JP2021082201A - Method, program, determination system to determine existence of persons in room - Google Patents

Abstract

To provide a method for determining existence of a person in a new room, which enables determination of the existence of the person without using a threshold value for determining the existence of the person in the room.SOLUTION: A system for determining the existence of an animal including a person himself or herself includes: means of measuring a concentration of carbon dioxide in a room over time; and means for calculating the time variation of the carbon dioxide concentration based on the latest measured value and the immediately proceeding measured value, each time the carbon dioxide concentration is measured, and executes the steps of: calculating a moving average value of time fluctuations; and determining the existence of the person in the room when the symbols of the time fluctuations are the same a certain number of times in a row. The symbols are positive or negative, and means for determining the existence of the person in the room includes means for determining that the animal is "entered" or "absent" when the symbols are the same a certain number of times in succession.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for determining the presence or absence of a room based on the concentration of carbon dioxide in the room.

A method for determining occupancy based on the concentration of carbon dioxide in a room has already been proposed. (For example, Patent Document 1).

However, in the method of the prior application, the threshold value for determining the presence / absence of a room is set to an appropriate value in advance based on the results of simulations and preliminary experiments considering the space volume of the target room and the degree of ventilation. Therefore, there is a problem in terms of convenience and reality because it is necessary to perform an individual simulation or the like for each room to be measured and set a threshold value.

Japanese Unexamined Patent Publication No. 2017-16185

The present invention has been made in view of the above problems in the prior art, and the present invention is a novel invention that makes it possible to determine the presence or absence of a room without using a threshold value for determining the presence or absence of a room. The purpose is to provide a method.

As a result of diligent studies on a method for determining the presence or absence of a room without using a threshold value for determining the presence or absence of a room, the present inventor came up with the following configuration and arrived at the present invention.

That is, according to the present invention, it is a method of determining the presence or absence of an animal including a human being in a room, and the step of measuring the carbon dioxide concentration in the room over time and the latest every time the carbon dioxide concentration is measured. The symbol includes a step of calculating the time variation of the carbon dioxide concentration based on the measured value and the immediately preceding measured value, and a step of calculating the moving average value of the time variation. In the step of determining the presence or absence of, when the signs (positive) are the same for a certain number of times in a row, it is determined that "the room has been entered", and the signs (negative) of the time fluctuation are the same for a certain number of times in a row. In that case, a determination method is provided that includes a step of determining that the animal is not in the room and swapping the "absent" and "in-room" states.

As described above, the present invention provides a novel method that makes it possible to determine the presence or absence of a room without using a threshold value.

The flowchart which shows the determination method of this embodiment. The figure which shows typically the structure of the determination system of this embodiment. The figure which shows the experimental apparatus of this Example. The graph which shows the time-dependent change of CO2 concentration. The graph which shows the time-dependent change of the time variation of CO2 concentration. Eight moving averages of time-varying concentration increments of CO2 concentration

Hereinafter, the present invention will be described with reference to the embodiments shown in the drawings, but the present invention is not limited to the embodiments shown in the drawings. In each of the figures referred to below, the same reference numerals are used for common elements, and the description thereof will be omitted as appropriate.

The present invention provides a method for determining whether or not an animal, including a human, is present in a room. In the present invention, the room is a concept that is generally a closed space and includes a whole space in which animals including humans can stay, and is not limited in its shape and use. Further, the animal in the present invention means an animal that breathes lungs and generally contains carbon dioxide in exhaled breath.

When an animal breathes lungs in a closed space, carbon dioxide (CO2) contained in exhaled breath increases the concentration of CO2 in the room. However, in an actual room, ventilation is always performed through a minute gap (or by opening and closing windows, adjusting equipment), so even if a person keeps breathing in the room, the CO2 concentration in the room will be high. It does not continue to increase and saturates at a constant value. On the other hand, when a person leaves a room where the CO2 concentration is saturated, the CO2 concentration in the room begins to decrease due to the above-mentioned ventilation action, decreases to the vicinity of the baseline, and then settles at a constant value.

The present invention has been made by paying attention to the above-mentioned points, and is based on the time variation of the CO2 concentration that occurs when an animal including a human (hereinafter, simply referred to as a human) enters or leaves the room. Determine the presence or absence. Hereinafter, the specific contents of the determination method of the present embodiment will be described with reference to the flowchart shown in FIG.

First, in step 101, the initial value of the variable to be used later is set.

In step 102, the latest CO2 concentration of the room is acquired based on the sensor output of the CO2 concentration sensor installed in the room to be determined.

In the following step 103, the time-varying DCO2 (T0) of the CO2 concentration is calculated based on the following formula (1). In the following formula (1), CO2 (T0) and T0 indicate the latest CO2 concentration and its acquisition time, respectively, and CO2 (T1) and T1 indicate the immediately preceding CO2 concentration and its acquisition time, respectively. Is shown. In other words, (T0-T1) in the following formula (1) corresponds to the sampling interval (cycle) of _{the CO 2 concentration.}

In the following step 104, the process of leveling the time-varying DCO2 (T0) calculated in step 103 is executed. In the present embodiment, the latest N time fluctuations (DCO2 (T0), DCO2 (T1), DCO2 (T2) ... DCO2 (T-) including the time fluctuation DCO2 (T0)) The moving average of (N1))) (N1 is N-1) is output as the time-varying DCO2 (T0)'after leveling. However, in other embodiments, the leveling process may be performed by other suitable methods.

In the following step 105, it is determined whether or not the time variation DCO2 (T0)'after leveling is positive.

As a result of the determination in step 105, if the time variation DCO2 (T0)'is positive (S105, YES), the process proceeds to step 112. On the other hand, if the time variation DCO2 (T0)'is different from positive (S105, NO), the process proceeds to step 106.

In the following step 106, it is determined whether or not the time fluctuation DCO2 (T0)'after leveling is negative.

As a result of the determination in step 106, if the time variation DCO2 (T0)'is negative (S106, YES), the process proceeds to step 107. On the other hand, when the time variation DCO2 (T0)'is different from negative (S106, NO), the process proceeds to step 113 and the previous determination value is maintained.

In the following step 107, it is determined whether or not the previous determination result is absent.

As a result of the determination in step 107, if the previous determination result is absent (S107, YES), the process proceeds to step 102. On the other hand, if the previous determination result is different from the absence (S107, NO), the process proceeds to step 108.

In step 108, the variable M indicating the number of consecutive occurrences when the time variation DCO2 (T0)'is positive is set to 0.

Subsequent step 109 Add 1 to the variable N indicating the number of consecutive occurrences when the time variation DCO2 (T0)'is negative.

In the following step 110, it is determined whether or not the number of consecutive occurrences N when the time variation DCO2 (T0)'is negative and the variable K indicating the number of consecutive occurrences given in advance match.

As a result of the determination in step 110, if the number of consecutive occurrences N when the time variation DCO2 (T0)'is negative and the variable K indicating the number of consecutive occurrences given in advance match (S110, YES), the process is step 111. Proceed to. On the other hand, if the number of consecutive occurrences N when the time variation DCO2 (T0)'is negative and the variable K indicating the number of consecutive occurrences given in advance do not match (S110, NO), the process returns to step 102.

In the following step 111, the determination result is absent.

In the following step 112, the variable N indicating the number of consecutive occurrences in the negative case is set to 0.

In the following step 114, it is determined whether or not the previous determination result is in the room.

As a result of the determination in step 114, if the previous determination result is in the room (S114, YES), the process proceeds to step 102. On the other hand, if the previous determination result is different from the absence (S114, NO), the process proceeds to step 115.

In step 115, the variable N indicating the number of consecutive occurrences when the time variation DCO2 (T0)'is negative is set to 0.

In the following step 116, 1 is added to the variable M indicating the number of consecutive occurrences when the time variation DCO2 (T0)'is positive.

In the following step 117, it is determined whether or not the number of consecutive occurrences M when the time variation DCO2 (T0)'is positive and the variable K indicating the number of consecutive occurrences given in advance match.

As a result of the determination in step 117, if the number of consecutive occurrences M when the time variation DCO2 (T0)'is positive and the variable K indicating the number of consecutive occurrences given in advance match (S117, YES), the process is step 118. Proceed to. On the other hand, if the number of consecutive occurrences M when the time variation DCO2 (T0)'is positive and the variable K indicating the number of consecutive occurrences given in advance do not match (S117, NO), the process returns to step 102.

In the following step 118, the determination result is set to be in the room.

In the following step 119, the variable M indicating the number of consecutive occurrences in the positive case is set to 0.

In the present embodiment, the series of processes (steps 101 to 119) described above are repeatedly executed in synchronization with the timing of sampling the CO2 concentration. The functional means for executing each step shown in FIG. 1 can be realized by a device-executable program described in C, C ++, C #, Java (registered trademark), or the like. Devices such as hard disk devices, CD-ROMs, MOs, DVDs, flexible disks, EEPROMs, and EPRO Ms can be stored and distributed in readable recording media, and can be transmitted via a network.

The determination method of the present embodiment has been described above, but subsequently, the determination system adopting the determination method of the present embodiment will be described.

FIG. 2 shows a network configuration of an “elderly person watching system” that can be referred to as one of the application development examples of the determination system of the present embodiment. In this system, elderly living alone CO2 concentration sensor 11 is installed in each room of the house 10, the sensor 11 is configured to detect the CO ₂ concentration of the room at a predetermined sampling period, it is detected The CO2 concentration is configured to be transmitted to the occupancy status monitoring server 50 in real time via the Internet or a WAN (wide area network) 40 referred to as a VPN.

On the other hand, the occupancy status monitoring server 50 is equipped with a functional means for executing each step of the determination method shown in FIG. 1, and determines in real time whether or not the elderly person 12 is present in each room of the house 10. It is configured to do. Further, the occupancy status monitoring server 50 is configured to record as time-series data the occupancy status of which room the elderly person 12 is in and how he / she has moved based on the determination result. According to this system, the family 25 of the elderly 12 living far away can check the occupancy status of the elderly 12 in real time by accessing the occupancy status monitoring server 50 from the PC 20 or the smartphone 30, and the elderly. The living condition of the person 12 can be grasped.

Since the "elderly person watching system" shown in FIG. 2 can be easily constructed by simply installing one CO2 concentration sensor in each room, there is an advantage that the introduction cost can be kept low. In addition, since the privacy of the elderly is protected to some extent by not using the camera, there is an advantage that the psychological barrier at the time of introduction is low.

The system configuration shown in Fig. 2 is applied as it is as a "pet watching system" that monitors the occupancy status of pets such as dogs and cats, and a "telework labor management support system" that grasps the occupancy status of workers. It is also possible to deploy. Further, in FIG. 2, an example is illustrated in which a functional means for executing each step of the determination method shown in FIG. 1 is mounted on one server, but the functional means is two or more information processing devices on the network. Needless to say, they may be distributed in appropriate units. Similarly, the CO2 concentration sensor 11 determines in real time whether or not the room is occupying, and transmits the result to the occupancy status monitoring server 50 in real time.

Although the present invention has been described above with embodiments, the present invention is not limited to the above-described embodiments, and the actions and effects of the present invention can be exhibited within the range of embodiments that can be conceived by those skilled in the art. As long as it works, it is included in the scope of the present invention.

Hereinafter, the determination method of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the Examples described later.

In this experiment, as shown in FIG. 3, seven adult subjects stayed indoors for 30 minutes in a room 60 (width 5800 x depth 5340 x height 2500 MMM) equipped with a door 62 and a window 61 that opened inward. The act of leaving the room was repeated twice. During that time, the CO2 concentration inside the room 60 was measured over time with a CO2 sensor module 11 (MCH-383SD manufactured by Lutron® Electronics Co., Ltd.) installed inside the room 60 (sampling cycle: 5 seconds). ..

(Changes in CO2 concentration over time)
FIG. 4 is a graph showing the change over time in the CO2 concentration inside the room 60. The square wave shown at the bottom of the graph indicates the actual period of absence / occupancy of the subject. As shown in FIG. 4, there is a clear difference in the state of the concentration change, such that the concentration increases when the room is present and decreases when the room is absent. In other words, the concentration increment (the measured value of this time minus the measured value of the previous time (5 seconds ago)) becomes positive when the room is present, and the concentration increment becomes negative when the room is absent.
In both the previous research and the method proposed this time, it is common to use this feature to determine the presence of a room, but the measured values fluctuate little by little, depending on whether the person is in the room or not. , The sign of concentration increment is not clearly divided into positive and negative.

(Moving average of CO2 concentration)
As a way to avoid the inconvenience that the sign of the concentration increment is not clearly divided into positive and negative depending on whether you are in the room or not, the first thing you can think of is to take the average value of the sections with a certain width. is there. Specifically, the average value of the measured value at that time and some measured values before that is calculated, and such an average value is called a moving average. If you take a moving average, the partial opposite tendency may be leveled and eliminated.
FIG. 5 shows the concentration increment before taking the moving average. It appears to be filled because the signs are swapped or 0s appear intermittently and frequently.
FIG. 6 shows eight moving averages of the concentration increment, but the number of data (N) when calculating the moving average is set to eight in the prior patent, so for the time being, it should be adjusted accordingly. saw. It can be seen that the frequent sign reversal and the appearance of 0 are drastically reduced.

(Evaluation of occupancy judgment method)
When the sign of the incremental average becomes the same for a certain number of times in a row, it is determined that "entered" or "exited", and the states of "absent" and "present" are exchanged. Details are as follows.
-The initial state (the state when the measuring device is started) is "absent".
-When the state is "in the room", when the sign of the incremental average becomes negative for a certain number of times in a row, the state is changed to "absent".
-When the state is "absent", when the sign of the incremental average becomes 0 or more continuously for a certain number of times, the state is changed to "in the room".
The method proposed this time uses the experimental fact that the sign of the incremental average is changed relatively frequently due to the gentle gradient, and the sign is not actually entered or exited. The previous judgment result is maintained until it continues a certain number of times. The accuracy rate of the judgment is around 85%, which is not much different from that of the previous application.

The correct answer rate of the judgment result was about 85%, because it takes several minutes instead of immediately reversing the increase / decrease of the CO2 concentration after entering or leaving the room. Therefore, it is considered that the determination method of the present invention has sufficient practicality in applications where a delay of about 4 to 5 minutes is allowed for determination of entry / exit.
In the method based on the prior application, it is necessary to determine the reference value to be used for judgment by conducting experiments and simulations for each individual environment, but this is not required in this proposal.

10 ... House 11 ... CO2 concentration sensor with occupancy monitoring function 12 ... Elderly people 20 ... PC
25 ... Family 30 ... Smartphone 40 ... WAN
50 ... PC (server)
55 ... Database

Claims (7)

It is a method of determining the presence or absence of a person, and it is a step of measuring the carbon dioxide concentration in the room over time, and each time the carbon dioxide concentration is measured, carbon dioxide is dioxide based on the latest measured value and the immediately preceding measured value. The code includes a step of calculating the time variation of the carbon concentration and a step of determining the presence or absence of a room when the signs of the time variation are the same a certain number of times in succession, and the symbols have a positive gradient and a negative sign. The step of determining whether or not the room is present is a tilt, and when the symbols are the same for a certain number of times in a row, it is determined that the user has "entered" or "exited", and "absent" and "existing". Judgment method including the step of exchanging the states of. Further, the step of determining the presence or absence of the room, including the step of leveling the calculated time fluctuation, is said to be "entered" or "exited" when the symbols are the same a certain number of times in succession. The determination method according to claim 1, which is a determination step. The determination method according to claim 2, wherein the leveling step is a step of obtaining a moving average of the latest N (N is an integer of 2 or more) including the calculated time variation. A program for causing a computer to perform each step of the method according to any one of claims 1 to 3. It is a system that determines the presence or absence of animals including humans, and it is a means to measure the carbon dioxide concentration in the room over time, and each time the carbon dioxide concentration is measured, the latest measured value and the immediately preceding measured value are used. Based on the means for calculating the time variation of the carbon dioxide concentration, the step of calculating the moving average value of the time variation, and the presence or absence of the room is determined when the signs of the time variation are the same for a certain number of times in a row. The means for determining the presence or absence of the room is positive or negative, and the means for determining the presence or absence of the room is said to be "entered" when the signs (positive) are the same for a certain number of times in a row. A determination system including means for determining that the animal is not present in the room when the sign (negative) of the time variation becomes the same for a certain number of times in succession. Further, the means for determining the presence or absence of the room, including the means for leveling the calculated time fluctuation, is said to be "entered" or "exited" when the symbols are the same for a certain number of times in a row. The determination system according to claim 5, further comprising a determination means. The determination system according to claim 6, wherein the leveling means includes a means for obtaining a moving average of the latest N (N is an integer of 2 or more) including the calculated time variation.

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