Abstract:
A diagnostic tool for an agricultural field irrigation system that has a control panel including at least depressible operating switches for controlling the operation of the system includes a wireless transmitter, a wireless receiver and an actuator. The wireless transmitter is configured to selectively encode and transmit an encoded signal, and the wireless receiver is configured to receive and decode the encoded signal, and provide an output signal to activate the actuator. The actuator is operatively connected to the wireless receiver, and is configured to be removably secured to the control panel. The actuator activates at least one of the system operating switches in response to receipt of the output signal from the receiver.

Description:
BACKGROUND 
       [0001]    Center pivot irrigation is a form of overhead crop irrigation in which equipment rotates around a central pivot. Several segments of pipe are joined together and supported by trusses, mounted on mobile towers, and sprinklers are positioned along the length of the pipe. The system is fed with water from a central pivot point attached to one end of the pipe, and the entire irrigation system rotates about the central pivot point. 
         [0002]    Each mobile tower uses wheels or tracks to move in a circular pattern. A master pace for the rotation is set by the outside wheels/tracks (i.e., the set of wheels or tracks furthest from the central pivot point), and the inner sets of wheels/tracks use angle sensors to determine when the bend at a truss/joint is exceeds a certain threshold, indicating that the tower should be moved forward to keep the pipe segments aligned. Originally, the irrigation systems were water powered, but currently most center pivot irrigation systems are powered by either electric or hydraulic motors mounted at each tower. The motor drives a reduction gearbox and transverse drive shafts transmit power to another reduction gearbox mounted behind each wheel. 
         [0003]    Each of the center pivot irrigation systems is controlled by at least a panel control mounted on the central pivot point. Typically, the panel control allows for at least manual push-button start/stop control of the irrigation system. The control panel may also include various displays indicating, for example, electrical output, water pressure, and the like. 
         [0004]    The center pivot irrigation systems occasionally malfunction. For example, the wheels or tracks may stop rotating. When this occurs, the process required for diagnosing and fixing the motor can be time consuming, requiring several trips through the field to repair. Typically, a worker would first need to walk to the central pivot point to shut down the malfunctioning irrigation system. Next, the worker would have to walk to the area of the span that malfunctioned to diagnose the problem. Following that, the worker probably has to retrieve any tools and repair parts required to make necessary repairs to the irrigation system. After making all required repairs, the worker returns to the central pivot to activate the system, and then must return to the area that had malfunctioned to ensure that the system is functioning properly. 
         [0005]    Some systems allow for basic control and monitoring of the center pivot irrigation system through a mobile phone. However, in some rural farming areas, mobile phone service is unreliable or simply non-existent. Moreover, mobile phone control requires special control panels for the irrigation system. Not only are these panels more costly than a typical control panel, but separate panels must be purchased for each center pivot irrigation system the user wishes to control via a mobile phone. Additionally, there is sometimes a time delay of up to an hour or more between issuing a command to the control panel via mobile phone and execution of the command by the control panel. 
       SUMMARY OF THE INVENTION 
       [0006]    An embodiment of the invention is a device which serves as a diagnostic tool for an agricultural field irrigation system that has a control panel including at least depressible operating switches for controlling the operation of the system. The diagnostic tool includes a wireless transmitter, a wireless receiver and an actuator. The wireless transmitter is configured to selectively encode and transmit an encoded signal, and the wireless receiver is configured to receive and decode the encoded signal, and provide an output signal to activate the actuator. The actuator is operatively connected to the wireless receiver, and is configured to be removably secured to the control panel. The actuator activates at least one of the system operating switches in response to receipt of the output signal from the receiver. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a block diagram of a center pivot irrigation system diagnostic tool according to an embodiment of the present invention; 
           [0008]      FIG. 2A  is a plan view of a wireless transmitter according to an embodiment of the present invention; 
           [0009]      FIG. 2B  is a block diagram of the wireless transmitter of  FIG. 2A ; 
           [0010]      FIG. 3  is a block diagram of a wireless receiver according to an embodiment of the present invention; 
           [0011]      FIG. 4  is a cross-sectional view of an actuator according to an embodiment of the present invention; and 
           [0012]      FIG. 5  is a flowchart illustrating an exemplary method of operation of the diagnostic tool of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0013]    An embodiment of the invention is a device used to start the center pivot irrigation system remotely, and that a safety switch located at one of the mobile towers can be used to stop the irrigation system, once the problem has been diagnosed. It is also contemplated that the device can be used to start and stop the center pivot irrigation system remotely, as well as control the irrigation system&#39;s direction of rotation, and cause the system to operate in a safety override mode. 
         [0014]    A preferred embodiment of the diagnostic tool includes a wireless transmitter, a wireless receiver, and an actuator connected to the receiver. The actuator may be removably mounted on a control panel for a center pivot irrigation system, and is used to start and stop the irrigation system from a distance, reducing the traveling distance, and thus the time required of a user when diagnosing a malfunctioning center pivot irrigation system. 
         [0015]    Preferred embodiments of the invention will now be discussed with respect to the drawings. The drawings include schematic representations, which will be understood by artisans in view of the general knowledge in the art and the description that follows. Features may be exaggerated in the drawings for emphasis, and features may not be to scale. 
         [0016]    Referring now to  FIG. 1 , an embodiment of a diagnostic tool is designated generally at  10 . The diagnostic tool  10  includes a wireless transmitter  12 , in wireless communication with a wireless receiver  14 . The wireless receiver  14  controls at least one actuator  16 . The receiver  14  is also connected to a power supply  18 . 
         [0017]      FIG. 2A  is a plan view of the wireless transmitter  12 . The wireless transmitter  12  is covered in a case  20 . The case  20  is preferably made from a hard plastic or metal, and is preferably substantially waterproof because of the irrigating environment in which it will be used. Formed on the front of the transmitter  12  is a button  22  which, when depressed, directs the transmitter to transmit a signal. It is contemplated that additional buttons  22  could be formed on the transmitter  12  to allow additional features to be controlled using the wireless transmitter. For example, an additional button  22  could be formed on the transmitter  12  to allow the transmitter to stop the irrigation system remotely. Additional buttons  22  formed on the transmitter  12  could also be used to regulate the speed and direction of rotation of the irrigation system. The transmitter  12  also includes an antenna  24 , for transmitting the control signal. 
         [0018]      FIG. 2B  is a schematic block diagram of the wireless transmitter  12 . When the button  22  is depressed, a corresponding switch  26  is closed, connecting a predetermined voltage Vcc to an encoder  28 . The encoder  28  also receives signals from dip switches  30 . Using inputs from the switch  26  and the dip switches  30 , the encoder  28  generates an encoded signal which includes at least information about the configuration of the dip switches  30  and information about the status of switch  26 . The encoded signal is then output to the antenna  24 , which is used to transmit the signal. 
         [0019]    The dip switches  30  are user-modifiable, and allow a user to set an identification (ID) code. After the encoded signal has been transmitted, only a receiver using the same ID code can interpret the encoded signal. A user establishes his or her ID code by manipulating the dip switches  30  to a desired configuration. The transmitter  12  preferably has twenty four dip switches  30 , allowing for more than sixteen million unique ID codes. A large number of ID codes allows for increased security, since it is more difficult for a malicious third party to identify the ID code that corresponds to a given transmitter. A larger number of ID codes also makes it possible for more diagnostic tools to operate within a small area, since a receiver will only respond to an encoded signal using a matching ID code. 
         [0020]    The antenna  24  allows for transmission of the encoded signal. The signal is preferably transmitted at a predetermined radio frequency, although other methods of wireless transmission are contemplated. The predetermined frequency is typically selected to be within the range of about 300 MHz to about 450 MHz, although frequencies outside of this range are also contemplated. The transmitted signal has a range of approximately 1,500-2,000 ft. 
         [0021]      FIG. 3  shows a schematic diagram of the wireless receiver  14 . The wireless receiver  14  includes a housing  32  which, like the housing  20  of the wireless transmitter  12 , is also preferably substantially waterproof due to the irrigation environment, and is preferably formed from a hard plastic or metal. The receiver  14  also includes at least two input terminals  34 , one or more output terminals  36 , and dip switches  38 . Additionally, the receiver  14  includes an antenna  40  configured to receive radio frequency transmissions of the same predetermined frequency that the antenna  24  of the wireless transmitter  12  transmits at. 
         [0022]    One of the input terminals  34  is connected to ground (Gnd), and another input terminal  34  is connected to a predetermined voltage Vin from the power supply  18 . The output terminal  36  is connected to the actuator  16 . 
         [0023]    The receiver  14  further includes a decoder  42 . The decoder  42  receives as inputs the ground voltage and the predetermined voltage from the input terminals  34 , the signals from the dip switches  38 , and the received signal from the antenna  40 . 
         [0024]    The antenna  40  is a relatively small internal or external antenna. It is also contemplated that the center pivot can act as the antenna  40 . When the antenna  40  receives a transmission, the received signal is input into the decoder  42 . The decoder  42  compares the received signal with the signals from the dip switches  38  to determine if the ID code from the wireless transmitter that transmitted the received signal matches the ID code specified by the dip switches  38  of the receiver  14 . If the ID codes do not match, the decoder  42  does nothing further. 
         [0025]    If the ID codes do match, the decoder  42  produces an output signal Vout that is sufficient to activate the actuator  16 . The output signal is sent to the output port  36 , and the output port sends the output signal to the actuator  16 . 
         [0026]    Referring now to  FIG. 4 , a cross-section of the actuator  16  is shown. The actuator  16  preferably includes a solenoid  44  having a cylindrical ferromagnetic plunger  46 . The actuator  16  further includes a housing  48 , including a collar portion  50 . One or more magnets  52  are embedded in the surface of the collar portion  50  of the housing  48 . Finally, the housing  48  and collar portion  50  are covered by a coating layer  54 . The coating layer  54  is preferably formed from soft plastic, rubber, or another material that is waterproof, rustproof, and non-conductive. 
         [0027]    The plunger  46  preferably has a diameter that is less than the diameter of the push button on the control panel. Alternatively, it is also contemplated that the plunger  46  may include a narrowed contact portion for contacting the push button on the control panel. 
         [0028]    The solenoid  44  includes a coil of wire surrounding the plunger  46 , and the coil is connected to a wire  56  carrying the output signal from the output port  36  of the wireless receiver  14 . When current is passed through the solenoid  44 , a uniform magnetic field is formed within the wire coil, which causes the plunger  46  to move linearly in the direction of the magnetic field. 
         [0029]    The throw of the ferromagnetic plunger  46  is preferably long enough to activate a start/stop push button control  58  on a control panel  60  made by any of the various manufacturers of center pivot irrigation control panels, but short enough to avoid damaging any of the push buttons. For example, the throw of the plunger  46  is approximately 19 mm (0.75 inches). Similarly, the generated magnetic field must provide the plunger  46  with a sufficient amount of force to activate the push button control  58  on the various manufacturers&#39; control panels  60 , but not so large that the plunger causes damage to the push button when activated. 
         [0030]    The start/stop push button  58  is connected to a momentary contact switch that toggles the state of the irrigation system between operating and standby modes. Thus, if the button  58  is pressed while the irrigation system is in standby mode, the system will enter the operating mode until the button is pressed again. Similarly, if the button  58  is pressed while the irrigation system is in operating mode, the system will enter standby mode until the button is pressed again. 
         [0031]    In operation, the actuator  16  is removably mounted onto the control panel  60  for a center pivot irrigation system. The actuator  16  is positioned such that, when the plunger  46  moves, it will strike the start/stop push button  58  mounted on the control panel  60 . The actuator  16  is preferably mounted on the control panel  60  using the magnets  52  embedded in the collar portion  50 . The actuator  16  is also secured using a thumb screw (not shown) mounted on the side of the actuator. It is also contemplated that the actuator  16  could be mounted via a releasable temporary adhesive that leaves no residue on the actuator or the control panel  60 , suction cups, or any other method of removable mounting. The removable mounting advantageously allows a user to transfer a single diagnostic tool  10  between multiple control panels  60 , if desired. The removable mounting also ensures that, should a user decide to purchase a new control panel  60 , the user will not need to purchase a new diagnostic tool  10  as well. 
         [0032]    The actuator  16  is preferably configured to have a length that is short enough so that, when mounted on the control panel  60 , the actuator does not interfere with the use of a protective covering that can be placed over the control panel. For example, the actuator  16  can have an axial length of approximately 50 mm (2 inches). The protective covering shields both the control panel  60  and the actuator  16  from water, dirt, and the like that may be present in the irrigation environment. 
         [0033]    Referring now to  FIG. 5 , a method of operating the diagnostic tool  10  is described. In step  62 , the wireless transmitter sends an encoded signal to the wireless receiver in response to a button press from a user. The signal is encoded using inputs from several dip switches, as well as an input from the button pressed by the user. The signal is preferably transmitted by radio frequency, and has a broadcast distance of about 1500-2000 feet. However, under ideal conditions, broadcast distances of up to two miles may be possible. 
         [0034]    The receiver receives and decodes the transmitted signal in step  64 . The transmitted signal is decoded using inputs from dip switches on the receiver which correspond to dip switches on the transmitter. In step  66  it is determined whether the ID code represented by the transmitter dip switches matches the ID code represented by the receiver dip switches. If the unique codes do not match, then processing is terminated in step  68 . Otherwise, in step  70 , the decoder outputs a signal to the output port of the receiver. The output signal is provided to a transistor closing a relay switch, and energizing the solenoid of the actuator. 
         [0035]    In step  72 , when the solenoid is energized, a magnetic field is formed. The magnetic field formed by the solenoid causes the plunger to move, striking a start/stop button on the control panel of a central pivot, causing the irrigation system to begin operation. Finally, in step  74 , the user examines the problem area of the center pivot irrigation system to determine what problem has occurred and how best to correct the malfunction. Once the diagnosis is made, the user may again press the button of the wireless transmitter, causing the irrigation system to halt operations so that necessary repairs may be made. 
         [0036]    While specific embodiments of the present invention have been shown and described, it should be understood that other modifications, substitutions and alternatives are apparent to one of ordinary skill in the art. Such modifications, substitutions and alternatives can be made without departing from the spirit and scope of the invention, which should be determined from the appended claims. 
         [0037]    Various features of the invention are set forth in the appended claims.