG. 4 , the first and second sensor assemblies  56 ,  90 , cooperate to divide the interior passage of the seed tube into a grid. By sensing the seed in one section of the grid or in two adjacent sections, the X and Y position of the seed is determined. By determining the seed location in both the X and Y directions, multiples of seed can be readily detected. For example, in  FIG. 4  seeds  114  and  116  are both being sensed by the same radiation detecting element  72   c  of the detector  68  and therefore assigned the same location in the X direction. With only the first sensor assembly  56 , seeds  114 ,  116  would be counted as a single seed. The use of both sensor assemblies  56  and  90 , the X and Y positions of the seeds is determined and both radiation detectors  104   b  and  104   d  will detect a seed, indicating two seeds, not one passing the sensors. The use of two sensors thus provides improved precision in counting seeds. 
     With continued reference to  FIG. 3 , when the seed  82  falls through the seed tube, it blocks a significant portion, approximately one half, of the radiation flowing across the seed tube and into the detector  72   e.  The portion of the normal radiation that is blocked with the sensor assembly  56  is much greater than the portion of radiation blocked in a conventional sensor that receives radiation across the entire width of the seed tube. As a result, the signal to noise ratio is much greater with the sensors in the present invention compared to prior sensors. This increased signal to noise ratio enables the sensor assemblies to better distinguish between seeds and dust. This in turn, allows the sensor assembly to be located closer to the seed tube outlet compared to other currently available seed sensors where there is more dust. The closer proximity to the furrow allows greater precision in determining seed spacing. 
     With reference to  FIGS. 5   a  and  5   b,  the dust noise signal and a passing seed is illustrated.  FIG. 5   a  shows the signal  202  generated by dust in the seed tube.  FIG. 5   b  shows the passing of a seed and the peak  204  in the signal generated by the seed. The peak  204  is relatively small from the dust signal  202  and can be easily missed by the signal processing algorithm. In contrast,  FIGS. 6   a  and  6   b  show the signals from three of the radiation detectors  72 .  FIG. 6   a  shows the signals  206 ,  208  and  210  generated by dust. This represents background noise.  FIG. 6   b  shows the peaks  212 ,  214 ,  216  generated by seeds passing the detectors. Since the seed blocks a larger percentage of the radiation incident upon the detectors, the seed generated peaks in the signal are much larger than the baseline dust noise and are easier to distinguish from the noise. 
       FIG. 7  shows a single seed passing solely by detectors  72   c  and  104   b.  Peaks  218  and  220  are generated in the detector signals while the other detectors,  72   a  and B and  104   a  have no peaks in their signals.  FIG. 8  shows two seeds passing through the sensor assemblies. One seed is sensed solely by detectors  72   a  and  104   a  generating peaks  222  and  224  in their output signals. The other seed is sensed by detectors  72   c  and  104   b,  generating peaks  226  and  228  in their output signals. 
       FIG. 9  shows one seed passing partially in front of adjacent detectors  72   b  and  72   c  but not in front of detector  72   a.  The signal from  72   a  continues to register the background noise. Signals from  72   b  and  72   c  have peaks  230  and  232  representing the seed but they are less then the peaks of  FIG. 6   b  where the seed is sensed entirely by one detector.  FIG. 10  is similar to  FIG. 9  with one seed passing partial in front of detectors  72   b  and  72   c  but with another seed is passing in front of detector  72   a,  generating the peak  234 . 
     Similarly,  FIG. 11   a  shows one seed partially passing both the detectors  104   a  and  104   b.  Like  FIG. 9 , shorter peaks  236  and  238  are generated.  FIG. 11   b  in turn shows two seeds simultaneously passing the detectors  104   a  and  104   b.  As a result of the two seeds, the peaks  240  and  242  generated are larger than the single seed peaks of  FIG. 11   a.    
     With reference to  FIG. 12 , a Tractor  120  is shown towing a planter  122 . The planter includes a toolbar  12  having a plurality of planting units  10  attached thereto. A number of support wheel and tire assemblies  124  are coupled to the toolbar for supporting the planter. Wheel and tire assemblies  124  are movable relative to the toolbar to raise and lower the toolbar between a working position in which the planter row units engage-the ground and a raised transport position for moving the planter without engaging the ground. Pivot arms  126  ( FIG. 13 ) carry the wheel and tire assemblies  124  and are in turn coupled to a pivot  128  mounted to the toolbar. A rotation sensor  130  at the hub  132  of one wheel and tire assembly is used to determine the speed of travel of the planter through a field. Alternatively, the tractor  120  is equipped with GPS receiver  134  and processor  136  from which the location, as well as the direction and speed of travel of the tractor and planter, can be determined. In yet another alternative, speed sensors, such as radar sensors  138  mounted to the toolbar can be used to determine the planter speed. Sensors  138  determine the speed by sensing the ground passing beneath the toolbar. While one sensor  138  is sufficient to determine the planter speed, having two sensors spaced apart along the length of the toolbar enables the speed of individual planter units  10  to be determined as the planter follows a contour path. Due to the curved path of the contour, the outside planter row unit moves at a faster speed than the inside planter row unit. Thus, the two sensors  138  are spaced as far apart as practical for greater precision in determining speed differences on a contour. Other types of speed sensors can be used as well. 
     A planter monitor  140  in the tractor has a processor  86  that receives input signals from the seed tube sensor assemblies 56  and  90  as well as input signals from the speed sensor or sensors. A seed trajectory can be predicted based on the release point of the seed in the meter and the X location of the seed as it passes the sensor assembly  56 . The trajectory, the height of the sensor assembly relative to the furrow and the ground speed of the planter unit are used to predict the seed spacing in the furrow. At a minimum, only the first sensor assembly  56  is needed to determine the X direction location of the seed and to predict the seed spacing. The use of the second sensor assembly  90  to determine the location in the Y direction can provide more accuracy to the seed spacing as it can better detect multiple seeds and predict bouncing of the seed caused by contact with the seed tube side walls  40 . 
     Further accuracy in predicting the seed spacing is provided from use of acceleration data of the planter row unit from the accelerometer  35  at the time the seed is release from the meter. Down force data from the down force sensor  33  can also provide greater accuracy by providing a more accurate location of the seed tube relative to the furrow. 
     Determination of the seed trajectory can be made with even more precision with the use of two sets of sensor assemblies  56 ,  90  and  56 ′,  90 ′ as shown in  FIG. 14 . Here, sensor assemblies  56 .  90  are vertically spaced above sensor assemblies  56 ′,  90 ′. With two sets of sensor assemblies, the X and Y positions of seeds are determined at two locations along the length of the seed tube. Having X and Y location data at two points along the seed tube enables greater precision in determining the seed trajectory and thus the final seed spacing in the furrow. 
     While the radiation travels across the seed tube in the substantially the X and or Y directions as described above, there will likely be some radiation inclined to these axes. There is no particular threshold amount of inclined radiation that distinguishes between the sensor working and not working. There will only be a degradation in the sensor accuracy with more inclined radiation leading to the point where the sensor is no longer providing useful information. 
     The invention has been described in the context of a generally vertically oriented seed tube having front, rear and side walls. The designation of the walls as front, rear and side is only for convenience in describing the invention. The sensor assemblies can be used in a horizontal seed tube as well and an inclined seed tube. The labels front, rear and side applied to the walls shall be construed solely as a means of distinguishing between walls without regard to the actual orientation of the walls in physical space. 
     Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.