In-canopy sprinkler monitoring system for center pivot irrigation systems

Monitoring systems for center pivot irrigation systems and methods of irrigating an agricultural crop using the irrigation systems are provided. The irrigation systems may comprise a plurality of in-canopy sprinklers. The monitoring systems are configured to detect an operational condition of the plurality of in-canopy sprinklers, including whether individual sprinkler heads have become detached from the irrigation system main line, or whether an individual sprinkler head has become clogged, and alert an operator with a time and/or location of the occurrence of an event associated with one or more of the sprinklers.

BACKGROUND OF THE INVENTION

Field of the Invention

Embodiments of the present invention are directed toward monitoring systems for center pivot irrigation systems comprising a plurality of in-canopy sprinklers. The monitoring systems are configured to detect an operational condition of the plurality of in-canopy sprinklers, including whether individual sprinkler heads have become detached from the irrigation system main line, or whether an individual sprinkler head has become clogged.

Description of the Prior Art

Agricultural irrigation has become the dominant use of freshwater supplies accounting for approximately 70% of the world's withdrawn freshwater. In 2010, the United States alone used 115,000 million gallons of freshwater per day for agricultural irrigation. To preserve limited aquifer resources used for irrigation, especially in the U.S. Great Plains region, the irrigation industry has transitioned to more water efficient and uniform center pivot irrigation systems.

Center pivot irrigation systems with in-canopy sprinklers are commonly used to provide efficient and uniform water irrigation for large-scale agricultural crop production. Conventional pivot systems include a lateral main line and a series of drop lines spaced along the main line. Each drop line has a sprinkler head positioned below the main line to discharge water. Current in-canopy sprinkler packages allow center pivot irrigation systems to operate more efficiently and uniformly.

However, prior art in-canopy irrigation systems have various deficiencies. For instance, prior art in-canopy sprinklers hang low in the canopy and have the potential to become entangled in crop biomass and detach from the center pivot. Thus, prior art in-canopy irrigation systems are prone to having one or more sprinkler heads become detached from the system main line (e.g., due to the drop line breaking and/or the sprinkler head separating from the drop line). A detached sprinkler head permits excessive water to flow from the corresponding drop line, while reducing water supply to adjacent sprinkler heads. This results in decreased crop yields, excessive runoff, soil erosion, anaerobic soil conditions, and deep percolation of nutrients. The current method to detect missing in-canopy sprinklers is manual inspection along the span of the center pivot, which requires significant time and labor. The sprinkler heads of prior art in-canopy systems are also prone to becoming plugged, which can greatly restrict water flow from the sprinkler head or preclude water flow entirely. Because of the sprinklers hang low in the canopy, it is normally difficult for producers to quickly detect and replace clogged in-canopy sprinklers. Thus, a need exists for a monitoring system that alerts producers when an in-canopy sprinkler becomes detached or becomes clogged so that the irrigation system can be promptly repaired before uniformity issue arise.

SUMMARY OF THE INVENTION

Embodiments of the present invention are directed to addressing the aforementioned needs by providing an irrigation system equipped with a sprinkler monitoring system that is able to promptly alert a producer to malfunctions in the operation of the irrigation system.

According to one embodiment of the present invention there is provided an agricultural irrigation system comprising an irrigation main line, one or more sprinkler heads operably coupled to the irrigation main line by one or more respective sprinkler lines, and a sprinkler monitoring system that is operable to detect an operating condition of the one or more sprinkler heads.

According to yet another embodiment of the present invention there is provided an agricultural irrigation system comprising an irrigation main line that is connected to a source of water, a plurality of in-canopy sprinkler heads operably coupled to the irrigation main line by a plurality of respective sprinkler lines, and a sprinkler monitoring system that is operable to detect at least one of a state of attachment of the plurality of in-canopy sprinkler heads to the plurality of respective sprinkler lines and a flow rate of water through each of the plurality of in-canopy sprinkler heads. The sprinkler monitoring system comprises at least one sprinkler sensor associated with each of the plurality of in-canopy sprinkler heads, a master controller node, one or more sprinkler nodes coupled with the sprinkler sensors, and a digital compass node operable to detect the compass bearing of the irrigation system's path of travel.

According to still another embodiment of the present invention there is provided a method of irrigating an agricultural crop. The method comprises delivering a stream of water to a center pivot irrigation system. The center pivot irrigation system comprises an irrigation mainline, one or more sprinkler heads operably coupled to and spaced along the irrigation mainline by one or more respective sprinkler lines, and a sprinkler monitoring system that is operable to detect an operating condition of the one or more sprinkler heads. Water is dispensed from the irrigation mainline, into the one or more sprinkler lines, out of the one or more sprinkler heads, and onto the agricultural crop. The sprinkler monitoring system is used to detect at least one of a flow rate of water through the one or more sprinkler heads and the state of attachment of the one or more sprinkler heads to the one or more respective sprinkler lines. An operator is alerted using the sprinkler monitoring system upon occurrence of at least one of a detachment of one or more sprinkler heads from the one or more respective sprinkler lines and a change in the water flow rate through the one or more sprinkler heads.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Generally, an agricultural irrigation system is configured to dispense water efficiently and uniformly to a field in which crops are being grown. Agricultural irrigation systems according to certain embodiments of the present invention are configured to monitor themselves via a sprinkler monitoring system and determine, for example, if irrigation sprinkler heads become detached or clogged. According to other embodiments, the present invention is directed toward methods of irrigating an agricultural crop using a center pivot irrigation system comprising one or more sprinkler heads and a sprinkler monitoring system to ensure proper operation of the sprinkler heads.

Turning toFIG.1, an exemplary center pivot irrigation system10is illustrated. The center pivot system10preferably comprises an irrigation device that provides one or more in-canopy sprinklers12. The use of in-canopy sprinklers12enables the center pivot system10to dispense water efficiently and uniformly across a field. The center pivot system10preferably includes, among other things, a main line14, a plurality of sprinkler lines16, and a plurality of sprinkler heads18. Water is delivered to the center pivot system10from a source of fresh water, such as a well, and introduced into the main line14. The main line14then distributes the water along the span thereof and into the plurality of sprinkler lines16. The water is then dispensed from sprinkler heads18onto the agricultural crop.

In certain embodiments, each sprinkler line16preferably includes a curved gooseneck line20and a drop hose22(seeFIG.2). The gooseneck line20is attached to a port24presented by the main line14and extends transversely from the main line to an outlet end26. The drop hose22is attached to the outlet end26and extends downwardly therefrom to a sprinkler end28spaced below the main line14. The sprinkler heads18are attached to the sprinkler end28of corresponding sprinkler lines16. A weight30may be attached to drop hose22in order to appropriately position the sprinkler head18in a downward facing direction during use. Additional preferred and alternative features of the center pivot system10are described below.

Although the depicted center pivot system10is preferred, it is within the scope of the present invention for an alternative irrigation device to be used. For instance, the center pivot system could have an alternative configuration of in-canopy sprinklers12. For some aspects of the present invention, the irrigation system10could have a sprinkler configuration other than in-canopy sprinklers.

Exemplary sprinkler monitoring systems according to embodiments of the present invention are depicted inFIGS.3and4. The monitoring systems32broadly include a master controller node34, one or more sprinkler nodes36that are operable to monitor the operation of each in-canopy sprinkler12, a digital compass node38operable to detect the compass bearing of the center pivot system10, and one or more sprinkler sensors associated with the sprinkler heads18that are operable to detect an operating condition of each sprinkler head18. Accordingly, methods of irrigating an agricultural crop according to the present invention include detecting at least one of a flow rate of water through the one or more sprinkler heads18and the state of attachment of the one or more sprinkler heads18to the one or more respective sprinkler lines16. If the sprinkler monitoring system32detects detachment of one or more sprinkler heads18from the one or more respective sprinkler lines16and/or a change in the water flow rate through the one or more sprinkler heads18, the center pivot system operator can be alerted so that necessary repairs can be made.

As depicted inFIG.3, the one or more sprinkler sensors comprise flow meters40that are positioned in the sprinkler lines16between the main line14and the sprinkler heads18. In this embodiment, the monitoring system32is configured to detect if one or more of the sprinkler heads18have become clogged or otherwise exhibit flow characteristics indicative of a malfunction and alert the system operator accordingly by transmitting a message, such as an SMS text message. As depicted inFIG.4, the one or more sprinkler sensors comprise switches42that are configured to change the configuration of an electrical circuit upon detachment of a sprinkler head18from the center pivot system10. The monitoring system32transmits the time and location that a sprinkler head18or drop hose22becomes detached from the main line14. All components of the system32can be joined over an I2C bus and mounted inside a weatherproof housing. It is noted that use of an I2C bus is an exemplary communication protocol that could be utilized in monitoring systems32according to the present invention. It is within the scope of the present invention for a variety of wired and wireless communication protocols to be used for communication between system components.

The master controller node34manages the entire system by monitoring and requesting data from all nodes while communicating pertinent information to the user. In an exemplary embodiment, the master controller node34comprises two processors (e.g., an Arduino MKR GSM 1400 processor and an Arduino Uno processor) connected through a bi-directional logic level converter (e.g., CYT1076). The logic level converter allows the Arduino MKR GSM 1400 processor to communicate with the digital compass node38and the sprinkler nodes36of the monitoring system32.

The master controller node program is configured to perform one or more of the following functions. The program checks the status of all sprinkler nodes36, calculates the coordinates of any detached in-canopy sprinklers12, checks the I2C bus for any missing sprinkler nodes36, requests compass bearing angle from the digital compass node38, reads and responds to applicable text messages sent to the system via a traditional cellular network, and reports any detached or clogged in-canopy sprinklers12in addition to malfunctioning nodes to the end user via a text message. Table 1 provides exemplary system responses to received text messages.

TABLE 1Received Text MessageSystem ResponseSprinklerChecks the status of all sprinkler nodes andtheir attached in-canopy sprinklers and reportsany missing components to the user.HelpSends the user a text message outlining whattext messages, when sent to the system, willgenerate a system response.CompassResponds with text message informing the userof current center pivot compass bearing.OnePauses the system for 1 minute and sends a textmessage informing the user of this.FivePauses system for 5 minutes and sends a textmessage informing the user of this.

If a detached in-canopy sprinkler12is reported, the master controller node34calculates the approximate geographic coordinates in decimal degrees format of the detachment site before reporting this information to the user. This coordinate pair is calculated using the coordinates of the rotational center of the center pivot10, the radius from the rotational center for the in-canopy sprinkler12, and the current compass bearing angle. In an exemplary embodiment, the coordinates of the detachment site are calculated as a long integer since the level of precision of 6 decimal places necessary for accurate coordinates in decimal degree format may not be possible for certain microcontrollers, such as that found on most Arduino boards. In such an embodiment, a latitude of 39.189826 would be denoted as 39189826.

Additionally, to calculate the coordinates of the detachment site, a reference to the length of one degree of latitude and longitude is required. This length is a function of latitude and can be calculated using equations (1) and (2) below where mDDLATand mDDLONare the change of one degree of latitude and longitude per meter, respectively, and Center Latitude is the latitude in decimal degrees format of the rotational center of the center pivot. The coefficients found in both equations ensure that the final value has been converted to the long integer format required by the program.
mDDLAT=0.00114*Center Latitude2−0.02439*Center Latitude+11.284  (1)
mDDLON=−3E−7*Center Latitude3+0.00005*Center Latitude2−0.00012*Center Latitude+11.057  (2)

The mDDLATand mDDLONvalues are set as permanent variables in the program to be utilized by the master controller node during normal operation. If an in-canopy sprinkler is reported missing the coordinates of the detachment site are calculated in long integer format using equations (3) and (4) below where LatSprinklerand LonSprinklerare the latitude and longitude of the detachment site, rSprinkleris the radius in meters from the rotational center the in-canopy sprinkler was attached, Center Latitude and Center Longitude are the latitude and longitude, respectively, of the rotational center in long integer format, and φ is the radian value of the current compass bearing angle.
LatSprinkler=mDDLAT*rSprinkler*cos(φ)+Center Latitude  (3)
LonSprinkler=mDDLON*rSprinkler*sin(φ)+Center Longitude  (4)

The LatSprinklerand LonSprinklervalues are then edited as strings to place the decimal point in the correct position allowing the final coordinates to have 6 decimal place precision. The system then sends a text message via a cellular network to the user informing them which in-canopy sprinkler is missing and approximately where it can be located (see,FIG.5).

The digital compass node38measures the center pivot system's compass bearing angle and reports this value to the master controller node34. In an exemplary embodiment, the digital compass node38comprises two Arduino Uno boards (A and B), two 5V relays, and a digital compass module. The digital compass module, HMC5883L, senses 3-axis magnetic vectors necessary for calculating a compass bearing angle. These values are then reported over the I2C bus to Arduino Uno B which uses the digital compass module's associated libraries to convert the raw vector information into a usable bearing angle. This bearing angle is then transferred to Arduino Uno A over software serial communication protocols where it is then broken into a two-byte integer and transferred over the I2C bus to the master controller node34. In alternative embodiments, a tilt-compensated digital compass module can be used to reduce error that gets introduced when the digital compass module is rotated off horizontal. Therefore, incorporating a tilt-compensated digital compass into the monitoring system32can result in more accurate compass bearing angles when the system32is calculating the geographic coordinates of detached in-canopy sprinkler heads18.

The sprinkler node36is responsible for monitoring respective in-canopy sprinkler heads18and reporting any detachments to the master controller node34. In certain embodiments, the sprinkler node36is configured to monitor up to four flowmeters40attached to individual in-canopy sprinklers12to ensure that the sprinklers are operating within their designed limits. With four flowmeters per sprinkler node, the monitoring system32can be configured to monitor up to 444 in-canopy sprinklers, which enables monitoring of most center pivot irrigation systems10.

However, one or more sprinkler nodes36could be configured to monitor an alternative number of sprinkler heads18. For example, it is possible for each sprinkler node to monitor more than four sprinkler heads18using the appropriate circuitry and control algorithms (e.g., each sprinkler node36could monitor all of the sprinklers12on each span of the center pivot system10). This can be accomplished by creating a unique response by each sprinkler node36to represent the detached in-canopy sprinkler head18instead of simply responding with either a value of “1” or “0”. Additionally, the code of the master controller node34can be modified to properly analyze the incoming messages and match it to a missing in-canopy sprinkler head18. If each sprinkler node36monitors two in-canopy sprinkler heads18, the maximum number of in-canopy sprinkler heads the system32can monitor immediately doubles. This relationship expands linearly and can be adjusted to meet the specific number of in-canopy sprinklers found on the center pivot system10without spacing sprinkler nodes36too far apart.

In an exemplary embodiment, the sprinkler node36is controlled by an ATMEGA 328-PU microcontroller. Normally, this microcontroller is limited to two interrupt pins, which are the inputs necessary for monitoring flowmeters. However, by using a series of transistors, the microcontroller can switch between two flowmeter inputs per interrupt pin. In one or more embodiments, the sprinkler node36also comprises a relay shield that prevents the master controller node from becoming unresponsive if the sprinkler node becomes unpowered. In one or more other embodiments, the board will automatically disconnect from the I2C bus when power is lost due to two transistors between the I2C inputs and the SDA and SCL input pins. This keeps the master controller node34from becoming unresponsive if the sprinkler node36loses power. The board can be accessed and programmed using an FTDI 232 chip that connects to the corresponding FTDI input headers on the board.

It is also within the scope of the present invention for customized printed circuit boards (PCBs) to be used in place of the separate sprinkler and digital compass nodes described above, which comprise commercially available boards. These customized PCBs would allow the overall cost of the monitoring system to decrease because mass produced PCBs incorporating only necessary electrical components are often much cheaper substitutes than purchasing commercially available boards and peripherals separately. It would also allow the assembly of these nodes to be less complex as most connections would already be etched into the PCBs.

Referring again toFIG.3, the sprinkler sensors each preferably comprise a flow meter40that is operable to measure the water flow rate through the corresponding sprinkler line16. The flow meter40may include a housing, a pinwheel rotatably mounted in the housing, and a hall effect magnet sensor operably coupled to the pinwheel. It will be appreciated that the flow meter40is configured to detect detachment of the sprinkler head18(associated with an abnormally-high water flow rate) or clogging of the sprinkler head18(associated with an abnormally-low water flow rate or no water flow).

An exemplary flow meter40is a Liquid Flow Meter—Plastic ½″ NPS Threaded, PRODUCT ID: 828, sold by Adafruit Industries. However, various types of flow meters could be used. For instance, the sprinkler sensor could include an ultrasonic flow meter that uses the Doppler effect to sense particulate flow using a receiving element. Such sensors would be mounted externally to the water line and would generally rely on particulates or bubbles in the flow to operate accurately. Furthermore, one or more sprinkler sensors could include another type of sensor to measure flow, such as a pressure sensor, a rotameter (i.e., variable area flow meter), a spring-and-piston flow meter, a vortex meter, pitot tube, differential pressure sensor, electromagnetic flow meter, or a positive displacement flow meter.

Referring again toFIG.4, the sprinkler sensor illustrated is a switch, namely a magnetic reed switch42. In this embodiment, the reed switch42is in an open configuration when the sprinkler head18is attached to the drop hose22. The switch closes when the head18detaches, thus alerting the operator to the detachment.

In certain embodiments, the sprinkler node program setup begins by digitally writing pins 4 through 7 as “HIGH” to ensure that all relays on the relay shield remain powered. The program then joins the sprinkler node36to the I2C bus with an address matching the in-canopy sprinkler head18it is monitoring. When the master controller node34requests data from the sprinkler node36over the I2C bus, it responds with an integer value of a “1” or a “0”. If the in-canopy sprinkler head18or drop hose22is detached from the center pivot main line14, the integer value sent to the master controller node is “1”.

The principles of the present invention are also applicable where each of multiple sprinkler heads18is associated with a combination of sensors to provide suitable monitoring of the respective sprinkler head operation (e.g., to monitor whether the sprinkler head has become detached or clogged). For instance, each sprinkler head18could be associated with a corresponding flow meter40and a corresponding pressure meter (e.g., where the combination cooperatively monitors detachment and clogging of the respective sprinkler head).

In alternative embodiments, a magnetic reed switch42and magnet44combination is secured above the in-canopy sprinkler head18where it is attached to the drop hose22(FIG.4). The magnetic reed switch42and magnet44combination may be mounted at a crimp connection that mounts the sprinkler head18to the rest of the drop hose22. In certain embodiments, the magnet44is secured to the in-canopy sprinkler head18directly below the magnetic reed switch42. The magnetic reed switch42can then be electrically coupled (wired or wirelessly) to the process of the respective sprinkler node36through a breakaway plug, for example. Half of the breakaway plug could be connected to the sprinkler node36processor, which can be secured to the main line14, while the other half of the breakaway plug is secured to the drop hose22. This allows the sprinkler node36to register any detachments from the in-canopy sprinkler head18or drop hose22since a loss of either component will result in the same loss of signal detected by sprinkler node's processor. The inclusion of break-away plugs between the drop hose22and the center pivot main line14allows the system32to also detect detachments of the drop hose22or gooseneck line20from the center pivot main line14.

Although not depicted, the magnetic reed switch42for each sprinkler head18could be used in combination with one or more other sensors. For example, each sprinkler head18could be associated with a corresponding flow meter40and a corresponding magnetic reed switch42. Such a combination could be used to cooperatively monitor detachment and clogging of the respective sprinkler head18.

If the system includes solenoid valves or any type of controllable valve attached to the drop hose22, the circuit and control algorithm of at least one sprinkler node36can be configured to automatically shut off a sprinkler head18once a detachment or plugged condition is detected. If the monitoring system32is coupled with controllable valves on each of the sprinkler heads18, the system could be adapted for additional applications. For example, the system32could be configured to provide variable rate irrigation (controlling spatially the amount of water applied across a field to meet changing conditions across a field, so that water is applied only where needed), monitoring of chemigation or fertigation (using the center pivot to apply chemicals or fertilizer to the field), and variable rate controlled chemigation and fertigation.

In certain embodiments, monitoring system32may also have the ability to warn the user if wire theft has occurred. By designing the master controller node34to alert the user if sprinkler nodes36have had their I2C communication lines disconnected or have lost power during normal operation, the system32can indirectly detect wire theft. If wires connecting the sprinkler nodes36to the master controller node34are cut, the user will receive a near immediate response from the system detailing which sprinkler nodes36are unavailable.

Also, in certain embodiments, system32can remotely sense center pivot rotational direction. With the incorporation of the “compass” message option in the user interface, users can request the current center pivot compass bearing angle. If a user wishes to remotely sense the direction the center pivot system is rotating, they would simply need to call this function a few minutes apart and compare the responses. If the bearing angle increases between the two messages, then the center pivot is moving in a clockwise direction. Inversely, if the bearing angle decreases between the two messages then the center pivot is moving in a counterclockwise direction. These relationships hold true except if the center pivot crosses North (0°) between the two messages.

In further embodiments, the monitoring system32may incorporate a watchdog timer. The purpose of a watchdog timer is to reset a computerized system if an error arises that causes the system to become unresponsive or prevents the system from carrying out normal functions. This component can be embedded into the master controller node34and would check for signals from the node. Anytime a signal is received, the watchdog timer resets its countdown. If the master controller node34fails to check in before the countdown elapses, the watchdog timer would reset the master controller node34and restart the countdown. The watchdog timer allows the system an additional level of automatic repair preventing the user from needing to physically restart the system anytime a system breaking error occurs.

It will be appreciated that the various embodiments described herein are not necessarily mutually exclusive unless otherwise indicated herein. For example, a feature described or depicted in one embodiment may also be included in other embodiments but is not necessarily included. Thus, the present invention encompasses a variety of combinations and/or integrations of the specific embodiments described herein.