NZ200165A - Computerised solar irrigation controller - Google Patents

Description

200165 Patents Form No.5 NEW ZEALAND PATENTS ACT 19 53 COMPLETE SPECIFICATION "COMPUTERIZED SOLAR IRRIGATION CONTROLLER" Vol C*» ~ WE STATE OF ISRAEL - MINISTRY OF AGRICULTURE, POD G ; Bet Dagan, Israel, and ELECTRA (ISRAEL) LTD., New Industrial Zone, Rishon-le-Zion, Israel, an Israel company, hereby declare the invention, for which -I/we pray that a patent may be granted to fne/us, .and the method by which it is to be performed, to be particularly described in and by the following statement:- Xo 016 5 FIELD OF THE INVENTION This invention relates to computer controlled irrigation systems in general and to computer controlled irrigation systems which utilize solar radiation and atmospheric conditions to control the irrigation in particular.

BACKGROUND OF THE INVENTION Numerous irrigation systems are known and in use today. Many of these systems either allow water to run through them continuously as long as water is available, or are manually controlled by opening gates and allowing the water to run onto the land. These systems do not provide water according to the needs of the crops resulting sometimes in overwatering and other times in lack of water.

Recently, systems have been designed which utilize complicated and sophisticated sensors and controls to monitor such characterisitics as the mois'ture in the plants, in the soil or in the air and the amount of sunlight striking the plants. These factors are then coordinated with other factors to provide a signal to turn on an irrigation system and bring water and nutrients to the plants being monitored. The present system is designed to provide results comparable to those obtained by the complicated, sophisticated and expensive systems without the high cost. j The present system is especially useful in desert environment or in environments having fully controlled watering, i.e. in greenhouses.

It has been shown experimentally that the major factor in a plant's usage of water is the amount of solar radiation that falls on the plant over a given period of time. Therefore, the amount of solar radiation impinging upon the plant is a major factor in determining how much water the plant requires at any given time. In addition, the temperature of the growing region affects the amount of water required by the growing plants. For example, on a day when the temperature is very high but there is not a great deal of solar radiation, the plants may require more water than would appear from the amount of solar radiation alone. A further factor which is preferably taken into account is the amount of water supplied to the plants by rainfall. In other words, when rain has 2 2 0 016 5 'S fallen, the plants have a lesser need of irrigation than would appear from the amount of solar radiation alone.

Irrigation systems controlled as a function of the amount of radiation have been provided in the past. However such systems have not proved satisfactory. They have either been over complicated, unreliable or not sufficiently responsive to the needs of the plants to accomplish theproper control of the irrigation systems under either controlled conditions or pseudo-control led conditions, SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide new and improved solar control irrigation systems in which the above-referred to disadvantages are substantially reduced or overcome.

It is a further object of the present invention to provide an improved computer controlled irrigation system which utilizes, in addition to solar radiation, atmospheric temperature and amount of rainfall to control the amount and duration of irrigation.

According to the present invention a solar radiation controlled system is provided, said system comprising: receptor means for providing a first signal which varies digitally as a function of radiation impinging on said receptor means; integrator means for providing an integrated signal responsive to the time summing of said first signal reaching a preset value; control means for causing the operation of the system to commence responsive to said integrated signal; and means for ending the operation of the system responsive to a determined condition.

There is further provided in accordance with an embodiment of tf • present invention an irrigation system comprising receptor., means for providing a,digital output signal that varies as a function of solar radiation impinging on the receptor means, temperature sensing means for providing a digital output signal that varies as a function of the temperature at the site of the sensor, integrator means for providing an integrated signal responsive to the time summation of the radiation reaching a preset value, temperature compensation means to adjust the integrated signal, control means for causing the operation of the system to commence responsive to the signal, and means for ending the operation of the system responsive to a determined condition. 2 0016 5 There is still further provided in accordance with an embodiment of the present invention such an irrigation system which further comprises rainfall sensing means for providing a digital output signal that varies as a function of the amount of rainfall, and rainfall compensation means to adjust the integrated signal responsive to the amount of rainfall.

When irrigation -fluid passes through irrigation pipes and throuc . the filters which are in those pipes., there is a buildup over time of dirt and other undesirable material on the filters. It is therefore desirable to have an easy means of cleaning out the filters without being required to dismantle the entire system. There is thus provided in*' accordance with ar: embodiment of the present invention control means which cause periodic backwashing of the filters to occur automatically.

There is thus provided in accordance with an embodiment of the present invention an irrigation system comprising integrator means for providing an integrated signal, control means for causing the operation of the system to commence responsive to the signal, metering means to provide a digital output signal to the integrator means responsive to the flow of a desired amount of water, and back^wash means operative in response to a signal from the control means to clean the irrigation systeir BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more fully understood and appreciated from the following detailed description taken in conjunction with the drawings in which; Fig. 1 is a block diagram showing a solar radiation controlled irrigation system; Fig. 2 is a schematic further showing the operation of the control blocks of Fig. 1; Fig. 3 is a schematic illustration of a preferred embodiment of the irrigation system of the present ivention; Fig. 4 schematically shows an alternate embodiment of one sensor of the present invention; and Fig. 5 is a detail illustration of a backwash means of the present invention. 4 200165 DETAILED DESCRIPTION OF THE INVENTION The solar irrigation system 11 shown in Fig. 1 comprises a radiation receptor assembly shown generally as 12 which provides a signal that varies digitally. In a preferred embodiment the signal varies in frequency as a function of the intensity of the radiation impinging upon the assembly. The signal is transmitted over conductor 13 to interface and integrating devices shown generally as block 14. The output of the integrating device of block 14 is a digital signal which is conducted over conductor 16 to control circuit 17 that controls the valve 18 used to enable the irrigation fluid in pipe 19 to flow through a- metering device such as water meter 21 with an electrical output such as an electrical contact closure, to an irrigation system, indicated generally as 22.

The receptor assembly 12 is comprised of a silicon chip 26 mounted within a container in a manner such that the radiation intensity is a function of the cosine of the angle between the sun and the vertical. The radiation input R. is equal to the R0 when the sun is directly overhead, times the cosine of the angle between the sun and the vertical, Thus, for example, when the sun is directly over the receptor then the maximum radiation is received. The receptor chip 26 is behind a diffuser plate 27 which diffuses the radiation striking it. The diffuser plate 27 is protected by a transparent dome 28.

The chip provides different frequencies as a function of the impinging radiation. The chip is sensitive to light within the spectrum that extends from infrared to ultra-violet or more quantitative!; from 350 to 1200 nanometers, with the peak sensitivity at approximately 800 nanometers. In a preferred embodiment, the output is 1 pulse per second for each kilojoule per square meter per second of incident global solar radiation.

Means are provided for coupling integrated circuitry to the receptor. More particularly it is preferred that there be complete isolation between the receptor assembly and the following circuitry.

This is accomplished in a preferred embodiment by the coupling means used between the receptor assembly 12 and the integrator circuitry 14. The coupling means 29 is an optical coupler 29 between conductors 13 and 15. 2 0016 5 The integrator circuitry 14 continuously sums the response of the receptor over a period of time and thus provides a signal that is dimensionally equivalent to kilojoules per square meter. The integrator circuitry is set for the receipt of a certain number of pulses equivalent to a certain number of kilojoules per square meter of incident global solar radiation at which time it provides a control signal on 16. The control signal on 16 operates through the controller 17 to activate an output device such as the valve 18 in pipe 19 leading to the irrigation fields from an irrigation water source such as a pump. Thus, for example, pipe 19 is connected to a high pressure water source and with the opening of the valve 18, water flows to the irrigation system as represented by 22.

The water flowing throughrthe irrigation system is measured by flow meter 21. The flow meter sends a pulse signal back to the control circuitry 17. The control circuitry is set for a certain quantity of water by control setting 31, for example. The set quantity is read out at display 32. When the quantity of water measured by flow meter 21 equals the quantity set as shown by readout 32 then the valve is deactivated and closed, stopping the flow of water to the irrigation system.

At the time of the operation of the valve 18, the integrating circuitry is reset, so that it can continue to operate during the time that the control circuit holds the valv6 18 open.

The circuitry of Fig. 2 shows in greater detail what is occurring in the blocks 14 and 17 of Fig. 1. In Fig. 2, for example, the output of the photo-coupler is coupled to the integrating circuit 14 which comprises a plurality of frequency dividers. The dividers provide the signal output responsive to the required or set number of kilojoules per meter squared.

. The integrator 14 is shown as comprising three frequency divide The first frequency divider 36 is for example, a preset divider circuit. The output of the receptor 12 in one preferred embodiment is in the range of 100 K.Hertz and the first divider network is set to have an output in the range such that the dividers can provide an output of .1 cycle/seco* i In a preferred embodiment the first divider circuit is preset to divide by 16. 6 200165 The second frequency divider 37 which is coupled to the output of the first frequency divider over conductor shown as 38 is an adjustable frequency divider that is in the order of divide by 1 or 10, or 100 or 1000.

The third frequency divider 39 which is connected to the output of the second frequency divider through conductor 41 is also adjustable and divides by 1 to 99. Thus operation of the control 23 on the integrator adjusts the two frequency dividers 37 and 39 to obtain the desired number of kilojoules per square meter. The output of the frequency divider 39 is conducted through conductor 16 to the control circuit 17. At the input to the control circuit is a timer 42. The timer assumes that there is sufficient time between the generation of the output signal by frequency divider 39 and the reset signal for the operation of a counter '43 in the control circuit. The output of the timer 42 is connected through conductor 44 to the input of the counter 43 which counts the number of irrigations applied by the system.

At the same time, the output of the timer 42 also activates the relay ^ which closes a contact. This contact activates the valve control portion of circuit 17 which then opens the solenoid valve starting the irrigation system by sending a valve operative signal over conductor 31.

The water meter 21 measures the water flow through the irrigation system and transmits a number of pulses corresponding to the water flow to control circuit 17 via conductor 32, When the number of pulses emitted by the water meter equals the number preset at counter 43, the solenoid valve' closes and irrigation ceases until a further signal is received from the control unit 17.

A further feature of the present invention is that the operation of an irrigation system is continuously controlled over wide spans of time. The system can cause irrigating water to be furnished either for short durations or long durations. The system can also keep the water supply turned off. over long periods of time.

Thus the system can spray plants for cooling purposes every few seconds or alternatively can turn on the water every few weeks. 7 200165 Thus, in a preferred embodiment at the peak incident solar radiation _2 flux density of 1 KW m , there is a variation in the number of seconds that the system is kept off or on ranging from 1 - 99,000 seconds.

With reference to Fig. 3 there is shown an irrigation system of a preferred embodiment of the present invention in a growing region generally designated 102. Primary irrigation pipe 104 leading from an irrigation water source such as a pump, is connected to a plurality of secondary irrigation pipes, sprinklers, drippers or other irrigation fluid distributing means 108 which are aligned in rows of crops. Primary pipe 104 is provided with inlet valve 103. Secondary pipes 108 are provided with valves 109 which are electrically controlled to open and close as desired to irrigate the growing region. Growing region 102 may be fields or greenhouses.

The control system comprises a solar radiation receptor assembly shown generally as 110, similar to that shown in Fig. 1., which provides a signal that varies digitally. Preferably the signal varies in frequency as a function of the intensity of the radiation impinging upon the assembly. The signal is transmitted over conductor 111 to interface and integrating apparatus 120.

There is additionally provided temperature sensing apparatus 112 which also provides a signal that varies digitally. Preferably the signal varies in frequency as a function of the temperature at the site of the sensing apparatus 112. The signal is transmitted over conductor 113 to interface and integrating apparatus 120. Integrating apparatus 120 comprises temperature compensation means which adjusts the output signal responsive to the temperature.

The output of integrating apparatus 120 is a digital signal which is transmitted over conductor 123 to control circuit 124. The integration performed by apparatus 120 follows an empirical formula which is a function of the two principal variables, radiation and temperature. Control circuit 124 controls valves 109 to enable the irrigation fluid in primary pipe 104 to flow through a metering -device such as water meter 126 with an electrical output such as an electrical contact closure, to secondary pipes 108. 2001 There is further provided rainfall sensing apparatus 114 which provides a digital output signal which varies as a function of the amount of rainfall* The signal is transmitted over conductor 113 to interface and integrating apparatus 120. In one embodiment of the invention, integrating apparatus 120 additionally comprises a rainfall compensation means which adjusts the output signal responsive to the amount of rainfall.

An alternate embodiment of a rainfall sensing apparatus is illustrated in Fig. 3. The system of Fig. 3 provides for summing water received by way of rainfall to the water provided through meter 21.

More particularly a quantitative rainfall sensor 20 is provided for providing a signal on conductor 35 that is a function of the quantity of rainfall. The output of the meter 21 and the output of the sensor 20 are both coupled to a summation circuit 25 over conductors 30 and 35 respectively. The amount of water is then placed on conductor 32 for operation of the comparator circuit. Thus for example, if the amoun of rainfall is more than the preset amount of water the valve 18 remains closed. If the amount of rainfall is less than the preset amount the valve 18 is opened and the rain water is augmented.

The receptor assembly 110 comprises a photodiode and a micro-processor which provides different frequencies as a function of the impinging radiation.

Temperature sensing apparatus 112 comprises a thermistor or any other suitable temperature sensing device and a microprocessor which comprises calibration circuitry and which provides different frequencies as a function of temperature.

Rainfall sensing apparatus 114 comprises a quantitative rainfall sensor which provides a signal that is a function of the amount of rainfall.

Integrating apparatus 120 continuously sums the response of receptor assembly 110 over a period of time and thus provides a signal that is dimensionally equivalent to kilojoules per square meter. This output signal will then be altered.to take into account the signal from temperature sensing apparatus 112, and, if desired, from rainfall sensing apparatus 114. Integrating apparatus 120 preferably comprises a plurality of frequency dividers to provide the signal output responsive to the required or set number of kilojoules per square meter, such as described witji reference to Fig. 1. 9 - 200165 The final output signal from integrating apparatus 120 operates through control circuit 124 to activate the irrigation system.

Conductor 125 operates to open and close valves 109 in response to signals from control circuit 124. Control circuit 124 further compri^s a comparator circuit which compares the preset, desired amount of irrigation fluid flow with the actual amount of fluid as measured by metering device 126. When the two amounts are equal, control circuit 12-sends a signal to close valves 109. In the alternative embodiment shown in Fig.'4 the output of the rainfall sensing apparatus enters the comparator circuit of control circuit 124 directly (rather than via integrating apparatus 120). Thus the amount of rainfall is added to the amount of water which has already passed through the meter and this tota is compared with the preset desired amount.

With reference to Fig. 5 there is shown an embodiment of the filter backwash system of the present invention. Secondary pipe 108 is provided with bypass 150 which enters pipe 108 on one side of filter 116 and leaves pipe 108 on the other side of filter 116. Bypass 150 is provided on either end with valves 152, such as three-way valves, to permit isolation of bypass 150 when the system is not being backwashed. Secondary pipe 108 is also provided with outlet 154 and associated valve 156. When a certain, predetermined amount of irrigation fluid has passe through the irrigation system, or when control circuit 124 receives a signal that the water pressure in pipe 108 has dropped a certain amount, control circuit 124 sends a signal via conductor 144 to commence back-washing. Valves 152 and 156 open so as to permit fluid to enter bypass 150 from primary pipe 104, to flow through pipe 108 and filter 116 in the direction opposite to the flow during irrigation (as shown by the arrows), and to exit via outlet 154. When backwashing is finished, control circuit 124 sends a signal to close valves 152 and 156 thus isolating bypass 150 in preparation for continued irrigation.

Thus the system provided herein enables exact control of the irrigation system inexpensively. The receptor 28 provides a cosine function in response to the impinging solar radiation. The coupling of the solar radiation receptor to the remaining circuitry is accomplished without loading the receptor. The coupling shown is a photocoupler such as that provided by the Motorola Company (M0C 1000). The dividers in the integrator circuit also facilitate the control of the integration 2 0 01 6 5 of the digital output of the receptor. The fixed divider is a commercially available 4040 unit. The adjustable dividers and solid state circuits are 4018 units. The timer circuit in the control circuitry 17 is a 555 circuii The counter 43 is an electromagnetic type counter.

It will be appreciated by those skilled in the art that the invention is not limited to what has been shown and described hereinabove ; rather, that the scope of the invention is limited only by the claims which follow:

Claims (1)

1. 200*65;WHAT ME CLAIM IS:;1. A solar radiation controlled irrigation system, said system comprising:;receptor means for providing a digital output signal that varies as a function of radiation impinging on said receptor means;;integrator means for providing an integrated signal responsive to the time summation of said radiation reaching a preset value;;control means for causing the operation of the system to commence responsive to said signal; and means for ending the operation of said system responsive to a determined condition.;2. The solar radiation controlled irrigation system of claim 1, wherein said receptor means provides a frequency output signal that varies as a function of the intensity of the radiation impinging on the receptor means.;3. The solar radiation controlled irrigation system of claim 2, wherein the receptor means is adapted such that the radiation intensity impinging thereon is a function of the cosine of the angle between the sun and a vertical line normal to the horizon.;4. The solar radiation controlled irrigation system as claimed in any one of the preceding claims, wherein the operation of the system commences responsive to the opening of valve means enabling irrigation water to flow through irrigating means, and the operation ends responsive to the flow of a determinable amount of water through the valve means.;" 12 - J;> • , . -N *7 /-/ 'V\ 200165 5. The solar radiation controlled irrigation system as claimed in any one of the preceding claims, wherein said integration means comprises at least one frequency divider network for dividing the frequency signal provided by said receptor means. 6. The solar radiation controlled irrigation system as claimed in any one of the preceding claims, wherein said control means includes a counter for counting the signals provided by said integrator means and for providing a power signal response to a determined count. 7. The solar radiation controlled irrigation system of claims 4 to 6, including flow meter means in a line to the irrigation system for determining the amount of water which is flowing through the irrigation system, and means responsive to the flow of a desired amount of water for operating said valve to the closed position. 8. The solar radiation controlled irrigation system of claims 5 to 7, wherein said at least one frequency divider circuit is reset responsive to the signal opening said valve. 9. An irrigation system comprising: receptor means for providing a digital output signal that varies as a function of solar radiation impinging on the receptor means; temperature sensing means for providing a digital output signal that varies as a function of the temperature at the site of a sensor; integrator means for providing an integrated signal responsive to the time summation of the radiation reaching a preset value; temperature compensation means to adjust the^^jp^ integrated signal; - 13 - 200165 control means for causing the operation of the system to commence responsive to the signal, and means for ending the operation of the system responsive to a determined condition. 10. An irrigation system according to claim 9 and further comprising: rainfall sensing means for providing a digital output signal that varies as a function of the amount of rainfall; and rainfall compensation means to adjust the integrated signal responsive to the amount of rainfall. 11. A solar radiation controlled irrigation system comprising: receptor means for providing a digital output signal that varies as a function of radiation impinging on said receptor means; integrator means for providing an integrated signal responsive to the time summation of said radiation reaching a preset value; control means for causing the operation of the system to commence responsive to said signal; metering means to provide a digital output signal to the integrator means responsive to the flow of a desired amount of irrigation fluid; means for ending the operation of said system responsive to a determined condition; and backwash means operative in response to a signal from said control means to clean the irrigation system. 200165 12. An irrigation system substantially as described hereinabove with reference to any one of the embodiments shown in the accompanying drawings. - 15 -