WIRELESS WATERLINE PRESSURE SENSOR SYSTEM FOR SELF-PROPELLED IRRIGATION SYSTEMS

A water pressure sensing system for self-propelled irrigation systems has a waterline pressure sensing device mounted at the outermost sprinkler in wireless communications with a master control unit (MCU) mounted elsewhere on the irrigation system. The waterline pressure sensing device includes a water pressure sensor and a processor to detect changes in waterline pressure, in addition to a short-range radio for wireless communication with the MCU. The MCU includes a short-range radio for wireless communication with the water pressure sensing device, a processor for processing the received waterline pressure status data, and a long-range transmitter for relaying this data to a remote internet-connected central computer. The remote central computer alerts mobile operator devices to inform the operator of the waterline pressure status.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is an overview pictorial diagram showing a center pivot irrigation system having a master control unit30(MCU) positioned on an outer-most drive tower15of a pivot span18and having a waterline pressure sensing device40located on an outer-most sprinkler nozzle60for the purpose of monitoring waterline pressure16and using a wireless radio path70to communicate between the waterline pressure sensing device40and the MCU30. The invention includes an MCU30equipped with a short-range radio33(shown inFIG. 3) that communicates locally to a short-range radio43(shown inFIG. 4) that is housed in the enclosure of the wireless pressure sensing device40. Xbee brand radios (commercially available from Digi International of Minnetonka, Minn.) or equivalents are suitable for this purpose. The MCU30also includes long-range radio31(shown inFIG. 3) for two-way communication with terrestrial or satellite networks.

FIG. 1details the mechanized irrigation systems10that are conventional and commercially available from a number of different manufacturers. The center pivot system10shown inFIG. 1is used for purposes of illustrating and explaining the present invention. Mechanized irrigation systems10are commonly used in a center pivot configuration such as shown inFIG. 1wherein the center pivot point12receives pressurized water14for delivery through a fluid delivery system16that includes spans of jointed pipe18supported by wheeled drive towers13for delivery onto the ground through a series of sprinkler nozzles19. Such center pivot irrigation systems10typically have wheels11and motors17at the pivot drive towers13. The center pivot pipe spans18and series of pivot drive towers13can add up to any desired length from the center pivot point12to the pivot end position20. Another type of mechanized irrigation system moves in a lateral or linear orientation across a field. The present invention is not limited in application to the type of mechanized irrigation system (center pivot10or lateral move).

Referring toFIG. 3, the MCU30includes a battery37, a solar panel36, a short-range radio33with an antenna38, a long-range radio31with an antenna39, and a GPS receiver35. Referring first toFIG. 1, the GPS unit35is used to track the position in degrees from north of the roving pivot10from the stationary center pivot point12. The end-of-system MCU30is typically located on the outermost drive tower15of the irrigation system10. As illustrated, the waterline pressure sensing device40is installed in the waterline16at the end position20of the pivot, and at the lower end of the last drop line50, just above the last spray nozzle60. This is the optimum placement of the water pressure sensing device40so as to measure the pressure status of the complete waterline16of the pivot10.

In order to easily locate the pressure sensing device40at an end-of-system location20, all connecting wires and terminals between water pressure sensing device40and the MCU30are eliminated through the use of short-range radios33and43, shown inFIGS. 4 and 5, respectively. These short-range radios33,43are housed in the respective enclosures of the water pressure sensing device40and the MCU30. The short-range radios33,43communicate via wireless path70.

InFIG. 2, the method of operation of the waterline pressure sensing device40and MCU30is set forth. The processor42in the waterline pressure sensing device40wakes up in step300. An internal clock or timer causes the processor42to power-up at predetermined intervals, such as every minute. This wake-up feature300causes the processor to sample the water pressure reading310from the pressure sensor41in the waterline pressure sensing device40and record the water pressure readings in memory44(shown inFIG. 4). This is conventional and conserves the battery within the device40. In step320, the processor42uses the current reading310and the previous reading(s) stored in memory44to determine whether a predetermined change in the waterline pressure status has occurred based on the water pressure readings. For example, whenever a water pressure reading310changes by a certain percentage of the pressure range monitored, the processor42using step320transmits the event over the short-range radio43using step330to the MCU30. Alternatively a pressure switch can be set to operate as an on/off switch. In this embodiment, the processor42in step310does not take and compare individual pressure readings. Rather, a pressure threshold for wet and dry (yes/no) status can be set for each individual pivot situation and used in step320.

In another example, using the processor42and a pressure transducer41that outputs actual pressure in PSI over a range of 0-25 PSI, the prior status stored in memory44could have been a pressure reading of 15.0 PSI. If the waterline pressure sensing data310currently being delivered indicates a pressure of 12.0 PSI, a status change320of −3.0 PSI has occurred, resulting in a 12% change ( 3/25) and a “yes” condition is assumed. Or, the prior status store in memory44could have been 12.0 PSI in which case, if the waterline pressure sensing data step310currently being delivered indicates 12.0 PSI, then a status change320of 0.0% has occurred, resulting in a “no” condition. InFIG. 2, the transmit data step330using the short-range radio43and antenna46is event driven, so that whenever the waterline pressure sensing device40determines that waterline pressure reading310of a pivot10at the waterline position60has changed320by a predetermined percentage over a preset period of time (in the first example with a prior reading of 12.0 PSI and a current PSI reading of 15.0, the percentage change is +12%), the status change result is “yes” and a data packet of waterline pressure status is sent by the short-range radio43in the waterline pressure sensing device40in step330, and is received in step340by the short-range radio33and its antenna38at the MCU30.

InFIG. 2, the MCU30receives the changed waterline pressure status320from the waterline pressure sensing device40. The changed status data from step320can be sent via a data packet330using wireless communications70to the MCU30. The data packet330could include data stored in memory44of prior waterline pressure status readings taken at timed intervals, but not previously sent based on “changed” status320criteria used by the processor42in the waterline pressure sensing device40.

Note that pressure sensing devices40operate over a range of pressures (e.g., 0-25 psi or 0-50 psi). The percentage change in pressure for the pressure sensing device would be typically calculated by using the changed pressure value (3 psi in the above example) as the numerator and the upper range of the pressure sensing device (25 PSI in the above example) as the denominator, resulting in a percentage change of 3/25 or 12%.

Referring toFIG. 2, the waterline pressure data is transmitted in step330using the short-range radio43of the waterline pressure sensing device40, and received by the short-range radio33of the MCU30in step340. In step350, the processor32in the MCU30can simply forward all received waterline pressure data310using step360to transmit the waterline pressure data310over conventional long-range telemetry using its long-range radio31and antenna39to a remote central computer in step350for final processing.

In another embodiment, the waterline pressure data310received by MCU30in step340could be further evaluated by the processor in MCU30using step350before transmitting to the central computer in step360. For example, the waterline pressure data310received by MCU30in step340could be compared by the processor in the MCU30to a prior waterline pressure reading310stored in its memory34using different criteria in step350as compared to the criteria used by the processor in the waterline pressure monitoring device40in step320. In other words, a 1% change in waterline pressure status in step310could result in a status change320of “yes” and the data310would be transmitted in step330to the MCU30and received in step340. However, the criteria used by the processor32in the MCU30in step350could be different from the criteria used by the processor42in the waterline pressure sensing device40in step320. For example, the MCU30in step350may require a 3%+ change in pressure before transmitting water pressure data310to the central server using step360. Because different criteria could be used by the processor32of the MCU30to determine if the waterline pressure status data310is to be transmitted to the remote central computer in step360, not all waterline pressure data310transmitted by the short-range radio43in step330and received by the short-range radio33in the MCU30in step340would, in turn, be transmitted to the remote central computer in step360using the long-range radio31.

FIG. 4is a block diagram of the waterline pressure sensing device40. Its components include a water pressure sensor41, processor42with memory44, short-range radio43with an antenna46, and a battery45powering the electrical components. Optionally, the battery45can be charged by a solar array47. As fully discussed above and shown inFIG. 1, the waterline pressure sensing device40is located at or near the end20of the waterline16of the center pivot10and preferably at the lower end of the drop line50just above the sprinkler60. It is also preferably a self-contained, universal device that will work with any of a number of conventional pivot or lateral move irrigation systems10from a wide variety of manufacturers. The term “self-contained” means that the waterline pressure sensing device40does not interface to the electronics or the wiring of the control or power circuitry for the mechanized irrigation system10. It provides a self-contained operation independent of, and isolated from the electrical circuitry of the irrigation system10. The waterline pressure sensing device40does not interface with any control electronics of the irrigation system10. It is, therefore, easily installed and easily relocated to different center pivots to maximize water pressure monitoring benefits.

It is understood that while a self-contained waterline pressure sensing device40has been shown and described in its preferred embodiment, it is also possible to locate elements, such as the solar array47and antenna46, remotely from the unit. In which case, they can be connected to the waterline pressure sensing device40by suitable cables and connectors.

The above disclosure sets forth a number of embodiments of the present invention described in detail with respect to the accompanying drawings. Those skilled in this art will appreciate that various changes, modifications, other structural arrangements, and other embodiments that could be practiced under the teachings of the present invention without departing from the scope of this invention as set forth in the following claims.