Abstract:
A system and method for obtaining real-time data regarding the condition of a crop and planning and executing an irrigation cycle in response to the data. The invention uses an unmanned aerial vehicle to survey the conditions within an irrigated area. The irrigation system includes components to vary the amount of water dispensed within particular areas. The data obtained is used to create an irrigation schedule that the irrigation system then carries out. For example, surveyed areas that contain more moisture may be given relatively less water during the next irrigation cycle. The data obtained may also be used to alter a scheduled delivery of fertilizer, pesticide, or some other substance.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This non-provisional patent application claims the benefit of an earlier filed provisional application. The provisional application listed the same inventor. It was filed on Jul. 11, 2016 and was assigned Ser. No. 62/360,753. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable 
       MICROFICHE APPENDIX 
       [0003]    Not applicable 
       BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0004]    This invention relates to the field of agriculture. More specifically, the invention comprises a system and method tor obtaining real-time data regarding the condition of a crop and planning and executing an irrigation cycle in response to the data. 
       2. Description of the Related Art 
       [0005]    The present invention is applicable to a wide variety of irrigation systems and should not be viewed as being limited to any one type. However, it is useful for the reader to have some background knowledge of a particular type of irrigation system so that the invention&#39;s application to that type can be explained in detail. “Center pivot” irrigation systems are now quite common throughout the world, and this type will be used in the examples provided. 
         [0006]      FIGS. 1 through 3  illustrate the components of a typical center pivot system.  FIG. 1  shows a perspective view. As the components are relatively large, the vantage point of  FIG. 1  represents an “aerial” view from an altitude of about 100 feet. Central pivot structure  12  is located in the center of the circular area to be irrigated. A line of booms (commonly referred to as “spans”) is connected to the central pivot structure. Boom assembly  14  connects directly to the central pivot structure. Boom assembly  16  connects to boom assembly  14  at drive tower  20 . Boom assembly  18  connects to boom assembly  16  at drive tower  22 . Drive tower  24  is located on the outer end of boom assembly  18 . End boom  26  (which typically mounts a sweeping nozzle) is also mounted to drive tower  24 . 
         [0007]    Water is pumped in through center pivot structure  12  and carried along the boom assemblies. Many spray nozzles are mounted along the boom assemblies. These nozzles distribute the water. The drive towers include geared drive motors (typically electric motors) that slowly move the booms around the irrigation circle. While a detailed discussion of the operation of center pivot systems is beyond the scope of this disclosure, the reader may wish to know a few basic facts about their operation. In many systems, the outermost drive tower is driven at a controlled rate. The inner drive towers are simply “keyed” off the motion of the outer drive tower. For instance, boom assembly  18  is joined to boom assembly  16  across a flexible joint near the top of drive tower  22 . This flexible joint includes an angular sensor. The angular sensor “trips” when, boom assembly  18  exceeds a small angle with respect to boom assembly  16  (the two booms become non-parallel). When this sensor trips the drive within drive tower  22  is activated and drive tower  22  drives in the same direction as drive tower  24 . in this example all the drive towers operate at the same linear speed. However, since drive tower  22  is running along a smaller circle than drive tower  24 , it will soon overtake the angular position of drive tower  24 . This will be sensed by the fact that boom assembly  16  again becomes parallel with boom assembly  18  (or nearly so). Drive tower  22  will then be shut off until the angular sensor on the flexible joint on drive tower  22  again senses that the boom assemblies are non-parallel. 
         [0008]    The same type of angular sensor is provided on the flexible joint at drive tower  20 . In this operational scheme, drive tower  24  is activated for a fixed period and drives at a set rate. Drive towers  20  and  22  periodically activate to drive forward and keep the boom assemblies parallel. The result is that the three aligned booms pivot around central tower structure  12 . They act as a single linear structure. 
         [0009]      FIG. 2  shows center pivot structure  12  and boom assembly  14  in more detail. The vertical water feed pipe on the center pivot structure is connected to elbow  30  via collector ring  28 . The collector ring allows the pressurized water to be transferred through a freely-rotating joint. The collector ring also often includes a rotating connection for electrical power (such as 440 VAC) and electrical control circuitry (110 VAC or sometimes low-voltage DC). 
         [0010]    Pipe  34  is connected to elbow  30  via joint  32 . The pipe may be arched as shown for greater structural strength. The pipe may be large (such as 10 inches or 25 cm in diameter). The overall length of the boom assembly may be 40 feet (2+ meters). The weight of the water carried in the pipe is quite significant (about 1,400 pounds or 640 kg). The bending forces on so slender a structure are also significant. Thus, these systems typically include reinforcing structure. The pipe shown in  FIG. 2  includes a series of truss assemblies  36 . The outer portions of the truss assemblies are connected by guy wires  38 . These guy wires are tensioned to add strength and rigidity to the overall structure. 
         [0011]    The outer portion of pipe  34  is joined to the next pipe via flex joint  50  on top of drive tower  20 . Drive tower  20  includes a pair of drive wheels  42  that are driven by an electric gear motor. The drive tower may also include a small sprinkler boom that is perpendicular to pipe  34 . This small boom mounts one or more sprinkler heads that are used  10  irrigate areas within the arc of the drive tower&#39;s motion. 
         [0012]    Most of the irrigation provided comes from pipe  34  itself. A series of U-couplings  44  come off the top of the pipe. Each of these couplings is connected to a pendant  46 . Each pendant includes a liquid dispenser of some type (in this case sprinkler head  48  located near its lower end). Each pendant also typically includes a weight to hold the pendant steady. In operation, pressurized water leaves the pipe through the U-couplings, descends through the attached pendants, and sprays out through the sprinkler heads onto the crop. 
         [0013]      FIG. 3  shows the same assembly in a plan view. Irrigation circle  52  is centered on center pivot structure  12 . Boom assembly  14  covers inner boom area  60 . Boom assembly  16  covers middle boom area  58 . Boom assembly  18  covers outer boom area.  36 . End boom  26  covers end boom area  54 . Those skilled in the art will know that most such systems have more than three boom assemblies. It is more common for such systems to have many more boom assemblies (such as ten boom assemblies). However, the principles of operation are the same for the larger versions. 
         [0014]    Those skilled in the art will, also know that such irrigation systems may be used to carry more than just water. Many other things may be dissolved in (or carried by) the water. These other things include fertilizers and pesticides. 
         [0015]      FIG. 4  shows a prior art unmanned aerial vehicle  62  (“UAV” or “drone’), UAV&#39;s come in many different configurations and the invention is by no means limited to any particular configuration. The version shown includes four separate powered rotors  66 . Frame  64  surrounds and guards the rotors. Landing gear  70  in this version comprise four spring steel legs—each of which includes a soft landing pad. 
         [0016]    Sensor array  68  is mounted to the bottom of UAV  62  and is oriented in a downward direction. The sensor array may include a wide variety of passive and active sensors. As one example, a short wavelength infrared (“SWIR”) sensor has been found useful in determining the moisture content of crops being surveyed. The sensor array may contain one or more SWIR receptors. 
         [0017]    The present invention uses the UAV to survey the soil and/or crop growing (and more specifically the crop canopy) within an irrigated area. The invention then uses the data obtained to tailor an irrigation cycle for the irrigated area. 
       BRIEF SUMMARY OF THE INVENTION 
       [0018]    The present invention comprises a system and method for obtaining real-time data regarding the condition of a crop and planning and executing an irrigation cycle in response to the data. The invention uses an unmanned aerial vehicle to survey the conditions within an irrigated area. The irrigation system includes components to vary the amount of water dispensed within particular areas known as “zones.” The data obtained is used to create an irrigation schedule that the irrigation system then carries out (often known as “zone management”). For example, surveyed areas that contain more moisture may be given relatively less water during the next irrigation cycle. The data obtained may also be used to alter a scheduled delivery of fertilizer, pesticide, or some other substance. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0019]      FIG. 1  is a perspective view, showing a prior art center pivot irrigation system. 
           [0020]      FIG. 2  is a detailed perspective view, showing the center pivot structure and the first boom assembly of the system from  FIG. 1 . 
           [0021]      FIG. 3  is a plan view, showing the system from  FIG. 1 . 
           [0022]      FIG. 4  is a perspective view, showing a prior art UAV. 
           [0023]      FIG. 5  is a detailed perspective view, showing a UAV base station as used in some embodiments of the present invention. 
           [0024]      FIG. 6  is a plan view, showing some exemplary survey data. 
           [0025]      FIG. 7  is a plan view, showing an exemplary survey pattern. 
           [0026]      FIG. 8  is a plan view, showing an exemplary irrigation schedule (“zone map”) 
           [0027]      FIG. 9  is a pan view, showing another exemplary survey pattern. 
       
    
    
     REFERENCE NUMERALS IN THE DRAWINGS 
       [0028]      10  center pivot irrigation system 
         [0029]      12  central pivot structure 
         [0030]      14  boom assembly 
         [0031]      16  boom assembly 
         [0032]      18  boom assembly 
         [0033]      20  drive tower 
         [0034]      22  drive tower 
         [0035]      24  drive tower 
         [0036]      26  end boom 
         [0037]      28  collector ring 
         [0038]      30  elbow 
         [0039]      32  joint 
         [0040]      34  pipe 
         [0041]      36  truss assembly 
         [0042]      38  guy wire 
         [0043]      42  drive wheel 
         [0044]      44  U-coupling 
         [0045]      46  pendant 
         [0046]      48  sprinkler head 
         [0047]      50  flex joint 
         [0048]      52  irrigation circle 
         [0049]      54  end boom area 
         [0050]      56  outer boom area 
         [0051]      58  middle boom area 
         [0052]      60  inner boom area 
         [0053]      62  unmanned aerial vehicle 
         [0054]      64  frame 
         [0055]      66  rotor 
         [0056]      68  sensor array 
         [0057]      70  landing gear 
         [0058]      72  UAV landing pad 
         [0059]      74  mounting chassis 
         [0060]      76  cover 
         [0061]      78  hinge 
         [0062]      80  actuator 
         [0063]      82  target 
         [0064]      84  control cable 
         [0065]      86  outlet 
         [0066]      88  valve 
         [0067]      90  connector 
         [0068]      92  mildly dry region 
         [0069]      94  moderately dry region 
         [0070]      96  oversaturated region 
         [0071]      98  UAV base station 
         [0072]      100  flight path 
         [0073]      102  transceiver 
         [0074]      104  CPU/memory 
         [0075]      106  sprinkler coverage arc 
         [0076]      108  wheel tracks 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0077]    The present invention seeks to use real-time or near-real-time data collected by an unmanned aerial vehicle (“UAV”) to modify the application of water and waterborne substances through an irrigation system. The invention can be used with any desired type of irrigation system. However, since a center pivot system was used for the description of the prior art, the embodiments disclosed, hereafter pertain to a center pivot system. 
         [0078]    The UAV is preferably stored on or near the irrigation area to be surveyed so that it does not waste time in transit. A landing pad and housing could be provided on a pole near the field. However, since the irrigation system already provides a substantial structure, it is preferable to use this structure to house the UAV. Returning briefly to  FIG. 2 , the reader will recall that a boom assembly of a center pivot system includes a large pipe  34 .  FIG. 5  shows an enlarged view of UAV base station  98  mounted on pipe  34 . 
         [0079]    The UAV base station includes a flat UAV landing pad  72  atop a mounting chassis  74 . The mounting chassis in this version is attached to pipe  74  using two metal straps. Cover  76  pivots down over UAV landing pad  72  (via hinge  78 ). Actuator  80  moves the cover between the open position (shown) and a closed position where it completely covers the UAV landing pad. 
         [0080]    Targets  82  are provided to guide the UAV onto the pad. There are many known UAV guidance systems and the invention is not limited to any particular one. However, in this version, a GPS receiver on board the UAV is used to guide it to a position just over the landing pad. A digital vision system in the UAV&#39;s sensor array then looks for the targets  82  and uses these to guide the UAV to a landing in the center of the pad. Once the UAV has landed, actuator  80  closes cover  76  over the UAV in order to protect it. The UAV remains under the cover when not in use and is thereby protected from sun, wind, and rain. 
         [0081]    The UAV landing pad includes an inductive charging system that recharges the UAV&#39;s internal batteries as the UAV sits on the pad. Energy may be provided from a solar panel or panels on top of cover  76 . However, as power is typically provided along the boom assembly, this power may be tapped to recharge the UAV batteries. For example, control cable  84  typically carries a low-power DC signal with sufficient capacity to recharge the UAV batteries. 
         [0082]      FIG. 5  shows additional details of an irrigation system modified according to the present invention. In the prior art, each U-coupling  44  is connected to an out let  86  along the top of pipe  34 . In the inventive embodiment shown, a valve  88  controls the flow of liquid from outlet  86  into U-coupling  44  (and from thence to the attached sprinkler head or heads). Each valve  88  is in turn connected by a connector  90  to control cable  84 . Control cable  84  contains multiple conductors. 
         [0083]    Control cable  84  is connected to CPU/memory  104 . The CPU (central processing unit)/memory may be remotely located or may be part of a control box assembly mounted an center pivot structure  12 . It is attached to a transceiver  102  configured to communicate with the UAV. 
         [0084]    In operation, the UAV flies a pattern to collect data in the irrigation area. The UAV or its associated landing station then transfers the data collected to CPU/memory  104  via transceiver  102 . The CPU/memory then uses the data to create a desired operating scheme for the irrigation system as a whole and valves  88  in particular. Some exemplary operating schemes will now be described in more detail. 
         [0085]      FIG. 6  shows a possible state for irrigation circle  52 . The moisture content of the soil and/or crop within the circle is not evenly distributed. Oversaturated region  96  exists, as do mildly dry region  92  and moderately dry region  94 . Prior art irrigation systems are typically designed to provide a uniform distribution of water. If this is done in the field shown in  FIG. 6 , some regions will be overwatered and others will be underwatered. 
         [0086]    Shortly before an irrigation cycle is initiated, the UAV is dispatched to survey the irrigation circle.  FIG. 7  shows this operation. UAV  62  flies away from UAV base station  98  and flies along flight path  100 . Flight path  100  is typically a prescribed pattern that provides good coverage of irrigation circle  52  (The irrigation circle is the irrigation area in question for a center pivot system. In other system types the irrigation area will not be a circle). In the example shown, the pattern is a series of parallel paths. 
         [0087]    Existing flight planning software may be used to create a desired flight pattern and the present invention is by no means limited to any one pattern. If, for example, GPS data is unavailable on a particular day, the UAV may be equipped with a computer vision, system that allows it to fly a pattern based on the wheel tracks of the irrigation system itself. Switching to vision-based information may also suggest the desirability of a different flight pattern and such a flight pattern can be stored in memory for use when needed. 
         [0088]    The UAV may use any desired sensor or sensors. As one example, the SWIR return serves as a good proxy for moisture content. The UAV may use a SWIR sensor to gather data. The UAV correlates this data with GPS-based positional data and preferably time data as well. In other words, each datum point would have a SWIR value, a GPS position value, and a time value. 
         [0089]    The UAV then downloads the data acquired to CPU/memory  104 . Software running on the CPU then analyzes the data. Positional accuracy is important for this analysis. It may be desirable to provide a “reference GPS receiver” that is located on a point fixed by an accurate survey. Such a point is preferably near the field. The signal from this reference GPS receiver may be used to determine the existence of any positional errors in the GPS system on board the UAV at any time. These positional errors may then be backed out of the GPS data. 
         [0090]    A simple example will explain this process. The reference location for the reference GPS receiver is very accurately surveyed. The reference receiver is then fixedly attached to this point. If the reference receiver receives and decodes a GPS signal indicating that it is 2 meters west of its known position, then the software running on the CPU “knows” to move all GPS data taken at that time 2 meters to the east. This technique is well known in the field of surveying and may be used to greatly enhance the accuracy of mobile GPS systems. 
         [0091]    The software eliminates positional overlaps to create a unified and accurate “snapshot” of conditions within the irrigation circle. This data is then used to create an irrigation schedule or zone map.  FIG. 8  shows an exemplary irrigation schedule. A portion of the motion of the boom assembly is shown as an arc in the view. Individual sprinklers are designated as A-M. Each sprinkler covers a sprinkler coverage arc  106 . At certain portions during the travel of the booms individual sprinklers are turned off. These are designated as exclusion periods  104  in the view. In this example the valves  88  are simple on/off devices. A maximum saturation for all areas would be achieved by leaving all valves on all the time. A selected reduction in some areas is achieved by turning some valves off some of the time. 
         [0092]    In other embodiments a more complicated valve might be employed. This type of valve could have three positions or more (such an off, on-low, and on-high). This would give the system more variability in control. 
         [0093]    It is preferable for the UAV to fly a pattern and build a data set immediately before an irrigation cycle begins. That way the very latest information is used. The term “immediately” in this context means within 8 hours and preferably within 1 hour. Even more preferably, the data set is completed within 10 minutes of the initiation of the irrigation cycle. 
         [0094]    The flight path used for the survey may be driven in different ways. As described previously, GPS data may be used to define the flight path. However, GPS data may not always be available.  FIG. 9  shows a plan view of a line of spans using three drive towers  20 ,  22 ,  24 . As those skilled in the art will know, each drive tower tends to create its own circular wheel track  108 . These wheel tracks may be detected by a computer vision system located on the UAV. The UAV may easily follow the wheel track. Flight path  100  in the example of  FIG. 9  starts at UAV base station  98  and then follows a wheel track. While the UAV is flying this pattern, it will capture images from an altitude in regards to camera resolution for centering the image based on the wheel track. The image will typically be rectangular. Because the UAV is flying a circular pattern the images should be taken at intervals that will produce an overlap between the edge of one image and the edge of the adjacent image. Images can be stitched together (using software) by connecting and overlapping edges by calculating the angle direction in which the UAV is in regards to the wheel track and previous image captured. This will create multiple point overlap for images in a circular direction. The software can then be used to create a unified data set for the area if desired). 
         [0095]    In this example, the UAV includes a digital flux compass that is able to measure the UAV&#39;s heading within +/−5 degrees. Once the UAV has followed a wheel track through 330 degrees of heading change, the UAV is programmed to make a 90 degree left turn and proceed outbound until it intersects the next wheel track. The UAV then follows the next wheel track and continues the process. Obviously there are many different ways to use the wheel tracks to guide the survey pattern. Other existing features may be used—such as the boundary between irrigated and non-irrigated regions. 
         [0096]    The central processing unit described may assume a wide variety of forms. In general an irrigation schedule or plan is created by control software running on a processor-based control system. The processor-based system may include a remote server or servers that actually creates the irrigation schedule and then downloads it to a programmable logic controller (including another processor) located on or near the irrigation system itself. Thus, although the control software may be run on a single processor the inventive method described herein may also be carried out using multiple processors that are not in the same location. 
         [0097]    Looking again at the irrigation plan of  FIG. 8 , those skilled in the art will realize that the angular position of the line of irrigation booms is important to the execution of the plan. Returning to  FIG. 2 , the reader should note that collector ring  28  typically includes an angular position sensor in addition to the other slip rings. This angular position sensor “tells” the control software where the booms are in their slow movement around the irrigation circle. Thus, the control software knows when a particular sprinkler head is passing over a particular arc segment that is scheduled to receive more or less liquid. The control software then modulates the valve feeding that sprinkler head accordingly (“modulation” meaning simply changing the state of flow through the valve). 
         [0098]    Other embodiments of the invention will include other features, such as: 
         [0099]    1. The valves may be controlled wirelessly, with only the power signal being hard-wired; 
         [0100]    2. A UAV stored in a UAV base station on one center pivot boom may be used to acquire data for one or more other separate center pivot irrigation circles (with the data acquired being loaded into a CPU/memory associated with the other center pivot system; and 
         [0101]    3. Digital video camera sensors may be used on the UAV to build an accurate visible-light map of the irrigation circle. 
         [0102]    The preceding description contains significant detail regarding the novel aspects of the present invention. It is should not be construed, however, as limiting the scope of the invention but rather as providing illustrations of the preferred embodiments of the invention. Thus, the scope of the invention should be fixed by the claims ultimately drafted, rather than by the examples given.