Irrigation system and control device

Abstract

To provide an irrigation system and a control device, enabling implementation of irrigation that can suppress unnecessary water consumption.SOLUTION: An irrigation system comprises a water supply valve that controls the amount of discharge water released from a water supply passage to the soil of a farm field, a soil sensor that detects the amount of moisture in the soil, and a control device that controls the valve opening degree of the water supply valve. The control device determines the valve opening degree for minimizing divergence between the amount of moisture in the soil and a target threshold value when the value of the amount of moisture in the soil detected by the soil sensor falls below the target threshold value. The control device controls the water supply valve opening to the valve opening degree determined in accordance with the deviation between the target threshold value and the amount of moisture in the soil detected by the soil sensor.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The disclosure in this specification relates to an irrigation system and a control device for controlling irrigation to a field.

Background Art

[0002] Patent Document 1 discloses a technique for controlling the valve opening degree for controlling the supply amount of irrigation water based on the soil moisture amount detected by a soil sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The above control does not consider the time when water soaks into the soil, and there may be an overshoot of the moisture amount with respect to the target value, resulting in wasteful use of water, and there is room for improvement.

[0005] The object of the disclosure in this specification is to provide an irrigation system and a control device capable of performing irrigation that can suppress wasteful use of water.

Means for Solving the Problems

[0006] The plurality of aspects disclosed in this specification employ different technical means in order to achieve their respective objects. Also, the scope of the claims and the reference numerals in parentheses described in this section are an example showing the correspondence relationship with the specific means described in the embodiments described later as one aspect, and do not limit the technical scope.

[0007] One of the disclosed irrigation systems includes a water supply path to which water is supplied to discharge water to plants in a field (20), a water supply valve (15) that controls the amount of discharged water released from the water supply path to the soil in the field during irrigation, a soil sensor (311) that detects the soil moisture content of the soil, and a control device (200) that controls the valve opening degree of the water supply valve. The control device controls the water supply valve to the valve opening degree determined according to the deviation between the target threshold value and the soil moisture content detected by the soil sensor.

[0008] One of the disclosed control devices includes a processing unit (334) that determines the valve opening degree of a water supply valve (15) that controls the amount of water discharged to the soil according to the deviation between the target threshold value and the soil moisture content detected by the soil sensor (311), and a signal output unit (332) that outputs a control signal for controlling the water supply valve to the valve opening degree determined by the processing unit.

[0009] This irrigation system and control device determine the valve opening degree according to the deviation between the target threshold value and the detected value of the soil moisture content by the soil sensor, and control the water supply valve to this valve opening degree. This irrigation system and control device can perform control to adjust the valve opening degree so as to suppress the deviation between the target threshold value and the soil moisture content according to this deviation. By this control, since it is possible to control the valve opening degree to suppress the deviation between the target threshold value and the soil moisture content, it is possible to adjust the amount of discharged water that suppresses the overshoot of the soil moisture content with respect to the target threshold value. Therefore, this irrigation system and control device can perform irrigation that can suppress the wasteful use of water.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Figure 25

Figure 26

Figure 27

[0011] Hereinafter, a plurality of embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to those described in the preceding embodiments may be denoted by the same reference numerals and redundant descriptions may be omitted. When only a part of the configuration is described in each embodiment, other embodiments described previously can be applied to other parts of the configuration. Not only combinations of parts explicitly shown to be combinable in each embodiment, but also partial combinations of embodiments are possible as long as there is no problem with the combination, even if not explicitly stated.

[0012] **First Embodiment** The first embodiment disclosing an example of an irrigation system will be described with reference to FIGS. 1 to 10. Hereinafter, three directions orthogonal to each other are shown as the x direction, the y direction, and the z direction. In this specification, the plane defined by the x direction and the y direction is along the horizontal plane. The z direction is along the vertical direction. In the drawings, the description of "direction" is omitted and simply denoted as x, y, and z.

[0013] <Field> Irrigation system 10 is applied to an outdoor field 20 reclaimed on a hill or plain. As shown in FIG. 1, a form in which the irrigation system 10 is applied to a field 20 reclaimed on a plain will be described. The area of this field 20 ranges from several tens of square meters to several thousand square kilometers. The field 20 is provided with a plurality of growing places such as ridges extending in the x direction. These plurality of growing places extending in the x direction are arranged at intervals in the y direction. Seeds or seedlings of plants are planted in each of these plurality of growing places. Examples of such plants include grapes, corn, almonds, raspberries, leafy vegetables, cotton, etc. The irrigation system 10 may also be configured to be applied to a field 20 provided indoors such as in a greenhouse. Therefore, the field 20 in this specification is applicable to the soil provided either outdoors or indoors.

[0014] A plurality of plants grow in one growing place. The plurality of plants are arranged side by side in the x direction to form a single row. Hereinafter, the plurality of plants arranged in a row in the x direction will be referred to as a plant group. In the field 20, a plurality of plant groups are arranged at intervals in the y direction. The shortest distance between the plurality of plant groups in the y direction is longer than the shortest distance between the plurality of plants included in one plant group in the x direction. The spacing between the plurality of plant groups in the y direction varies depending on the type of plant to be grown, the undulation of the field 20, and the climate. The spacing between the plurality of plant groups in the y direction is about 1 m to 10 m. Even if the branches and leaves of the plants grow thickly in the y direction, at least a width is ensured such that a person can move in the x direction between two plant groups.

[0015] <Irrigation system> The irrigation system 10 includes a water supply device 100 and a control device 200. The water supply device 100 supplies irrigation water to the plants in the field 20. The control device 200 determines the supply time and amount of the irrigation water supplied from the water supply device 100 to the plants during the irrigation period. The control device 200 determines the irrigation schedule of the water supply device 100. The irrigation system 10 can detect abnormal states such as water leakage and clogging during irrigation and implement irrigation recovery (fail-safe) when an abnormal state occurs.

[0016] <Water supply device> The water supply device 100 includes a pump 110, a water supply pipe 130, etc. The pump 110 functions as a water supply source that causes irrigation water to flow down into the water supply pipe 130.

[0017] <Pump> The pump 110 is in a constantly driven state. Alternatively, the pump 110 is in a driven state during the day. Also, the driving and stopping of the pump 110 are controlled by a control device 200. The pump 110 pumps out the irrigation water stored in a tank or a reservoir and supplies it to the water supply pipe 130. The irrigation water is well water, river water, rainwater, municipal water, etc. A plurality of water supply valves 15 capable of controlling the flow rate of the irrigation water discharged to the farmland 20 are provided in the water supply pipe 130. When each of these water supply valves 15 is in a closed state and there is no leakage of irrigation water from the water supply pipe 130, the water supply pipe 130 is filled with water. At this time, the water pressure in the water supply pipe 130 becomes a value depending on the discharge capacity of the pump 110, for example, the pump pressure. When the water supply valve 15 changes from the closed state to the open state, irrigation water is discharged from the water supply pipe 130 to the farmland 20. When the discharge amount of the irrigation water is stable on average over time, the water pressure in the water supply pipe 130 becomes a flow pressure lower than the pump pressure.

[0018] <Water supply pipe> The water supply pipe 130 includes a main pipe. The main pipe is connected to the pump 110. The pump 110 supplies irrigation water to the main pipe. The irrigation water is supplied to the farmland 20 through the main pipe.

[0019] <Main pipe> The main pipe includes a vertical pipe 133 and a first connecting pipe 134. The vertical pipe 133 extends in the y direction. The first connecting pipe 134 extends in the x direction. The vertical pipe 133 and the first connecting pipe 134 are connected to each other. Due to such a configuration, the irrigation water flows in the main pipe in the y direction and the x direction. In an example shown in FIG. 1, one vertical pipe 133 is connected to one pump 110. A plurality of first connecting pipes 134 extend from the vertical pipe 133 extending in the y direction.

[0020] The configuration of the water supply path shown in FIGS. 1 and 7 is merely an example of the passage configuration related to irrigation. The number of pumps 110 and vertical pipes 133 provided in the farmland 20, the number of vertical pipes 133 connected to one pump 110, the number of vertical pipes 133 connected to one first connecting pipe 134, and the z-direction positions of the first connecting pipe 134 and the vertical pipe 133 are not particularly limited.

[0021] The plurality of first connecting pipes 134 are arranged side by side with a gap in the y direction. The shortest separation distance in the y direction of the plurality of first connecting pipes 134 is equal to the shortest separation distance in the y direction of the plurality of plant groups. One of the plurality of first connecting pipes 134 is provided for one of the plurality of plant groups. The first connecting pipe 134 extends along the direction in which the plurality of plants included in the plant group are arranged. A supply pipe is connected to this first connecting pipe 134.

[0022] The irrigation system 10 has a plurality of distribution tubes 136 that discharge irrigation water downstream of the water supply path from the first connecting pipe 134. Each distribution tube 136 is a supply unit that supplies irrigation water to the plants in the farmland 20. Each distribution tube 136 is installed at a position where it can supply irrigation water to the ridges provided in the farmland 20. The distribution tube 136 is configured to expand and contract according to the water pressure flowing inside. The distribution tube 136 is formed of, for example, a material or hardness that can be elastically deformed according to the water pressure.

[0023] A plurality of through holes that communicate the inside and outside of the tube through which the irrigation water flows are formed in the distribution tube 136. The plurality of through holes are arranged side by side at a predetermined interval in the axial direction of the tube in each tube. Also, the through holes may be configured to be arranged side by side at a predetermined interval in the circumferential direction of the tube in each tube. The separation distance in the axial direction (for example, the x direction) of the plurality of through holes is equal to the separation distance in the x direction of the plurality of plants. Also, the separation distance of the plurality of through holes and the separation distance of the plurality of plants may be different.

[0024] <Flow of irrigation water> The irrigation water supplied to the vertical pipe 133 by the pump 110 flows in the y direction within the vertical pipe 133. This irrigation water is supplied to each first connecting pipe 134 connected to the vertical pipe 133. The irrigation water flows in the x direction through each of the plurality of first connecting pipes 134. The irrigation water flowing through the first connecting pipe 134 flows down to the distribution tube 136. The irrigation water is discharged from each through-hole in the distribution tube 136 and supplied to the plants. The irrigation water supplied from each through-hole of the distribution tube 136 is mainly supplied to the trunk and the roots of the plants.

[0025] The through-holes of the distribution tube 136 are provided, for example, at a position higher than the portion facing the ground in each distribution tube 136. In this case, the irrigation water discharged from the through-holes spreads in a direction radiating with respect to the central axis of the distribution tube 136 and can be sprinkled at a position away from the tube.

[0026] <Water supply valve> The water supply valve 15 is provided upstream of the distribution tube 136 in the water supply path. When the water supply valve 15 is in the open state, the water supply pipe 130 communicates with each through-hole of the distribution tube 136. Thereby, the irrigation water is discharged from the through-holes. Conversely, when the water supply valve 15 is in the closed state, the communication between the water supply pipe 130 and each through-hole of the distribution tube 136 is blocked. Thereby, the discharge of the irrigation water from the through-holes of the distribution tube 136 stops.

[0027] The water supply valve 15 controls the flow rate of the irrigation water discharged from the through-holes of the distribution tube 136 by controlling the valve opening degree by the control device 200. The control device 200 controls the valve opening degree of the water supply valve 15 to an arbitrary value over the range from a predetermined opening degree to fully open. The water supply valve 15 is a flow rate adjustment valve or a pressure adjustment valve that can precisely vary the flow rate passing through by adjusting the downstream or upstream pressure. The predetermined opening degree is set to a value including a slightly opened opening degree or an opening degree of 0%, that is, fully closed.

[0028] The control device 200 controls the discharge flow rate or discharge velocity per unit time discharged from each through-hole by controlling the valve opening degree of the water supply valve 15. By this control, the control device 200 can control the splash distance, which is the distance at which the irrigation water discharged from the distribution tube 136 lands after separating from the distribution tube 136, or the discharge amount. The splash distance is the distance between the soil landing point of the irrigation water that has jumped out from the distribution tube 136 through the through-hole and the distribution tube 136. According to the technique of controlling this splash distance, efficient irrigation to the place where irrigation is required can be carried out, which also contributes to water conservation. The water supply valve 15 is an on-off valve that controls the flow-down and cut-off of the water supply, and functions as a flow rate adjustment valve capable of controlling the water supply flow rate.

[0029] The control device 200 determines the splash distance of the irrigation water based on the type of plant to which the irrigation water is supplied, the range of the soil layer in the field 20, and the like. The control device 200 controls the valve opening degree of the water supply valve 15 so that the determined splash distance can be obtained. For example, the valve opening degree of the water supply valve 15 is controlled to increase the splash distance when the plant spreads its roots widely or the soil layer is shallow and extensive. Also, the valve opening degree of the water supply valve 15 is controlled to keep the splash distance small when the plant spreads its roots deeply or the soil layer is located near the distribution tube 136. The splash distance can be paraphrased as the irrigation distance.

[0030] <Water pressure sensor> The water pressure sensor 14 is provided in the pipe included in the water supply pipe 130. The water pressure sensor 14 is a pressure sensor that detects the water pressure in the pipe. The water pressure detected by the water pressure sensor 14 is output to the control device 200. The water pressure sensor 14 is installed at an upstream position of the distribution tube 136 in the water supply path. Further, the water pressure sensor 14 may be configured to be installed at a downstream position of the distribution tube 136 in the water supply path.

[0031] When the water supply valve 15 is in the closed state and the inside of the pipe is filled with irrigation water, the pump pressure is detected by the water pressure sensor 14. When the water supply valve 15 changes from the closed state to the open state, irrigation water is discharged from the distribution tube 136. When the discharge amount of the irrigation water becomes stable on a time average basis, the flow pressure is detected by the water pressure sensor 14. When the water supply valve 15 changes from the open state to the closed state, the discharge of the irrigation water from the water supply pipe 130 stops. The water pressure in the water supply pipe 130 gradually recovers from the flow pressure to the pump pressure. The water pressure sensor 14 detects the water pressure in the transient period during which the water pressure gradually recovers from the flow pressure to the pump pressure.

[0032] If the water supply pipe 130 or the water supply valve 15 is damaged and irrigation water leaks from the damaged part, the water pressure detected by the water pressure sensor 14 decreases. Thus, it is possible to detect whether or not damage has occurred. This damage detection process is executed by the control device 200. The irrigation system 10 may be configured to include a flow rate sensor that detects the flow rate of the fluid flowing through the passage instead of the water pressure sensor 14. The irrigation system 10 performs feedback control on the valve opening degree of the water supply valve 15 using the detection values of the water pressure sensor 14 and the flow rate sensor.

[0033] <Control device> As shown in FIGS. 1 and 2, the control device 200 includes a monitoring unit 300, an integrated communication unit 400, an information storage unit 500, and an integrated calculation unit 600. In the drawings, the integrated communication unit 400 is denoted as ICD. The control device 200 has a plurality of monitoring units 300. Each of the plurality of monitoring units 300 corresponds to a predetermined divided area in the farmland 20.

[0034] The water pressure detected by the water pressure sensor 14 is input to the monitoring unit 300. The monitoring unit 300 detects an environmental value which is a physical quantity related to the environment of the farmland 20. Each of the plurality of monitoring units 300 outputs the water pressure and the environmental value to the integrated communication unit 400 by wireless communication.

[0035] The integrated communication unit 400 outputs the water pressure and environmental values input from each monitoring unit 300 to the information storage unit 500 by wireless communication. The information storage unit 500 stores these water pressure and environmental values. An example of the information storage unit 500 is a so-called cloud. The integrated calculation unit 600 reads out various information such as the water pressure and environmental values stored in the information storage unit 500. The integrated calculation unit 600 appropriately processes the read-out various information, and displays the various information and the processing results on the monitor 700 of the user's smartphone or personal computer.

[0036] The integrated calculation unit 600 is included in the user's smartphone, personal computer, etc. The integrated calculation unit 600 has an information processing calculation device 610, a memory 620, and a communication device 630. In the drawings, the information processing calculation device 610 is denoted as IPCE, the memory 620 as MM, and the communication device 630 as CD. The information processing calculation device 610 includes a processor. The information processing calculation device 610 performs calculation processing related to irrigation treatment. Such a function is realized by downloading an irrigation application program to the information processing calculation device 610. The integrated calculation unit 600 may be a calculation device implemented on the cloud. In this case, the integrated calculation unit 600 and the information storage unit 500 may be implemented on the cloud together.

[0037] The memory 620 is a non-transitory physical storage medium that non-temporarily stores various programs and various information that can be read by a computer or a processor. The memory 620 has a volatile memory and a non-volatile memory. The memory 620 stores various information input to the communication device 630 and the processing results of the information processing calculation device 610. The information processing calculation device 610 executes various calculation processes using the information stored in the memory 620.

[0038] The communication device 630 has a wireless communication function. The communication device 630 converts the received wireless signal into an electrical signal and outputs it to the information processing and computing device 610. The communication device 630 outputs the processing result of the information processing and computing device 610 as a wireless signal. Hereinafter, without particularly distinguishing between the information processing and computing device 610, the memory 620, and the communication device 630, the technical content of the first embodiment will be described using the integrated computing unit 600 as a general term. The information processing and computing device 610 corresponds to the processing and computing unit.

[0039] The user inputs a user instruction related to the irrigation process or irrigation schedule to the integrated computing unit 600 using an input device 800 such as a touch panel or a keyboard. Based on this user instruction and various information read from the information storage unit 500, the integrated computing unit 600 outputs an irrigation process command or determines an irrigation schedule. When there is no instruction from the user, the integrated computing unit 600 automatically determines the irrigation schedule based on the various information.

[0040] When the integrated computing unit 600 detects an irrigation process command or determines that it is the start time of water supply based on the irrigation schedule, it outputs an instruction signal for controlling the water supply valve 15 to the information storage unit 500. This instruction signal is input from the information storage unit 500 to the monitoring unit 300 via the integrated communication unit 400. The monitoring unit 300 controls the output and non-output of the water supply signal to the water supply valve 15 based on the instruction signal. As a result, the opening and closing state of the water supply valve 15 is controlled. As a result, the supply of irrigation water to the field 20 is controlled. At least one of the instruction signal and the water supply signal corresponds to a control signal.

[0041] <Partition area> One monitoring unit 300 is provided for each distribution tube 136. The monitoring unit 300 may be configured such that one monitoring unit 300 is provided for a predetermined number of distribution tubes 136. The monitoring unit 300 may also be configured to be provided corresponding to each ridge. As shown in FIG. 1, a plurality of monitoring units 300 are arranged in a matrix in the field 20 with the x direction as the row direction and the y direction as the column direction, together with the water supply valve 15 and the water pressure sensor 14.

[0042] With such a configuration, the environment in each of a plurality of divided areas separated by the row direction and the column direction is individually monitored by a monitoring unit 300 corresponding to each divided area. Further, the supply of irrigation water in each divided area is individually controlled by the corresponding monitoring unit 300.

[0043] <Monitoring unit> As shown in FIG. 2, the monitoring unit 300 has a control unit 320 and the like. An environment sensor 310, a water supply valve 15, a water pressure sensor 14, a water temperature sensor 160, etc. are electrically connected to the control unit 320. In the drawings, the environment sensor 310 is denoted as ES, the water supply valve 15 as WV, and the water pressure sensor 14 as WPS.

[0044] A plurality of environment sensors 310 are arranged in a matrix in the field 20 corresponding to a plurality of divided areas. Each environment sensor 310 detects the environmental value of each divided area. The water pressure sensor 14 detects the water pressure of each divided area. The detected environmental value and water pressure of each divided area are stored in the information storage unit 500.

[0045] The control unit 320 includes a microcomputer 330, a communication unit 340, an RTC 350, and a power generation unit 360. The microcomputer is an abbreviation for a microcomputer. The RTC is an abbreviation for Real Time Clock. In the drawings, the communication unit 340 is denoted as CDP.

[0046] Environmental values and water pressure are input to the microcomputer 330. The microcomputer 330 outputs these environmental values and water pressure to the integrated communication unit 400 via the communication unit 340. An instruction signal is input to the microcomputer 330 from the integrated communication unit 400. The microcomputer 330 outputs a water supply signal to the water supply valve 15 based on this instruction signal. The microcomputer 330 corresponds to an arithmetic processing unit. The microcomputer 330 is a control device that controls the operation of the water supply valve 15. The microcomputer 330 has a sleep mode and a normal mode as operation modes. The sleep mode is a state in which the microcomputer 330 stops arithmetic processing. The normal mode is a state in which the microcomputer 330 executes arithmetic processing. The normal mode consumes more power than the sleep mode.

[0047] The communication unit 340 performs wireless communication with the integrated communication unit 400. The communication unit 340 outputs the electrical signal output from the microcomputer 330 as a wireless signal to the integrated communication unit 400. At the same time, the communication unit 340 receives the wireless signal output from the integrated communication unit 400 and converts it into an electrical signal. The communication unit 340 outputs the electrical signal to the microcomputer 330. When the electrical signal contains an instruction signal, the microcomputer 330 switches from the sleep mode to the normal mode. The microcomputer 330 may be in a form that wakes up before receiving the electrical signal.

[0048] The RTC 350 has a clock function for marking time and a timer function for measuring time. When the preset time is reached or when the preset time has elapsed, the RTC 350 outputs a wake-up signal to the microcomputer 330. When this wake-up signal is input to the microcomputer 330 in the sleep mode, the microcomputer 330 switches from the sleep mode to the normal mode.

[0049] The power generation unit 360 converts the light energy obtained by the solar cell 361 into electrical energy. The power generation unit 360 functions as a power supply for the monitoring unit 300. Power is continuously supplied from the power generation unit 360 to the RTC 350. Thereby, it is suppressed that the clock function and the timer function of the RTC 350 are impaired. The solar cell 361 may be configured to be replaceable with a primary battery or a secondary battery.

[0050] <Environmental Sensor> One of the environmental values that are assumed to be different for each divided area of the farmland 20 is the soil moisture content. The environmental sensor 310 detects the environmental value in the corresponding divided area. The environmental sensor 310 includes a soil sensor 311 that detects the soil moisture content and the like. The plurality of soil sensors 311 detect the soil moisture content of the plurality of divided areas arranged in the farmland 20. In the drawing, the soil sensor 311 is denoted as SMS.

[0051] Depending on the undulations of the field 20 and the growth status of the plants, solar radiation amount is one of the environmental values that is assumed to vary for each divided area. In this specification, each environmental sensor 310 is equipped with a solar radiation sensor that detects the solar radiation amount. A plurality of solar radiation sensors detect the solar radiation amounts of a plurality of divided areas in the field 20.

[0052] On the monitor 700, by arranging the soil moisture amounts and solar radiation amounts detected in a plurality of divided areas in a matrix, the soil moisture amount distribution and the solar radiation amount distribution in the field 20 are displayed as maps. Similarly, on the monitor 700, by arranging the water pressures detected by the plurality of water pressure sensors 14 in a matrix, the water pressure distribution of the water supply pipe 130 in the field 20 is displayed as a map on the monitor 700. Such map display processing is performed by the integrated arithmetic unit 600.

[0053] The environmental values in the field 20 include rainfall amount, temperature, humidity, atmospheric pressure, carbon dioxide concentration, and wind volume. The sensors that detect these environmental values are a rain sensor, a ground temperature sensor, a humidity sensor, an atmospheric pressure sensor, a CO2 sensor, a wind sensor, and the like. These are included in at least one environmental sensor 310 among the plurality of monitoring units 300.

[0054] The environmental sensor 310 of the monitoring unit 300 includes various sensors that detect the environmental values of the entire field 20. In the drawings, the ground temperature sensor is denoted as GTS. The wind sensor may be configured to detect not only the wind volume but also the wind direction. At least one of the rain sensor, the ground temperature sensor, the humidity sensor, the atmospheric pressure sensor, and the wind sensor may adopt a configuration arranged in a matrix in the field 20.

[0055] Such a configuration is effective, for example, when the rainfall, temperature, humidity, air pressure, and wind volume vary greatly for each divided area because the field 20 is large, the undulation of the field 20 is severe, or the climate change of the field 20 is intense. By arranging the rainfall, temperature, humidity, air pressure, and wind volume detected by these sensors in a matrix, these environmental values can be mapped and displayed on the monitor 700. The outputs of these sensors are output to the communication unit 340 via the integrated communication unit 400. At the same time, the outputs of these sensors are stored in the information storage unit 500 via the integrated communication unit 400.

[0056] <Soil moisture content> Among the various environmental values described so far, the environmental values controlled by the irrigation system 10 include the soil moisture content. The irrigation system 10 controls the supply time and supply amount of irrigation for each divided area. Thereby, the soil moisture content for each divided area is individually controlled.

[0057] Plants have roots in the soil layer of the field 20. The growth of plants depends on the amount of water (also referred to as soil moisture content) contained in the soil of this soil layer. When the soil moisture content exceeds the growth inhibition moisture point, diseases occur in the plants. When the soil moisture content drops below the permanent wilting point, the wilting of the plants cannot be recovered. These growth inhibition moisture point and permanent wilting point vary depending on the type of plant, and these values are stored in the information storage unit 500.

[0058] The current value of the soil moisture content is detected by the soil sensor 311. Physical quantities related to the soil moisture content include soil moisture tension (pF value) and soil dielectric constant (ε). The soil sensor 311 in this specification detects the pF value.

[0059] The soil moisture content of the cultivation layer increases or decreases due to environmental changes in field 20. When it rains in field 20, the soil moisture content increases. When water evaporates from the cultivation layer, the soil moisture content decreases. Also, when plants absorb water or water penetrates to a layer below the cultivation layer, the soil moisture content decreases. The amount of rain (rainfall) poured onto the cultivation layer is detected by a rain sensor. The evaporation amount, which is the amount of water evaporated from the cultivation layer, depends on the solar radiation amount, temperature, humidity, and wind volume. These are detected by a solar radiation sensor, a ground temperature sensor, a humidity sensor, and a wind sensor.

[0060] The water absorption amount by which a plant absorbs water per unit time can be estimated in advance according to the type of plant. The amount of water that penetrates to a layer below the cultivation layer per unit time can be estimated in advance according to the water retention capacity of the soil. These estimated values are stored in the information storage unit 500.

[0061] As described above, the environmental sensor 310 detects each of the current value of the soil moisture content of the cultivation layer, the increase from the current value of the soil moisture content of the cultivation layer due to environmental changes, and the predicted value related to the decrease prediction. These are stored in the information storage unit 500 as environmental values. The information storage unit 500 stores the growth inhibition moisture point and the permanent wilting point of the plant, the water absorption amount by which the plant absorbs water per unit time, and the water retention capacity of the soil. The user instruction, which is the above-described instruction from the user, is stored in the information storage unit 500. Thus, various information for determining the irrigation schedule is stored in the information storage unit 500. The irrigation system 10 may be configured to check the detection value of the soil sensor in real time and perform control to stop irrigation when the detection value reaches a threshold value.

[0062] <Microcomputer> As shown in FIG. 2, the microcomputer 330 includes an acquisition unit 331, a signal output unit 332, a storage unit 333, and a processing unit 334. In the drawings, the acquisition unit 331 is denoted as AD, the signal output unit 332 as SOU, the storage unit 333 as MU, and the processing unit 334 as PU. The environmental values detected by the environmental sensor 310 are input to the acquisition unit 331. The water pressure detected by the water pressure sensor 14 is input to the acquisition unit 331. The acquisition unit 331 is electrically connected to each of these environmental sensor 310 and water pressure sensor 14.

[0063] The signal output unit 332 is electrically connected to the water supply valve 15. A control signal (water supply signal) for controlling the valve opening degree of the water supply valve 15 is output from the signal output unit 332 to the water supply valve 15. When the water supply signal is not input, the water supply valve 15 is in a closed state. When the water supply signal is input, the water supply valve 15 is in an open state. Also, the water supply valve 15 may be configured to maintain the current state when there is no input of the water supply signal and to open and close according to the input content when there is an input. For example, when no control signal is input, the valve opening degree of the water supply valve 15 is maintained, and when there is an input, the valve opening degree of the water supply valve 15 is adjusted according to the control signal of the opening degree instruction input at that time.

[0064] The storage unit 333 is a non-transitory physical storage medium that non-temporarily stores programs and data readable by a computer or a processor. The storage unit 333 has a volatile memory and a non-volatile memory. A program for the processing unit 334 to execute arithmetic processing is stored in the storage unit 333. This program includes at least a part of the above-described irrigation application program. Data for the processing unit 334 to execute arithmetic processing is temporarily stored in the storage unit 333. Various data input to each of the acquisition unit 331 and the communication unit 340 and the acquisition times of the various data are stored in the storage unit 333.

[0065] When a wake-up signal is input from the RTC 350, the processing unit 334 switches from the sleep mode to the normal mode. In the normal mode, the processing unit 334 reads the programs and various data stored in the storage unit 333 and executes arithmetic processing. This arithmetic processing includes calculating the valve opening necessary for the water splashed through the through-hole of the distribution tube 136 to reach the desired irrigation position. The processing unit 334 corresponds to an arithmetic unit. This calculation may be executed by the information processing arithmetic device 610 of the integrated arithmetic unit 600.

[0066] The processing unit 334 reads the acquisition times of various sensor signals input to the acquisition unit 331 and instruction signals input to the communication unit 340 from the RTC 350. The processing unit 334 stores the instruction signals and the acquisition times in the storage unit 333. The acquisition time may be read in such a configuration that the integrated communication unit 400 records the data acquisition time when receiving data wirelessly from each monitoring unit 300. Also, the information storage unit 500 may record the data acquisition time when receiving data wirelessly from the integrated communication unit 400.

[0067] The processing unit 334 stores the environmental values, water pressure, and their acquisition times input from the environmental sensor 310 and the water pressure sensor 14 in the information storage unit 500 via the communication unit 340 and the integrated communication unit 400. Based on the instruction signal input from the integrated arithmetic unit 600 via the information storage unit 500, the integrated communication unit 400, and the communication unit 340, the processing unit 334 outputs a water supply signal to the water supply valve 15 via the signal output unit 332.

[0068] <Communication Unit> The communication unit 340 converts the electrical signal input from the processing unit 334 into a wireless signal. The communication unit 340 outputs this wireless signal to the integrated communication unit 400. The communication unit 340 converts the wireless signal output from the integrated communication unit 400 into an electrical signal. The communication unit 340 outputs this electrical signal to the processing unit 334. The wireless signal output by the communication unit 340 contains an address and data. Wireless signal transmission and reception are performed between the plurality of communication units 340 and the integrated communication unit 400. The address contained in the wireless signal is an identification code indicating from which of the plurality of communication units 340 it is output. In other words, the address contained in the wireless signal is an identification code indicating from which of the plurality of processing units 334 it is output. Unique addresses are stored in each of the plurality of storage units 333.

[0069] The wireless signal output from the integrated communication unit 400 also contains an address. And the data of this wireless signal contains an instruction signal. Each communication unit 340 receives this wireless signal. This wireless signal is converted into an electrical signal by each communication unit 340. And this electrical signal is input to each processing unit 334. Among the plurality of processing units 334, only the processing unit 334 having the same address as the address contained in the electrical signal executes arithmetic processing based on the electrical signal. The microcomputer 330 performs intermittent driving that alternately repeats the sleep mode and the normal mode. Therefore, wireless communication between the communication unit 340 and the integrated communication unit 400 is not frequently performed.

[0070] <Power generation unit> The power generation unit 360 includes a solar cell 361, a power storage unit 362, a current sensor 363, and a power sensor 364. In the drawings, the solar cell 361 is denoted as SB, the power storage unit 362 as ESU, the current sensor 363 as CS, and the power sensor 364 as PS. The solar cell 361 converts light energy into electrical energy. The power storage unit 362 stores the electrical energy (power). The power stored in the power storage unit 362 is utilized as the driving power of the monitoring unit 300.

[0071] The current sensor 363 detects the current output from the solar cell 361 to the power storage unit 362. The power sensor 364 detects the power output from the power storage unit 362. The processing unit 334 stores the detected current value and power value in the information storage unit 500 via the communication unit 340 and the integrated communication unit 400. The driving power of the monitoring unit 300 depends on the power generated by the power generation unit 360. For this reason, when the amount of light incident on the power generation unit 360 is small, the driving power of the monitoring unit 300 may be insufficient. To avoid this, the microcomputer 330 of the monitoring unit 300 performs intermittent driving. Also, the power generation unit 360 may be configured not to include a current sensor.

[0072] <rtc> The RTC 350 outputs a wake-up signal to the microcomputer 330 every time the above-described intermittent drive time interval (drive cycle) elapses. As a result, the microcomputer 330 alternately repeats the sleep mode and the normal mode. The above drive cycle is determined by the integration calculation unit 600 according to the amount of power stored in the power storage unit 362 (power storage amount). The intermittent drive interval is determined by the integration calculation unit 600 according to the power storage amount.

[0073] The integration calculation unit 600 calculates the power storage amount based on the power stored in the information storage unit 500. The integration calculation unit 600 sets a longer intermittent drive interval as the power storage amount is smaller. The integration calculation unit 600 sets a shorter intermittent drive interval as the power storage amount is larger. The integration calculation unit 600 includes the intermittent drive interval in the instruction signal. When the processing unit 334 of the microcomputer 330 acquires this instruction signal, the processing unit 334 adjusts the intermittent drive interval. The processing unit 334 adjusts the drive cycle of the RTC 350. It is rare for the environment of the farmland 20 to change extremely in units of several seconds. Therefore, the intermittent drive interval is in units of several tens of seconds to several tens of hours. Accordingly, the time interval for performing wireless communication is also in units of several tens of seconds to several tens of hours.

[0074] <Irrigation System Drive> In the irrigation system 10, signal transmission and reception between the plurality of monitoring units 300 and the integration calculation unit 600, and storage of various data in the information storage unit 500 are performed. Each of the plurality of monitoring units 300 and the integration calculation unit 600 executes a cycle task to be processed every drive cycle and an event task to be processed suddenly.

[0075] There is a processing priority for these cycle tasks and event tasks. When the processing timings of these tasks are the same, the processing of the event task is prioritized over the cycle task. As the cycle task, each monitoring unit 300 executes sensor processing. The integration calculation unit 600 executes update processing. As the event task, each monitoring unit 300 executes monitoring processing and water supply processing. The integration calculation unit 600 executes irrigation processing, user update processing, and forced update processing.

[0076] <Sensor processing> Before sensor processing, the microcomputer 330 of the monitoring unit 300 is in the sleep mode, and a wake-up signal is input to this microcomputer 330 from the RTC 350. As a result, the microcomputer 330 switches from the sleep mode to the normal mode. Then, the microcomputer 330 starts to execute sensor processing. The sensor processing is executed at the intermittent drive interval of the microcomputer 330. First, sensor signals input from various sensors are acquired, and further, the acquisition time of the sensor signals is acquired based on the output of the RTC 350. Further, the acquired sensor signals and acquisition times are stored respectively. Next, the sensor signals and acquisition times as sensor information are output from the communication unit 340 to the integrated communication unit 400 by wireless communication. This sensor information is stored in the information storage unit 500 by the integrated communication unit 400. The microcomputer 330 shifts to the sleep mode and ends the sensor processing.

[0077] <Update processing> The integrated arithmetic unit 600 executes the update processing every time the update cycle elapses. This update cycle is approximately the same as the intermittent drive interval of the microcomputer 330. First, various information stored in the information storage unit 500 is read out. Next, based on the read various information, the irrigation schedules of the respective plurality of monitoring units 300 are updated. Also, the integrated arithmetic unit 600 updates the sensor processing in each monitoring unit 300. The integrated arithmetic unit 600 updates the intermittent drive interval corresponding to the timing of executing the sensor processing. The integrated arithmetic unit 600 holds the updated irrigation schedule and intermittent drive interval by itself, stores them in the information storage unit 500, and ends the update processing. As shown above, the sensor information, irrigation schedule, and intermittent drive interval are updated by the cycle task.

[0078] Each of the monitoring process, water supply process, and irrigation process is executed during the day in order to avoid depletion of the drive power of the monitoring unit 300. The determination of whether it is daytime or not can be detected by the current time and the amount of solar radiation detected by the solar sensor.

[0079] <Monitoring process> Before the monitoring process, the microcomputer 330 of each monitoring unit 300 is in the sleep mode. An instruction signal is input to the microcomputer 330 from the integrated operation unit 600 by wireless communication. As a result, the microcomputer 330 switches from the sleep mode to the normal mode and starts to execute the monitoring process.

[0080] First, the input instruction signal and the acquisition time thereof are stored. Next, it is determined whether or not the instruction signal includes a water supply instruction to change the water supply valve 15 from the closed state to the open state. If the water supply instruction is included in the instruction signal, the water supply process is executed. In the water supply process, the microcomputer 330 outputs a water supply signal to the water supply valve 15 according to the water supply instruction. Further, the microcomputer 330 determines whether or not the water supply time included in the instruction signal has elapsed. If the water supply time has not elapsed, the output of the water supply signal to the water supply valve 15 is continued. If the water supply time has elapsed, the output of the water supply signal is stopped and the water supply process is terminated.

[0081] If the water supply instruction is not included in the instruction signal, the water supply process is not executed, and it is determined whether or not the instruction signal includes an update instruction for the intermittent drive interval. The update instruction for the intermittent drive interval is periodically or irregularly output as an instruction signal from the integrated operation unit 600 or the information storage unit 500 to each monitoring unit 300. If the update instruction for the intermittent drive interval is included in the instruction signal, the processing unit 334 of the microcomputer 330 adjusts the time interval for outputting the wake-up signal of the RTC 350.

[0082] If the update instruction for the intermittent drive interval is not included in the instruction signal, sensor processing is executed. When the water supply process is executed, the environmental value after the irrigation water supply is detected in the sensor processing. When the water supply process is not executed, the environmental value when no irrigation water is supplied is detected in the sensor processing. This environmental value is stored in the information storage unit 500. After finishing the sensor processing, the microcomputer 330 shifts to the sleep mode and ends the monitoring process. The start condition of the monitoring process is not limited to the instruction signal from the integrated operation unit 600. After the RTC 350 activates the microcomputer 330, after the microcomputer 330 processes, it sends the sensor data to the integrated operation unit 600. And it may be configured to send an instruction for the next intermittent drive timing together with the valve opening instruction from the integrated operation unit 600.

[0083] <Irrigation water supply process> The integrated operation unit 600 executes the irrigation water supply process at the timing of supplying irrigation water in the irrigation water supply schedule of each monitoring unit 300. First, the integrated operation unit 600 outputs a water supply signal including a water supply instruction to the monitoring unit 300 in the divided area where irrigation water is scheduled to be supplied among the plurality of monitoring units 300. The water supply instruction includes the start of the output of the water supply signal and the output time of the water supply signal (water supply time). The monitoring unit 300 that receives this water supply instruction executes the above-described monitoring process.

[0084] The integrated operation unit 600 waits until the monitoring process of the monitoring unit 300 ends. When the monitoring process ends, an update process is executed. The determination as to whether or not the monitoring process has ended is made based on, for example, whether or not a time sufficient for the monitoring process to end has elapsed. The determination as to whether or not the monitoring process has ended can be made by inquiring the monitoring unit 300. The method for determining the end of the monitoring process is not particularly limited.

[0085] <User update process> The integrated arithmetic unit 600 executes the user update process when a user instruction related to the adjustment of the irrigation schedule or the intermittent drive interval is input from the input device 800. The integrated arithmetic unit 600 first stores the input user instruction in the information storage unit 500. Next, it executes the above-described update process. Thus, based on the user instruction, the irrigation schedule and the intermittent drive interval are updated.

[0086] <Forced update process> The integrated arithmetic unit 600 executes the forced update process when a user instruction related to the update of the irrigation schedule and the intermittent drive interval is input. The integrated arithmetic unit 600 first outputs a request signal including a request instruction for requesting the execution of sensor processing. This request signal is output to the monitoring unit 300 by wireless communication. Next, the update process waits until the sensor processing of the monitoring unit 300 is completed.

[0087] When the sensor processing is completed, the above-described update process is executed. The determination of whether the sensor processing has been completed can be made, for example, based on whether the time when the sensor processing is expected to be completed has elapsed. Also, it can be made by inquiring the monitoring unit 300 about whether the sensor processing has been completed. The method for determining the end of the sensor processing is not particularly limited. The irrigation schedule and the intermittent drive interval are updated based on various data at the time of the user's update request.

[0088] <Individual irrigation process> As described above, the integrated arithmetic unit 600 determines the irrigation schedule in each of the plurality of divided areas. The integrated arithmetic unit 600 controls the supply of irrigation water based on each irrigation schedule. Also, although the irrigation schedule in each divided area is determined by the integrated arithmetic unit 600, a configuration may be adopted in which the supply of irrigation water based on each irrigation schedule is individually controlled by each monitoring unit 300.

[0089] <Independent update> As a further example, a configuration may be adopted in which the irrigation schedule in each divided area is independently determined by the corresponding monitoring unit 300. In such a configuration, each monitoring unit 300 executes the above-described update process.

[0090] <Weather Forecast and Irrigation Schedule> The information storage unit 500 stores the current value of the soil moisture content, the predicted value of the decreasing change, and the user instruction. The information storage unit 500 stores the growth inhibition moisture point and the permanent wilting point of the plant, the water absorption amount by which the plant absorbs moisture per unit time, and the moisture retention capacity of the soil. In addition to these, the information storage unit 500 stores the weather forecast of the field 20 output and distributed from the external information source 1000. In FIG. 1, the external information source 1000 is denoted as ESI. The integrated operation unit 600 reads out various information including this weather forecast from the information storage unit 500 in the update process. The integrated operation unit 600 determines the irrigation schedule in each monitoring unit 300.

[0091] <Target Value and Estimated Value> When determining the irrigation schedule, the integrated operation unit 600 calculates the target value and the estimated value of the soil moisture content. Naturally, the target value of the soil moisture content is set to a value between the growth inhibition moisture point and the permanent wilting point. In order to attempt to grow the plant soundly, the target value of the soil moisture content is set to a value that is a certain distance away from the growth inhibition moisture point and the permanent wilting point, which are theoretical values.

[0092] The integrated operation unit 600 sets an upper limit target value on the growth inhibition moisture point side and a lower limit target value on the permanent wilting point side as the target value of the soil moisture content. In the irrigation period of the irrigation schedule, the integrated operation unit 600 determines the irrigation schedule so that the estimated value of the soil moisture content is between the upper limit target value and the lower limit target value. Even when it is predicted that the estimated value of the soil moisture content exceeds the upper limit target value due to rainfall, the integrated operation unit 600 determines the irrigation schedule so that the estimated value of the soil moisture content does not exceed the growth inhibition moisture point.

[0093] There is a deviation between the growth-inhibiting moisture point and the upper limit target value. This upper limit deviation width is determined based on the sound growth of the above-mentioned plants and the climate of the field 20. The climate of the field 20 includes the expected value of the average rainfall in the field 20 during the irrigation period of the irrigation schedule and the total rainfall predicted by the weather forecast during the irrigation period. The expected value of the average rainfall in the field 20 during the irrigation period is stored in the information storage unit 500.

[0094] There is a deviation between the permanent wilting point and the lower limit target value. This lower limit deviation width is determined in consideration of the sound growth of the plants and based on factors such as the recovery time when a failure occurs in the water supply device 100 and the amount of decrease in soil moisture per unit time. For example, the lower limit deviation width is determined based on the value obtained by multiplying the recovery time and the amount of decrease in soil moisture per unit time. The recovery time is stored in the information storage unit 500.

[0095] For example, when weather forecasts for one week are stored in the information storage unit 500 from the external information source 1000, the integrated calculation unit 600 determines the irrigation schedule for one week. During this one week, if there is no rainfall forecast according to the weather forecast, it is expected that the estimated value of the soil moisture content will gradually decrease over time. The amount of decrease in the estimated value of the soil moisture content per unit time is determined based on the predicted value of the change in the decrease of the soil moisture content in the soil layer. Hereinafter, for the sake of simplicity of notation, the estimated value of the soil moisture content is simply denoted as the estimated value as necessary.

[0096] As described above, the irrigation schedule is determined based on the estimated value of the soil moisture content based on environmental values and the like and the weather forecast. According to this, it is possible to suppress the soil moisture content in the divided area in the field from becoming unsuitable for the plants due to climate changes such as rainfall and dryness.

[0097] The integrated arithmetic unit 600 supplies water when the estimated value of the soil moisture content in the irrigation schedule reaches the lower limit target value. This can prevent the soil moisture content from falling below the lower limit target value. The integrated arithmetic unit 600 makes the rainfall forecast time different from the irrigation water supply time. According to this, even if the rainfall amount is larger than the rainfall forecast, an excessive increase in the soil moisture content can be suppressed. Also, the irrigation system 10 may perform control to check the detection value of the soil sensor 311 in real time and stop the irrigation when the detection value reaches the threshold value. In this case, it is not necessary to calculate the estimated value of the soil moisture content.

[0098] With reference to FIGS. 3 to 5, an example of a valve device applicable to the water supply valve 15 will be described below. This valve device is a so-called rotary valve device. This valve device includes one fluid inlet and three fluid outlets. By connecting an upstream pipe to the fluid inlet and connecting the distribution tube 136 to any one of the fluid outlets, this valve device is mounted on the irrigation system 10. Further, a blocking member may be attached to the fluid outlet to which the distribution tube 136 is not connected so as to block the passage.

[0099] As shown in FIG. 3, the valve device includes a housing 9, a valve 90, a drive unit 70, a drive unit cover 80, etc. The valve device is configured as a ball valve that performs the opening and closing operation of the valve device by rotating the valve 90 around the axis of the shaft 92. In this specification, the direction along the axis of the shaft 92 will be described as the axial direction DRa, and the direction that is perpendicular to the axial direction DRa and extends radially from the axial direction DRa will be described as the radial direction DRr.

[0100] The housing 9 is a housing portion that houses the valve 90. The housing 9 is formed of, for example, a resin member. The housing 9 includes a housing main body portion 21 having a hollow shape in which the valve 90 is housed, a pipe member 50 for discharging cooling water from the housing main body portion 21, and a partition portion 60 attached to the housing main body portion 21. The housing main body portion 21 has an outer appearance that is substantially rectangular parallelepiped-shaped and is formed in a bottomed shape having an opening on the other side in the axial direction DRa. The housing main body portion 21 has a housing outer wall portion 22 that constitutes an outer peripheral portion of the housing main body portion 21. The housing outer wall portion 22 forms a cylindrical valve housing space 23 having an axis in the axial direction DRa inside the housing main body portion 21.

[0101] An inlet port 251 for allowing supply water to flow into the valve housing space 23 is formed in the housing outer wall portion 22. The inlet port 251 is formed to open in a circular shape and is connected to the connecting pipe 135. The inlet port 251 corresponds to a fluid inflow portion.

[0102] The housing outer wall portion 22 has the pipe member 50 attached thereto. The housing outer wall portion 22 has a first outlet port 261, a second outlet port 262, and a third outlet port 263 for discharging the cooling water that has flowed into the valve housing space 23 through the inlet port 251 to the pipe member 50. The first outlet port 261, the second outlet port 262, and the third outlet port 263 correspond to fluid outflow portions.

[0103] The housing opening surface 24 of the housing outer wall portion 22 has the partition portion 60 attached thereto. The housing opening surface 24 is disposed on the other side in the axial direction DRa in the housing main body portion 21. A housing opening 241 that communicates the valve housing space 23 with the outside of the housing main body portion 21 is formed in the housing opening surface 24. The housing opening 241 is closed by attaching the partition portion 60 to the housing opening surface 24.

[0104] The pipe member 50 includes a first pipe portion 51, a second pipe portion 52, and a third pipe portion 53, each of which is formed in a cylindrical shape. The first pipe portion 51, the second pipe portion 52, and the third pipe portion 53 are connected by a pipe connection portion 54. The pipe connection portion 54 is a portion that connects the first pipe portion 51, the second pipe portion 52, and the third pipe portion 53 and attaches the pipe member 50 to the housing outer wall portion 22. The upstream side of the first pipe portion 51 is disposed inside the first outlet port 261. The upstream side of the second pipe portion 52 is disposed inside the second outlet port 262. The upstream side of the third pipe portion 53 is disposed inside the third outlet port 263.

[0105] The partition portion 60 closes the housing opening 241 and holds the valve 90 housed in the valve accommodation space 23. The partition portion 60 is in a disk shape with the axial direction DRa being the plate thickness direction, and is arranged to be fitted from the other side to the one side in the axial direction DRa with respect to the housing opening 241. When the partition portion 60 is fitted into the housing opening 241, the outer peripheral portion of the partition portion 60 abuts against the housing inner peripheral surface, thereby closing the housing opening 241.

[0106] The drive unit cover 80 houses the drive unit 70. The drive unit cover 80 has a hollow shape made of resin, and a drive unit space for housing the drive unit 70 is formed inside. The drive unit cover 80 has a connector portion 81 for connecting to the microcomputer 330. The connector portion 81 is for connecting the valve device to the microcomputer 330 and incorporates terminals to which the drive unit 70 and the rotation angle sensor 73 are connected.

[0107] The drive unit 70 includes a motor 71 that outputs a rotational force for rotating the valve 90, a gear unit 72 that transmits the output of the motor 71 to the valve 90, and a rotation angle sensor 73 that detects the rotation angle of the gear unit 72. As shown in FIG. 4, the motor 71 includes a motor body, a motor shaft 711, a worm gear 712, and motor-side terminals. The motor 71 is configured such that the motor body can output power when power is supplied to the motor-side terminals. The motor body is formed in a substantially cylindrical shape, and the motor shaft 711 protrudes from the other end of the motor body. The power output from the motor body is output to the gear unit 72 via the motor shaft 711 and the worm gear 712.

[0108] The gear unit 72 is composed of a reduction mechanism having a plurality of resin gears, and is configured to be able to transmit the power output from the worm gear 712 to the shaft 92. The gear unit 72 includes a first gear 721, a second gear 722 that meshes with the first gear 721, and a third gear 723 that meshes with the second gear 722. The shaft 92 is connected to the third gear 723. The gear unit 72 is formed such that the outer diameter of the second gear 722 is larger than the outer diameter of the first gear 721, and the outer diameter of the third gear 723 is larger than the outer diameter of the second gear 722.

[0109] The first gear 721, the second gear 722, and the third gear 723 are arranged such that their respective axial centers are orthogonal to the axial center of the worm gear 712. The third gear 723 is arranged such that the axial center of the third gear 723 is on the same axis as the axial center of the shaft 92. The shaft 92 is connected to the third gear 723. The drive unit 70 is configured such that the worm gear 712, the first gear 721, the second gear 722, the third gear 723, and the valve 90 rotate integrally, and their respective rotations have a correlation with each other. The rotations of these gears and the shaft 92 have a correlation with each other, and the rotation angle of any one of the components having a correlation can be calculated from the rotation angles of the other components.

[0110] In the inner peripheral portion of the drive unit cover 80, a rotation angle sensor 73 for detecting the rotation angle of the third gear 723 is attached to a portion facing the third gear 723. The rotation angle sensor 73 is a Hall sensor incorporating a Hall element and is configured to be able to detect the rotation angle of the third gear 723 in a non-contact manner. The rotation angle sensor 73 is connected to the microcomputer 330 via the connector portion 81. The detected rotation angle of the third gear 723 is transmitted to the microcomputer 330. The processing unit 334 of the microcomputer 330 is configured to be able to calculate the rotation angle of the valve 90 based on the rotation angle of the third gear 723 transmitted from the rotation angle sensor 73.

[0111] The shaft 92 and the valve 90 will be described with reference to FIGS. 3 and 5. The shaft 92 is configured to be rotatable about its axis by the rotational force output by the drive unit 70. The shaft 92 is connected to the valve 90 and is configured to be able to rotate the valve 90 integrally with the shaft 92 when the shaft 92 rotates. The shaft 92 is formed to extend in a columnar shape along its axis and penetrates from one side to the other side of the valve 90. One side of the shaft 92 in the axial direction DRa is connected to the shaft support portion of the housing main body portion 21, and the other side is connected to the gear portion 72. The valve 90 is fixed to the outer peripheral portion of the shaft.

[0112] The valve 90 is configured to be able to adjust the flow rate of the output fluid by rotating about its axis. A shaft 92 is inserted into the valve 90 and is rotatably accommodated integrally with the shaft 92 in the valve accommodation space 23. The valve 90 is cylindrical with an axis extending along the axial direction DRa. The valve 90 is formed by connecting a cylindrical first valve 93, a second valve 94, a third valve 95, a cylindrical connection part 914, and a cylindrical valve connection part 915 in sequence. The first valve 93, the cylindrical connection part 914, the second valve 94, the cylindrical valve connection part 915, and the third valve 95 are arranged in this order from one side to the other side of the axial direction DRa. The first valve 93 and the second valve 94 are connected via the cylindrical connection part 914. The second valve 94 and the third valve 95 are connected via the cylindrical valve connection part 915.

[0113] In the valve accommodation space 23, the second valve 94 and the cylindrical connection part 914 of the valve 90 face the inlet port 251 in the radial direction DRr. The valve 90 has a cylindrical shaft connection part 916 into which the shaft 92 is inserted at the center. The valve 90 is connected to the shaft 92 when the shaft 92 is inserted into the shaft connection part 916. The valve 90, for example, is integrally formed by injection molding of the first valve 93, the second valve 94, the third valve 95, the cylindrical connection part 914, the cylindrical valve connection part 915, and the shaft connection part 916.

[0114] The valve 90 is a valve body for allowing the cooling water flowing into the valve 90 to flow out to the first outlet port 261, the second outlet port 262, and the third outlet port 263. By rotating, the first valve 93 opens and closes the first outlet port 261, the second valve 94 opens and closes the second outlet port 262, and the third valve 95 opens and closes the third outlet port 263.

[0115] The first valve 93, the second valve 94, and the third valve 95 are arranged such that their respective axial centers are on the same axis as the axial center of the shaft 92. Each of the first valve 93, the second valve 94, and the third valve 95 has a central portion in the axial direction DRa that bulges outward in the radial direction DRr compared to both end sides. Each of the first valve 93, the second valve 94, and the third valve 95 is configured such that fluid can flow through the inside thereof.

[0116] As shown in FIG. 5, the first valve 93 has a first valve outer peripheral portion 931 that forms an outer peripheral portion, and a first flow path portion 961 is formed inside the first valve outer peripheral portion 931. The first valve 93 is formed with a first inner opening 936 for allowing fluid to flow into the first flow path portion 961. In the first valve 93, the fluid that has flowed into the valve accommodation space 23 flows into the first flow path portion 961 through the first inner opening 936. The first flow path portion 961 corresponds to the flow path portion in the valve device.

[0117] As shown in FIG. 5, the first valve outer peripheral portion 931 is formed with a first outer opening 934 that communicates the first flow path portion 961 with the first outlet port 261 through the first seal opening 581 when the shaft 92 rotates. The first valve 93 allows the fluid that has flowed into the first flow path portion 961 to flow out from the first outlet port 261 when the first outer opening 934 communicates with the first outlet port 261. The first outer opening 934 formed in the first valve outer peripheral portion 931 corresponds to the outer opening formed in the valve outer peripheral portion. The first outer opening 934 is formed to extend along the circumferential direction of the axial center of the shaft 92 in the first valve outer peripheral portion 931. The flow rate of the fluid flowing out of the device from the first valve 93 is adjusted according to the area where the first outer opening 934 and the first seal opening 581 overlap when the shaft 92 rotates. The first inner opening 936 functions as a communication path that communicates the outside of the first valve 93 with the first flow path portion 961.

[0118] As shown in FIG. 5, the second valve 94 has a second valve outer peripheral portion 941 that forms an outer peripheral portion, and a second flow path portion 962 is formed inside the second valve outer peripheral portion 941. The second valve 94 is formed with a second inner opening 946 on one side in the axial direction DRa to allow fluid to flow into the second flow path portion 962. The second valve 94 is configured such that the fluid flowing into the valve housing space 23 through the inlet port 251 can flow through the second flow path portion 962 via the second inner opening 946. The second flow path portion 962 corresponds to the flow path portion in the valve device.

[0119] As shown in FIG. 5, the second valve outer peripheral portion 941 is formed with a second outer opening 944 that communicates the second flow path portion 962 with the second outlet port 262 via the second seal opening 582 when the shaft 92 rotates. When the second outer opening 944 of the second valve 94 communicates with the second outlet port 262, the fluid flowing into the second flow path portion 962 flows out from the second outlet port 262. The second outer opening 944 formed in the second valve outer peripheral portion 941 corresponds to the outer opening formed in the valve outer peripheral portion.

[0120] The second outer opening 944 is formed to extend in the circumferential direction around the axis of the shaft 92. The flow rate of the fluid flowing out from the second valve 94 to the outside of the device is adjusted according to the area where the second outer opening 944 and the second seal opening 582 overlap when the shaft 92 rotates. The second inner opening 946 functions as a communication path that connects the outside of the second valve 94 and the second flow path portion 962. The second inner opening 946 faces the first inner opening 936. The cylindrical connection portion 914 is for connecting the first valve 93 and the second valve 94. The cylindrical connection portion 914 forms a first inter-valve space 97 between the outer peripheral portion of the cylindrical connection portion 914 and the inner peripheral surface of the housing. The first flow path portion 961 and the second flow path portion 962 communicate with each other via the first inter-valve space 97.

[0121] The second valve 94 has a shaft connection portion 916 disposed at a substantially central position inside thereof to cover the outer peripheral portion of the shaft 92. The second valve 94 has a cylindrical valve connection portion 915 connected to the other side in the axial direction DRa of the second valve outer peripheral portion 941. The second valve 94 is configured such that the fluid flowing into the second flow path portion 962 can flow into the third valve 95 via the cylindrical valve connection portion 915.

[0122] The cylindrical valve connection portion 915 has a second valve space 98 formed inside thereof. The second valve space 98 communicates with the second flow path portion 962 and the third flow path portion 963. The outer diameter on one side in the axial direction DRa of the cylindrical valve connection portion 915 is the same as the outer diameter of the portion on the other side in the axial direction DRa of the second valve 94. The outer diameter on the other side in the axial direction DRa of the cylindrical valve connection portion 915 is the same as the outer diameter of the portion on one side in the axial direction DRa of the third valve 95. The cylindrical valve connection portion 915 is formed continuously with the second valve outer peripheral portion 941 and the third valve outer peripheral portion 951.

[0123] As shown in FIG. 5, the third valve 95 has a third valve outer peripheral portion 951 that forms the outer peripheral portion of the third valve 95, and a third flow path portion 963 is formed inside the third valve outer peripheral portion 951. One side in the axial direction DRa of the third valve outer peripheral portion 951 is connected to the cylindrical valve connection portion 915. In the third valve 95, the fluid flowing into the second flow path portion 962 flows into the third flow path portion 963 via the second valve space 98. The third flow path portion 963 corresponds to the flow path portion in the valve device.

[0124] As shown in FIG. 5, a third outer peripheral opening 954 is formed in the third valve outer peripheral portion 951 to communicate the third flow path portion 963 with the third outlet port 263 via the third seal opening 583 when the shaft 92 rotates. When the third outer peripheral opening 954 of the third valve 95 communicates with the third outlet port 263, the third valve 95 causes the fluid flowing into the third flow path portion 963 to flow out of the device from the third outlet port 263. The third outer peripheral opening 954 formed in the third valve outer peripheral portion 951 corresponds to the outer peripheral opening formed in the valve outer peripheral portion.

[0125] The third outer peripheral opening 954 is formed to extend along the circumferential direction of the axis at the third valve outer peripheral portion 951. The flow rate of the fluid flowing out from the third valve 95 to the outside of the device is adjusted according to the area where the third outer peripheral opening 954 and the third seal opening 583 overlap when the shaft 92 rotates. The shaft connection portion 916 is cylindrical, and connects the valve 90 and the shaft 92 by fixing the inserted shaft 92. When the shaft 92 rotates, the shaft connection portion 916 transmits the rotational force of the shaft 92 to the valve 90 via the shaft connection portion 916. The shaft connection portion 916 is formed to extend toward the other side in the axial direction DRa from the second valve 94 to the third valve 95.

[0126] The operation of the water supply valve 15 will be described. The microcomputer 330 calculates the rotation angle of the valve 90, that is, the rotation angle of the motor 71, for supplying the necessary flow rate to the distribution tube 136. The microcomputer 330 transmits the information on the calculated rotation angle of the motor 71 to the water supply valve 15. At this time, blocking members are attached to the two fluid outflow portions that are not connected to the distribution tube 136. The calculation of the rotation angle of the motor 71 may be performed by the information processing calculation device 610 of the integrated calculation unit 600.

[0127] The water supply valve 15 rotates the motor 71 based on the rotation angle information received from the microcomputer 330. By rotating the motor 71, the water supply valve 15 rotates the valve 90 via the gear portion 72 and the shaft 92, and causes the fluid of the necessary flow rate to flow out from the first outer peripheral opening 934, the second outer peripheral opening 944, and the third outer peripheral opening 954.

[0128] For example, the case where the first outlet port 261 is adopted as the fluid outflow part communicated with the distribution tube 136 will be described. The water supply valve 15 communicates the first outer peripheral opening 934 of the first valve 93 with the first outlet port 261 by rotating the valve 90. The water supply valve 15 adjusts the overlapping area between the first outer peripheral opening 934 and the first seal opening 581 by adjusting the rotational position of the valve 90. The water supply valve 15 allows the fluid flowing into the valve housing space 23 from the inlet port 251 to flow into the first flow path part 961 through the first inner opening 936, and flow out from the first outer peripheral opening 934 to the first outlet port 261. The microcomputer 330 controls the splash distance of the irrigation water by controlling the valve opening degree, which is the overlapping area between the first outer peripheral opening 934 and the first seal opening 581, and supplies the irrigation water to the required position.

[0129] For example, the case where the second outlet port 262 is adopted as the fluid outflow part communicated with the distribution tube 136 will be described. The water supply valve 15 communicates the second outer peripheral opening 944 of the second valve 94 with the second outlet port 262 by rotating the valve 90. The water supply valve 15 adjusts the overlapping area between the second outer peripheral opening 944 and the second seal opening 582 by adjusting the rotational position of the valve 90. The water supply valve 15 allows the fluid flowing into the valve housing space 23 from the inlet port 251 to flow into the second flow path part 962 through the second inner opening 946, and flow out from the second outer peripheral opening 944 to the second outlet port 262. The microcomputer 330 controls the splash distance of the irrigation water by controlling the valve opening degree, which is the overlapping area between the second outer peripheral opening 944 and the second seal opening 582, and supplies the irrigation water to the required position.

[0130] For example, the case where the third outlet port 263 is adopted as the fluid outflow part communicated with the distribution tube 136 will be described. The water supply valve 15 communicates the third outer peripheral opening 954 of the third valve 95 with the third outlet port 263 by rotating the valve 90. The water supply valve 15 adjusts the overlapping area between the third outer peripheral opening 954 and the third seal opening 583 by adjusting the rotation position of the valve 90. The water supply valve 15 allows the fluid flowing into the valve accommodation space 23 from the inlet port 251 to flow into the third flow path part 963 through the second flow path part 962 of the second valve 94, and flow out from the third outer peripheral opening 954 to the third outlet port 263. The microcomputer 330 controls the splash distance of the irrigation water by controlling the valve opening degree, which is the overlapping area between the third outer peripheral opening 954 and the third seal opening 583, and supplies the irrigation water to the required position. The control of these valve opening degrees may be configured to be executed by the information processing computing device 610 of the integrated operation unit 600.

[0131] The water supply valve 15 adjusts the rotation angle of the motor 71 by the rotation angle sensor 73 detecting the rotation angle of the third gear 723 and feeding back the detected rotation angle information to the microcomputer 330.

[0132] With reference to the graph of FIG. 6, the relationship between the rotation angle of the shaft 92 and the flow rate of the valve device will be described. FIG. 6 has the rotation angle RA of the motor 71 on the horizontal axis and the flow rate FR of the fluid flowing out from the valve device on the vertical axis. In FIG. 6, FO1 is the first valve 93, FO2 is the second valve 94, and FO3 is the third valve 95. In FIG. 6, FS indicates that the valve opening degree is in the fully open state, FC indicates that the valve opening degree is in the fully closed state, and MO indicates that the valve opening degree is in the intermediate opening degree. The intermediate opening degree is the opening degree between the fully closed state and the fully open state. The solid line graph in FIG. 6 shows the relationship between the flow rate of the fluid flowing out from the third valve 95 and the rotation angle. The dashed line graph in FIG. 6 shows the relationship between the flow rate of the fluid flowing out from the second valve 94 and the rotation angle. The dotted line graph in FIG. 6 shows the relationship between the flow rate of the fluid flowing out from the first valve 93 and the rotation angle.

[0133] As shown in Fig. 6, near the rotation angle of 0 degrees, the third valve 95 is fully open, the other valves are fully closed, and the fluid flows out of the device only through the third valve 95. When the rotation angle is increased from this state, the third valve 95 shifts to an intermediate opening degree. When the rotation angle is further increased, all three valves become fully closed.

[0134] When the rotation angle is increased from the state where all three valves are fully closed, only the second valve 94 shifts to the fully open state through the intermediate opening degree. When the rotation angle is further increased, the first valve 93 shifts to the fully open state through the intermediate opening degree, and the first valve 93 and the second valve 94 become fully open. When the rotation angle is increased from this state, the second valve 94 shifts to the fully closed state through the intermediate opening degree, and the second valve 94 and the third valve 95 become fully closed. When the rotation angle is further increased, the first valve 93 shifts to the fully closed state through the intermediate opening degree, and all the valves become fully closed.

[0135] As described above, according to the rotation angle, the opening degree of each valve changes, and the fluid flow rate flowing out of each valve changes. Each water supply valve 15 in the irrigation system 10 controls the splash distance and the water supply amount to the field 20 according to the rotation angle by a configuration that supplies fluid from only one of the three valves.

[0136] Next, the operation of the irrigation system 10 for performing irrigation that suppresses adverse effects on plant growth will be described with reference to Figs. 7 to 10. Fig. 7 shows an example of an irrigation system including a water supply source, a water supply path, a water supply valve, and a soil sensor installed in the soil. The water supply path shown in Fig. 7 shows an example in which the vertical pipe 133 and the distribution tube 136 are connected without passing through the first connecting pipe 134. The vertical pipe 133 is connected to a plurality of passages leading to a plurality of distribution tubes 136. Each of the plurality of passages is a passage connecting the distribution tube 136 and the vertical pipe 133. A water supply valve 15 is provided in the passage between each distribution tube 136 and the vertical pipe 133.

[0137] Each distribution tube 136 is provided at a position where it can discharge irrigation water to the corresponding ridge through a plurality of through holes. The vertical pipe 133 communicates with a plurality of passages leading to one end of the plurality of distribution tubes 136. The passage on the one end side is a passage that communicates the vertical pipe 133 through which the water supply from the water supply source flows down and one end of the distribution tube 136. The water supply valve 15 controls the pressure of the water supply from the one end side flowing down from one end to the other end of the distribution tube 136.

[0138] The water pressure sensor 14 detects water supply information regarding the water supply in the passage flowing down toward the through hole of the distribution tube 136. Also, the water pressure sensor 14 may be configured to be provided upstream of the distribution tube 136, or may be configured to be provided further downstream than the lowermost through hole. The signal output unit 332 outputs a control signal for controlling the valve opening degree to the water supply valve 15 by feedback control using the water supply information detected by the water pressure sensor 14. The control device 200 can obtain the discharge flow rate in each distribution tube 136 using the water supply pressure detected by the water pressure sensor 14.

[0139] The vertical pipe 133 is connected to the passage leading to the inlet port 251 of each water supply valve 15. Each distribution tube 136 is connected to the passage leading to the first pipe portion 51 which is one of the fluid outflow portions in each water supply valve 15. In this case, the second pipe portion 52 and the third pipe portion 53 which are the other fluid outflow portions are blocked by a blocking member.

[0140] A plurality of soil sensors 311 are installed in the ridges corresponding to the respective distribution tubes 136. The plurality of soil sensors 311 are installed in the soil at intervals in the extending direction of the distribution tube 136. As shown in FIG. 2, detection values detected by the soil sensors 311 are output to the microcomputer 330 of the monitoring unit 300. The processing unit 334 can detect the percentage of moisture content contained in each part of the soil based on this detection value. The processing unit 334 determines whether to start irrigation according to the soil moisture content detected by the soil sensors 311. The processing unit 334 sets the valve opening degree of the water supply valve 15 according to the soil moisture content detected by the soil sensors 311. The signal output unit 332 outputs a control signal based on the set value of the valve opening degree to the water supply valve 15.

[0141] When performing irrigation processing, the irrigation system 10 executes the processing shown in the flowchart of FIG. 8. FIG. 8 is a flowchart showing an example of the operation at the time of an irrigation command. The control device 200 executes the processing shown in FIG. 8 by, for example, the monitoring unit 300 or the integrated calculation unit 600. Hereinafter, an example in which the monitoring unit 300 executes each process will be described as a representative.

[0142] The integrated calculation unit 600 outputs an irrigation execution command to the monitoring unit 300 corresponding to the divided area where irrigation is to be performed. In this state, the water supply valve 15 is controlled to be in a closed state. The microcomputer 330 of the monitoring unit 300 that has received the signal related to the irrigation processing output from the integrated calculation unit 600 executes the processing shown in FIG. 8. The processing shown in FIG. 8 is executed at the timing when the irrigation time arrives or at the timing when the irrigation execution command is output, and is repeated several times a day, for example. The processing shown in FIG. 8 is started, for example, when any of the timer arrival for irrigation execution, the irrigation execution timing according to the irrigation schedule, and the irrigation command manually input by the user occurs.

[0143] The processing unit 334 sets a first threshold value in step S100. The first threshold value is stored in the storage unit 333. The first threshold value is a reference value that is one of the end conditions of the irrigation treatment and is a target threshold value for the amount of soil moisture required for plant growth, and is indicated, for example, by a percentage indicating the ratio of the amount of moisture in the soil. When the detected soil moisture amount is below the first threshold value, it means that the amount of moisture required for plant growth is not contained in the soil. The acquisition unit 331 acquires the amount of moisture in the soil detected by the soil sensor 311 in step S110. The processing unit 334 determines in step S120 whether the detected value of the soil moisture amount is below the first threshold value.

[0144] If the detected value of the soil moisture amount is equal to or greater than the first threshold value, the flowchart of FIG. 8 is ended without performing irrigation. When the soil moisture amount is below the first threshold value, the microcomputer 330 sets the valve opening degree VT of the water supply valve 15 according to the deviation between the detected value of the moisture amount and the first threshold value in step S130. The valve opening degree VT is a target valve opening degree calculated to achieve the target irrigation water amount that can achieve the purpose disclosed in the specification. The valve opening degree VT is set to a larger opening degree as the deviation between the detected value of the moisture amount and the first threshold value is larger, and the water discharge amount from the distribution tube 136 increases. The valve opening degree VT is set to a smaller opening degree as the deviation between the detected value of the moisture amount and the first threshold value is smaller, and the water discharge amount from the distribution tube 136 is throttled. In step S140, the signal output unit 332 outputs a control signal based on the set valve opening degree VT to the water supply valve 15. Thereby, the water discharge amount from the distribution tube 136 is controlled by the water supply valve 15 set to the valve opening degree VT, and irrigation to the plant is started.

[0145] The acquisition unit 331 acquires the amount of soil moisture detected by the soil sensor 311 during the watering time in step S150. In step S160, the processing unit 334 determines whether the deviation between the first threshold value and the detected value of the soil moisture amount is equal to or greater than a predetermined value. The predetermined value is stored in the storage unit 333. The predetermined value is set to a small value close to zero so that watering can be performed at a flow rate when the detected value of the soil moisture amount slightly exceeds the first threshold value. The watering controlled by the valve opening VT continues in step S160 until it is determined that the deviation between the first threshold value and the detected value of the soil moisture amount is equal to or greater than the predetermined value. When the deviation between the first threshold value and the detected value of the soil moisture amount becomes equal to or greater than the predetermined value, the microcomputer 330 controls the valve opening to be fully closed in step S170 to end the watering. Thereby, the flowchart shown in FIG. 8 is ended.

[0146] Hereinafter, an example of the watering control performed in steps S130 to S170 will be described with reference to FIGS. 9 to 10.

[0147] FIG. 9 shows a comparison between the control of the first embodiment and the control of the comparative example as an example of the timing chart of the valve opening and the soil moisture amount during watering. The upper chart in FIG. 9 is a timing chart defining the valve opening as a percentage on the vertical axis and time (minutes) on the horizontal axis. The lower chart in FIG. 9 is a timing chart defining the moisture amount as a percentage contained in the soil on the vertical axis and time (minutes) on the horizontal axis.

[0148] The solid line in FIG. 9 indicates the control of the first embodiment, and the two-dot chain line in FIG. 9 indicates the control of the comparative example. The first embodiment shown in FIG. 9 is an example of performing control to increase the valve opening compared to the comparative example. The comparative example is an example of providing watering with a small water discharge amount by controlling the water supply valve to a small valve opening VC as shown by the two-dot chain line in the upper chart of FIG. 9.

[0149] As shown by the two-dot chain line in the lower chart of FIG. 9, in the comparative example, the amount of moisture contained in the soil starts to rise from the initial value W2 with a delay of T2 - T1 (minutes) with respect to the start time T1 of irrigation. This is because there is a time delay from the start time of irrigation until it is detected by the soil sensor. Then, when the soil moisture amount detected by the soil sensor exceeds the first threshold value TH1 at time T3, the valve opening degree is controlled to the closed state of V0 and irrigation is terminated. Thus, in the comparative example, since it is irrigation with a small water discharge amount, the irrigation time becomes T3 - T1 (minutes), which is longer than the irrigation time in the control of the first embodiment. In the comparative example, since the water discharge amount is small and water seeps and diffuses into the soil little by little and evaporates before reaching the soil sensor, the total irrigation water amount tends to increase.

[0150] In the control of the first embodiment shown in FIG. 9, the processing unit 334 obtains the set value VT of the valve opening degree by the following mathematical formula (1). The mathematical formula (1) is included in the arithmetic program or stored in the storage unit 333. k1 is a constant. TH1 is the first threshold value. W1 is the percentage of the moisture amount contained in the soil immediately before the irrigation is performed or at the initial stage of irrigation, and is detected by the soil sensor 311.

[0151] [Equation 1] VT = k1 × (TH1 - W1) ···(1) In this way, the processing unit 334 uses the mathematical formula (1) to determine the valve opening degree VT of the water supply valve 15 according to the deviation between the detected value of the soil moisture amount and the first threshold value. In this way, the valve opening degree VT is set to a value proportional to the deviation between the detected value of the soil moisture amount and the first threshold value.

[0152] In the control of the first embodiment, as shown by the solid line in the upper chart of FIG. 9, the water supply valve is controlled to a valve opening degree VT larger than VC, providing irrigation water with a larger water discharge amount than in the comparative example. As shown by the solid line in the lower chart of FIG. 9, in the control of the first embodiment, the amount of moisture contained in the soil starts to rise from the initial value W1 slightly before T2 with respect to the start time T1 of irrigation. In the control of the first embodiment, since it is controlled to a valve opening degree VT larger than VC, the time delay from the start time of irrigation until it is detected by the soil sensor can be made shorter than in the comparative example. And when the soil moisture amount detected by the soil sensor exceeds the first threshold value TH1 at time T2, the valve opening degree is controlled to the closed state V0 to end the irrigation.

[0153] Thus, in the control of the first embodiment, compared with the comparative example, since the irrigation has a large rate of change of water discharge amount with time, the irrigation time can be shortened to T2 - T1 (minutes). In the control of the first embodiment, the rate of change of water discharge amount with time is large and water easily penetrates in the gravity direction, so the irrigation time can be shortened compared with the comparative example. Also, in the control of the first embodiment, the time delay from the start time of irrigation until it is detected by the soil sensor can be made small. According to the control of the first embodiment shown in FIG. 9, it is possible to shorten the irrigation time and the time from the start of irrigation to the irrigation detection time, and perform irrigation that can suppress wasteful use of water.

[0154] Next, an example of the irrigation control performed in steps S130 to S160 will be described with reference to FIG. 10. FIG. 10 shows the control of the first embodiment and the control of the comparative example as an example of a timing chart of the valve opening degree and the soil moisture amount during irrigation. The upper chart of FIG. 10 is a timing chart defining the valve opening degree as a percentage on the vertical axis and time (minutes) on the horizontal axis. The lower chart of FIG. 10 is a timing chart defining the moisture amount as a percentage contained in the soil on the vertical axis and time (minutes) on the horizontal axis.

[0155] The solid line in Fig. 10 shows the control of the first embodiment, and the two-dot chain line in Fig. 10 shows the control of the comparative example. The first embodiment shown in Fig. 10 is an example of performing control to reduce the valve opening degree with respect to the comparative example. The comparative example is an example in which the water supply valve is controlled to a large valve opening degree VC as shown by the two-dot chain line in the upper chart of Fig. 10, and a large amount of watering with a large water discharge amount is provided.

[0156] As shown by the two-dot chain line in the lower chart of Fig. 10, in the comparative example, when the soil moisture amount detected by the soil sensor exceeds the first threshold value TH1 at time T2, the valve opening degree is controlled to the closed state of V0 and the watering ends. At this time, the moisture amount contained in the soil reaches W3, which greatly exceeds the first threshold value TH1. This is because the water discharge amount during watering is large and the time change rate of the soil moisture amount is large, so that the moisture amount of the soil overshoots the first threshold value TH1 and becomes excessive. Thus, in the comparative example, since it is watering that provides a large amount of water discharge amount, the soil moisture amount exceeds the first threshold value all at once, and the total watering amount tends to increase.

[0157] In the control of the first embodiment shown in Fig. 10, the processing unit 334 obtains the set value VT of the valve opening degree by the following mathematical formula (2). The mathematical formula (2) is included in the arithmetic program or stored in the storage unit 333. k1, TH1, and W1 are the same values as described above.

[0158] [Equation 2] VT = k1×(TH1 - W1) ···(2) In this way, the processing unit 334 uses the mathematical formula (2) to determine the valve opening degree VT of the water supply valve 15 according to the deviation between the detected value of the soil moisture amount and the first threshold value. The valve opening degree VT is set to a value proportional to the deviation between the detected value of the soil moisture amount and the first threshold value.

[0159] In the control of the first embodiment, as shown by the solid line in the upper chart of FIG. 10, the water supply valve is controlled to a valve opening degree VT smaller than VC, and irrigation water with a smaller water discharge amount than in the comparative example is provided. As shown by the solid line in the lower chart of FIG. 10, in the control of the first embodiment, the amount of moisture contained in the soil starts to rise from the initial value W1 a little before T3, which is delayed with respect to the start time T1 of irrigation. In the control of the first embodiment, since it is controlled to the valve opening degree VT smaller than VC, the rate of change of the soil moisture amount over time after irrigation is detected by the soil sensor can be made smaller than that of the comparative example. Then, when the soil moisture amount detected by the soil sensor exceeds the first threshold value TH1 at time T3, the valve opening degree is controlled to the closed state of V0 to end the irrigation.

[0160] Thus, in the control of the first embodiment, compared with the comparative example, since the irrigation has a small rate of change of the water discharge amount over time, it is possible to perform irrigation in which the amount of moisture in the soil does not greatly exceed the first threshold value TH1. According to the control of the first embodiment shown in FIG. 10, since the amount of irrigation water can be suppressed and an excessive state of the soil moisture amount can be avoided, it is possible to perform irrigation that can suppress wasteful use of water.

[0161] Further, the processing unit 334 may be configured to obtain the valve opening degree VT from the characteristic data stored in the storage unit 333 and the detection value of the soil sensor 311. The characteristic data is data showing the correlation between the soil moisture amount and information on the valve opening degree and the water discharge amount. Alternatively, the control device 200 may be configured to acquire this type of characteristic data from the outside via the integrated communication unit 400.

[0162] The irrigation system 10 of the first embodiment includes a water supply path to which water supply is supplied to discharge water to the plants in the field 20, and a water supply valve 15 that controls the amount of water discharged from the water supply path to the soil in the field 20 during irrigation. The irrigation system 10 includes a soil sensor 311 that detects the soil moisture amount of the soil, and a control device that controls the valve opening degree of the water supply valve 15. The control device controls the water supply valve 15 to the valve opening degree determined according to the deviation between the target threshold value and the soil moisture amount detected by the soil sensor 311.

[0163] The control device includes a processing unit 334 and a signal output unit 332 that outputs a control signal for controlling the valve opening degree determined by the processing unit 334 to the water supply valve 15. The processing unit 334 determines the valve opening degree of the water supply valve 15 that controls the water discharge amount to the soil according to the deviation between the target threshold value and the soil moisture amount detected by the soil sensor 311.

[0164] The irrigation system 10 and the control device determine the valve opening degree according to the deviation between the target threshold value and the detected value of the soil moisture amount by the soil sensor 311, and control the water supply valve 15 to this valve opening degree. The irrigation system 10 and the control device can perform control to adjust the valve opening degree so as to suppress the deviation between the target threshold value and the soil moisture amount according to this deviation. Therefore, it can be adjusted to the water discharge amount that suppresses the overshoot of the soil moisture amount with respect to the target threshold value. Therefore, the irrigation system 10 and the control device can perform irrigation that can suppress the waste of water.

[0165] The control device determines the valve opening degree in proportion to the deviation between the target threshold value and the detected value of the soil sensor 311. Thereby, it is possible to perform an irrigation process that speeds up the rise of the irrigation supply amount and shortens the time lag from the start of irrigation until irrigation is detected by the soil sensor 311. For this reason, the irrigation time from the start to the end of irrigation can be suppressed, and labor saving such as the operation of the pump, communication time, and power consumption of the battery can be achieved by suppressing the amount of water used.

[0166] When the deviation between the target threshold value and the detected value of the soil sensor 311 is small, the control device determines a small valve opening degree. Thereby, it is possible to provide irrigation that prevents irrigation supply in which the soil moisture amount greatly exceeds the target threshold value.

[0167] Second Embodiment The second embodiment will be described with reference to FIGS. 11 to 13. The irrigation system 10 of the second embodiment is different from that of the first embodiment in that irrigation control is performed according to the flowchart shown in FIG. 11. The irrigation system 10 of the second embodiment is different from the control shown in FIG. 8 of the first embodiment in that the valve opening degree is determined using the detected value of the soil moisture content in the previous irrigation. Regarding the configuration, operation, and effects not particularly described in the second embodiment, they are the same as those in the foregoing embodiments, and the differences will be described below.

[0168] The control device 200 executes the control shown in FIG. 11, for example, by the monitoring unit 300 and the integrated arithmetic unit 600. The control shown in FIG. 11 is different from the control shown in FIG. 8 of the first embodiment in steps S200, S220 to S235, and S270. The processes of steps S205, S210, S240, and S250 to S265 are the same as the processes of steps S100, S110, S120, and S140 to S170, respectively. The control shown in FIG. 11 executes the process of step S270 before ending the control shown in FIG. 8, and executes the process of step S200 before performing the control shown in FIG. 8. Further, the control shown in FIG. 11 executes the processes of steps S220 to S235 between steps S110 and S120 shown in FIG. 8. Step S245 shown in FIG. 11 is different from step S130 shown in FIG. 8 in the mathematical formula for obtaining the valve opening degree VT.

[0169] The process shown in FIG. 11 is executed at the timing when the irrigation time arrives or when the irrigation execution command is output, and is repeated several times a day, for example. After the microcomputer 330 finishes the irrigation process in step S265, it records the irrigation time, irrigation amount, soil moisture content, etc. in the current irrigation process in the storage unit 333 in step S270. When various data related to the current irrigation process are recorded as past data in step S270, the flowchart of FIG. 11 ends.

[0170] When the microcomputer 330 starts the control shown in FIG. 11, first, in step S200, it reads the past data recorded for the previous irrigation treatment. After the processing in steps S205 and S210, the processing unit 334 determines in step S220 whether the deviation between the first threshold value and the detected value of the soil moisture content after the previous irrigation ends is greater than or equal to a predetermined value. This predetermined value is stored in the storage unit 333. If the deviation is greater than or equal to the predetermined value in step S220, then in step S225, the valve opening VT is set using the detected value by the soil sensor 311 after the previous irrigation ends. The processing unit 334 sets the valve opening VT of the water supply valve 15 according to the deviation between the first threshold value and the detected value of the soil moisture content after the previous irrigation ends.

[0171] If this deviation is less than the predetermined value in step S220, then the processing unit 334 sets the optimal irrigation time in step S230. The optimal irrigation time is set to the irrigation time corrected by a predetermined time shorter than the irrigation time in the previous irrigation treatment. The processing unit 334 sets the valve opening VT according to the deviation between the optimal irrigation time and the previously measured irrigation time in step S235. Thus, the processing in steps S225 and S235 sets the valve opening VT of the water supply valve 15 according to the deviation between the first threshold value and the detected value of the soil sensor in the past irrigation.

[0172] In step S240, the processing unit 334 determines whether the current soil moisture content detected by the soil sensor 311 is less than the first threshold value. If the detected value of the current soil moisture content is greater than or equal to the first threshold value, the flowchart of FIG. 11 ends without performing irrigation. If the current soil moisture content is less than the first threshold value, the microcomputer 330 obtains the valve opening VT suitable for the current irrigation in step S245. The method for obtaining this valve opening VT will be described later in the explanation of the irrigation control with reference to FIGS. 12 and 13.

[0173] The irrigation control performed in steps S245 to S260 is as shown in the examples in the timing charts of FIGS. 12 and 13. An example of the irrigation control will be described below with reference to FIGS. 12 and 13.

[0174] Figure 12 shows an example of a timing chart of valve opening and soil moisture content during irrigation, showing the current irrigation control and the previous irrigation control. The upper chart in Figure 12 is a timing chart with time (minutes) on the horizontal axis and valve opening percentage on the vertical axis. The lower chart in Figure 12 is a timing chart with time (minutes) on the horizontal axis and moisture content percentage in the soil on the vertical axis.

[0175] The solid line in Figure 12 shows the current irrigation control, and the dashed line in Figure 12 shows the previous irrigation control. The current irrigation control shown in Figure 12 is an example of performing a process of reducing the valve opening compared to the previous irrigation control. The current irrigation control is an example of providing irrigation with a small discharge rate by correcting the water supply valve to a small valve opening VT compared to the previous irrigation control, and suppressing an overshoot of the soil moisture content.

[0176] In the previous irrigation shown by the dashed line in the lower chart of Figure 12, when the soil moisture content reaches the first threshold TH1 at time T2, the valve opening is controlled to the closed state of V0 and the irrigation ends. At this time, the moisture content contained in the soil reaches W1A, which greatly exceeds the first threshold TH1. This is because the discharge rate during the previous irrigation was large and the time change rate of the soil moisture content was large, so the soil moisture content excessively overshot the first threshold TH1. Thus, in the previous irrigation, since it is an irrigation that provides a large discharge rate, the soil moisture content exceeds the first threshold all at once, and the total irrigation amount tends to be large.

[0177] In the current irrigation control shown in FIG. 12, the processing unit 334 obtains the set value VT of the valve opening degree according to the following mathematical formulas (3) and (4). The mathematical formulas (3) and (4) are included in the arithmetic program or stored in the storage unit 333. TH1 is the same value as in the first embodiment described above. W1 is the percentage of moisture content contained in the soil immediately before or at the initial stage of irrigation for the previous irrigation or the current irrigation. W1A is the percentage of soil moisture content after the previous irrigation ends and is the excessive moisture content that overshoots the first threshold TH1. k1 and k2 are coefficients for converting the degree of soil wetness into the valve opening degree. k1(1) is the conversion coefficient for the first correction. In the valve opening degree setting for the current irrigation, as shown in the mathematical formula (3), the conversion coefficient for the first correction is used for the previous irrigation. Furthermore, when setting the valve opening degree at the time of the next irrigation, the conversion coefficient for the second correction will be used. Therefore, k1(1) in the mathematical formula (3) is replaced by k1(2), k1(1) in the mathematical formula (4) is replaced by k1(2), and k1(0) is replaced by k1(1).

[0178] [Equation 3] VT = k1(1)×(TH1 - W1) ···(3)

[0179] [Equation 4] k1(1) = k1(0) - k2×(W1A - TH1) / 100 ···(4) In this way, the processing unit 334 determines the valve opening degree VT of the water supply valve 15 according to the deviation between the detected value of the past soil moisture content and the first threshold value by the correction using the mathematical formulas (3) and (4).

[0180] In this irrigation control, as shown by the solid line in the upper chart of FIG. 12, the water supply valve is corrected to a valve opening degree VT smaller than V1 to provide a water discharge amount smaller than that of the previous irrigation. As shown by the solid line in the lower chart of FIG. 12, in this irrigation control, the amount of water contained in the soil starts to rise from the initial value W1 a little before T2, which is delayed with respect to the start time T1 of the irrigation. In this irrigation, since it is controlled to a valve opening degree VT smaller than V1, the rate of change of the soil moisture content over time after the irrigation is detected by the soil sensor can be made smaller than that of the previous irrigation. Then, when the soil moisture content detected by the soil sensor exceeds the first threshold value TH1 at time T2, the valve opening degree is controlled to the closed state of V0 to end the irrigation.

[0181] Thus, in this control, compared with the previous control, since it is irrigation with a small rate of change of the water discharge amount over time, it is possible to perform irrigation in which the amount of water in the soil does not greatly exceed the first threshold value TH1. According to the current irrigation control shown in FIG. 12, since the amount of irrigation water can be suppressed and an excessive state of the soil moisture content can be avoided, it is possible to perform irrigation that can suppress wasteful use of water.

[0182] Next, an example of the irrigation control performed in steps S245 to S260 will be described with reference to FIG. 13. FIG. 13 shows the current irrigation control and the previous irrigation control as an example of a timing chart of the valve opening degree and the soil moisture content during irrigation. The upper chart of FIG. 13 is a timing chart in which time (minutes) is defined on the horizontal axis and the valve opening degree as a percentage is defined on the vertical axis. The lower chart of FIG. 13 is a timing chart in which time (minutes) is defined on the horizontal axis and the percentage of the amount of water contained in the soil is defined on the vertical axis.

[0183] The solid line in FIG. 13 shows the current irrigation control, and the dashed line in FIG. 13 shows the previous irrigation control. The current irrigation control shown in FIG. 13 is an example in which the valve opening degree is increased with respect to the previous irrigation control. The current irrigation control is an example in which, with respect to the previous irrigation control, the water supply valve is corrected to a large valve opening degree VT to provide a large water discharge amount, and the soil is wetted in a short time to reach the target soil moisture content.

[0184] In the previous watering indicated by the broken line in the lower chart of FIG. 13, the amount of moisture contained in the soil starts to increase from the initial value W1 slightly before T3, with a significant delay relative to the start time T1 of watering. This is because, due to the small amount of water discharge, it takes time for the watering to be detected by the soil sensor. Then, when the soil moisture amount detected by the soil sensor reaches the first threshold value TH1 at time T3, the valve opening is controlled to the closed state of V0 to end the watering. Thus, in the previous watering, since the watering is with a small amount of water discharge, the watering time becomes long, and since the water penetrating into the soil spreads over a wide area, the total amount of water during watering tends to increase.

[0185] In the current watering control shown in FIG. 13, the processing unit 334 obtains the set value VT of the valve opening according to the following mathematical formulas (5) and (6). Mathematical formulas (5) and (6) are included in the arithmetic program or stored in the storage unit 333. TH1 and W1 are the same values as those described in relation to FIG. 12 and the first embodiment. k1 and k3 are coefficients for converting the degree of soil wetness into the valve opening. In the setting of the valve opening for the current watering, as shown in mathematical formula (5), k1(1), which is the first conversion coefficient for correction with respect to the previous watering, is used. Furthermore, when setting the valve opening for the next watering, as described above, the second conversion coefficient for correction will be used.

[0186] [Equation 5] VT = k1(1)×(TH1 - W1) ···(5)

[0187] [Equation 6] k1(1)=k1(0)+k3×(T3 - T1) ···(6) In this way, the processing unit 334 determines the valve opening VT of the water supply valve 15 according to the deviation between the detected value of the past soil moisture amount and the first threshold value through the correction using mathematical formulas (5) and (6).

[0188] In this irrigation control, as shown by the solid line in the upper chart of FIG. 13, the water supply valve is corrected to a valve opening degree VT larger than V1, so that a larger water discharge amount than the previous irrigation is provided. As shown by the solid line in the lower chart of FIG. 13, in this irrigation control, the amount of moisture contained in the soil begins to rise from the initial value W1 a little before the early T2 with respect to the previous irrigation. In this irrigation, since it is controlled to a valve opening degree VT larger than V1, the rate of change of the soil moisture amount over time after the irrigation is detected by the soil sensor can be made larger than that of the previous irrigation. This irrigation ends when the valve opening degree is controlled to the closed state of V0 when the soil moisture amount detected by the soil sensor reaches the first threshold value TH1 at time T2.

[0189] Thus, this irrigation has a larger rate of change of the water discharge amount over time than the previous irrigation, so that the irrigation time can be shortened to T2 - T1 (minutes). In this irrigation, the rate of change of the water discharge amount is large and water easily penetrates in the gravitational direction, so that the irrigation time can be shortened compared to the previous irrigation. Also, in this irrigation control, the time delay until the irrigation is detected by the soil sensor can be reduced from the start time. According to the irrigation control shown in FIG. 13, it is possible to shorten the irrigation time and the time from the start of irrigation to the irrigation detection time, and to perform irrigation that can suppress wasteful use of water.

[0190] The control device of the second embodiment records at least the irrigation time and the amount of soil moisture detected by the soil sensor 311 after the irrigation ends. The control device determines the valve opening degree in this irrigation according to the deviation between the target threshold value and the amount of soil moisture recorded after the past irrigation ends. Thereby, when the amount of soil moisture after the end of the previous irrigation or an earlier irrigation deviates from the target threshold value, it is possible to perform control to adjust the valve opening degree so as to reduce the deviation amount. For this reason, it is possible to provide control that can save water in this irrigation by utilizing the surplus water supply in the past irrigation.

[0191] The control device determines the current irrigation time for opening the valve to a fully open state as the irrigation time corrected to be shorter than the irrigation time recorded after the past irrigation ended. As a result, when the soil moisture content was excessive after the past irrigation ended, the irrigation supply amount can be suppressed in the current irrigation. Alternatively, when the irrigation time was long and the soil was excessively wet in the past irrigation, it is possible to provide control that can save water in the current irrigation by shortening the irrigation time. Further, by controlling the valve opening to be large and shortening the irrigation time this time, it is possible to provide irrigation that allows water to reach the roots of plants quickly, contributing to the implementation of irrigation with reduced waste of water.

[0192] Third Embodiment The third embodiment will be described with reference to FIGS. 14 to 16. The irrigation system 10 of the third embodiment is different from the first embodiment in that it performs irrigation control according to the flowchart shown in FIG. 14. The third embodiment is different from the control of the first embodiment in that it determines the timing for switching the valve opening in the current irrigation using the detected value of the soil moisture content in the past irrigation. Regarding the configuration, operation, and effects not particularly described in the third embodiment, they are the same as those in the foregoing embodiments, and the differences will be described below.

[0193] The control device 200 executes the control shown in FIG. 14 by, for example, the monitoring unit 300 or the integrated calculation unit 600. The control shown in FIG. 14 executes the process of step S365 after the irrigation is completed, and executes the process of step S300 as the first process.

[0194] The process shown in FIG. 14 is executed at the timing when the irrigation time arrives or at the timing when the irrigation execution command is output, and is repeated several times a day, for example. After the microcomputer 330 controls the valve opening to be fully closed in step S360 and ends the irrigation process, it records the irrigation time, irrigation amount, soil moisture content, etc. in the current irrigation process in the storage unit 333 in step S365. When various data related to the current irrigation process are recorded as past data in step S365, the flowchart of FIG. 14 ends.

[0195] When the microcomputer 330 starts the control shown in FIG. 14, first, in step S300, it reads the past data recorded about the past irrigation treatment. The processing unit 334 sets the first threshold value in step S305 and executes the process of setting the throttle opening of the valve. The throttle opening of the valve is, for example, a predetermined opening stored in the storage unit 333. The processing unit 334 does not execute the process of setting the throttle opening of the valve in step S305 at the first irrigation. The acquisition unit 331 acquires the moisture content of the soil detected by the soil sensor 311 in step S310. The processing unit 334 determines in step S315 whether the deviation between the first threshold value and the detected value of the soil moisture content after the past irrigation is stored in the storage unit 333 is greater than or equal to a predetermined value.

[0196] If this deviation is greater than or equal to the predetermined value, the processing unit 334 sets the switching timing of the valve opening using the detected value of the soil sensor 311 after the past irrigation in step S320. The processing unit 334 determines the timing to switch the valve opening according to the deviation between the first threshold value and the detected value of the soil moisture content after the past irrigation. When the deviation is less than the predetermined value in step S315, the processing unit 334 sets the timing to switch the valve opening in step S316. In step S316, the timing to switch the valve opening is determined using the deviation between the first threshold value and the current initial moisture content. The current initial moisture content is the current soil moisture content detected by the soil sensor 311 before the start of this irrigation. The method for obtaining the valve opening switching timing in steps S316 and S320 will be described later in the explanation of the irrigation control with reference to FIGS. 15 and 16.

[0197] After steps S316 and S320, the processing unit 334 determines whether the current soil moisture content detected by the soil sensor 311 in step S325 is less than the first threshold value. If the detected value of the current soil moisture content is greater than or equal to the first threshold value, the flowchart of FIG. 14 is ended without performing irrigation. If the current soil moisture content is less than the first threshold value, the processing unit 334 obtains and sets the valve opening degree VT before switching in the current irrigation process in step S330. The valve opening degree VT before switching corresponds to the valve opening degree before the switching timing determined in steps S316 and S320 arrives. The method for obtaining the valve opening degree VT before switching in step S330 is the same as the method described in the first embodiment obtained using mathematical formula (1) or mathematical formula (2).

[0198] In step S335, the signal output unit 332 outputs a control signal based on the set valve opening degree VT to the water supply valve 15. By this process, the water discharge amount from the distribution tube 136 is controlled by the water supply valve 15 set to the valve opening degree VT, and irrigation to the plants is started.

[0199] The processing unit 334 determines whether the switching timing of the valve opening degree has arrived in step S340. When the switching timing of the valve opening degree arrives, the microcomputer 330 outputs a signal for controlling the valve to the valve closing opening degree in order to switch the valve opening degree in step S345. The valve closing opening degree is the opening degree set in step S305, and control for reducing the water discharge amount of irrigation is executed by the process of step S345.

[0200] The acquisition unit 331 acquires the amount of soil moisture detected by the soil sensor 311 during the irrigation time in step S350. The processing unit 334 determines in step S355 whether or not the detected value of the soil moisture amount is equal to or greater than the first threshold value. The irrigation controlled by the valve throttle opening described above continues until it is determined in step S355 that the detected value of the soil moisture amount is equal to or greater than the first threshold value. When the detected value of the soil moisture amount becomes equal to or greater than the first threshold value, the microcomputer 330 controls the valve opening to be fully closed in step S360 to end the irrigation. As a result, the flowchart shown in FIG. 14 ends.

[0201] The irrigation control performed in steps S335 to S360 is as shown in the examples in the timing charts of FIGS. 15 and 16. An example of the irrigation control will be described below with reference to FIGS. 15 and 16.

[0202] FIG. 15 shows an example of a timing chart of the valve opening during irrigation, showing the current irrigation control and the past irrigation control. FIG. 16 shows an example of a timing chart of the soil moisture amount during irrigation, showing the current irrigation control and the past irrigation control. The three charts shown in FIG. 15 are timing charts that define the time (minutes) on the horizontal axis and the valve opening as a percentage on the vertical axis. The three charts shown in FIG. 16 are timing charts that define the time (minutes) on the horizontal axis and the soil moisture amount as a percentage on the vertical axis.

[0203] In each of the upper charts in FIG. 15 and the upper charts in FIG. 16, the broken line indicates the first irrigation control, and the solid line indicates the second irrigation control. In each of the middle charts in FIG. 15 and the middle charts in FIG. 16, the solid line indicates the second irrigation control, and the one-dot chain line indicates the third irrigation control. In each of the lower charts in FIG. 15 and the lower charts in FIG. 16, the solid line indicates the second irrigation control, and the two-dot chain line indicates the fourth irrigation control.

[0204] The second irrigation control shown in the upper charts of FIGS. 15 and 16 is an example of performing a process of switching the valve opening degree from VT1 to VT3 at time T3 during irrigation. In the first irrigation, the valve opening degree is controlled to VT1 from time T1, and when the soil moisture content reaches the first threshold value TH1 between times T3 and T5, the valve opening degree is controlled to the closed state to end the irrigation. In the first irrigation, the water content contained in the soil reaches W1A which greatly exceeds the first threshold value TH1. This is because the water discharge amount during the first irrigation is large and the time change rate of the soil moisture content is large, so the soil moisture content excessively overshoots the first threshold value TH1. Thus, in the first irrigation, since it is an irrigation that provides a large water discharge amount, the soil moisture content greatly exceeds the first threshold value, and the total irrigation amount tends to increase.

[0205] In the second irrigation control, the processing unit 334 obtains the timing for switching the valve opening degree to the throttled opening degree in step S320 using the following mathematical formulas (7) and (8). By using the mathematical formula (8), the processing unit 334 determines the timing for switching the valve opening degree according to the deviation between the first threshold value and the detected value of the soil moisture content after the past irrigation ends. The mathematical formulas (7) and (8) are included in the arithmetic program or stored in the storage unit 333. k4 and k5 are coefficients for converting the degree of wetness of the soil into the valve opening degree. k4(1) is the conversion coefficient for the first correction. At the timing of switching the valve throttled opening degree, as shown in the mathematical formula (7), the conversion coefficient for the first correction is used for the first irrigation.

[0206] [Equation 7] T3 - T1 = k4(1)×(TH1 - W1) ···(7)

[0207] [Equation 8] k4(1) = k4(0) - k5×(W1A - TH1) / 100 ···(8) In this way, the processing unit 334 can determine the time T3 which is the valve opening degree switching timing for the second irrigation through the calculation using the mathematical formulas (7) and (8).

[0208] In the second irrigation control, as shown by the solid line in the upper chart of FIG. 15, the valve opening is reduced from VT1 to VT3 at time T3, and the water discharge amount is changed to be less than that in the first irrigation. The irrigation controlled to the valve opening VT3 continues until the soil moisture content reaches the first threshold value, and when the first threshold value is reached, the valve opening is controlled to the closed state to end the irrigation. As shown by the solid line in the upper chart of FIG. 16, in the second irrigation control, the time change rate of the moisture content contained in the soil starts to change small from time T3. Thereby, since the degree of increase of the soil moisture content becomes slow before reaching the first threshold value TH1, it is possible to suppress that the saturated soil moisture content overshoots the first threshold value after the irrigation ends.

[0209] In the second control, compared with the first control, since the time change rate of the water discharge amount is changed small midway, it is possible to perform irrigation such that the soil moisture content does not greatly exceed the first threshold value TH1. According to the second irrigation control, since it is possible to avoid an excessive state of the soil moisture content by making the increase of the irrigation amount slow midway, it is possible to perform irrigation that can suppress wasteful use of water.

[0210] The third irrigation control shown in the middle charts of FIGS. 15 and 16 is an example of performing a process of switching so as to reduce the valve opening from VT1 to VT3 at time T2 during irrigation. That is, the third irrigation control performs a process of switching so as to reduce the valve opening at a timing earlier than that of the second irrigation control.

[0211] In the third irrigation control, the processing unit 334 obtains the timing for switching the valve opening to the throttle opening in step S316 using the following mathematical formula (9). By using the mathematical formula (9), the processing unit 334 determines the timing for switching the valve opening according to the deviation between the first threshold value and the detected value of the initial soil moisture content. The mathematical formula (9) is included in the arithmetic program or stored in the storage unit 333. W3 in the third embodiment is the moisture content percentage in the soil immediately before the third irrigation is carried out or at the initial stage of irrigation, and is detected by the soil sensor 311. k4(x) is a conversion coefficient for converting the degree of soil wetness into the valve opening. k4(x) is a conversion coefficient for which correction is performed x times until the deviation between the soil moisture content saturated after the first irrigation and the first threshold value becomes zero.

[0212] [Equation 9] T2 - T1 = k4(x) × (TH1 - W3) ···(9) In this way, the processing unit 334 can determine the time T2, which is the valve opening switching timing for the third irrigation, through the calculation using the mathematical formula (9).

[0213] In the third irrigation, as shown by the dashed line in the central chart of FIG. 15, the valve opening is throttled to VT3 at time T2, and the water discharge amount is changed to be less and earlier than that of the second irrigation. The irrigation controlled to the valve opening VT3 continues until the soil moisture content reaches the first threshold value. When the first threshold value is reached, the valve opening is controlled to the closed state and the irrigation ends. As shown by the solid line in the central chart of FIG. 16, in the third irrigation control, the time change rate of the moisture content contained in the soil begins to change small from time T2. Thereby, the degree of increase of the soil moisture content before reaching the first threshold value TH1 becomes gentle, so that the amount by which the soil moisture content exceeds the first threshold value by the third irrigation can be made smaller than that of the second irrigation.

[0214] In the third control, since the time change rate of the water discharge amount is changed to be small during the second control, irrigation can be performed while suppressing the amount by which the soil moisture content exceeds the first threshold TH1. According to the third irrigation control, since the increase in the irrigation amount is slowed down during the process earlier than the second time, irrigation can be performed that can suppress more wasteful use of water than the second time.

[0215] The fourth irrigation control shown in the lower charts of FIGS. 15 and 16 is an example in which a process of switching the valve opening degree from VT1 to VT3 is performed at the time T5 during irrigation. That is, the fourth irrigation control performs a process of switching to throttle the valve opening degree at a timing later than the second irrigation control.

[0216] In the fourth irrigation control, the processing unit 334 obtains the timing for switching the valve opening degree to the throttled opening degree in step S316 using the following mathematical formula (10). By using the mathematical formula (10), the processing unit 334 determines the timing for switching the valve opening degree according to the deviation between the first threshold value and the detected value of the initial soil moisture content. The mathematical formula (10) is included in the arithmetic program or stored in the storage unit 333. W5 in the third embodiment is the moisture content percentage contained in the soil immediately before or at the initial stage of the fourth irrigation, and is detected by the soil sensor 311. k4(x) is a conversion coefficient as described above, and is a conversion coefficient for which correction is performed x times until the deviation between the soil moisture content saturated after the end of the first irrigation and the first threshold value becomes zero.

[0217] [Equation 10] T5 - T1 = k4(x) × (TH1 - W5) ···(10) The processing unit 334 can determine the time T3, which is the valve opening degree switching timing, according to the deviation between the first threshold value and the detected value of the past soil moisture content by performing an operation using the mathematical formula (10).

[0218] In the fourth irrigation, as shown by the two-dot chain line in the lower chart of Fig. 15, the valve opening is reduced to VT3 at time T5, and the irrigation water discharge amount is changed to be less and later than that in the second irrigation. The irrigation with the valve opening changed to VT3 continues until the soil moisture content reaches the first threshold value. When the first threshold value is reached, the valve opening is controlled to the closed state to end the irrigation. As shown by the solid line in the lower chart of Fig. 16, in the fourth irrigation control, the time change rate of the moisture content contained in the soil starts to change small from time T5. Thereby, since the rising degree of the soil moisture content before reaching the first threshold value TH1 becomes gentle, the amount by which the soil moisture content exceeds the first threshold value by the fourth irrigation can be made smaller than that by the second irrigation.

[0219] In the fourth control, compared with the second control, since the time change rate of the irrigation water discharge amount is changed small halfway, irrigation can be carried out while suppressing the amount by which the soil moisture content exceeds the first threshold value TH1. According to the fourth irrigation control, irrigation can be ended earlier than the second irrigation, and irrigation can be carried out that can suppress more wasteful use of water than the second irrigation.

[0220] The control device of the third embodiment records at least the irrigation time and the soil moisture content detected by the soil sensor 311 after the irrigation ends. The control device determines the switching timing to reduce the valve opening in the current irrigation according to the deviation between the target threshold value and the soil moisture content recorded after the past irrigation ends. By this control, appropriate timing can be provided to reduce the valve opening so as to reduce the deviation amount between the soil moisture content after the past irrigation ends and the target threshold value. For this reason, irrigation can be provided that utilizes the surplus water supply in the past irrigation to bring the current soil moisture content closer to the target threshold value and save water.

[0221] The control device determines the switching timing to reduce the valve opening in the current irrigation according to the deviation between the target threshold value and the soil moisture content before the start of the current irrigation. By this control, appropriate timing can be provided to reduce the valve opening so as to reduce the deviation amount between the soil moisture content before the start of the current irrigation and the target threshold value. For this reason, irrigation can be provided that brings the current soil moisture content closer to the target threshold value and saves water.

[0222] Fourth Embodiment The fourth embodiment will be described with reference to FIGS. 17 to 19. The irrigation system 10 of the fourth embodiment is different from the first embodiment in that it performs irrigation control according to the flowchart shown in FIG. 17. The fourth embodiment is different from the control of the third embodiment in that, using the detected value of the soil moisture content in past irrigation, it determines the timing to change the valve opening degree to fully closed in this irrigation. Regarding the configuration, operation, and effects not particularly described in the fourth embodiment, they are the same as those in the foregoing embodiments, and the differences will be described below.

[0223] The control device 200 executes the control shown in FIG. 17, for example, by the monitoring unit 300 and the integrated calculation unit 600. The control shown in FIG. 11 is different from the control shown in FIG. 14 of the third embodiment in steps S416, S420, S435 to S475. The processes of steps S400 to S415 and S425 to S431 are the same as the processes of steps S300 to S315 and S325 to S335 of the third embodiment, respectively.

[0224] After the irrigation process is completed, the microcomputer 330 records the irrigation time, irrigation amount, soil moisture content, etc. in this irrigation process in the storage unit 333 in step S475. When various data related to this irrigation process are recorded as past data in step S475, the flowchart in FIG. 17 ends.

[0225] When starting the control shown in FIG. 17, steps S400 to S415, which are the same processes as in the third embodiment, are executed. When the deviation is greater than or equal to a predetermined value in step S415, the timing to switch the valve opening degree to fully closed in this irrigation is set in step S420. The processing unit 334 determines the timing to switch the valve opening degree to fully closed according to the deviation between the first threshold value and the detected value of the soil moisture content after the past irrigation is completed.

[0226] If the deviation is less than a predetermined value in step S415, the processing unit 334 sets, in step S416, the timing at which the valve opening degree is switched to fully closed in the current irrigation. In step S416, the timing at which the valve opening degree is switched to fully closed is determined using the deviation between the first threshold value and the current initial water content. The current initial water content is the current soil water content detected by the soil sensor 311 before the start of the current irrigation. The method for obtaining the valve fully closed switching timing in steps S416 and S420 will be described later in the description of the irrigation control with reference to FIGS. 18 and 19.

[0227] After the processing in step S416 and step S420, steps S425 to S431, which are the same processing as in the third embodiment, are executed to start irrigation of the plant. The processing unit 334 determines, in step S435, whether or not the valve fully closed switching timing has arrived. The microcomputer 330 continues the valve opening degree at the start of irrigation until the valve fully closed switching timing arrives. When the valve fully closed switching timing arrives, the microcomputer 330 outputs, in step S440, a signal for closing the valve opening degree to the water supply valve. By this processing, the water discharge to the soil stops.

[0228] The acquisition unit 331 acquires, in step S445, the detected value of the soil water content by the soil sensor 311 after a predetermined time has elapsed after the valve fully closed process. The predetermined time is determined in consideration of the time from when the water discharge to the soil stops until the water discharge that has penetrated into the soil reaches the soil sensor 311. The processing unit 334 determines, in step S450, whether or not the detected value of the soil water content is equal to or greater than the first threshold value. When the detected value of the soil water content becomes equal to or greater than the first threshold value, the microcomputer 330 records, in step S475, data such as the irrigation time, irrigation amount, and soil water content related to the current irrigation process in the storage unit 333. Then, the flowchart shown in FIG. 17 ends.

[0229] When the detected value of the soil moisture content is less than the first threshold, the microcomputer 330 outputs a signal for controlling the valve throttle opening to the water supply valve in step S455 to start irrigation. The valve throttle opening is the opening set in step S405. Due to the start of this irrigation, the water discharge that had once stopped resumes with a water discharge amount smaller than that before the stop.

[0230] The acquisition unit 331 acquires the soil moisture content detected by the soil sensor 311 in step S460. The processing unit 334 determines in step S465 whether or not the detected value of the soil moisture content is greater than or equal to the first threshold. The irrigation controlled by the aforementioned valve throttle opening continues until it is determined in step S465 that the detected value of the soil moisture content is greater than or equal to the first threshold. When the detected value of the soil moisture content becomes greater than or equal to the first threshold, the microcomputer 330 outputs a signal for closing the valve opening completely to the water supply valve in step S470 to end the irrigation. After that, in step S475, various data related to the current irrigation process are recorded as past data, and the flowchart in FIG. 17 is terminated.

[0231] The irrigation control performed in steps S431 to S470 is as shown in the examples in the timing charts of FIGS. 18 and 19. An example of the irrigation control will be described below with reference to FIGS. 18 and 19.

[0232] FIG. 18 shows an example of the timing chart of the valve opening during irrigation, showing the current irrigation control and the past irrigation control. FIG. 19 shows an example of the timing chart of the soil moisture content during irrigation, showing the current irrigation control and the past irrigation control. The three charts shown in FIG. 18 are timing charts with time (minutes) on the horizontal axis and the valve opening percentage on the vertical axis. The three charts shown in FIG. 19 are timing charts with time (minutes) on the horizontal axis and the soil moisture content percentage on the vertical axis.

[0233] In each of the upper charts of FIG. 18 and FIG. 19, the dashed line indicates the first irrigation control, and the solid line indicates the second irrigation control. In each of the middle charts of FIG. 18 and FIG. 19, the solid line indicates the second irrigation control, and the one-dot chain line indicates the third irrigation control. In each of the lower charts of FIG. 18 and FIG. 19, the solid line indicates the second irrigation control, and the two-dot chain line indicates the fourth irrigation control.

[0234] The second irrigation control shown in the upper charts of FIG. 18 and FIG. 19 is an example of performing a process of switching the valve opening from VT1 to fully closed at time T3 during irrigation. In the first irrigation, the valve opening is controlled to VT1 from time T1, and when the soil moisture content reaches the first threshold value TH1, the valve opening is controlled to the closed state to end the irrigation. In the first irrigation, the moisture content contained in the soil reaches W1A, which greatly exceeds the first threshold value TH1. In the first irrigation, since the water discharge amount is large and the time change rate of the soil moisture content is large, the soil moisture content overshoots the first threshold value TH1 excessively. Thus, in the first irrigation, the soil moisture content greatly exceeds the first threshold value, and the total irrigation amount tends to increase.

[0235] In the second irrigation control, the processing unit 334 obtains the timing for switching the valve opening to fully closed in step S420 using the following mathematical formulas (11) and (12). By using the mathematical formula (12), the processing unit 334 determines the timing for switching the valve opening to fully closed according to the deviation between the first threshold value and the detected value of the soil moisture content after the past irrigation ends. The mathematical formulas (11) and (12) are included in the arithmetic program or stored in the storage unit 333. k6 and k7 are coefficients for converting the degree of soil wetness into the valve opening. k6(1) is the first correction conversion coefficient. At the timing of switching the valve throttle opening, as shown in the mathematical formula (11), the first correction conversion coefficient is used for the first irrigation.

[0236] [Equation 11] T3 - T1 = k6(1) × (TH1 - W1) ···(11)

[0237] [Number 12] k6(1) = k6(0) - k7 × (W1A - TH1) / 100 ···(12) The processing unit 334 can determine the time T3 which is the valve fully closed switching timing according to the deviation between the first threshold value and the detected value of the past soil moisture content by performing the calculation using the above formula.

[0238] In the second irrigation control, as shown by the solid line in the upper chart of FIG. 18, at time T3, the valve opening degree is changed from VT1 to fully closed and the water discharge amount is changed to zero. As shown by the solid line in the upper chart of FIG. 19, in the second irrigation control, from the stop of water discharge, the time change rate of the soil moisture content infiltrating into the soil changes smaller from time T3. Thereby, since the degree of increase of the soil moisture content after the stop of water discharge is dull, it is possible to suppress that the soil moisture content saturated after the end of irrigation overshoots the first threshold value.

[0239] In the second control, compared with the first control, since the time change rate of the water discharge amount is changed considerably smaller in the middle, it is possible to perform irrigation while suppressing the amount by which the soil moisture content exceeds the first threshold value TH1. According to the second irrigation control, since the water discharge can be stopped earlier to slow down the increase of the irrigation amount and avoid the excessive state of the soil moisture content, it is possible to perform irrigation that can suppress the wasteful use of water.

[0240] The third irrigation control shown in the middle chart of FIG. 18 and FIG. 19 is an example of performing the process of switching the valve opening degree to fully closed at time T2 during irrigation. That is, the third irrigation control performs the process of switching the valve opening degree to fully closed at a timing earlier than the second irrigation control.

[0241] In the third irrigation control, the processing unit 334 obtains the timing for switching the valve opening to fully closed in step S416 using the following mathematical formula (13). By using the mathematical formula (13), the processing unit 334 determines the timing for switching the valve opening to fully closed according to the deviation between the first threshold value and the detected value of the initial soil moisture content. The mathematical formula (13) is included in the arithmetic program or stored in the storage unit 333. W3 in the fourth embodiment is the moisture content percentage contained in the soil immediately before the third irrigation is carried out or at the initial stage of irrigation, and is detected by the soil sensor 311. k6(x) is a conversion coefficient for converting the degree of soil wetness into a valve opening. k6(x) is a conversion coefficient for which correction is performed x times until the deviation between the saturated soil moisture content after the first irrigation is completed and the first threshold value becomes zero.

[0242] [Equation 13] T2 - T1 = k6(x) × (TH1 - W3) ···(13) In this way, the processing unit 334 can determine the time T2, which is the valve fully closed switching timing for the third irrigation, through the calculation using the mathematical formula (13).

[0243] In the third irrigation, as shown by the dashed line in the central chart of FIG. 18, the valve opening is changed to fully closed at time T2 and the water discharge amount is changed to zero. As shown by the solid line in the central chart of FIG. 19, in the third irrigation control, from the stop of water discharge, the time change rate of the soil moisture content penetrating into the soil changes small from time T2. As a result, the degree of increase in the soil moisture content after the stop of water discharge becomes large and dull at an earlier time compared to the second time. According to the third irrigation control, since water discharge can be stopped early to blunt the increase in the irrigation amount and avoid an excessive state of the soil moisture content, irrigation that can suppress wasteful use of water can be carried out.

[0244] The fourth irrigation control shown in the lower chart of FIG. 18 and FIG. 19 is an example of performing a process of switching the valve opening to fully closed at time T5. That is, the fourth irrigation control performs a process of switching the valve opening to fully closed at a timing later than the second irrigation control.

[0245] In the fourth irrigation control, the processing unit 334 obtains the timing for switching the valve opening to fully closed in step S416 using the following mathematical formula (14). By using the mathematical formula (14), the processing unit 334 determines the timing for switching the valve opening to fully closed according to the deviation between the first threshold value and the detected value of the initial soil moisture content. The mathematical formula (14) is included in the operation program or stored in the storage unit 333. W4 in the fourth embodiment is the moisture content percentage in the soil immediately before the fourth irrigation is carried out or at the initial stage of irrigation, and is detected by the soil sensor 311. The initial moisture content W4 in the fourth irrigation is lower than the initial moisture content W4 in the second irrigation.

[0246] [Equation 14] T5 - T1 = k6(x)×(TH1 - W4) ···(14) In this way, the processing unit 334 can determine the time T5, which is the valve fully closed switching timing for the fourth irrigation, through the calculation using the mathematical formula (14).

[0247] In the fourth irrigation, as shown by the two-dot chain line in the lower chart of FIG. 18, the valve opening is changed to fully closed at time T5 and the water discharge amount is changed to zero. As shown by the solid line in the lower chart of FIG. 19, in the fourth irrigation control, from the stop of water discharge, the time change rate of the soil moisture content penetrating into the soil changes smaller from time T5. According to the fourth irrigation control, irrigation that can suppress the waste of water can be carried out.

[0248] The control device of the fourth embodiment records at least the irrigation time and the soil moisture content detected by the soil sensor 311 after the irrigation is completed. The control device determines the switching timing for closing the valve opening to fully closed in the current irrigation according to the deviation between the target threshold value and the soil moisture content recorded after the past irrigation is completed. By this control, an appropriate timing for closing the valve opening to fully closed can be provided so as to reduce the deviation amount between the soil moisture content after the past irrigation is completed and the target threshold value. In order to appropriately control the end of irrigation in this way, the surplus water supply in the past irrigation can be utilized to bring the current soil moisture content closer to the target threshold value and achieve water conservation.

[0249] The control device determines the switching timing to fully close the valve opening in the current irrigation according to the deviation between the target threshold value and the soil moisture content before the start of the current irrigation. By this control, it is possible to provide an appropriate timing to fully close the valve opening so as to reduce the deviation amount between the soil moisture content before the start of the current irrigation and the target threshold value. In order to appropriately control the end of irrigation in this way, it is possible to save water by bringing the current soil moisture content closer to the target threshold value.

[0250] Fifth Embodiment The fifth embodiment will be described with reference to FIGS. 20 to 21. The irrigation system 10 of the fifth embodiment is different from the first embodiment in that it performs irrigation control according to the flowchart shown in FIG. 20. The fifth embodiment is different from the control of the first embodiment in that it adjusts the valve opening according to the deviation between the threshold value and the current soil moisture content. Regarding the configuration, operation, and effects not particularly described in the fifth embodiment, they are the same as those in the foregoing embodiments, and the differences will be described below.

[0251] The control device 200 executes the control shown in FIG. 20, for example, by the monitoring unit 300 and the integrated calculation unit 600. The control shown in FIG. 20 is different in steps S535 to S545 from the control shown in FIG. 8 of the first embodiment. The processes of steps S500 to S530 and S550 are the same as the processes of steps S100 to S150 and S170 of the first embodiment, respectively. The setting of the valve opening VT in step S535 is performed in the same manner as the description of the first embodiment.

[0252] After the start of irrigation, the microcomputer 330 sets the valve opening degree VT of the water supply valve 15 according to the deviation between the first threshold value and the detected value of the current soil moisture content in step S535. The method for obtaining the valve opening degree in step S535 will be described later in the description of the irrigation control with reference to FIG. 21. The valve opening degree VT is changed to a smaller opening degree as the deviation between the first threshold value and the detected value of the current soil moisture content becomes smaller, and the water discharge amount from the distribution tube 136 is reduced. The signal output unit 332 outputs a control signal based on the set valve opening degree VT to the water supply valve 15. As a result, the valve opening degree VT set in the previous step S520 is changed in step S535, and the soil moisture content approaches the first threshold value.

[0253] The acquisition unit 331 acquires the soil moisture content detected by the soil sensor 311 in step S540. The processing unit 334 determines in step S545 whether the detected value of the soil moisture content is equal to or greater than the first threshold value. If it is determined in step S545 that the detected value of the soil moisture content is less than the first threshold value, the valve opening degree VT is changed again in step S535 and the water discharge amount changes. The valve opening degree VT is repeatedly changed in step S535 until it is determined in step S545 that the deviation is equal to or greater than a predetermined value, and the time change rate of the soil moisture content continuously changes. When the deviation becomes equal to or greater than a predetermined value in step S545, the microcomputer 330 controls the valve opening degree to be fully closed in step S550 and ends the irrigation. As a result, the flowchart shown in FIG. 20 ends.

[0254] The irrigation control performed in steps S535 to S550 is as shown in the example of the timing chart in FIG. 21. An example of the irrigation control will be described below with reference to FIG. 21.

[0255] FIG. 21 shows a comparison between the control of the fifth embodiment and the control of the comparative example as an example of the timing chart of the valve opening degree during irrigation. The upper chart in FIG. 21 is a timing chart defining the valve opening degree as a percentage on the vertical axis and time (minutes) on the horizontal axis. The lower chart in FIG. 21 is a timing chart defining the moisture content as a percentage contained in the soil on the vertical axis and time (minutes) on the horizontal axis.

[0256] The solid line in FIG. 21 shows the control of the fifth embodiment, and the two-dot chain line shows the control of the comparative example. The fifth embodiment shown in the upper chart of FIG. 21 is an example of performing control to gradually decrease the valve opening degree with respect to the comparative example. In the comparative example, as shown by the two-dot chain line in the upper chart of FIG. 21, the valve opening degree VT is constantly controlled.

[0257] As shown by the two-dot chain line in the lower chart of FIG. 21, in the comparative example, when the soil moisture content detected by the soil sensor exceeds the first threshold value TH1 at time T3, the valve opening degree is controlled to be fully closed and irrigation is terminated. At this time, the moisture content contained in the soil reaches a value that greatly exceeds the first threshold value TH1. This is because the water discharge amount during irrigation is large and the time change rate of the soil moisture content is large, so that the moisture content of the soil overshoots the first threshold value TH1 and becomes excessive. In this comparative example, since it is irrigation that provides a large water discharge amount, the soil moisture content exceeds the first threshold value at once, and the total irrigation amount tends to increase.

[0258] In the control of the fifth embodiment shown in FIG. 21, the processing unit 334 obtains the valve opening degree by the following mathematical formula (15) in step S535. The mathematical formula (15) is included in the arithmetic program or stored in the storage unit 333. k1 and TH1 are the same values as described above. WP is the moisture content percentage contained in the current soil, and is detected by the soil sensor 311 in step S530.

[0259] [Equation 15] VT = k1×(TH1 - WP) ···(15) In this way, the processing unit 334 uses the mathematical formula (15) to determine and vary the valve opening degree according to the deviation between the detected value of the current soil moisture content and the first threshold value. The valve opening degree is set to a value proportional to the deviation between the detected value of the current soil moisture content and the first threshold value.

[0260] In the control of the fifth embodiment, as shown in the upper chart of FIG. 21, the valve opening degree is gradually reduced toward zero from time T2 earlier than time T3 to time T4. The processing unit 334 determines the valve opening degree so as to become smaller as time elapses, and the valve opening degree is controlled so as to become smaller as it approaches zero. Then, when the valve opening degree becomes zero, the water discharge stops and the irrigation ends.

[0261] As shown in the lower chart of FIG. 21, in the control of the fifth embodiment, the valve opening degree and the water discharge amount gradually decrease, and the water discharge amount is throttled so as to become smaller as the soil moisture amount approaches the first threshold value. The control of the fifth embodiment enables irrigation in which the time change rate of the water discharge amount gradually becomes smaller compared with the comparative example. Therefore, the control of the fifth embodiment can provide irrigation in which the soil moisture amount softly lands with respect to the first threshold value and can perform irrigation that hardly exceeds the first threshold value greatly.

[0262] The control device of the fifth embodiment determines to throttle the valve opening degree as the deviation between the target threshold value and the soil moisture amount detected by the soil sensor during irrigation decreases. By this control, since the valve opening degree is gradually throttled as the soil moisture amount during irrigation approaches the target threshold value, it is possible to save water by making the current soil moisture amount asymptotic to the target threshold value.

[0263] Sixth Embodiment The sixth embodiment will be described with reference to FIGS. 22 to 25. The irrigation system 10 of the sixth embodiment is different from that of the first embodiment in that irrigation control is performed using the detection values of a plurality of soil sensors having different depths of the detection units in the soil. The configurations, operations, and effects not particularly described in the sixth embodiment are the same as those of the foregoing embodiments, and the different points will be described below.

[0264] Irrigation system 10 includes a plurality of soil sensors 311 installed such that the depths of the detection units in the soil are different. The plurality of soil sensors 311 include a soil sensor 311u with a shallower installation depth of the detection unit and a soil sensor 311d with the detection unit installed at a deeper position than the soil sensor 311u. Acquisition unit 331 acquires the soil moisture content detected by each of the soil sensor 311u and the soil sensor 311d.

[0265] Acquisition unit 331 acquires an image of the plants in the field 20 captured by the camera 312 shown in FIG. 22. In the drawings, the camera 312 is denoted as IS. Processing unit 334 or integrated calculation unit 600 analyzes the captured image of the camera 312 to estimate the root spread distance of the plants. Processing unit 334 or integrated calculation unit 600 determines the branch spread distance of the plants from the captured image of the plants by the camera 312 and estimates the root spread distance from this branch spread distance. This estimation is calculated based on the relationship that the branch spread distance is proportional to the root spread distance. Characteristics data indicating the relationship between the branch spread distance and the root spread distance, such as that of the processing unit 334, is stored in the storage unit 333, for example.

[0266] Processing unit 334 or integrated calculation unit 600 determines which of the soil sensor 311u and the soil sensor 311d to use to detect the soil moisture content according to the estimated root spread distance. When the processing unit 334 or the like estimates the root spread distance corresponding to the shallow roots in FIG. 23 based on the captured image of the camera 312, the soil moisture content is detected using the soil sensor 311u at the shallow position. When selecting the soil sensor 311u at the shallow position, among the plurality of sensors shown in FIG. 23, any one sensor detection value or the average value of two or more sensor detection values is used for detection. When the processing unit 334 or the like estimates the root spread distance corresponding to the deep roots in FIG. 24 based on the captured image of the camera 312, the soil moisture content is detected using the soil sensor 311d at the deep position. The irrigation system 10 contributes to performing irrigation suitable for the growth of the plants by selecting a soil sensor for detecting the soil moisture content according to the growth degree of the plants.

[0267] The irrigation control of the sixth embodiment is as shown in the timing chart of FIG. 25. An example of the irrigation control will be described below with reference to FIG. 25. FIG. 25 shows an example of a timing chart of the valve opening degree and the soil moisture content during irrigation, including an example using the soil sensor 311u and an example using the soil sensor 311d. The upper chart in FIG. 25 is a timing chart with the time (minutes) on the horizontal axis and the valve opening degree in percentage on the vertical axis. The lower chart in FIG. 25 is a timing chart with the time (minutes) on the horizontal axis and the moisture content percentage in the soil on the vertical axis.

[0268] The solid line in FIG. 25 indicates the control using the soil sensor 311u, and the dashed line in FIG. 25 indicates the control using the soil sensor 311d. In the control using the soil sensor 311u, the valve opening degree is controlled to be in the open state between times T1 and T2. In the control using the soil sensor 311u, the soil moisture content starts to increase with a delay from time T1 and becomes constant a little after time T2. In the control using the soil sensor 311d, the valve opening degree is controlled to be in the open state between times T1 and T3. In the control using the soil sensor 311d, the soil moisture content starts to increase with a delay from time T2 and becomes constant a little after time T3.

[0269] When the plant is small, irrigation can be carried out to end the guttation after the guttation reaches the shallow roots by the control using the soil sensor 311u, and irrigation that saves wasteful guttation can be provided. When the plant is large, irrigation can be continued until the guttation reaches the deep roots by the control using the soil sensor 311d, so effective irrigation can be provided.

[0270] The control device selects, according to the growth degree of the plant, either the soil sensor at a shallow position or the soil sensor at a deep position as the soil sensor used to determine the valve opening degree. Thereby, an optimal irrigation amount can be supplied according to the growth stage of the plant, and irrigation that suppresses excessive or insufficient irrigation supply can be provided.

[0271] Seventh Embodiment The seventh embodiment will be described with reference to FIGS. 26 to 27. The irrigation system 10 of the seventh embodiment is different from the first embodiment in that irrigation control is performed using the detection values of a plurality of soil sensors having different depths of the detection units in the soil. For the configurations, operations, and effects not particularly described in the seventh embodiment, they are the same as those in the foregoing embodiments, and the differences will be described below.

[0272] Similar to the sixth embodiment, the irrigation system 10 includes a plurality of soil sensors 311 installed such that the depths of the detection units in the soil are different. The control configuration according to the seventh embodiment is the same as the configuration shown in FIG. 22 of the sixth embodiment.

[0273] When performing irrigation processing, the irrigation system 10 executes the processing shown in the flowchart of FIG. 26. FIG. 26 is a flowchart showing an example of the operation at the time of an irrigation command. The control device 200 executes the processing shown in FIG. 26 by, for example, the monitoring unit 300 or the integrated calculation unit 600. The processing shown in FIG. 26 is started, for example, when any of the arrival of the irrigation execution timer, the irrigation execution timing according to the irrigation schedule, and the manual irrigation command by the user occurs. Hereinafter, an example in which the monitoring unit 300 executes each processing shown in FIG. 26 will be described as a representative.

[0274] The processing unit 334 sets a first threshold value in step S600 and executes a process of setting the throttle opening of the valve. The throttle opening of the valve is, for example, an opening stored in advance in the storage unit 333. The acquisition unit 331 acquires the moisture content of the soil detected by each of a plurality of soil sensors 311 having different depths of the detection units in the soil in step S610. The processing unit 334 determines in step S615 whether the detection values of the plurality of soil sensors 311 are below the first threshold value. In the determination process of step S615, the determination is made for the detection values of all the sensors of the soil sensor 311u installed at a shallow position and the soil sensor 311d installed at a deep position.

[0275] If the detected value of the soil moisture content for all sensors in step S615 is equal to or greater than the first threshold, the flowchart of FIG. 26 is terminated without performing irrigation. In this case, it can be determined that the soil moisture content is sufficient such that irrigation is not required for the soil in both the case where the root spread distance of the plant is shallow and the case where it is deep.

[0276] If, in step S615, the detected value of the soil moisture content of at least one sensor is less than the first threshold, the processing unit 334 sets the valve opening degree VT of the water supply valve 15 in step S620. In step S620, the microcomputer 330 sets the valve opening degree VT according to the deviation between the detected value of the soil moisture content and the first threshold. The method for obtaining the valve opening degree VT in step S620 is the same as the method described in the first embodiment obtained using the above-mentioned mathematical formula (1) or mathematical formula (2). In step S625, the signal output unit 332 outputs a control signal based on the set valve opening degree VT to the water supply valve 15. The water discharge amount from the distribution tube 136 is controlled by the water supply valve 15 set to the valve opening degree VT, and irrigation of the plant is started.

[0277] After the start of irrigation, the acquisition unit 331 acquires, in step S630, the soil moisture content detected by each of the soil sensors 311u installed at a shallow position. In step S635, the processing unit 334 determines whether or not the detected value of the soil sensor 311u installed at a shallow position exceeds a predetermined value. The determination process in step S635 is repeated until the detected value of the soil sensor 311u exceeds the predetermined value. For the determination process in step S635, the detected value of any one of the plurality of soil sensors 311u may be used, or the average value based on the detected values of two or more soil sensors 311u may be used. The predetermined value is a value smaller than the first threshold, which is the target threshold, a reference value that is one of the end conditions of the irrigation process, and is stored in the storage unit 333.

[0278] When the detected value of the soil sensor 331u exceeds a predetermined value in step S635, the microcomputer 330 outputs a signal for controlling the valve throttle opening to the water supply valve in step S640. The valve throttle opening is the opening set in step S600, and control for reducing the water discharge amount of irrigation is executed by the process of step S640.

[0279] After the water discharge amount is reduced, the acquisition unit 331 acquires the moisture content of the soil detected by the soil sensor 311d installed at a deep position in step S645. The processing unit 334 determines whether the detected value of the soil sensor 311d installed at a deep position is greater than or equal to a first threshold value in step S650. The determination process in step S650 is repeated until the detected value of the soil sensor 311d becomes greater than or equal to the first threshold value. When the detected value of the soil sensor 311d becomes greater than or equal to the first threshold value, the microcomputer 330 controls the valve opening to be fully closed in step S655 to end the irrigation. Thereby, the flowchart shown in FIG. 26 is ended.

[0280] Hereinafter, an example of irrigation control performed in steps S620 to S655 will be described with reference to FIG. 27.

[0281] The upper chart in FIG. 27 is a timing chart defining the valve opening percentage on the vertical axis and time (minutes) on the horizontal axis. The lower chart in FIG. 27 is a timing chart defining the moisture content percentage in the soil on the vertical axis and time (minutes) on the horizontal axis. In the lower chart of FIG. 27, the solid line represents the transition of the soil moisture content detected by the soil sensor at a deep position, and the two-dot chain line represents the transition of the soil moisture content detected by the soil sensor at a shallow position.

[0282] As shown in Fig. 27, the irrigation control of the seventh embodiment switches to reduce the valve opening from VT1 to VT2 at time T3 during irrigation, and performs a process of controlling the opening to zero at time T5. As shown in the lower chart of Fig. 27, the soil moisture content at the shallow position starts to increase rapidly from time T3 and continues to increase even after the moisture reaches the deep position. The soil moisture content at the deep position starts to increase after passing time T3, with a delay compared to the shallow position, and the rate of change with respect to time becomes gentle shortly before time T5 and approaches the first threshold value. The irrigation control of the seventh embodiment can suppress irrigation that excessively overshoots the target threshold value by reducing the water discharge amount using the detection value of the soil sensor at the shallow position. Therefore, according to the irrigation control of the seventh embodiment, it is possible to avoid an excessive state of the soil moisture content by slowing down the increase in the irrigation amount in the middle, and thus implement irrigation that can suppress wasteful use of water.

[0283] The control device of the seventh embodiment switches to reduce the valve opening at the timing when the detection value by the soil sensor 311u at the shallow position exceeds a predetermined value that is lower than the target threshold value. By this control, it is possible to reduce the irrigation supply amount at the stage when the soil moisture content on the side closer to the ground surface reaches a predetermined value lower than the target threshold value, and suppress excessive irrigation supply to the soil. For this reason, it is possible to provide water-saving irrigation so that the soil moisture content at the shallow position of the soil does not overshoot the target threshold value.

[0284] <Other Embodiments> The disclosure of this specification is not limited to the illustrated embodiments. The disclosure includes the illustrated embodiments and modifications by those skilled in the art based thereon. For example, the disclosure is not limited to the components and combinations of elements shown in the embodiments, and can be implemented with various modifications. The disclosure can be implemented by various combinations. The disclosure can have additional parts that can be added to the embodiments. The disclosure includes those in which the components and elements of the embodiments are omitted. The disclosure includes the replacement or combination of components and elements between one embodiment and another. The disclosed technical scope is not limited to the description of the embodiments. The disclosed technical scope should be construed as being indicated by the description of the claims and including all changes within the meaning and scope equivalent to the description of the claims.

[0285] In the sixth embodiment, a soil sensor that detects the soil temperature by a soil sensor capable of detecting the soil temperature and detects the soil moisture content using the detected value of the soil temperature may be selected.

[0286] In the sixth embodiment, a soil sensor that obtains the harvest time of the plant from the detection value of the soil sensor and detects the soil moisture content using the estimated root growth degree may be selected.

Description of Reference Numerals

[0287] 20... field, 15... water supply valve, 200... control device, 311... soil sensor 332... signal output unit, 334... processing unit< / rtc>

Claims

1. A water supply path to which water supply is provided to water the plants in the field (20), A water supply valve (15) for controlling the amount of water discharged from the water supply path to the soil of the field during irrigation, A soil sensor (311) for detecting the soil moisture content of the soil, A control device (200) for controlling the valve opening degree of the water supply valve, Comprising, The control device controls the water supply valve to the valve opening degree determined according to the deviation between the target threshold value and the soil moisture content detected by the soil sensor. An irrigation system.

2. After the irrigation is completed, the control device records at least the irrigation time and the soil moisture content detected by the soil sensor, The irrigation system according to claim 1, wherein the valve opening degree in the current irrigation is determined according to the deviation between the target threshold value and the soil moisture content recorded after the past irrigation is completed.

3. After the irrigation is completed, the control device records at least the irrigation time and the soil moisture content detected by the soil sensor, The irrigation system according to claim 1, wherein the irrigation time in the current irrigation with the valve opening degree in the open state is determined to be a corrected irrigation time shorter than the irrigation time recorded after the past irrigation is completed.

4. After the irrigation is completed, the control device records at least the irrigation time and the soil moisture content detected by the soil sensor, The irrigation system according to claim 1, wherein the switching timing for reducing the valve opening degree in the current irrigation is determined according to the deviation between the target threshold value and the soil moisture content recorded after the past irrigation is completed.

5. After the irrigation is completed, the control device records at least the irrigation time and the soil moisture content detected by the soil sensor, The irrigation system according to claim 1, wherein the switching timing for reducing the valve opening degree in the current irrigation is determined according to the deviation between the target threshold value and the soil moisture content before the start of the current irrigation.

6. After the irrigation is completed, the control device records at least the irrigation time and the soil moisture content detected by the soil sensor, The irrigation system according to claim 1, wherein the switching timing for closing the valve opening degree completely in the current irrigation is determined according to the deviation between the target threshold value and the soil moisture content recorded after the past irrigation is completed.

7. After the irrigation is completed, the control device records at least the irrigation time and the soil moisture content detected by the soil sensor, The irrigation system according to claim 1, which determines the switching timing to fully close the valve opening in the current irrigation according to the deviation between the target threshold value and the soil moisture content before the start of the current irrigation.

8. The irrigation system according to claim 1, wherein the control device determines to reduce the valve opening as the deviation between the target threshold value and the soil moisture content detected by the soil sensor during irrigation decreases.

9. The soil sensor includes a shallow-position soil sensor (311u) in which the depth of the detection part in the soil is installed shallowly, and a deep-position soil sensor (311d) in which the depth of the detection part is installed deeper than that of the shallow-position soil sensor. The irrigation system according to claim 1, wherein the control device selects, according to the growth degree of the plant, either the shallow-position soil sensor or the deep-position soil sensor as the soil sensor used to determine the valve opening.

10. The irrigation system according to claim 9, wherein the control device switches to reduce the valve opening at the timing when the detection value by the shallow-position soil sensor exceeds a predetermined value that is lower than the target threshold value.

11. A processing unit (334) that determines the valve opening of a water supply valve (15) that controls the water discharge amount to the soil according to the deviation between the target threshold value and the soil moisture content detected by the soil sensor (311); A signal output unit (332) that outputs a control signal for controlling the valve opening determined by the processing unit to the water supply valve; A control device comprising the above.

Images