Abstract:
A method of selectively eradicating plants includes generating images of multiple plants arranged in a bed using a machine vision system mounted to a platform moving along the bed, determining respective locations of the multiple plants from the generated images, selecting from among the multiple plants one or more target plants to be eradicated, and eradicating the one or more target plants by forcing the one or more target plants into the bed using a plunger moving along the bed.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to selectively eradicating plants, and more particularly to mechanically thinning and/or weeding crops in an automated manner. 
       BACKGROUND 
       [0002]    Cultivating crops often involves routine thinning and weeding of the crops. Thinning a field of plants can include destroying and/or removing certain plants in order to maintain a desired spacing between remaining plants (e.g., saved plants). Weeding a field of plants can include destroying and/or removing undesired growths located in proximity to the plants. Thinning and weeding are often performed manually using a standard garden tool (e.g., a hoe) to remove a plant or weed, which can be a laborious task. Thinning and weeding may also be performed using chemical treatments (e.g., fertilizers or herbicides) that may be sprayed on the plants and weeds to chemically kill the plants and weeds. Such chemical treatments can require precise application, may be limited in chemical effectiveness, and may be prohibited on certain (e.g., organic) farms. Additionally, manual and chemical thinning and weeding techniques may be associated with significant costs, risks to personnel safety, and risks to food safety. 
       SUMMARY 
       [0003]    The invention involves a realization that mechanically thinning and weeding plants in an automated manner can increase the precision of a thinning and weeding operation, while eliminating the need to use chemical treatments, eliminating disadvantages associated with such treatments, and reducing costs associated with manual thinning and weeding operations. 
         [0004]    One aspect of the invention features a method of selectively eradicating plants, including generating images of multiple plants arranged in a bed using a machine vision system mounted to a platform moving along the bed, determining respective locations of the multiple plants from the generated images, selecting from among the multiple plants one or more target plants to be eradicated, and eradicating the one or more target plants by forcing the one or more target plants into the bed using a plunger moving along the bed. 
         [0005]    Another aspect of the invention features a plant eradication system that includes a machine vision system that is configured to generate images of multiple plants arranged in a bed and determine respective locations of the multiple plants while the plant eradication system is moved in a direction along the bed, a controller that is configured to select one or more target plants from among the multiple plants that should be eradicated, the controller being communicably coupled to the machine vision system, and a plunger that is operable to eradicate the one or more target plants by forcing the one or more target plants into the bed as the plant eradication system is moved in the direction along the bed, the plunger being communicably coupled to the controller. 
         [0006]    In some embodiments, the machine vision system includes at least one camera that is directed towards the bed and a processor that is operable to analyze the images. 
         [0007]    In certain embodiments, the machine vision system includes at least one hood that surrounds the at least one camera. 
         [0008]    In some embodiments, the method further includes identifying the multiple plants in the image using a recognition algorithm. 
         [0009]    In certain embodiments, the multiple plants include one or more of beets, carrots, lettuce, romaine, onions, parsnips, radishes, rutabagas, spinach, corn, and turnips. 
         [0010]    In some embodiments, determining the respective locations of the multiple plants includes analyzing the images using a blog analysis algorithm. 
         [0011]    In certain embodiments, selecting the one or more target plants includes comparing the respective locations of the multiple plants to a predetermined spacing. 
         [0012]    In some embodiments, the method further includes identifying one or more plants that are positioned within the predetermined spacing as the one or more target plants. 
         [0013]    In certain embodiments, eradicating the one or more target plants includes pushing the one or more target plants about ½ inch to about 2 inches into the bed. 
         [0014]    In some embodiments, the method further includes cutting the one or more target plants using the plunger. 
         [0015]    In certain embodiments, cutting the one or more target plants includes severing one or more of leaves and stems of the one or more target plants. 
         [0016]    In some embodiments, the method further includes identifying one or more weeds in the bed using a recognition algorithm. 
         [0017]    In certain embodiments, the method further includes cutting the one or more weeds using the plunger and forcing the one or more weeds into the bed using the plunger. 
         [0018]    In some embodiments, the method further includes saving desired plants of the multiple plants. 
         [0019]    In certain embodiments, saving desired plants includes rotating the plunger around the desired plants. 
         [0020]    In some embodiments, the plunger defines one or more gaps sized to surround a desired plant. 
         [0021]    In certain embodiments, the plunger is a rotary plunger including a base and multiple teeth that extend from an outer edge of the base. 
         [0022]    In some embodiments, the multiple teeth are configured to cut the multiple plants. 
         [0023]    In certain embodiments, the plunger is positioned at a height above the bed such that the plunger can push the one or more target plants into the bed as the plunger rotates. 
         [0024]    In some embodiments, the base of the plunger defines one or more gaps sized to surround a desired plant. 
         [0025]    In certain embodiments, forcing the one or more target plants into the bed includes dragging the plunger along the bed. 
         [0026]    In some embodiments, forcing the one or more target plants into the bed includes rotating the plunger as the plunger moves in the direction along the bed. 
         [0027]    In certain embodiments, the plunger is movable via a floating frame configured to move vertically as a function of a height of a surface of the bed. 
         [0028]    In some embodiments, a vertical adjustment device is mounted to the floating frame, the vertical adjustment device supporting the plunger. 
         [0029]    In certain embodiments, forcing the one or more target plants into the bed includes controlling a rotatory motor to rotate the plunger. 
         [0030]    In some embodiments, prior to forcing the one or more target plants into the bed, the plunger is moved in a lateral direction by an actuator configured to translate the plunger. 
         [0031]    In certain embodiments, the images are generated, the respective locations of the multiple plants are determined, the one or more target plants are selected, and the one or more target plants are eradicated, while the platform moves at a constant speed along the bed. 
         [0032]    In some embodiments, the controller is configured to control the plunger via one or more of a rotary motor and an actuator. 
         [0033]    In certain embodiments, the plunger is operable to push the one or more target plants about ½ inch to about 2 inches into the bed. 
         [0034]    In some embodiments, the plunger is configured to cut the one or more target plants. 
         [0035]    In certain embodiments, the plunger is operable to force one or more weeds into the bed. 
         [0036]    In some embodiments, the plant eradication system further includes a floating frame that is configured to move vertically as a function of a height of a surface of the bed. 
         [0037]    In certain embodiments, the plant eradication system further includes a vertical adjustment device that is mounted to the floating frame, the vertical adjustment device supporting the plunger. 
         [0038]    In some embodiments, the plant eradication system further includes a rotary motor that is communicably coupled to the controller and that is configured to rotate the plunger. 
         [0039]    In certain embodiments, the plant eradication system further includes an actuator that is communicably coupled to the controller and that is configured to translate the plunger. 
         [0040]    In some embodiments, the plant eradication system further includes an encoder that is communicably coupled to the controller and that is configured to detect a speed at which the plant eradication system moves along the bed. 
         [0041]    In certain embodiments, the plant eradication system operates autonomously. 
         [0042]    In some embodiments, the plant eradication system is moved along the bed by a tractor. 
         [0043]    Embodiments may include one or more of the following advantages. The method and system may be used to mechanically thin and weed undesired plants without damaging desired plants that are to be saved and without using chemical treatments (e.g., fertilizers or herbicides) to remove the undesired plants and weeds. Accordingly, expenses that would otherwise be incurred by purchasing and using chemical treatments and the risks to food safety associated with using such chemical treatments may also be substantially reduced or eliminated. In some examples, the mechanical action performed by the plant eradication system can be particularly beneficial on organic farms, where the use of certain chemical treatments may be prohibited. Furthermore, the automated actions performed by the plant eradication system can alleviate the need to manually identify and remove undesired plants and weeds, thereby saving time and substantially reducing costs. 
         [0044]    The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the invention will be apparent from the description, drawings, and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0045]      FIG. 1  is a rear perspective view of a thinning and weeding system. 
           [0046]      FIG. 2  is a front perspective view of the thinning and weeding system of  FIG. 1 . 
           [0047]      FIG. 3  is a perspective view showing a portion of the thinning and weeding system of  FIG. 1 , including a plunger defining two gaps, as the plunger eradicates a plant disposed within a bed of plants. 
           [0048]      FIG. 4  is a perspective view showing the portion of the thinning and weeding system of 
           [0049]      FIG. 3 , including the plunger, as the plunger passes over a plant disposed within the bed of plants. 
           [0050]      FIG. 5  is a side perspective view showing a portion of the thinning and weeding system of  FIG. 1 , including a lower frame that supports the plunger of  FIG. 3 . 
           [0051]      FIG. 6  is a rear perspective view showing the portion of the thinning and weeding system of  FIG. 5 , including the lower frame that supports the plunger of  FIG. 3 . 
           [0052]      FIG. 7  is a flow chart of an example process for thinning and/or weeding crops. 
           [0053]      FIG. 8  is a side perspective view showing a portion of a thinning and weeding system, including a plunger defining a single gap. 
           [0054]      FIG. 9  is a side perspective view showing a portion of a thinning and weeding system, including a plunger formed as a stake. 
           [0055]      FIG. 10  is a perspective view showing a portion of a thinning and weeding system, including a plunger that has wide, spaced apart teeth. 
           [0056]      FIG. 11  is a rear perspective view of the thinning and weeding system of  FIG. 1 , attached to a tractor. 
       
    
    
       [0057]    Like reference symbols in the various figures indicate like elements. 
       DETAILED DESCRIPTION 
       [0058]    A thinning and weeding system for thinning and weeding a variety of crops will be described below. In some embodiments, the thinning and weeding system includes mechanical plungers, a machine vision system, and associated control elements that allow the thinning and weeding system to mechanically remove undesired crops and save desired crops in an automated manner, thereby substantially eliminating a need to use chemical treatments for thinning and weeding the crops. In some examples, the crops may be planted by seed. Example crops that may be thinned and weeded by the thinning and weeding system include beets, carrots, lettuce, romaine, onions, parsnips, radishes, rutabagas, spinach, corn, turnips, and other crops. 
         [0059]      FIGS. 1 and 2  display rear and front perspective views, respectively, of a thinning and weeding system  100  that is operable to mechanically thin and weed a variety crops in an automated manner. In some examples, the thinning and weeding system  100  may be configured to operate autonomously, as will be described in more detail below, or may be configured to operate with other vehicles, as will be described in detail with respect to  FIG. 11 . In the example of  FIGS. 1 and 2 , the thinning and weeding system  100  is positioned over two spaced apart beds  101  of plants  103  that are located in a field of plants. As illustrated, the plants  103  are arranged in two opposing seed lines  105  along a surface  107  of each bed  101 . In some examples, the beds  101  may be spaced about 14 inches to about 22 inches (e.g., 18 inches) apart, depending on the type of plants  103  being cultivated in the beds  101 . In some examples, the two opposing seed lines  105  of plants  103  may be spaced about 10 inches to about 14 inches (e.g., 12 inches) apart along the bed  101 , depending on the type of plants  103  being cultivated in the beds  101 . In some examples, the plants  103  may be spaced about ½ inch to about 2 inches (e.g., 1.75 inches) apart, depending on the type of plants  103  being cultivated. 
         [0060]    The thinning and weeding system  100  includes an upper frame  102  supported by four outer wheels  104 , two adjacent lower frames  106  that are each supported by two inner wheels  108 , and two electrical enclosures  110  mounted to opposing sides of the upper frame  102 . The thinning and weeding system  100  further includes a machine vision system  112  that identifies plants  103  and weeds (not shown) that need to be removed from the surfaces  107  of the beds  101  and a programmable logic controller (PLC) that is located within one of the electrical enclosures  110  and that is electrically coupled to the machine vision system  112 . The thinning and weeding system  100  additionally includes four plungers  114  that are operable to mechanically remove the identified plants  103  and weeds from the surfaces  107  of the beds  101 , four respective motors  116  that are operable to rotate the plungers  114 , and an encoder  128  that is operable to detect an angular velocity of the outer wheels  104 . Additionally, the thinning and weeding system  100  includes a GPS system (located, for example, within one of the electrical enclosures  110 ) that provides a field location to the PLC and a generator (not shown) that provides power to the thinning and weeding system  100 . The thinning and weeding system  100  further includes high capacity batteries  120  that can power the thinning and weeding system  100  for a limited period of time should the generator malfunction. 
         [0061]    The various components of the thinning and weeding system  100  may be powered by, for example, hydraulic or electrical mechanisms that are known to a person skilled in the art. In some examples, the generator converts the hydraulic power to electrical power to provide functionality to the various components of the thinning and weeding system  100 . 
         [0062]    In some embodiments, the outer wheels  104  have a radius of about 6 inches to about 12 inches (e.g., 9 inches), thereby positioning the upper frame  102  (e.g., and any components mounted to the upper frame  102 ) of the thinning and weeding system  100  above the level of the field. In some embodiments, the inner wheels  108  have a radius of about 2 inches to about 4 inches (e.g., 3 inches), thereby positioning the lower frames  106  (e.g., and any components mounted to the lower frame  106 ) of the thinning and weeding system  100  above the surfaces  107  of the beds  101  of plants  103 . In this manner, the lower frames  106  are floating frames that have an adjustable height relative to the upper frame  102  such that the thinning and weeding system  100  may adapt to a variable height of the surfaces  107  of the beds  101  of plants  103 . As illustrated, the lower frames  106  are attached to opposing sides of the upper frame  102  such that each lower frame  106  is aligned with a respective bed  101  of plants  103 . In some embodiments, the lower frame  106  is attached to the upper frame via a four bar linkage mechanism. 
         [0063]    Still referring to  FIGS. 1 and 2 , the machine vision system  112  includes two cameras  122  and two respective hoods  124  that surround the cameras  122 . The cameras  122  and the hoods  124  are located along a frontal member  126  of the upper frame  102 . The cameras  122  are oriented and positioned to image respective fields of view along the beds  101  of plants  103 . In the example embodiment of  FIGS. 1 and 2 , the cameras  122  and the respective hoods  124  may be spaced apart by about 38 inches to about 44 inches (e.g., 40 inches) along the frontal member  126  of the upper frame  102 . The hoods  124  are adapted to block (e.g., reduce the amount of) natural light (e.g., which varies depending on a season, weather, and a time of day) from impinging upon the fields of view. 
         [0064]    The cameras  122  include light-emitting diodes (LEDs) and filters for sufficient illumination and desired image characteristics. The cameras  122  may be standard resolution, color video graphics array (VGA) cameras known to a person skilled in the art. For example, the cameras  122  may have a pixel count of 480×640, thereby allowing each camera  122  to capture both seed lines  105  of the respective bed  101  of plants  103  within one field of view (e.g., a 14 inch×18 inch field of view). The camera resolution (e.g., pixel dimension) of such a field of view may be 0.030 inch, which is adequate for identifying individual leaves of the plants  103  and weeds. Processors of the cameras  122  may have a frame processing time of 25 ms and accordingly allow the cameras  122  to acquire images at a rate of 40 fps, which is fast enough to map locations of the plants  103  while the thinning and weeding system  100  moves at a predetermined speed (e.g., 2 ft/sec). Following capture of an image by a camera  122 , the image is processed by the processor of the camera  122  and further analyzed according to an algorithm that identifies a location (e.g., using an XY coordinate system) of a plant  103  or weed with respect to the camera  122 , as will be described in more detail with respect to  FIG. 7 . 
         [0065]      FIGS. 3 and 4  display perspective views of one of the plungers  114  while removing an undesired plant  103  from the surface  107  of the bed  101  and while saving a desired plant  103 , respectively. Two plungers  114  are mounted to each lower frame  106  and are spaced apart such that the plungers  114  are located on opposing sides of the inner wheels  108  of the respective lower frames  106 . The plunger  114  is operable to rotate with respect to the lower frame  106 . The plunger  114  includes a generally disc-shaped base  115  and multiple teeth  132  that are located along an outer edge of the base  115 . A profile of the base  115  defines two opposing gaps  130  that allow desired plants  103  to be saved as the plunger  114  rotates with respect to the lower frame  106  while the thinning and weeding system  100  moves along the beds  101  of plants  103 . The gaps  130  extend from a center of the base  115  to the outer edge of the base  115 . In some examples, the gaps  130  include an angle of about 20 degrees to about 60 degrees (e.g., 45 degrees). 
         [0066]    The teeth  132  are configured to tear and sever roots and leaves of undesired plants  103  as the plunger  114  rotates with respect to the lower frame  106  while the thinning and weeding system  100  moves along the beds  101  of plants  103 . The teeth  132  extend within the plane of the base  115  and have a maximum thickness that is substantially less than or about equal to a thickness of the base  115 . In some examples, the teeth  132  have a width of about ⅛ inch to about 1 inch (e.g., ½ inch) and a length of about ⅛ inch to about ¾ inch (e.g., ¼ inch). A diameter of the base  115  is generally sized such that the gaps  130  of the plunger  116  may be aligned to surround the desired plants  103  as the plunger  114  rotates along the bed  101  of plants  103 . The diameter of the base  115  is further sized such that the teeth  132  may adequately contact an undesired plant  103  to sever the leaves of the undesired plant  103  and such that the plunger  114  may remove the undesired plant  103  from the surface  107  of the bed  101  by forcing (e.g., pushing) the undesired plant  103  into the bed  101  of plants  103 . In some embodiments, the base  115  of the plunger  114  has a diameter of about 4 inches to about 14 inches (e.g., 10 inches). In some examples, the plunger  114  may force the undesired plant into the bed  101  by about ½ inch to about 2 inches below the surface  107  of the bed  101 . In some embodiments, the base  115  of the plunger  114  has a thickness of about ⅛ inch to about 1 inch (e.g., ½ inch). 
         [0067]    Each plunger  114  is rotated in the direction of travel of the thinning and weeding system  100 , as indicated by an arrow in  FIGS. 3 and 4 . The plungers  114  are rotated by the respective motors  116  (e.g., servo-controlled motors) located near centers of the plungers  114 , as will be described in more detail with respect to  FIG. 7 . 
         [0068]      FIGS. 5 and 6  display perspective views of two plungers  114  supported by the lower frame  106  of the thinning and weeding system  100 . In particular, each plunger is supported by a vertical adjustment device  134  that is mounted to the lower frame  106  and that includes an internal rotating gear mechanism (e.g., a threaded rod). The vertical adjustment device  134  can variably lower the plunger  114  to an appropriate location above the surface  107  of the bed  101  (e.g., to a location such that the outer edge of the plunger  114  extends about ½ inch to about 2 inches below the surface  107  of the bed  101 ). Additionally, two actuators  136  (e.g., servo drive actuators) are located on each lower frame  106  and are operable to translate the respective plungers  114  in a direction transverse to the seed lines  105  such that the plungers  114  can be aligned with the seed lines  105  as the seed lines  105  vary in position (e.g., lateral position). Accordingly, the plungers  114  may also be positioned to remove weeds located between the opposing seed lines  105 . Cam rollers  138  mounted to respective vertical adjustment devices  134  allow the plungers  114  to move smoothly with respect to the lower frames  106  as the thinning and weeding system  100  moves along the beds  101  of plants  103 . 
         [0069]    In operation, the thinning and weeding system  100  travels along the beds  101  of plants  103 . In some examples, the thinning and weeding system  100  travels in an autonomous manner. For example, the thinning and weeding system  100  uses analyses of the images captured by the machine vision system  112 , as well as field locations provided by the GPS system, to guide itself along the beds  101  of plants  103 . Additionally, the thinning and weeding system  100  uses a field mapping provided by the GPS system to determine when the thinning and weeding system  100  has reached an edge of the field and accordingly when to turn and travel in a different direction. 
         [0070]    As the thinning and weeding system  100  travels in the field, wireless communication is maintained over a network between a remote operator and the PLC controller and GPS system so that a status of the thinning and weeding system  100  can be monitored. Example parameters that may be monitored by the remote operator include a field location of the thinning and weeding system  100 , a velocity of the thinning and weeding system  100  (e.g., an angular velocity of the outer wheels  104  and the inner wheels  108 ), a number and location of plants  103  that have been eradicated, a number and location of plants  103  that have been saved, a frame rate of the camera, and a rotational speed of the plunger  114 . The remote operator may change any of such parameters by sending a signal that includes a corresponding instruction over the network to the PLC of the thinning and weeding system  100 . The PLC may accordingly control the corresponding components of the thinning and weeding system  100 . In some examples, the remote operator may monitor and control multiple thinning and weeding systems  100  simultaneously. 
         [0071]    In some examples, the thinning and weeding system  100  travels at a speed of about 1 ft/sec to about 3 ft/sec (e.g., about 2 ft/sec). The thinning and weeding system  100  moves with respect to the beds  101  of plants  103  such that each camera  122  images a respective bed  101  of plants  103 . Accordingly, the outer wheels  104  rotate along outer edges of the beds  101 , and the inner wheels  106  rotate between opposing seed lines  105  of respective beds  101 . 
         [0072]      FIG. 7  displays a flow chart of an example process  200  that may be implemented to thin and/or weed the beds  101  of plants  103  using, for example, the thinning and weeding system  100 . As the thinning and weeding system  100  travels, the cameras  122  generate images of the beds  101  of plants  103  ( 202 ). In some examples, the cameras  122  acquire images at a rate of 20 fps to 60 fps (e.g., 40 fps). In some examples, the filters on the cameras  122  may produce an image that highlights the plants  103  and weeds in respective desired colors and shows the soil in grayscale. Once the images are acquired, the images are analyzed using algorithms implemented by the respective camera processors. The images may be analyzed using standard algorithms known to a person skilled in the art, such as a blog analysis. In some examples, the analysis identifies the individual plants  103  and weeds and determines their respective locations (e.g., in an XY coordinate system) ( 204 ) with respect to the camera  122 . In some examples, the processor may distinguish a plant  103  from a weed using a standard recognition algorithm (e.g., pattern recognition) known to a person skilled in the art. The locations of the identified plants  103  and weeds are sent to the PLC, and the PLC determines which plants  103  (e.g., selects target plants) and weeds should be removed from the surface  107  of the beds  101  ( 206 ) and which plants  103  should be saved. In some examples, the PLC determines which plants  103  should be removed and which plants  103  should be saved by comparing the locations of the identified plants  103  to a predetermined spacing between consecutive plants  103 . For example, plants  103  located at certain interval locations (e.g., corresponding to the predetermined spacing) may be saved, while plants  103  located within the interval locations may be eradicated. In some examples, the predetermined spacing may be between about 8 inches and about 12 inches (e.g., 10.5 inches), depending on the type of plants  103  being cultivated. 
         [0073]    As the thinning and weeding system  100  travels along the beds  101  of plants  103 , the encoder  128  monitors an angular speed of the outer wheels  104  and sends this information to the PLC. Using the speed of the outer wheels  104  and the determination of which plants  103  and weeds should be removed and saved, the PLC determines a relationship (e.g., calculates a distance) between the plungers  114  and the plants  103  and weeds. The PLC accordingly controls the motors  116  and the actuators  136  such that the plungers  114  eradicate the undesired plants  103  and weeds ( 208 ) by forcing the undesired plants and weeds into the bed  101  and pass over the desired plants  103 . For example, the plungers  114  may be rotated (e.g., at a speed that is greater than the speed of the outer wheels  104  of the thinning and weeding system  100 ) such that the plungers  114  sever leaves from the undesired plants  103  and weeds (e.g., thereby preventing the plants  103  and weeds from growing further) and forces (e.g., pushes) the undesired plants  103  and weeds beneath the surfaces  107  of the beds  101 . While the plungers  114  rotate, the gaps  130  of the plungers  114  surround the desired plants  103  such that the desired plants  103  are saved. In some examples, the plungers  114  may not be rotated (e.g., the plungers  114  may have an angular speed of zero), but instead be translated (e.g., dragged) with the movement of the lower frame  106  such that the plungers  114  contact and therefore remove a series of consecutive plants  103 . In this manner, the plungers  114  are rotated at a variable angular speed according to which plants  103  and weeds will be removed from the surfaces  107  of the beds  101  and which plants  103  will be saved. In some examples, two opposing plungers  114  may be rotated synchronously along opposing seed lines  105 . In some examples, the two opposing plungers  114  may be rotated asynchronously along the opposing seed lines  105 . 
         [0074]    Accordingly, the thinning and weeding system  100  may be used to mechanically eradicate undesired plants  103  and weeds within the beds  101  of plants  103  without damaging the desired plants  103  that are to be saved and without using chemical treatments (e.g., fertilizers or herbicides) to eradicate the undesired plants  103  and weeds. Accordingly, expenses that would otherwise be incurred by purchasing and using chemical treatments and the risks to food safety associated with using such chemical treatments may also be substantially reduced or eliminated. In some examples, the mechanical action performed by the thinning and weeding system  100  can be particularly beneficial on organic farms, where the use of certain chemical treatments may be prohibited. Furthermore, such automated actions performed by the thinning and weeding system  100  can alleviate the need to manually identify and remove undesired plants  103  and weeds, thereby saving time and substantially reducing costs. 
         [0075]    While the thinning and weeding system  100  has been described and illustrated as including two lower frames  106  with respective cameras  122 , plungers  114 , and other associated components, in some embodiments, a thinning and weeding system may include more than two lower frames with respective cameras, plungers, and other associated components in order to thin and weed multiple respective beds of plants. In such cases, an upper frame of the thinning and weeding system may be sized for appropriate accommodation of the number of lower frames. 
         [0076]    While the thinning and weeding system  100  has been described and illustrated as including two plungers  114  located on opposing sides of the inner wheels  108  of the lower frames  106 , in some embodiments, a thinning and weeding system may include a different number of plungers  114  (e.g., three plungers  114 ) in order to thin and weed a bed of plants  103  including more than two seed lines  105  or in order to remove weeds located between the seed lines  105 . 
         [0077]    While the thinning and weeding system  100  has been described as including the plunger  114  that defines two opposing gaps, in some embodiments, a thinning and weeding system may include a plunger that defines a single gap. For example,  FIG. 8  displays a side perspective view of a portion of a thinning and weeding system  300  that includes a plunger  314  that defines a single gap  330 . The thinning and weeding system  300  is substantially similar in construction and function to the thinning and weeding system  100 , with the exception that the thinning and weeding system  300  includes the plunger  314  instead of the plunger  114 . For example, as shown in  FIG. 8 , the thinning and weeding system  300  includes the lower frames  106 , the inner wheels  108 , the vertical adjustment devices  134 , the motors  116 , the actuators  136 , and other components of the thinning and weeding system  100  that are not shown. 
         [0078]    The plunger  314  is substantially similar in construction and function to the plunger  114 , with the exception that a base  315  of the plunger  314  defines the single gap  330  instead of the two opposing gaps  130 . Accordingly, the plunger  314  is operable to rotate with respect to the lower frame  106  in order to remove undesired plants  103  from the surfaces  107  of the beds  101  and to save desired plants  103 . The gap  330  extends from a center point of the base  315  to an outer edge of the base  315 . Additionally, the plunger  314  includes the teeth  132  disposed along the outer edge of the base  315  of the plunger  314 . In some examples, the gap  330  includes an angle of about 120 degrees to about 180 degrees (e.g., 150 degrees). The larger angle of the gap  330  (e.g., as compared to the angle of the gaps  130 ) allows the plunger  314  to pass over (e.g., save) larger plants as compared to the plants  103  that may be saved by the plunger  114  or to pass over a series of consecutive plants  103 . Additionally, the larger gap  330  of the plunger  314  requires a greater degree of rotation (e.g., as compared to the rotation of the plunger  114 ) in order for the plunger  314  to encounter the undesired plants  103 . In some examples, the greater degree of rotation of the plunger  314  results in more tearing at the undesired plants  103 , which may be appropriate for larger plants or plants  103  that are more difficult to cut. 
         [0079]    While the thinning and weeding systems  100 ,  300  have been described as including the plungers  114 ,  314  that are generally disc-shaped and define one or more gaps  130 ,  330 , in some embodiments, a thinning and weeding system may include a plunger that is generally formed as a stake. For example,  FIG. 9  displays a side perspective view of a portion of a thinning and weeding system  400  that includes a generally elongate-shaped plunger  414 . The thinning and weeding system  400  is substantially similar in construction and function to the thinning and weeding systems  100 ,  300 , with the exception that the thinning and weeding system  400  includes the plunger  414  instead of the plunger  114  or the plunger  314 . For example, as shown in  FIG. 9 , the thinning and weeding system  400  includes the lower frame  106 , the inner wheels  108 , the vertical adjustment devices  134 , the motors  116 , the actuators  136 , and other components of the thinning and weeding system  100  that are not shown. 
         [0080]    The plunger  414  is substantially similar in function to the plungers  114 ,  314 , with the exception that the plunger  414  is operable to rotate with respect to the lower frame  106  in order to remove one plant  103  or weed at time from the surface  107  of the bed  101  of plants  103 , instead of removing a series of consecutive plants  103 . The plunger  414  includes a base  415  and the teeth  132  disposed along opposing outer edges of the base  415 . In some examples, the plunger  414  has a length of about 4 inches to about 6 inches (e.g., 5 inches), a width of about ½ inch to about 1.5 inches (e.g., 1 inch), and a thickness of about ⅛ inch to about 1 inch (e.g., ½ inch). In some examples, the configuration of the plunger  414  may be useful for removing occasional weeds that are sparsely located between opposing seeds lines  105 . 
         [0081]    While the thinning and weeding systems  100 ,  300 ,  400  have been described as including the plungers  114 ,  314 ,  414  that include the teeth  132  extending in a plane of the plungers  114 ,  314 ,  414 , in some embodiments, a thinning and weeding system may include a plunger including teeth that extend beyond opposing surfaces of (e.g., out of the plane of) a base of the plunger. For example,  FIG. 10  displays a perspective view of a portion of a thinning and weeding system  500  that includes a plunger  514  including oblong-shaped teeth  532  that extend beyond opposing surfaces of a base  515  of the plunger  514 . The thinning and weeding system  500  is substantially similar in construction and function to the thinning and weeding systems  100 ,  300 ,  400 , with the exception that the thinning and weeding system  500  includes the plunger  514  instead of any of the plungers  114 ,  314 ,  414 . For example, as shown in  FIG. 10 , the thinning and weeding system  500  includes the lower frame  106 , the inner wheels  108 , the vertical adjustment devices  134 , the motors  116 , the actuators  136 , and other components of the thinning and weeding system  100  that are not shown. 
         [0082]    The plunger  514  is substantially similar in function to the plungers  114 ,  314 ,  414  and accordingly is operable to rotate with respect to the lower frame  106  in order to remove plants  103  or weeds from the surface  107  of the bed  101  of plants  103  and save desired plants  103 . The base  515  of the plunger  514  is substantially similar in construction to the base  315  of the plunger  314  (e.g., the base  515  defines one gap  530 ). The teeth  532  are evenly spaced along the outer edge of the base  515  and have a length L that is greater than a thickness of the base  515 , such that the teeth  532  extend beyond opposing surfaces of the base  515 . In some examples, the teeth  532  have a thickness t of about ⅛ inch to about ½ inch (e.g., ¼ inch), a length L of about 1 inch to about 2 inches (e.g., 1.5 inches), and a width w of about ¼ inch to about 1 inch (e.g., ¾ inch). In some examples, the teeth  532  are spaced about 1 inch to about 2 inches (e.g., about 1.5 inches) apart from one another. In some examples, the thickness of the teeth  532  may be useful for removing plants  103  and weeds that are located along crooked seed lines  105  (e.g., seed lines  105  that vary in lateral position). For example, in such cases, using the plunger  515  (as compared to any of the plungers  114 ,  314 ,  414 ) may require less lateral adjustment of the plunger  515  using the actuator  136  as the thinning and weeding system  500  travels along the beds  101  of plants  103 . 
         [0083]    While the thinning and weeding system  100  has been described as operating autonomously, in some embodiments, any of the thinning and weeding systems  100 ,  300 ,  400 ,  500  may be attached to a vehicle (e.g., tractor) that is operable to pull the thinning and weeding system  100 ,  300 ,  400 ,  500 . For example,  FIG. 11  displays the thinning and weeding system  100  attached to a tractor  109 . The thinning and weeding systems  100 ,  300 ,  400 ,  500  may be attached to the tractor  109  via a three-point hitch or any other suitable attachment mechanisms known to a person skilled in the art. In the example of  FIG. 11 , the tractor  109  is controlled by an operator (e.g., who rides the tractor  109 ) using a wireless monitor (not shown) to control the thinning and weeding system  100  as the thinning and weeding system  100  travels along the beds  101  of plants  103 . Accordingly, the operator of the tractor  109  may determine one or more of the various operational parameters (e.g., a travel speed) of the thinning and weeding system  100 . 
         [0084]    Thus, while a number of examples have been described for illustration purposes, the foregoing description is not intended to limit the scope of the invention, which is defined by the scope of the appended claims. There are and will be other examples and modifications within the scope of the following claims.