Moisture status measuring device that measures moisture status in soil, moisture status measuring method, and non-transitory computer-readable medium storing a program

A moisture status measuring device includes a moisture amount sensor that acquires an output value according to an amount of moisture contained in soil, a drainage sensor that detects water discharge from the soil, and a moisture status deriver that derives moisture status information expressing a moisture status of the soil based on the output value acquired by the moisture amount sensor and detection of the water discharge by the drainage sensor. Every time when the drainage sensor detects the water discharge, the moisture status deriver acquires the output value at a time when the drainage sensor detects the water discharge. The moisture status deriver derives moisture status information expressing the moisture status of the soil at an arbitrary time based on the output value acquired at the time when the drainage sensor detects the water discharge and the output value at the arbitrary time.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Japanese Patent Application No. 2012-195722, filed on Sep. 6, 2012, the entire disclosure of which is incorporated by reference herein.

FIELD

This application relates to a moisture status measuring device that measures the status of moisture in soil, to a moisture status measuring method, and to a non-transitory computer-readable medium that stores a program.

BACKGROUND

Among methods of measuring the amount of moisture in soil, there exists an Amplitude Domain Reflectometry (ADR) method and a Time Domain Reflectometry (TDR) method, for example. These methods utilize the property that electric permittivity increase as the amount of moisture in soil increases. By electrically measuring the permittivity, the amount of moisture in soil is measured. Also, as a method of measuring the amount of moisture in soil, there exists a moisture content monitoring device that includes multiple electrodes able to be inserted into gardening soil. By measuring the electrical resistance value between these electrodes, the moisture content monitoring device measures the moisture content, and emits a warning sound in the case where the moisture content becomes less than or equal to a set boundary level (see Japanese Patent No. 2608679, for example).

SUMMARY

However, with a method that measures moisture content from electrical permittivity such as that described in Japanese Patent No. 2608679, the electrical permittivity differs if the soil itself differs, even if the soils were to hypothetically have the same moisture content by volume. For this reason, differing measurement results are obtained. Consequently, since the amount of moisture of some soils cannot be accurately measured, sufficiently managing the moisture status in that soil is difficult.

The present invention has been devised in light of such problems, and takes as an objective to provide a moisture status measuring device, moisture status measuring method and a non-transitory computer-readable medium that stores a program enabling measurement of the moisture status of moisture in soil housed in a container.

In order to achieve the above objective, a moisture status measuring device according to the present invention is provided with:

a moisture amount sensor that acquires an output value according to an amount of moisture contained in soil;

a drainage sensor that detects water discharge from the soil; and

a moisture status deriver that derives moisture status information expressing a moisture status of the soil based on the output value acquired by the moisture amount sensor and the detection of the water discharge by the drainage sensor;

wherein the moisture status deriver derives the moisture status information according to the following formula:

θ(t) is the moisture status information,

V(t) is a voltage value acquired by the moisture amount sensor as the output value at an arbitrary time t,

Vfis a voltage value acquired by the moisture amount sensor as the output value at a time when the drainage sensor detects the water discharge, and

Vois a voltage value acquired by the moisture amount sensor as the output value in a state of dry soil.

A moisture status measurement method according to the present invention includes:

acquiring an output value according to an amount of moisture contained in soil;

detecting water discharge from the soil; and

deriving moisture status information expressing a moisture status of the soil based on the acquired output value and the detection of the water discharge;

wherein the moisture status information is derived according to the following formula:

θ(t) is the moisture status information,

V(t) is a voltage value acquired as the output value at an arbitrary time t,

Vfis a voltage value acquired as the output value at a time when the water discharge is detected, and

Vois a voltage value acquired as the output value in a state of dry soil.

A non-transitory computer-readable medium according to the present invention stores a program, the program being executable by a computer of a moisture status measurement device including a moisture amount sensor and a drainage sensor, to control the moisture status measurement device to perform functions including:

acquiring an output value according to an amount of moisture contained in soil, by the moisture amount sensor;

detecting water discharge from the soil, by the drainage sensor; and

deriving moisture status information expressing a moisture status of the soil based on the acquired output value and the detection of the water discharge;

wherein the moisture status information is derived according to the following formula:

θ(t) is the moisture status information,

V(t) is a voltage value acquired by the moisture amount sensor as the output value at an arbitrary time t,

Vfis a voltage value acquired by the moisture amount sensor as the output value at a time when the drainage sensor detects the water discharge, and

Vois a voltage value acquired by the moisture amount sensor as the output value in a state of dry soil.

According to the present invention, providing a moisture status measuring device that can measure the status of moisture in soil housed in a container, a moisture status measuring method, and a non-transitory computer-readable medium that stores a program is possible.

DETAILED DESCRIPTION

FIG. 1is a diagrams illustrating exemplary usage of a moisture status measuring device1according to the present embodiment.

In the usage examples illustrated inFIG. 1, the moisture status measuring device1measures the moisture status of soil21housed in a pot2. The moisture status measuring device1then transmits information expressing the measured moisture status (moisture status information) to a communication terminal device3. Then communication terminal device3displays an image expressing the received moisture status information on a display31.

The moisture status measuring device1is equipped with a main body100, and a drainage sensor120communicably connected to the main body100by a wire200. The main body100acquires moisture status information on the basis of output values from a moisture sensor110(seeFIG. 2) that includes electrodes111inserted into the soil21, and the drainage sensor120, and transmits the acquired moisture status information to the communication terminal device3. Note that a detailed configuration and operation of the moisture status measuring device1will be described later.

The pot2is a container housing the soil21in which a plant22is growing. Specifically, the pot2is configured in a shape having sidewalls and a bottom, with an open top. Also, the bottom of the pot2includes multiple drainage holes23. Water poured in from above the soil21filters through the soil21, and is discharged out from the drainage holes23.

In addition, a saucer24is provided under the pot2. The saucer24is able to collect water discharged from the drainage holes23of the pot2within a range that does not exceed the height of its sidewalls.

The communication terminal device3is a terminal device able to communicate with the moisture status measuring device1, and is made up of a terminal device such as a mobile phone, for example. The communication terminal device3is equipped with a display31, and displays moisture status information received from the moisture status measuring device1. The communication terminal device3is also equipped with an input device (not illustrated) such as a touch panel, buttons, or keys, which receives input from the user, and transmits received information to the moisture status measuring device1.

Next, a hardware configuration of a moisture status measuring device1according to the present embodiment will be described.

FIG. 2is a block diagram that schematically illustrates an exemplary hardware configuration of a moisture status measuring device1according to the present embodiment. As illustrated inFIG. 2, the moisture status measuring device1is equipped with a moisture sensor110, a drainage sensor120, a controller130, read-only memory (ROM)140, random access memory (RAM)150, a communication device160, and an operating device170. In addition, the moisture sensor110, controller130, ROM140, RAM150, communication device160, and operating device170constitute the main body100.

The moisture sensor110is a sensor that outputs an output value according to the amount of moisture contained in the soil21. A typical moisture sensor using the ADR method, for example, is potentially used as the moisture sensor110. The moisture sensor110includes electrodes111(seeFIG. 1) inserted into the soil21. The moisture sensor110then detects a voltage value according to the moisture in the soil21as an output value, which is input into the controller130.

The relationship between the voltage value output by the moisture sensor110and the amount of moisture contained in soil will now be described.FIG. 3is a diagram illustrating the relationship between the voltage value output by the moisture sensor110, and the amount of moisture per unit volume contained in soil. Note thatFIG. 3illustrates the relationship between the voltage value and the amount of moisture for two soils A and B with different components constituting the soil. As illustrated inFIG. 3, for both soils A and B, the detected voltage value linearly increases as the amount of moisture increases. In this way, a moisture sensor110according to the present embodiment outputs voltage values in a linear relationship with the amount of moisture contained in soil.

The drainage sensor120is a sensor that detects water discharged from the drainage holes23. The drainage sensor120is made up of a typical leak sensor, for example. The drainage sensor120is provided in the saucer24, and detects water discharged from the drainage holes23by detecting the water collected in the saucer24. Specifically, the drainage sensor120includes electrodes (not illustrated), and outputs the voltage value between the electrodes to the controller130. The controller130detects the water in the saucer24on the basis of the output value from the drainage sensor120. Note that the drainage sensor120is not limited to a leak sensor. An arbitrary sensor is applicable insofar as the sensor is able to detect water in the saucer24.

The controller130is made up of a central processing unit (CPU), for example, and controls the moisture status measuring device1overall.

The ROM140is non-volatile memory that stores programs and data by which the controller130controls the moisture status measuring device1overall. For example, the ROM140stores a program by which the controller130executes a moisture status measuring process discussed later.

The RAM150is made up of non-volatile memory such as flash memory. The controller130loads a program being stored in the ROM140into the RAM150, which is used as a work area.

The communication device160is made up of a wireless communication device or the like, for example, it connects to a given network as necessary, and communicates with the communication terminal device3.

The operating device170is made up of input devices such as buttons for operating the moisture status measuring device1. The operating device170receives from the user an input operation indicating to start measurement of the moisture status, which is input into the controller130.

Next, a functional configuration of the controller130of the moisture status measuring device1will be described.FIG. 4is a block diagram illustrating a functional configuration of the controller130in a moisture status measuring device1according to the present embodiment. As illustrated inFIG. 4, the controller130functions as a moisture acquirer131, a drainage detector132, a moisture status acquirer133, and a report controller134.

The moisture acquirer131acquires, from the moisture sensor110, an output value according to the amount of moisture contained in the soil21. Specifically, the moisture acquirer131acquires a voltage value detected by the moisture sensor110at a given time interval.

The drainage detector132detects water discharged from the drainage holes23on the basis of an output value from the drainage sensor120. Specifically, the drainage detector132acquires a voltage value detected by the drainage sensor120at a given time interval. The drainage detector132then determines whether or not water has been detected on the basis of the acquired voltage value.

The moisture status acquirer133acquires moisture status information expressing the current moisture status of moisture in the soil21, on the basis of the output value from the moisture sensor110at the time when the drainage sensor120detected water, and the current output value from the moisture sensor110.

Herein, in the present embodiment, the moisture status acquirer133acquires, as the moisture status information, a moisture status coefficient θ indicated as a degree of moisture, taking 0 to be a state in which the soil21is dry, and 100 to be the state of the soil21at the time when water is discharged from the drainage holes23.

Next, an example of an acquisition method for the moisture status coefficient θ by the moisture status acquirer133will be specifically described. Provided that V(t) is the voltage value acquired by the moisture acquirer131at a time t, Vf is the voltage value acquired by the moisture acquirer131at the time when the drainage detector132detected water, and Vo is the voltage value output by the moisture sensor110in a state of dry soil, the moisture status coefficient θ(t) at time t is expressed by the following Eq. 1.

Herein, Vo is a voltage value measured by the moisture sensor110for the soil21or another soil, for example, in a state in which that soil is dry, and is stored in the ROM140in advance. Note that the relative permittivity of soil in a completely dry state is conceivably small, with little fluctuation due to factors such as the soil properties. Consequently, a voltage value measured by the moisture sensor110in standard soil in a dry state that is preset as Vo is still usable in the computation of the moisture status coefficient θ in the present embodiment, since the difference in the computed moisture status coefficient θ is not large compared to the case of setting a voltage value measured by the moisture sensor110in the soil21in a dry state as Vo.

The report controller134transmits moisture status information acquired by the moisture status acquirer133to the communication terminal device3(seeFIG. 1) via the communication device160. Transmitted moisture status information is displayed on the display31.

Next, operation of a moisture status measuring device1according to the present embodiment will be described with reference to the drawings.FIG. 5is a flowchart illustrating an exemplary flow of a moisture status measuring process executed by the controller130in a moisture status measuring device1according to the present embodiment. Note that this moisture status measuring process is assumed to be stored in advance as a program in the ROM140discussed earlier, with the actual process being conducted due to the controller130reading out and executing the program.

The controller130of the moisture status measuring device1starts the moisture status measuring process illustrated inFIG. 5when triggered by the user operating the operating device170, for example.

First, the moisture status acquirer133substitutes an initial value into Vf (step S11). Note that the initial value to substitute is assumed to be stored in advance in the ROM140, for example.

Next, the moisture acquirer131acquires a voltage value V(t) at a given time interval from the moisture sensor110(step S12). The moisture acquirer131then stores the acquired voltage value V(t) in the RAM150, for example.

Next, the drainage detector132determines whether or not water discharged from the drainage holes23has been detected, on the basis of a voltage value acquired from the drainage sensor120(step S13). In the case of determining that water has not been detected (step S13; No), the drainage detector132proceeds to step S15.

In the case of determining that water has been detected (step S13; Yes), the moisture status acquirer133acquires, as Vf, the V(t) acquired at the time when water was detected (step S14). Specifically, from the RAM150the moisture status acquirer133acquires, as Vf, the most recent voltage value V(t) acquired by the moisture acquirer131at the time when the drainage detector132determined that water was present.

Next, the moisture status acquirer133uses Eq. 1 to acquire the current moisture status coefficient θ(t) from the most recent voltage value V(t) acquired by the moisture acquirer131, Vf, and Vo at the current time (step S15).

Next, the report controller134transmits the moisture status coefficient θ(t) acquired in step S15to the communication terminal device3via the communication device160(step S16). The process then returns to step S12.

The controller130repeatedly executes the processing in the above steps S12to S16. In addition, the controller130ends the moisture status measuring process in the case of receiving input indicating to end the moisture status measuring process from the user via the operating device170, for example.

The moisture status information displayed on the communication terminal device3will now be described.FIG. 6Ais a diagram illustrating the relationship between the voltage value V output from the moisture sensor110and the moisture status coefficient θ, whileFIG. 6Bis a diagram illustrating an example of moisture status information displayed on the display31of the communication terminal device3.

As illustrated inFIG. 6A, the moisture status coefficient θ is a value that varies linearly with respect to the voltage value V. The moisture status coefficient θ is 0 when the voltage value V is Vo, and the moisture status coefficient θ is 100 when the voltage value V is the voltage value Vf. The moisture status coefficient θ is expressed as a bar graph, an example of which is illustrated inFIG. 6B. Namely, in the case where the moisture status coefficient θ(t) is the acquired coefficient θ for a voltage value V(t) at time t, moisture status coefficient θ is expressed as a bar (the shaded portion inFIG. 6B) of height corresponding to the magnitude of that moisture status coefficient θ(t). With such a display, the user is easily able to ascertain the current moisture status of the soil21. However, the display format of moisture status information is not limited thereto, and displaying the numerical value of the moisture status coefficient θ is also possible, for example.

According to a moisture status measuring device1configured as above, a moisture status coefficient θ is acquired as moisture status information, moisture status coefficient θ being a ratio of the current output value from a moisture sensor versus the output value from the moisture sensor110at the time when the drainage sensor120detected water from the drainage holes23. Consequently, measuring the moisture status of moisture in arbitrary soil is possible.

In other words, the basic watering method of “generously provide water if the soil is dry” is a watering method that typically applies to almost all foliage plants. Herein, “generously” refers to an extent to which water drips out from the bottom of the pot, because providing water to this extent enables fresh air to enter into the soil. In the present embodiment, moisture status information is acquired whereby the moisture status is taken to be a “full” state for the amount of water at the time when water drips out from the pot2in which the plant22to be watered is planted. Consequently, measuring the moisture status is possible regardless of the type of soil.

Meanwhile, soil properties typically change over time. In the present embodiment, Vf is updated with every watering (see step S14inFIG. 5), thereby enabling the acquisition of moisture status information that reflects the properties of the soil21at the time of measurement.

In the moisture status measuring device1according to the above embodiment, the report controller134reports moisture status information to the user by transmitting moisture status information acquired by the moisture status acquirer133to the communication terminal device3, which is then displayed on the display31. However, the device that reports moisture status information is not limited to the display31, and an arbitrary reporting device is applicable.

For example, equipping the moisture status measuring device1with a display such as a liquid crystal display as a device that reports moisture status information is also possible. In this case, the report controller134is able to report moisture status information by displaying moisture status information on the display provided in the moisture status measuring device1.

As another example, equipping the moisture status measuring device1with an audio output device such as a speaker or buzzer as a device that reports moisture status information is also possible. In this case, the report controller134is able to report moisture status information by controlling the audio output device to output moisture status information as audio.

As another example, equipping the moisture status measuring device1with a light emitter such as a light-emitting diode (LED) as a device that reports moisture status information is also possible. In this case, the report controller134is able to report moisture status information by turning the light emitter on/off and controlling the emitted color, emitted light intensity, and the like according to the moisture status information.

Also, not equipping the moisture status measuring device1itself with a reporting device such as the above audio output device and light emitter is also possible. For example, the report controller134transmitting moisture status information to a communication client device3equipped with an audio output device or light emitter is also possible. In this case, reporting moisture status information is possible with the audio output device or light emitter of the communication terminal device3.

Additionally, in the above embodiment and Modification 1, the report controller134reports moisture status information acquired by the moisture status acquirer133. However, the content and timing of the reporting by the report controller134is not limited thereto. For example, when the drainage sensor120detects drainage, the report controller134controls a reporting device provided in the moisture status measuring device1or the communication terminal device3to report that the moisture status of the soil21is full. In this way, when the drainage sensor120detects the discharge of water, it is possible to report to the user who waters the plant22that the moisture status of the soil21is full, thereby preventing overwatering.

Also, it is possible for the report controller134to report that watering the soil21is not allowed in the case where the moisture status expressed by moisture status information acquired by the moisture status acquirer133is a state of greater moisture than a moisture state of moisture in soil at a timing when watering the soil21is appropriate (hereinafter designated the “appropriate moisture status”). It is also possible for the report controller134to report that the soil21should be watered in the case where the moisture status expressed by moisture status information acquired by the moisture status acquirer133is a state of less moisture than the appropriate moisture status.

Specifically, the moisture status measuring device1stores a threshold value θth expressing the appropriate moisture status in advance in the ROM140, for example. The report controller134then reports that watering the soil21is not allowed in the case where the moisture status coefficient θ acquired by the moisture status acquirer133is equal to or greater than the threshold value θth. Meanwhile, the report controller134reports that the soil21should be watered in the case where the moisture status coefficient θ acquired by the moisture status acquirer133is less than the threshold value θth.

FIGS. 7A and 7Billustrate moisture status information displayed on the display31as specific examples of a reporting format. The moisture status information illustrated inFIGS. 7A and 7Bis expressed as a bar graph C having a height corresponding to the magnitude of the moisture status coefficient θ. In addition, the area D where the bar graph C is displayed is split into a partial area D1corresponding to θth≤θ≤100 and a partial area D2corresponding to 0≤θ≤θth, taking the position of a height corresponding to the magnitude of the threshold value θth as a boundary. Consequently, when the tip of the bar graph C is positioned inside the partial area D1as illustrated inFIG. 7A, for example, the display31indicates that watering the soil21is not allowed. Meanwhile, when the tip of the bar graph C is positioned inside the partial area D2as illustrated inFIG. 7B, for example, the display31indicates that the soil21should be watered. With such a display, the user is easily able to determine the timing for watering the soil21.

As discussed above, the reason for providing water “if the soil is dry” is because even if water is generously provided, if the inside of the pot is in a continually wet state, the roots will be unable to breathe and thus rot, and the plant will wither. However, determining whether or not soil is in a dry state is difficult for beginners unaccustomed to growing plants. With respect to such a problem, in the moisture status measuring device1according to the present modification, a threshold value θth indicating an appropriate moisture state is preset, and a report indicating that watering is not allowed or that watering should be performed is issued on the basis of the threshold value θth and the current moisture status coefficient θ. For this reason, the user is easily able to determine whether or not the soil21is dry, or in other words, whether or not the timing is appropriate for watering.

In the above Modification 3, it is also possible for the moisture status measuring device1to store, in the ROM140, type-specific threshold values expressing the appropriate moisture states for growing particular types of plants, for example.

FIG. 8illustrates an example of a type-specific threshold value table stored in the ROM140. The plant type-specific threshold value table illustrated inFIG. 8stores, for individual types of plants, a type-specific threshold value expressing the appropriate moisture status of soil in which that type of plant will grow. For example, in the case where the type of plant is “Monstera”, a type-specific threshold value “θth-m” expressing the appropriate moisture status of soil in which “Monstera” will grow is stored in association with “Monstera”.

In this case, the user selects, from the type-specific threshold value table, the type of plant corresponding to the plant22growing in the soil21. The report controller134then specifies the type-specific threshold value corresponding to the selected type of plant from the type-specific threshold value table. The report controller134then treats the specified type-specific threshold value as the threshold value θth, and reports that watering is not allowed or that watering should be performed, similarly to Modification 3. Thus, it is possible to report that watering is not allowed or that watering should be performed at timings appropriate to the plant22actually growing in the soil21.

The foregoing thus describes an embodiment of the present invention and modifications thereof. However, the present invention is not limited to the above embodiment and modifications thereof.

For example, a drainage sensor120is provided in the saucer24, and detects water discharged from the drainage holes23by detecting the water collected in the saucer24. However, the position where the drainage sensor120is provided is not limited to the above. For example, in the case where a saucer24is not provided under the pot2, the drainage sensor120may be provided on the edge of a drainage hole23. The position where the drainage sensor120is provided is arbitrary insofar as the detection of water discharged from the drainage holes23is possible.

Also, although the above embodiment and modifications describe an example of acquiring a moisture status coefficient θ as moisture status information expressing the moisture status of the soil21, the format of expressing the moisture status is not limited thereto. The current moisture status of the soil21is expressible in an arbitrary format, insofar as the format is expressed as a comparison between an output value from a moisture sensor at the time when the drainage sensor120detected water, and the current output value from the moisture sensor.

Also, although Vf is taken to be a voltage value acquired by the moisture acquirer131at a time when the drainage detector132detected water, it is also possible to take Vf to be a voltage value acquired by the moisture acquirer131several seconds after the drainage detector132detected water.

In addition, the moisture status measuring device1according to the present invention is realizable using an ordinary computer system rather than a specialized device. For example, it is possible to store and distribute, on a computer-readable recording medium (such as a CD-ROM or MO), a program for executing the foregoing operations on a computer connected to a network, whereby the moisture status measuring device1that executes the processes discussed earlier is constituted by installing the program onto a computer system.

Furthermore, the method of providing a program to a computer is arbitrary. For example, it is possible for a program to be uploaded to a bulletin board system (BBS) on a communication line, and delivered to a computer via the communication line. It is also possible for a program to be transmitted by a modulated wave obtained by modulating a carrier wave with a signal expressing a program, whereby a device receiving the modulated wave demodulates the modulated wave to restore the program. The computer then activates the program, and under control by an OS, executes the program similarly to other applications. Thus, the computer functions as the moisture status measuring device1that executes the processes discussed earlier.