TW202000010A - Cultivation system and lighting control method for cultivation system - Google Patents

Abstract

The present invention comprises: a sap flow sensor 7 which measures the sap flowrate in a plant 2 cultivated within a plastic greenhouse 3; a shade curtain 5 which blocks the path of light entering the plastic greenhouse 3 from the sun 4; and a control device that controls the degree of opening of the shade curtain 5 on the basis of the sap flowrate.

Description

Cultivation system and illuminance control method of cultivation system

The invention relates to a cultivation system and an illumination control method of the cultivation system.

Conventionally, as a cultivation system, a cultivation system that controls the illuminance in a greenhouse by opening and closing a curtain provided in a greenhouse (for example, refer to Patent Document 1).

This cultivation system is equipped with an insolation meter that measures the insolation intensity of the greenhouse, and the shade device is controlled by a computer so that the maximum value of the insolation intensity of the cultivation unit in the past 15 minutes becomes less than the preset maximum insolation intensity. The shading device is a combination of two layers of shading with different shading rates, and controls any of the four shading states that each shading curtain is opened or closed.

Here, in the conventional cultivation system as described above, only the control of setting the shading curtain to any one of the four shading states based on the sunlight intensity can be realized. Therefore, there may be a problem that depending on the state of the plant being cultivated, it may not be possible to control the optimal illuminance. [Prior Art Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 8-103173

[Problems to be solved by the invention] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a technique that can be controlled to a more appropriate illuminance in accordance with the state of the plant being planted in a plant cultivation system. [Means to solve the problem]

The present invention for solving the above-mentioned problem is a cultivation system, which is characterized by comprising: a water flow measuring means for measuring the flow of water in the plant; and an illuminance control means based on the measured by the water flow measuring means, The flow rate of water in the plant controls the illuminance of light irradiated from the light source to the plant.

According to the present invention, the illuminance of light irradiated from the light source to the plant is controlled based on the water flow in the plant, which has a strong correlation with the photosynthesis rate of the cultivated plant, so the photosynthesis can be controlled according to the state of the plant More active and more appropriate illuminance.

Furthermore, in the present invention, the illuminance control means for controlling the illuminance by controlling the input operation amount may be a method of measuring the water flow rate in the plant measured by the water flow measuring means The ratio of the change to the change in the operation amount is set as a first ratio, and the illuminance is controlled based on the first ratio.

According to this, since the illuminance is controlled based on the first ratio including the operation amount of the illuminance control member, it is possible to more accurately grasp the state of the photosynthesis speed of the cultivated plant based on the relationship between the illuminance and the water flow in the plant. Therefore, it is possible to control the illuminance to make the photosynthesis more active and appropriate according to the state of the plant.

Furthermore, in the present invention, the illuminance control means may determine whether to increase, maintain, or decrease the illuminance based on whether the first ratio is positive, negative, or 0.

Here, the case where the first ratio is 0 is not limited to the case where it is strictly numerically 0, but includes a certain degree of width across positive or negative. In the case where the first ratio is positive or negative, it does not mean that only regions other than 0 are strictly excluded in value. In addition, regarding the direction of change, the sign of the first ratio is different according to the case where the increase direction is used as a reference and the case where the decrease direction is used as a reference, but which one is used as a reference may be appropriately set.

Furthermore, the present invention may further include: an illuminance measurement unit that measures the illuminance, and the illuminance control unit compares the change in the water flow in the plant measured by the water flow measurement unit with respect to the illuminance The ratio of the change in the illuminance measured by the measuring means is set as the second ratio, and the illuminance is controlled based on the second ratio.

According to this, since the illuminance is controlled based on the second ratio including the illuminance measured by the illuminance measuring means, it is possible to more accurately grasp the speed of photosynthesis of the cultivated plant based on the relationship between the illuminance and the water flow in the plant Kind of status. Therefore, it is possible to control the illuminance to make the photosynthesis more active and appropriate according to the state of the plant.

Furthermore, in the present invention, the illuminance control means may determine whether to increase, maintain, or decrease the illuminance based on whether the second ratio is positive, negative, or 0.

Here, the case where the second ratio is 0 is not limited to the case where it is strictly numerically 0, but includes a certain degree of width across positive or negative. In the case where the second ratio is positive or negative, it does not mean that only regions other than 0 are strictly removed numerically. In addition, the sign of the second ratio is different for the direction of change according to the case where the increase direction is used as the reference and the case where the decrease direction is used as the reference. However, whichever is used as the reference may be appropriately set.

Furthermore, the present invention may further include: a saturation difference acquiring means to acquire the saturation difference of the air around the plant, and the illuminance control means to compare the moisture flow in the plant measured by the moisture flow measuring means The ratio of the saturation difference acquired by the saturation difference acquisition means is set as the third ratio, and the ratio of the change of the third ratio to the change of the illuminance measured by the illuminance measurement means is set This is the fourth ratio, and the illuminance is controlled based on the fourth ratio.

According to this, the illuminance is controlled based on the ratio that more accurately reflects the photosynthesis speed of the cultivated plant relative to the change in illuminance, so it can be based on the photosynthesis speed of the cultivated plant. More accurate grasp of the state to control the illuminance. Therefore, it is possible to control the illuminance to make the photosynthesis more active and appropriate according to the state of the plant.

Furthermore, in the present invention, the illuminance control means may determine whether to increase, maintain, or decrease the illuminance based on whether the fourth ratio is positive, negative, or 0.

Here, the case where the fourth ratio is 0 is not limited to the case where it is strictly numerically 0, but includes a certain degree of span across positive or negative. In the case where the fourth ratio is positive or negative, it does not mean that only regions other than 0 are strictly removed numerically. In addition, regarding the direction of change, the sign of the fourth ratio is different according to the case where the increase direction is used as the reference and the case where the decrease direction is used as the reference, but which one should be appropriately set as the reference.

Furthermore, in the present invention, the water flow rate measuring means may be a sap flow rate measuring means that measures the flow rate of the sap flowing in the duct of the plant.

Moreover, in the present invention, the illuminance control part may include: a light blocking member that blocks an optical path of light incident from the light source to the plant; and an opening degree control part that controls the light blocking member to the optical path The opening ratio controls the illuminance by controlling the opening ratio.

According to this, when using light from a light source outside the cultivation system such as the sun, by controlling the opening ratio of the shading member, it is possible to control the photosynthesis more actively and more actively according to the state of the plant Appropriate illuminance. The opening ratio of the light blocking member is not limited to the ratio of the opened portion in the optical path of the incident light, and may be the ratio of the portion that is not opened and blocked.

Furthermore, in the present invention, the illuminance control means may control the illuminance by controlling the input to the light source.

According to this, when a light source capable of controlling the output according to the input is provided in the cultivation system, by controlling the input of the light source, it is possible to control the illuminance for more active photosynthesis and more appropriate according to the state of the plant.

Furthermore, the present invention is a method for controlling the illuminance of a cultivation system, which is a method for controlling the illuminance of light irradiated to the plants from a light source in a cultivation system for cultivating plants. The method for controlling the illuminance of the cultivation system includes the following steps: Acquiring the amount of change in water flow in the plant when the illuminance is changed; and controlling the illuminance based on the amount of change.

According to this, the illuminance is controlled based on the amount of change in the water flow in the plant when the illuminance is changed, so the relationship between the illuminance and the water flow in the plant that has a strong relationship with the rate of photosynthesis can be more accurately grasped What is the speed of photosynthesis of the cultivated plants? Therefore, it is possible to control the illuminance to make the photosynthesis more active and appropriate according to the state of the plant.

Furthermore, the present invention is a method for controlling the illuminance of a cultivation system, which is a method for controlling the illuminance of light irradiated to the plants from a light source in a cultivation system for cultivating plants. The method for controlling the illuminance of the cultivation system includes the following steps: Obtain the amount of change in the operation amount; obtain the amount of change in the water flow in the plant when the operation amount changes; obtain a first ratio, the first ratio is the amount of moisture in the plant The ratio of the change amount to the change amount of the operation amount; and controlling the illuminance based on the first ratio.

According to this, the illuminance is controlled based on the amount of change in the water flow in the plant when the operation amount of the illuminance control member is changed. Therefore, the relationship between the illuminance and the water flow in the plant that has a strong relationship with the photosynthesis rate can be used. To more accurately grasp the state of the photosynthesis rate of the cultivated plants. Therefore, it is possible to control the illuminance to make the photosynthesis more active and appropriate according to the state of the plant.

The step of controlling the illuminance based on the first ratio may also include the steps of: determining whether the first ratio is positive, negative, or 0; and based on the first ratio being positive, negative, or Which of 0 determines whether to increase, maintain, or decrease the illuminance.

Here, the case where the first ratio is 0 is not limited to the case where it is strictly numerically 0, but includes a certain degree of width across positive or negative. In the case where the first ratio is positive or negative, it does not mean that only regions other than 0 are strictly excluded in value. In addition, the sign of the first ratio is different for the direction of change according to the case where the increase direction is used as the reference and the case where the decrease direction is used as the reference. However, whichever is used as the reference may be appropriately set.

Furthermore, the present invention is a method for controlling the illuminance of a cultivation system, which is a method for controlling the illuminance of light irradiated to the plants from a light source in a cultivation system for cultivating plants. The method for controlling the illuminance of the cultivation system includes the following steps: Measuring the illuminance; obtaining the flow rate of water in the plant; obtaining a second ratio, the second ratio being a ratio of a change in the flow rate of water in the plant to the change in illuminance; and based on the second Ratio to control the illuminance.

According to the present invention, the illuminance is controlled based on the ratio of the change in the flow of water in the plant to the change in illuminance, that is, the second ratio. Therefore, the relationship between the illuminance and the flow of water in the plant that has a strong relationship with the rate of photosynthesis can be changed. Accurately grasp the state of the photosynthesis speed of the cultivated plants. Therefore, it is possible to control the illuminance to make the photosynthesis more active and appropriate according to the state of the plant.

Furthermore, in the present invention, the step of controlling the illuminance based on the second ratio may include the steps of: determining whether the second ratio is positive, negative, or 0; and based on the second Whether the ratio is positive, negative, or 0, determines whether the illuminance is increased, maintained, or decreased.

Here, the case where the second ratio is 0 is not limited to the case where it is strictly numerically 0, but includes a certain degree of width across positive or negative. In the case where the second ratio is positive or negative, it does not mean that only regions other than 0 are strictly removed numerically. In addition, the sign of the second ratio is different for the direction of change according to the case where the increase direction is used as the reference and the case where the decrease direction is used as the reference. However, whichever is used as the reference may be appropriately set.

Furthermore, the present invention is a method for controlling the illuminance of a cultivation system, which is a method for controlling the illuminance of light irradiated to the plant from a light source in a cultivation system for cultivating plants, wherein the flow rate of water in the plant relative to the The ratio of the saturation difference of the air around the plant is set as the third ratio. The illumination control method of the cultivation system includes the following steps: acquiring a fourth ratio, the fourth ratio is the change of the third ratio with respect to the A ratio of the change in illuminance; and controlling the illuminance based on the fourth ratio.

According to this, the illuminance is controlled based on the ratio that more accurately reflects the photosynthesis speed of the cultivated plant relative to the change in illuminance, so it can be based on the photosynthesis speed of the cultivated plant. More accurate grasp of the state to control the illuminance. Therefore, it is possible to control the illuminance to make the photosynthesis more active and appropriate according to the state of the plant.

Furthermore, in the present invention, the step of controlling the illuminance based on the fourth ratio may include the steps of: determining whether the fourth ratio is positive, negative, or 0; and based on the fourth Whether the ratio is positive, negative, or 0, determines whether the illuminance is increased, maintained, or decreased.

Here, the case where the fourth ratio is 0 is not limited to the case where it is strictly numerically 0, but includes a certain degree of span across positive or negative. In the case where the fourth ratio is positive or negative, it does not mean that only regions other than 0 are strictly removed numerically. In addition, regarding the direction of change, the sign of the fourth ratio is different according to the case where the increase direction is used as the reference and the case where the decrease direction is used as the reference, but which one should be appropriately set as the reference. [Effect of invention]

According to the present invention, it is possible to provide a technique that can be controlled to a more appropriate illuminance according to the state of the cultivated plant in the cultivation system of cultivated plants.

〔Application example〕 Hereinafter, an application example of the present invention will be described with reference to the drawings. The present invention is applied to, for example, the cultivation system 1 shown in FIG. 1. The cultivation system 1 controls the illuminance of light irradiated to the cultivated plant 2 from the sun 4 as a light source by a shade 5 that is a blocking member that blocks the incident light path, and is based on the moisture flow rate measured by the moisture flow rate in the plant 2 The flow rate of the sap measured by the sap flu sensor 7 as a measuring means controls the opening ratio of the shade 5 as an example of the opening ratio. The flow rate measured by the moisture flow rate measuring means includes not only the flow rate itself but also the flow rate per predetermined time, that is, the flow rate. In the following embodiments, a sap flu sensor that measures the flow rate of the sap will be described as the moisture flow rate measuring means.

The illuminance and photosynthesis speed in plants are shown in Figure 2, following the following changes: as the illuminance increases, the photosynthesis speed increases. At a certain illuminance, the change in photosynthesis speed becomes fixed, and when this illuminance increases, The speed of photosynthesis is reduced. The photosynthesis rate is an index that indicates the degree of photosynthesis activity, and also changes according to the plant's own conditions such as the growth stage of the plant or environmental conditions such as carbon dioxide concentration. Therefore, in order to cultivate in a more active state of photosynthesis, it is necessary to control the illuminance of the light irradiated to the plant 2 to achieve the illuminance (optimum illuminance) in which the photosynthesis speed becomes maximum in FIG. 2.

At this time, there is a strong correlation between the flow rate of the water flowing in the body of the plant 2, that is, the flow rate of the sap, and the photosynthesis rate. This is because when the plant 2 wants to extract carbon dioxide for photosynthesis from the surrounding air to open the stomata, the water in the plant 2 will evaporate through the stomata, and the amount of transpiration is related to the flow of sap.

In the cultivation system shown in FIG. 1, the opening degree of the shade 5 is controlled based on the flow rate of the sap flow measured by the sap flu sensor 7. Therefore, regardless of changes in the conditions of the plant 2 itself or environmental conditions, it can be immediately ( real time) and control the illuminance appropriately to achieve the illuminance for more active photosynthesis.

Moreover, it can also be applied to the system 21 as in the second embodiment shown in FIG. 5, and the system 21 further includes an illuminance sensor 10 as an illuminance measurement component, which is controlled based on the ratio of the change in the flow rate of the sap to the change in illuminance The opening degree of the shade 5. Moreover, it can also be applied to the cultivation system 31 as in Embodiment 3 shown in FIG. 7, and the cultivation system 31 further includes a humidity sensor 11 as a humidity measurement component and a temperature sensor 12 as a temperature measurement component, based on The opening degree of the shade 5 is controlled as the ratio of the change in the stomatal conductance to the change in illuminance defined as the flow rate of the sap relative to the difference in saturation. The present invention can also be applied to a system that controls the output of the artificial light source 13 as in the fourth embodiment shown in FIG. 9.

[Example 1] Hereinafter, the cultivation system according to Embodiment 1 of the present invention will be described in more detail using drawings.

<System structure> Fig. 1 shows a schematic configuration of the cultivation system of the first embodiment. The cultivation system 1 includes a house 3 that houses plants 2. Furthermore, the cultivation system 1 includes a light-shielding curtain 5 that opens and closes to block a part or all of the light irradiated from the sun 4 as a light source to the plant 2 to control the incident amount. Moreover, the cultivation system 1 includes a diffusion film 6 that diffuses light irradiated to the plant 2 through the shade 5. Furthermore, the cultivation system 1 includes: a sap flu sensor 7 to measure the sap flow of the plant 2; and a control device 8 to control the opening degree of the shade 5 based on the sap flux measured by the sap flu sensor 7. In FIG. 1, only one plant 2 is shown, but for a schematic illustration, the number of plants 2 cultivated in the house 3 is not limited, and in fact, many plants 2 are cultivated.

The shade 5 is a sheet-like member that extends and closes, shrinks or winds up, and opens. The opening degree of the shade 5 is not only in two states of fully open and fully closed, but can be changed steplessly from fully open to fully closed. As will be described later, the opening degree is changed by causing the shade 5 to perform an opening operation or a closing operation for a predetermined time. In addition, the method of changing the opening degree of the shade 5 is not limited to this, and may be set so that it can be changed in stages from fully opened to fully closed. The shade 5 is wirelessly connected to the control device 8 and has a transmission and reception function as follows: that is, it receives a control signal from the control device 8 that sets the opening degree of the shade 5 and displays the current opening degree as needed The information is sent to the control device 8. The light-shielding member is not limited to this kind of light-shielding curtain 5, and may be a blind that includes a plurality of louvers to control the incident amount by the angle of the louver, or it may be by changing the transparency of the liquid crystal To control the incident amount of the liquid crystal panel (panel). Here, the shading curtain 5 corresponds to the shading member, the control device 8 corresponds to the shading control member, and the shading curtain 5 and the control device 8 correspond to the illuminance control member.

The diffusion film 6 has a function of diffusing incident light to make the illuminance distribution of the light irradiated to the plant 2 cultivated in the house 3 uniform. For the diffusion film 6, the structural members such as the roof, ceiling, and side walls may be the diffusion film 6, or the diffusion film 6 may be attached to the structural member. Moreover, as long as the member has a function of diffusing incident light, it is not limited to a film-shaped member.

In FIG. 1, the sap flu sensor 7 is installed on the stem 2a of the plant 2, but the installation location of the sap flu sensor 7 is not limited to the stem 2a, and a leaf 2b or other parts may be selected. Moreover, the plant 2 to which the sap flu sensor 7 is installed can be appropriately selected among a plurality of plants 2. The sap flu detector 7 can be installed on all the plants 2 cultivated, or the sap flu detector 7 can be installed on a plurality of selected plants 2. Here, the sap flu sensor 7 corresponds to a water flow measurement means and a sap flow velocity measurement means.

As a method for measuring the flow rate of the sap, various methods such as a stem heat balance method, a heat pulse method, and a heat dissipation method (Granier method) are proposed. The measurement method of the sap flu sensor 7 can be based on the installation target Conditions such as the type of plant 2 and its part are appropriately selected. The sap flu detector 7 is wirelessly connected to the control device 8 and has a transmission and reception function as follows: that is, the measurement result is sent to the control device 8 and the control signal is received from the control device 8 as necessary.

As the control device 8, for example, a programmable logic controller (PLC) pre-loaded with a program that controls the opening degree of the shade 5 based on the measurement result of the sap fluometer 7 can be used . The control device 8 is not limited to a PLC, but may also use a personal computer (Personal Computer, PC) that reads the opening of the shade 5 in a memory device such as a read-only memory (Read Only Memory, ROM). The control program is executed by the Central Processing Unit (CPU). The control device 8 includes a communication unit that communicates with the sap flu sensor 7 and the shade 5. The control device 8 and the sap flu sensor 7, the shade 5 and the like are not limited to the case of wireless connection, but may also be connected by wire.

In the house 3, various devices for adjusting the cultivation environment, such as a irrigation device that supplies water to the plant 2 through a culture medium, a temperature adjustment device that performs cooling and/or heating in the house 3, and a ventilation device, may be included. The description of these devices is omitted.

It is generally known that the illuminance of light irradiated to plants and the photosynthesis speed of plants have a relationship shown in the light-photosynthesis curve in FIG. 2. Of course, various conditions such as carbon dioxide concentration, temperature, and humidity will also affect the photosynthesis rate of plants, but these conditions are assumed to be fixed here. As shown in Figure 2, as the illuminance increases, the photosynthesis speed also increases, but when the illuminance further increases, the photosynthesis speed decreases. In this way, if other conditions are set to be fixed, the photosynthesis speed reaches the maximum at a certain illuminance. Therefore, as long as the incident light beam from the light source is controlled to reach the maximum illuminance at a speed close to the photosynthesis rate, it is expected that photosynthesis can be carried out most actively to promote plant growth and the harvest amount will also increase.

Furthermore, under photosynthesis, in plants, the carbon and carbon contained in carbon dioxide are fixed to organic matter from the pores on the surface by water and light energy absorbed from the medium or soil through the roots and transported by the duct. Since the stomata are opened to absorb carbon dioxide for photosynthesis, the water in the plant will also evaporate through the opened stomata. Here, the sap flow conveyed through the duct includes water decomposed by photosynthesis and water transpired through stomata, and is measured by the sap fluometer 7. When photosynthesis is actively carried out and the absorption of carbon dioxide per unit time increases, the water transpired through the open pores also increases, and the sap flow rate increases. Therefore, it is known that there is a strong correlation between the photosynthesis rate and the sap flow rate .

Therefore, the relationship between illuminance and sap flow rate is also shown in FIG. 3, and similarly to the relationship between illuminance and photosynthesis rate, it becomes a curve that follows the following, that is, the sap flow rate increases in response to an increase in illuminance, when a certain illuminance is exceeded When the illuminance increases further, the sap flow rate decreases. According to this relationship between illuminance and sap flow rate, the sap flow sensor 7 is used to measure the sap flow rate, and the opening of the shade is controlled to approach the maximum illuminance of the sap flow rate, by which the photosynthesis can be more active The best illumination. This optimal illuminance itself varies depending on the plant 2 type, growth stage and other conditions related to the plant 2 itself, or changes in other environmental conditions such as carbon dioxide concentration, but by monitoring the measured value of the sap flu sensor 7, Always achieve the best illumination instantly.

<Control method> FIG. 4 shows a flowchart illustrating the method of controlling the shade of the first embodiment. In step 1 (denoted as S1 in the figure, the same applies hereinafter), a control signal is sent from the control device 8 to the shade 5 to move the shade 5 to a predetermined initial position. In step 2, the sap flow rate is measured by the sap flu sensor 7. In the control device 8, in step 3, i=0 is set, and in step 4, the opening degree of the shade 5 is substituted into the variable b(i). Here, the opening degree of the shade 5 corresponds to the amount of operation input to the shade 5 and the control device 8 corresponding to the illuminance control member. Regarding the opening degree of the shade 5, for example, the opening degree of the state where all the shades 5 are closed is set to 0 (%), and the opening degree of the state where all the shades are open is set to 100 (%). In step 5, the sap flow rate measured in step 2 is substituted into the variable a(i) and memorized. In step 6, a control signal is sent from the control device 8 to the shade 5 to cause the opening operation of the shade 5 to be performed for T seconds. The opening operation of the shade 5 is to detect whether the direction of change in the flow rate of the sap flow is increased or decreased or fixed by the illuminance change caused by the change in the opening degree of the shade 5 at the initial stage of control. Therefore, the time T of the opening operation may be appropriately selected to detect such a significant change in the flow rate of the sap. In step 7, the sap flow rate is measured by the sap flu sensor 7 in a state after the opening operation of the shade 5. In the control device 8, in step 8, i=i+1 is set, and in step 9, the opening degree of the shade 5 after the opening operation of T seconds in step 6 is substituted into the variable b(i) . In step 10, the sap flow rate measured in step 7 is substituted into the variable a(i) and memorized. In step 11, in the control device 8, calculate k1={a(i)-a(i-1)}/{b(i)-b(i-1)} as the photosynthesis of plant 2 The photosynthesis coefficient k1 for speed evaluation. Here, k1 corresponds to the first ratio. In step 12, the control device 8 determines the magnitude relationship between k1 and 0 calculated in step 11. In step 12, illuminance control is determined based on whether k1 is positive, negative, or 0. Here, if it is determined in step 12 that k1>0, the process proceeds to step 13 and a control signal is sent from the control device 8 to the shade 5 to perform the opening operation of the shade 5 for t1 seconds to increase the illuminance. If the determination in step 12 is that k1=0, the process proceeds to step 14, and a control signal is sent from the control device 8 to the shade 5 so that the shade 5 is not operated to maintain the illuminance. If the determination in step 12 is that k1<0, the process proceeds to step 15 and a control signal is sent from the control device 8 to the shade 5 to perform the closing operation of the shade 5 for t2 seconds to reduce the illuminance. After step 13, step 14 or step 15, return to step 7 and repeat the processing from step 7 to step 13, step 14 or step 15. Here, the case where k1=0 (the same applies to k2, k3, and k4 described later) is not limited to the case where the value is strictly 0, but includes a certain degree of span across positive or negative. Regarding the case where the third ratio is positive or negative, it does not mean that only regions other than 0 are strictly excluded in numerical values. For the opening degree control of the shade 5, an end condition may be appropriately set so that the control device 8 ends when k1 satisfies a predetermined condition, or when a predetermined timing information such as a sunset time is acquired. In addition, for the opening control of the shade 5, a start condition may be appropriately set so as to start when the predetermined timing information such as the sunrise time is acquired. In step 14, the shading curtain 5 may not be operated by not sending a control signal from the control device 8 to the shading curtain 5. Furthermore, the time t1 for opening the shade 5 when k1>0 in step 13 and the time t2 for closing the shade 5 when k1<0 in step 15 may be set to t1=t2, or It can be set to t1≠t2. Furthermore, the values of t1 and t2 may be changed according to the magnitude of the absolute value of k1 during the control process. For example, as the absolute value of k1 becomes smaller, the values of t1 and t2 may be reduced. In this way, the sap flow sensor 7 is used to measure the sap flow velocity that has a strong correlation with the photosynthesis rate, and the opening degree of the shade 5 is controlled to maintain the sap flow rate in the house 3 to a fixed illuminance. The optimal illuminance that photosynthesis becomes active can be realized instantly.

[Example 2] Hereinafter, the cultivation system 21 of the second embodiment of the present invention will be described based on FIG. 5.

<System structure> The cultivation system 21 of the second embodiment includes, in addition to the cultivation system 1 of the first embodiment, an illuminance sensor 10 that measures the illuminance in the house 3. The configuration common to the cultivation system 1 of Example 1 is denoted by the same reference numerals, and the description is omitted. The illuminance sensor 10 is arranged in the house 3 at an appropriate position where the illuminance of the light irradiated to the plant 2 can be measured. FIG. 5 is an example, and the installation position and the number of the illuminance sensors 10 can be appropriately set. One may be provided at a position representing the illuminance distribution in the house 3, or the house 3 may be divided into a plurality of areas, and an illuminance sensor 10 may be provided in each area. Furthermore, an illuminance sensor 10 corresponding to each sap flu sensor 7 may be provided. Here, the illuminance sensor 10 corresponds to an illuminance measurement part.

As described in Example 1, there is a relationship as shown in FIG. 3 between the illuminance and the sap flow velocity. Here, let the sap flow rate be a and the illuminance be b. The photosynthesis coefficient k2 for evaluating photosynthesis speed is defined as k2=Δa/Δb. In this way, k2>0 in the area where the sap flow rate increases with increasing illuminance, k2=0 in the area where the sap flow rate reaches the maximum with respect to the increase in illuminance, and in the area where the sap flow rate decreases with the increase in illuminance Inside is k2<0. Therefore, in the control device 8, the photosynthesis coefficient k2 is calculated based on the measurement result of the sap flu sensor 7 and the measurement result of the illuminance sensor 10, the magnitude relationship between k2 and 0 is determined, and the opening of the shade 5 is controlled accordingly With this, the illuminance in the house 3 can be instantly set as the optimal illuminance in which the photosynthesis of the plant 2 becomes active.

<Control method> 6 is a flowchart showing a method of controlling the shade 5 of the second embodiment. In step 21, the sap flow rate of the plant 2 is measured by the sap flu detector 7. Then, in step 22, the illuminance of the house 3 is measured by the illuminance sensor 10. In step 23, the control device 8 calculates the photosynthesis coefficient k2=Δa/Δb based on the measured value a of the sap flow rate in step 21 and the measured value b of the illuminance in step 22. Here, k2 corresponds to the second ratio. The measurement of the flow rate of the sap in step 21 and the measurement of the illuminance in step 22 are performed in parallel, but the timing of sampling may not necessarily be the same. It is only necessary to calculate the corresponding changes in sap flow rate and illuminance based on the information obtained by processing the measured values sampled multiple times in the overlapping time range, and calculate the photosynthesis coefficient k2 according to these parameters . In addition, when a plurality of sap flu sensors 7 or illuminance sensors 10 are provided, processing such as averaging of each measurement result is also performed. In step 24, the control device 8 determines the magnitude relationship between the calculated photosynthesis coefficient k2 and 0. In step 24, illuminance control is determined based on whether k2 is positive, negative, or 0. Here, when it is determined in step 24 that k2>0, in step 25, a control signal is sent from the control device 8 to the shading curtain 5, and the opening operation of the shading curtain 5 is performed for t3 seconds to increase the illuminance. In addition, when it is determined in step 24 that k2=0, in step 26, a control signal is sent from the control device 8 to the shade 5, and the shade 5 is not operated to maintain the illuminance. In addition, when it is determined in step 24 that k2<0, in step 27, a control signal is sent from the control device 8 to the shade 5 to perform the closing operation of the shade 5 for t4 seconds to reduce the illuminance. After performing the processing from step 25 to step 27, return to step 21 and step 22, and thereafter, repeat the processing from step 21 to step 27 at a predetermined time interval. In step 26, the shading curtain 5 may not be operated by not sending a control signal from the control device 8 to the shading curtain 5. Furthermore, the time t3 for opening the shade 5 when k2>0 in step 25 and the time t4 for closing the shade 5 when k2<0 in step 27 may be set to t3=t4, or It can be set to t3≠t4. Furthermore, the values of t3 and t4 may be changed according to the magnitude of the absolute value of k2 during the control. For example, the values of t3 and t4 may be reduced as the absolute value of k2 becomes smaller.

[Example 3] Hereinafter, the cultivation system 31 according to Embodiment 3 of the present invention will be described based on FIG. 7.

<System structure> The cultivation system 31 of the third embodiment includes, in addition to the cultivation system 21 of the second embodiment, a humidity sensor 11 that measures the humidity in the house 3 and a temperature sensor 12 that measures the temperature in the house 3. The configurations common to the cultivation system 1 of the first embodiment and the cultivation system 21 of the second embodiment are denoted by the same symbols and their description is omitted. The humidity sensor 11 and the temperature sensor 12 are arranged at appropriate positions in the house 3. FIG. 7 is an example, and the installation positions and the number of the humidity sensors 11 and the temperature sensors 12 can be appropriately set. It can be set one by one to represent the humidity distribution and temperature distribution in the house 3, or the house 3 can be divided into a plurality of areas, and a humidity sensor 11 and a temperature sensor 12 are provided in each area. Furthermore, a humidity sensor 11 and a temperature sensor 12 corresponding to each sap flu sensor 7 may be provided. Instead of using the humidity sensor 11 to measure the humidity and the temperature sensor 12 to measure the temperature, a temperature and humidity sensor that can measure both humidity and temperature may be used.

In Example 2, as the photosynthesis coefficient for evaluating the photosynthesis speed, the photosynthesis coefficient k2 defined by Δa/Δb for the sap flow rate a and the illuminance b was used. In Example 3, a new photosynthesis coefficient k3 for evaluating photosynthesis speed was introduced. To evaluate the photosynthesis speed more accurately, the difference in saturation (the difference between the saturated water vapor pressure in the air at a certain temperature and the actual water vapor pressure) must be considered. Therefore, here, the saturation difference is set to v, and the stomatal conductance (also referred to as stomatal conductance and stomatal conductance) c defined by c=a/v is used. The saturation difference v can be derived from the temperature and the relative humidity and saturated water vapor pressure at that temperature. Actually, the stomatal conductance c is expressed as α(a/v) including a coefficient α according to the leaf area, health state, etc., but here, the explanation is made assuming that α is a constant 1. Using this stomatal conductance c, the photosynthesis coefficient k3 is set to k3=Δc/Δb. Therefore, the control device 8 calculates the photosynthesis coefficient k3 based on the measurement result of the sap flu sensor 7, the measurement result of the illuminance sensor 10, and the measurement results with the humidity sensor 11 and the temperature sensor 12, The relationship between k3 and 0 is judged, and the opening degree of the shade 5 is controlled accordingly. This makes it possible to instantly set the illuminance in the house 3 to the optimal illuminance in which the photosynthesis of the plant 2 becomes active. Here, the stomatal conductance c corresponds to the third ratio, and the photosynthesis coefficient k3 corresponds to the fourth ratio. Moreover, a part of the control device 8 having the function of deriving the saturation difference based on the measurement results of the humidity sensor 11, the temperature sensor 12, and their corresponding results corresponds to the saturation difference acquisition means.

<Control method> 8 is a flowchart showing a method of controlling the blackout curtain of the third embodiment. In step 31, the sap flow rate of the plant 2 is measured by the sap flu detector 7. In step 32, the illuminance in the house 3 is measured by the illuminance sensor. In step 33, the humidity in the house 3 is measured by the humidity sensor 11, and the temperature in the house 3 is measured by the temperature sensor 12. In step 34, in the control device 8 that receives each measurement result from the sap flu sensor 7, the illuminance sensor 10, the humidity sensor 11, and the temperature sensor 12, first, based on the humidity sensor 11 and The measurement result of the temperature sensor 12 calculates the saturation difference v. Here, the control device 8 obtains the temperature measured by the temperature sensor 12 by using a table of the temperature and the saturated water vapor pressure stored in advance or a calculation formula for calculating the saturated water vapor pressure based on the temperature Saturated water vapor pressure, the saturation difference v is obtained from the saturated water vapor pressure and the relative humidity, which is the measurement result of the humidity sensor 11. Furthermore, the control device 8 calculates the stomatal conductance c=a/v from the saturation difference v and the sap flow rate a, and calculates the photosynthesis coefficient k3=Δc/Δb from the illuminance b which is the measurement result of the illuminance sensor 10. The measurement of the sap flow rate in step 31, the measurement of the illuminance in step 32, and the measurement of the humidity and temperature in step 33 are performed in parallel, but the sampling timing may not necessarily be the same. As long as based on the information obtained by processing the measured values sampled multiple times within the overlapping time range, the corresponding saturation difference change and illuminance change can be calculated, and the photosynthesis coefficient k3 can be calculated according to these parameters. . In step 35, the magnitude relationship between the photosynthesis coefficient k3 calculated by the control device 8 and 0 is determined. In step 35, the control of illuminance is determined based on whether k3 is positive, negative, or 0. Here, when it is determined that k3>0, in step 36, a control signal is sent from the control device 8 to the shade 5 to cause the opening operation of the shade 5 to be performed for t5 seconds to increase the illuminance. Furthermore, when it is determined that k3=0, in step 37, the control device 8 transmits a control signal to the shading curtain 5 so that the shading curtain 5 is not operated to maintain the illuminance. In addition, when it is determined that k3<0, in step 38, a control signal is sent from the control device 8 to the shade 5 to perform the closing operation of the shade 5 for t6 seconds to reduce the illuminance. After performing the processing from step 36 to step 38, return to step 31, step 32, and step 33, and thereafter, repeat the processing from step 31 to step 38 at a predetermined time interval. In step 37, the shading curtain 5 may not be operated by not sending a control signal to the shading curtain 5 from the control device 8. In addition, the time t5 for the opening operation of the shade 5 when k3>0 in step 36 and the time t6 for the closing operation of the shade 5 when k3<0 in step 38 may be set to t5=t6, or It can be set to t5≠t6. In addition, the values of t5 and t6 may be changed according to the magnitude of the absolute value of k3 during the control. For example, the values of t5 and t6 may be reduced as the absolute value of k3 becomes smaller.

[Example 4] Hereinafter, the cultivation system 41 according to the fourth embodiment of the present invention will be described based on FIG. 9.

<System structure> The cultivation system 41 of Example 4 replaces the sun 4, which is a light source in the cultivation system 1 of Example 1, and uses a light source 13 such as a light emitting diode (LED) that radiates artificial light. Therefore, the cultivation system 41 of Example 4 does not include the shade 5 which adjusts the illuminance of the light irradiated to the plant 2 in the house 3. FIG. 9 is a schematic illustration. Therefore, only one plant 2 is shown, but in reality, a plurality of plants 2,... 2 are arranged in the house 3. In order to uniformize the illuminance distribution of the light to the plurality of plants 2,... 2, the diffusion film 6 is used in the cultivation system 1 of Example 1. However, in the cultivation system 41 of the fourth embodiment, by arranging a plurality of light sources 13, ... 13 at appropriate positions in the house 3, the illuminance distribution of the light to the plurality of plants 2, ... 2 can be made uniform, so Does not include diffusion film 6. The cultivation system 41 does not include the shading curtain 5 and the diffusion film 6, and has a structure common to the cultivation system 1. The configuration common to the cultivation system 1 of Example 1 is denoted by the same reference numerals, and the description is omitted. However, in the cultivation system 41, the control device 8 does not control the opening degree of the shade 5 but controls the light intensity of the light source 13. In the cultivation system 41, the diffusion film 6 is not included, but the diffusion film 6 can also be used to diffuse the light from the light source 13. Here, the control device 8 corresponds to illuminance control means. As shown in Fig. 3, the curve follows the following change: the sap flow rate increases corresponding to the increase in illuminance. At a certain illuminance, the change in the sap flow rate becomes fixed, and when the illuminance further increases, the sap flow rate decreases. Based on this relationship between the illuminance and the sap flow rate, the sap flow sensor 7 is used to measure the sap flow rate, and the luminosity of the light source 13 is controlled to achieve the maximum illuminance close to the sap flow rate, by which the photosynthesis can be set to the most active Good illumination. This optimal illuminance itself varies depending on the plant 2 type, growth stage and other conditions related to the plant 2 itself, or changes in other environmental conditions such as carbon dioxide concentration, but by monitoring the measured value of the sap flu sensor 7, Always achieve the best illumination instantly.

<Control method> FIG. 10 shows a flowchart explaining the control method of the light source 13 of the fourth embodiment. In step 41, a control signal is sent from the control device to the light source 13, and the input current of the light source 13 is set to the initial value I0. In this embodiment, the following case will be explained as follows: the input current to the light source 13 is controlled to control the light intensity of the light source, and even the illuminance of the light irradiated to the plant 2, but in order to control the light intensity of the light source 13 The input operation amount can be appropriately selected according to the light source 13 such as voltage, power, and the like. In step 42, the sap flow rate is measured by the sap flu sensor 7. In the control device 8, in step 43, i=0 is set. In step 44, the input current value to the light source 13 (here, the initial value I0) is substituted into the variable I(i). In step 45, the sap flow rate measured in step 42 is substituted into a(i) and memorized. In step 46, a control signal is sent from the control device 8 to the light source 13, and the input current value to the light source 13 is set to I0+ΔI. The change of the input current value of the light source is to detect whether the direction of change of the sap flow rate is increased or decreased or fixed by changing the input current value of the light source 13 at the initial stage of control. Therefore, the change amount ΔI of the input current value may be appropriately selected to detect such a significant change in the flow rate of the sap. In step 47, the sap flow rate is measured by the sap flow sensor 7 in a state where the input current to the light source 13 is changed. In step 48, set i=i+1. In step 49, the input current value (here I0+ΔI) set in step 46 is substituted into the variable I(i). In step 50, the sap flow rate measured in step 47 is substituted into the variable a(i) and memorized. In step 51, in the control device 8, calculate k4={a(i)-a(i-1)}/{I(i)-I(i-1)} as the photosynthesis of plant 2 The photosynthesis coefficient k4 to be evaluated. Here, k4 corresponds to the first ratio. In step 52, the control device 8 determines the magnitude relationship between k4 and 0 calculated in step 51. In step 52, the control of illuminance is determined based on whether k4 is positive, negative, or 0. Here, if the determination in step 52 is that k4>0, the process proceeds to step 53 and a control signal is sent from the control device 8 to the light source 13 to increase the input current to the light source 13 by I1 to increase the light intensity. If the determination in step 52 is k4=0, the process proceeds to step 54 and a control signal is sent from the control device 8 to the light source 13 without changing the input current to the light source 13. If the determination in step 52 is that k4<0, the process proceeds to step 55, and a control signal is sent from the control device 8 to reduce the input current to the light source 13 by I2 to reduce the light intensity. After step 53, step 54 or step 55, return to step 47 and repeat the processing from step 47 to step 53, step 54 or step 55. The increase I1 of the input current to the light source 13 when k4>0 in step 53 and the decrease I2 of the input current to the light source 13 when k4<0 in step 55 can be set to I1=I2, or Set to I1≠I2. Furthermore, the values of I1 and I2 may be changed according to the magnitude of the absolute value of k4 during the control. For example, as the absolute value of k4 becomes smaller, the values of I1 and I2 may be reduced. For the input current control of the light source 13, an end condition may be appropriately set to end when k4 satisfies a predetermined condition. In addition, the starting conditions may be appropriately set to start when the predetermined timing information such as the progress of the growth stage of the plant 2 or the deterioration of the light source 13 is acquired.

In addition to the cultivation system 41 of the fourth embodiment, as in the cultivation system 21 of the second embodiment, an illumination sensor 10 may be further included to control the light source according to the magnitude relationship of the photosynthesis coefficient k2=Δa/Δb and 0 13 input current. Furthermore, as in the cultivation system 31 of the third embodiment, the humidity sensor 11 and the temperature sensor 12 may be further included, and the input current of the light source 13 may be controlled according to the magnitude relationship of the photosynthesis coefficient k3=Δc/Δb and 0.

In addition, in the following, in order to compare the constitutional requirements of the present invention with the structures of the embodiments, the symbols of the drawings are attached to describe the constitutional requirements of the present invention.

<Invention 1> A cultivation system (1, 21, 31, 41), characterized by including: A water flow measurement unit (7), which measures the flow of water in the plant (2); and The illuminance control unit (5, 8, 8) controls the irradiation of light from the light source (4, 13) to the base based on the water flow in the plant (2) measured by the water flow measurement unit (7) The light illuminance of the plant (2). <Invention 2> An illumination control method of a cultivation system, which is a method of controlling the operation amount input to an illumination control part to control the illumination, the illumination control part of the cultivation system (1, 41) of the cultivated plant (2) The illuminance of light irradiated from the light sources (4, 13) to the plant (2) is controlled. The illuminance control method of the cultivation system includes: Steps (S4, S9), obtaining the change amount of the operation amount; Steps (S5, S10, S45, S50), obtaining the amount of change in the water flow in the plant when the illuminance is changed; Steps (S11, S51), obtaining a first ratio (k1, k4), where the first ratio (k1, k4) is the ratio of the amount of change in the amount of water in the plant to the amount of change in the operation amount; as well as Steps (S12 to S15, S52 to S55) control the illuminance based on the first ratio (k1, k4). <Invention 3> An illuminance control method of a cultivation system, which is a method of controlling the illuminance of light irradiated from a light source (4) to the plant (2) in a cultivation system (21) of a cultivated plant (2), the illuminance of the cultivation system Control methods include: Step (S22), measuring the illuminance; Step (S21), obtaining the flow rate of water in the plant; Step (S23), obtaining a second ratio (k2), the second ratio (k2) being the ratio of the change in the water flow in the plant to the change in the illuminance; and Steps (S24 to S27) control the illuminance based on the second ratio. <Invention 4> An illumination control method of a cultivation system, which is a method of controlling the illumination of light irradiated from the light source (4) to the plant (2) in the cultivation system of the cultivation plant (2), wherein, Let the ratio of the flow rate of water in the plant (2) to the saturation difference of the air around the plant (2) be the third ratio, The illumination control method of the cultivation system includes: Step (S34), obtaining a fourth ratio (k3), the fourth ratio (k3) being the ratio of the change in the third ratio (c) to the change in illuminance; and Steps (S35-38) control the illuminance based on the fourth ratio.

1‧‧‧Cultivation system 2‧‧‧plant 3‧‧‧House 4‧‧‧Sun 5‧‧‧blind 6‧‧‧Diffusion film 7‧‧‧Sap Flu Tester 8‧‧‧Control device

FIG. 1 is a diagram showing a schematic configuration of a cultivation system in Embodiment 1 of the present invention. FIG. 2 is a graph showing the relationship between illuminance and photosynthesis speed. 3 is a graph showing the relationship between illuminance and sap flow rate. 4 is a flowchart showing a method of controlling illuminance in Embodiment 1 of the present invention. 5 is a diagram showing a schematic configuration of a cultivation system in Embodiment 2 of the present invention. 6 is a flowchart showing a method of controlling illuminance in Embodiment 2 of the present invention. 7 is a diagram showing a schematic configuration of a cultivation system in Embodiment 3 of the present invention. 8 is a flowchart showing a method of controlling illuminance in Embodiment 3 of the present invention. 9 is a diagram showing a schematic configuration of a cultivation system in Embodiment 4 of the present invention. 10 is a flowchart showing a method of controlling illuminance in Embodiment 4 of the present invention.

Claims (17)

A cultivation system, characterized by including: Moisture flow measuring unit to measure the flow of water in the plant; and The illuminance control means controls the illuminance of the light irradiated to the plant from the light source based on the water flow in the plant measured by the water flow measurement means. The cultivation system as described in item 1 of the patent application scope, wherein For the illuminance control part that controls the illuminance by controlling the input operation amount, the change in the water flow rate in the plant measured by the water flow measurement part relative to the change in the operation amount The ratio is set to the first ratio, The illuminance is controlled based on the first ratio. The cultivation system as described in item 2 of the patent application scope, wherein The illuminance control means determines whether to increase, maintain, or decrease the illuminance based on whether the first ratio is positive, negative, or 0. The cultivation system as described in item 1 of the patent application scope includes: An illuminance measuring part to measure the illuminance, The illuminance control means sets the ratio of the change in the water flow in the plant measured by the water flow measurement means to the change in the illuminance measured by the illuminance measurement means as the second ratio, The illuminance is controlled based on the second ratio. The cultivation system as described in item 4 of the patent application scope, in which The illuminance control means determines whether to increase, maintain, or decrease the illuminance based on whether the second ratio is positive, negative, or 0. The cultivation system as described in item 4 of the patent application scope includes: A saturation difference obtaining component to obtain the saturation difference of the air around the plant, The illuminance control means sets the ratio of the water flow in the plant measured by the water flow measurement means to the saturation difference acquired by the saturation difference acquisition means as the third ratio, Let the ratio of the change in the third ratio to the change in illuminance measured by the illuminance measuring means be the fourth ratio, The illuminance is controlled based on the fourth ratio. The cultivation system as described in item 6 of the patent application scope, wherein The illuminance control means decides whether to increase, maintain, or decrease the illuminance based on whether the fourth ratio is positive, negative, or 0. The cultivation system as described in any one of patent application items 1 to 7, wherein The water flow rate measuring means is a sap flow rate measuring means that measures the flow rate of the sap flowing in the duct of the plant. The cultivation system as described in any one of patent application items 1 to 7, wherein The illuminance control component includes: A light blocking member that blocks the light path of light incident from the light source to the plant; and An opening control part for controlling the opening ratio of the shading member to the optical path, The illuminance is controlled by controlling the opening ratio. The cultivation system as described in any one of patent application items 1 to 7, wherein The illuminance control part controls the illuminance by controlling input to the light source. An illumination control method of a cultivation system is a method of controlling the illumination intensity of light irradiated to the plants from a light source in a cultivation system of cultivated plants. The illumination control method of the cultivation system is characterized by including the following steps: Obtaining the amount of change in water flow in the plant when the illuminance is changed; and The illuminance is controlled based on the amount of change. An illumination control method of a cultivation system is a method of controlling the illumination intensity of light irradiated to the plants from a light source in a cultivation system of cultivated plants. The illumination control method of the cultivation system is characterized by including the following steps: Obtaining the amount of change in the operation amount; Acquiring the amount of change in the water flow in the plant when the operation amount is changed; Acquiring a first ratio, which is a ratio of the amount of change in the amount of moisture in the plant to the amount of change in the operation amount; and The illuminance is controlled based on the first ratio. The illumination control method of the cultivation system as described in item 12 of the patent application scope, wherein The step of controlling the illuminance based on the first ratio includes the following steps: Determine whether the first ratio is positive, negative or 0; and Based on whether the first ratio is positive, negative, or 0, it is determined whether to increase, maintain, or decrease the illuminance. An illumination control method of a cultivation system is a method of controlling the illumination intensity of light irradiated to the plants from a light source in a cultivation system of cultivated plants. The illumination control method of the cultivation system is characterized by including the following steps: Measuring the illuminance; Obtaining the flow rate of water in the plant; Acquiring a second ratio, which is the ratio of the change in the water flow in the plant to the change in the illuminance; and The illuminance is controlled based on the second ratio. The illumination control method of the cultivation system as described in item 14 of the patent application scope, wherein The step of controlling the illuminance based on the second ratio includes the following steps: Determine whether the second ratio is positive, negative or 0; and Based on whether the second ratio is positive, negative, or 0, it is determined whether to increase, maintain, or decrease the illuminance. An illumination control method of a cultivation system is a method of controlling the illumination intensity of light irradiated to the plant from a light source in a cultivation system of cultivated plants, the illumination control method of the cultivation system is characterized by, The ratio of the water flow in the plant to the saturation difference of the air around the plant is set as the third ratio, The illumination control method of the cultivation system includes the following steps: Acquiring a fourth ratio, which is the ratio of the change in the third ratio to the change in illuminance; and The illuminance is controlled based on the fourth ratio. The illumination control method of the cultivation system as described in item 16 of the patent application scope, wherein The step of controlling the illuminance based on the fourth ratio includes the following steps: Determine whether the fourth ratio is positive, negative or 0; and Based on whether the fourth ratio is positive, negative, or 0, it is determined whether to increase, maintain, or decrease the illuminance.

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