JP2013142605A - Human body detecting device, human body detecting method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a human body detecting device, a human body detecting method and a program that can appropriately determine the presence or absence of any human body without being affected by a change in background temperature or other factors.SOLUTION: A human body detecting device determines the presence or absence of any human body with a plurality of sensors that detect motions of any human body, if present, and output electric signals. The human body detecting device comprises acquiring means that acquires output values matching the electric signals outputted by the plurality of sensors and determining means that determines, on the basis of the output values of the plurality of sensors, the presence or absence of any human body within a detectable range of the sensors. More specifically, the determining means determines the presence of a human body when an output value of any one of the plurality of sensors surpasses a first threshold and determines when, after the determination, an attenuation amount of all the output values of the plurality of sensors surpass a second threshold, determines the absence of any human body.

Description

  The present invention relates to the technical field of detecting the presence of a human body using a sensor.

  Conventionally, a technique for determining the presence or absence of a human body using a pyroelectric sensor or the like has been proposed. For example, Patent Document 1 proposes a technique for determining the presence / absence of an infrared ray generation object using a threshold value adjusted according to variations in background temperature and temperature changes. Specifically, in this technology, a background temperature (temperature of an area where no human body exists) is measured by providing a shutter (chopper) that periodically opens and closes in front of the sensor, and a threshold used for determination is updated. Yes.

JP 9-33662 A

  However, in the technique described in Patent Document 1 described above, if the output of the sensor for an area where no human body exists does not change, the threshold used for the determination is not updated, and therefore the presence or absence of the human body is appropriately determined. There was a case that could not be.

  The above-mentioned thing is mentioned as an example as a subject which the present invention tends to solve. An object of the present invention is to provide a human body detection device, a human body detection method, and a program that can appropriately determine the presence or absence of a human body without being affected by changes in background temperature or the like.

  According to the first aspect of the present invention, the human body detection device that determines the presence / absence of a human body using a plurality of sensors that detect the movement of the human body and output an electrical signal, the electrical sensor output by the plurality of sensors. Acquisition means for acquiring an output value corresponding to a target signal, and determination means for determining whether or not a human body exists within a detection range of the sensor based on the output values of the plurality of sensors, The determination unit determines that the human body exists when the output value of any one of the plurality of sensors exceeds a first threshold, and determines that the human body exists, and then determines all of the plurality of sensors. When the amount of attenuation at the output value exceeds a second threshold, it is determined that the human body does not exist.

  In the invention according to claim 8, the human body detection method performed by the human body detection device for determining the presence / absence of the human body using the plurality of sensors that detect the movement of the human body and output an electrical signal includes the plurality of sensors. An acquisition step of acquiring an output value corresponding to the electrical signal output by the sensor, and a determination for determining whether or not a human body exists within a detection range of the sensor based on the output value of the plurality of sensors And when the output value of any one of the plurality of sensors exceeds a first threshold, it is determined that the human body exists, and after determining that the human body exists, When the attenuation values of all the output values of the plurality of sensors exceed the second threshold value, it is determined that the human body does not exist.

  According to the ninth aspect of the present invention, there is provided a program that is executed in a human body detection device that includes a computer, and that uses a plurality of sensors that detect movement of a human body and output an electrical signal to determine whether or not a human body exists. An acquisition means for acquiring output values corresponding to the electrical signals output by the plurality of sensors from the computer, and a human body exists within a detection range of the sensors based on the output values of the plurality of sensors. Determining means for determining whether or not the human body is present when the output value of any one of the plurality of sensors exceeds a first threshold, and the human body After determining that the human body exists, it is determined that the human body does not exist when the attenuation amount of all the output values of the plurality of sensors exceeds the second threshold value.

  In a tenth aspect of the present invention, a human body detection device that determines the presence or absence of a human body using a sensor that detects the movement of the human body and outputs an electrical signal corresponds to the electrical signal output by the sensor. Acquisition means for acquiring an output value to be performed, and determination means for determining whether or not a human body exists within a detection range of the sensor based on the output value of the sensor, wherein the determination means includes the When the output value of the sensor exceeds the first threshold, it is determined that the human body exists, and after the determination that the human body exists, the attenuation in the output value of the sensor exceeds the second threshold value It is determined that the human body does not exist.

It is a block diagram which shows schematic structure of the system containing the human body detection apparatus which concerns on a present Example. The example of arrangement | positioning of the sensor apparatus in a present Example is shown. An example of the sensor value of a sensor apparatus is shown. It is a figure for demonstrating the problem which may generate | occur | produce in the human body detection method which concerns on a comparative example. The figure for demonstrating the human body detection method concerning a present Example concretely is shown. The figure for demonstrating the effect | action and effect of the human body detection method based on a present Example about the case where the level of a sensor value changes with the change of background temperature is shown. The figure for demonstrating the effect | action and effect of the human body detection method based on a present Example about the case where the sensor value of a sensor apparatus has dispersion | variation is shown. It is a flowchart which shows the human body detection process which concerns on a present Example. The schematic structure of the system which concerns on a modification is shown. A configuration example in the case of using four sensor devices is shown.

  In one aspect of the present invention, a human body detection device that determines the presence / absence of a human body using a plurality of sensors that detect the movement of the human body and output an electrical signal is used for the electrical body output by the plurality of sensors. Acquisition means for acquiring an output value corresponding to a signal, and determination means for determining whether or not a human body exists within a detection range of the sensor based on the output values of the plurality of sensors, The determination unit determines that the human body exists when the output value of any one of the plurality of sensors exceeds a first threshold, and determines that the human body exists, and then determines all of the plurality of sensors. When the attenuation in the output value exceeds a second threshold, it is determined that the human body does not exist.

  The above human body detection device is suitably used for determining the presence or absence of a human body using a human body detection sensor such as a pyroelectric sensor. The acquisition means acquires output values (sensor values) corresponding to the electrical signals output by the plurality of sensors, and the determination means has a human body within the detection range of the sensors based on the output values of the plurality of sensors. It is determined whether or not to do. Specifically, the determination unit outputs any one of the plurality of sensors in a state where all output values of the plurality of sensors are below the first threshold (that is, a state where it is determined that no human body exists). When the value exceeds the first threshold, it is determined that a human body exists. Then, in the state where it is determined that the human body exists as described above, the determination unit determines that the human body does not exist when the attenuation amount of all the output values of the plurality of sensors exceeds the second threshold value.

  In this way, the determination means uses a different determination value (first threshold value and second threshold value) for the state where it is determined that the human body does not exist and the state where it is determined that the human body exists. Determine presence or absence. As a result, it is possible to appropriately determine the presence or absence of a human body without being affected by fluctuations in the level of the output value due to changes in the background temperature, or by fluctuations in the output value of the sensor.

  In one aspect of the human body detection device, the determination unit sets the second threshold value for each of the plurality of sensors according to the output value of each of the plurality of sensors. As a result, it is possible to appropriately suppress the influence of the change in the output value level or the variation in the output value in each sensor.

  In another aspect of the above-described human body detection device, the determination unit sets the second threshold according to the maximum value of the output values of each of the plurality of sensors. For example, the determination means can set the second threshold value having a larger value as the maximum value of the output value is larger, and can set the second threshold value having a smaller value as the maximum value of the output value is smaller.

  Preferably, in the human body detection device, the determination unit can obtain the second threshold value by multiplying a maximum value of the output values of each of the plurality of sensors by a predetermined attenuation rate.

  In another aspect of the human body detection device, the determination unit sequentially updates the second threshold value according to the output value of each of the plurality of sensors. In this aspect, the determination unit sequentially updates the second threshold value according to the output values of the plurality of sensors each time. Thereby, the influence by the change of the level of the output value in each sensor, the dispersion | variation in output value, etc. can be suppressed effectively.

  In a preferred example, the plurality of sensors are arranged such that detection ranges of two or more of the plurality of sensors overlap.

  In a preferred example, the acquisition unit acquires, as the output value, a signal after smoothing processing is performed on the electrical signals output from the plurality of sensors. Accordingly, an output value from which noise or the like mixed in the output signal of the sensor is appropriately removed can be used for the above-described determination.

  In another aspect of the present invention, the human body detection method performed by the human body detection device that determines the presence / absence of a human body using a plurality of sensors that detect the movement of the human body and output an electrical signal includes the plurality of sensors. An acquisition step of acquiring an output value corresponding to the electrical signal output from the sensor, and a determination step of determining whether or not a human body exists within a detection range of the sensor based on the output value of the plurality of sensors. The determination step determines that the human body exists when the output value of any one of the plurality of sensors exceeds a first threshold, and after determining that the human body exists, When the attenuation amount of all the output values of a plurality of sensors exceeds the second threshold, it is determined that the human body does not exist.

  In still another aspect of the present invention, a program executed in a human body detection apparatus that includes a computer and uses a plurality of sensors that detect movement of a human body and output an electrical signal to determine the presence or absence of the human body. An acquisition means for acquiring output values corresponding to the electrical signals output by the plurality of sensors from the computer, and a human body exists within a detection range of the sensors based on the output values of the plurality of sensors. Determining means for determining whether or not the human body is present when the output value of any one of the plurality of sensors exceeds a first threshold, and the human body After determining that the human body exists, it is determined that the human body does not exist when the attenuation amount of all the output values of the plurality of sensors exceeds the second threshold value.

  In still another aspect of the present invention, a human body detection device that determines the presence / absence of a human body using a sensor that detects the movement of the human body and outputs an electrical signal corresponds to the electrical signal output by the sensor. Acquisition means for acquiring an output value to be performed, and determination means for determining whether or not a human body exists within a detection range of the sensor based on the output value of the sensor, wherein the determination means includes the When the output value of the sensor exceeds the first threshold, it is determined that the human body exists, and after the determination that the human body exists, the attenuation in the output value of the sensor exceeds the second threshold value It is determined that the human body does not exist.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[Device configuration]
With reference to FIG. 1, the human body detection apparatus according to the present embodiment will be described. FIG. 1 is a block diagram illustrating a schematic configuration of a system including a human body detection device 2 according to the present embodiment. As shown in FIG. 1, the human body detection apparatus 2 is an apparatus for acquiring the outputs of the two sensor devices 1a and 1b and determining the presence or absence of a human body based on the outputs.

  The sensor devices 1a and 1b include sensor units 11a and 11b and signal processing units 12a and 12b, respectively.

  The sensor units 11a and 11b are constituted by pyroelectric sensors, for example. Here, the principle of the pyroelectric sensor will be briefly described. An object of absolute zero or higher emits infrared rays corresponding to its temperature, and its energy wavelength distribution is expressed by Planck's law. According to the Wien displacement law, the distribution peak shifts to the short wavelength side when the temperature of the object increases. The pyroelectric element is usually spontaneously polarized but is in an electrically neutral state. When this element absorbs infrared rays as heat rays, the temperature change is output as an electrical signal by the pyroelectric effect. The pyroelectric sensor can output only when the intensity of incident infrared rays changes. As for the human body, when the person is stationary, the infrared intensity incident on the pyroelectric sensor does not change, so no output is obtained from the pyroelectric sensor, but when the person moves, the infrared intensity incident on the pyroelectric sensor is Since it changes, an output is obtained from the pyroelectric sensor. The pyroelectric sensor has a large temperature difference between the surface temperature of the human body and the background temperature (meaning the temperature around the human body such as a wall, floor, or ceiling within the detection range of the pyroelectric sensor; the same applies hereinafter). The output level increases, and the output level decreases as the temperature difference between the human body surface temperature and the background temperature decreases.

  The signal processing units 12a and 12b acquire output signals from the sensor units 11a and 11b and perform predetermined processing on the output signals. Specifically, the signal processing units 12a and 12b perform smoothing processing after performing full-wave rectification on the output signals of the sensor units 11a and 11b. Full-wave rectification corresponds to a process of inverting data below a predetermined value to the side above the predetermined value based on the predetermined value. The smoothing process is a process for smoothing data changes. For example, the smoothing process corresponds to a process for obtaining a moving average of data. In one example, the smoothing process corresponds to a process of obtaining an average value of a predetermined number of data in the vicinity of the data of interest and setting the average value to the value of the data of interest.

  Hereinafter, the signal after processing by the signal processing units 12a and 12b is referred to as “sensor value”. The sensor value is an example of the “output value” in the present invention. The sensor devices 1a and 1b are examples of the “sensor” in the present invention. Note that the present invention is not limited to performing both full-wave rectification and smoothing processing as described above, and only smoothing processing may be performed without performing full-wave rectification.

  The human body detection device 2 includes a signal acquisition unit 21, a fixed threshold value comparison unit 22, a dynamic threshold value comparison unit 23, a human body detection determination unit 24, and a detection state holding unit 25.

  The signal acquisition unit 21 acquires the outputs of the sensor devices 1a and 1b. Specifically, the signal acquisition unit 21 acquires sensor values processed by the signal processing units 12a and 12b in the sensor devices 1a and 1b, respectively. The signal acquisition unit 21 is an example of the “acquisition unit” in the present invention.

  The fixed threshold value comparison unit 22 compares the sensor value acquired by the signal acquisition unit 21 with a predetermined fixed threshold value. Specifically, the fixed threshold value comparison unit 22 determines whether any of the sensor values of the sensor devices 1a and 1b exceeds the fixed threshold value. As the fixed threshold value, the same value is used for the sensor values of the sensor devices 1a and 1b in making the determination. The fixed threshold is an example of the “first threshold” in the present invention.

  The dynamic threshold comparison unit 23 compares the sensor value acquired by the signal acquisition unit 21 with a dynamic threshold set according to the sensor value. Specifically, the dynamic threshold value comparison unit 23 determines whether or not attenuation in which the sensor values of the sensor devices 1a and 1b both exceed the dynamic threshold value has occurred. That is, the dynamic threshold value comparison unit 23 determines whether or not the attenuation amount (meaning the amount attenuated from the maximum value; the same applies hereinafter) in the sensor values of the sensor devices 1a and 1b has exceeded the dynamic threshold value. To do. The dynamic threshold value comparison unit 23 sets a dynamic threshold value used for such determination for each sensor value of the sensor devices 1a and 1b. Specifically, the dynamic threshold value comparison unit 23 represents a predetermined attenuation rate (the ratio of the attenuation amount from the maximum value to the maximum value) with respect to the maximum value of the sensor values of the sensor devices 1a and 1b. The dynamic threshold used for each sensor value of the sensor devices 1a and 1b is obtained by multiplying the same. The dynamic threshold value comparison unit 23 sequentially updates the dynamic threshold value according to the sensor values of the sensor devices 1a and 1b. The dynamic threshold is an example of the “second threshold” in the present invention.

  The human body detection determination unit 24 determines whether or not a human body exists within the detection ranges of the sensor devices 1a and 1b based on the determination results of the fixed threshold value comparison unit 22 and the dynamic threshold value comparison unit 23. In this case, the human body detection determination unit 24 performs such determination with reference to a flag indicating whether or not the human body held in the detection state holding unit 25 exists. When it is determined that a human body exists, the human body detection determination unit 24 sets a flag to be held in the detection state holding unit 25 to “detection”, and when it is determined that no human body exists, the detection state holding unit 25 Set the flag to be held to “not detected”. In the following, a state determined that the human body is present is simply referred to as “detection”, and a state determined that the human body is not present is simply referred to as “non-detection”.

  Specifically, in the state where the flag of the detection state holding unit 25 is set to “non-detection”, the human body detection determination unit 24 uses the fixed threshold comparison unit 22 to detect any sensor value of the sensor devices 1a and 1b. Is determined to have exceeded the fixed threshold value, it is determined that a human body exists within the detection range of the sensor devices 1a and 1b. In this case, the human body detection determination unit 24 sets the flag to be held in the detection state holding unit 25 from “non-detection” to “detection”. On the other hand, in the state where the flag of the detection state holding unit 25 is set to “detection”, the human body detection determination unit 24 uses the dynamic threshold comparison unit 23 to set the sensor values of the sensor devices 1a and 1b to the dynamic threshold. When it is determined that the attenuation exceeding 1 occurs, it is determined that the human body does not exist within the detection ranges of the sensor devices 1a and 1b. In this case, the human body detection determination unit 24 sets the flag to be held in the detection state holding unit 25 from “detection” to “non-detection”.

  Thus, the fixed threshold value comparison unit 22, the dynamic threshold value comparison unit 23, and the human body detection determination unit 24 correspond to an example of the “determination unit” in the present invention.

  Here, with reference to FIG. 2, the example of arrangement | positioning of the sensor apparatus 1a, 1b in a present Example, etc. are demonstrated.

  In FIG. 2, a region 50a indicates a detection range of the sensor device 1a (specifically, a detection range of the sensor unit 11a in the sensor device 1a), and a region 50b indicates a detection range of the sensor device 1b (specifically, in the sensor device 1b). The detection range of the sensor unit 11b) is shown. The region 50c indicates a region where the detection range 50a of the sensor device 1a and the detection range 50b of the sensor device 1b overlap (hereinafter, referred to as “overlap region” as appropriate). Note that a range (including the overlap region 50c) in which the detection range 50a of the sensor device 1a and the detection range 50b of the sensor device 1b are combined is appropriately referred to as a “detection range 50” below.

  As shown in FIG. 2, the sensor devices 1a and 1b are arranged such that the detection ranges 50a and 50b overlap. When the sensor devices 1a and 1b are arranged as described above, it is considered that a person moves from left to right as indicated by a thick arrow. In this case, in the first period T1, a person stays in the vicinity of the sensor device 1a, and in a period T2 after the period T1, the person moves in the direction from the sensor device 1a to the sensor device 1b. In period T3, it is assumed that a person is staying near the sensor device 1b. Such an arrangement position of the sensor devices 1a and 1b and a movement direction of the person shown in FIG. 2 are assumed in all examples to be described later.

  FIG. 3 shows an example of sensor values of the sensor devices 1a and 1b obtained in the configuration shown in FIG. FIG. 3 shows time on the horizontal axis, and sensor values on the vertical axis (values after smoothing processing is performed by the signal processing units 12a and 12b of the sensor devices 1a and 1b. The same applies hereinafter). Is shown. Specifically, the graph 60a shows an example of the sensor value of the sensor device 1a, and the graph 60b shows an example of the sensor value of the sensor device 1b. From the graphs 60a and 60b, it can be seen that the sensor values of the sensor devices 1a and 1b fluctuate greatly during the period T2 in which a person is moving from the sensor device 1a to the sensor device 1b. Specifically, it can be seen that the sensor value once increases to the maximum value, and then the sensor value attenuates from the maximum value.

[Human body detection method]
Next, the human body detection method according to the present embodiment will be specifically described.

  First, before describing the human body detection method according to the present embodiment, problems that may occur in the human body detection method according to the comparative example will be described. The human body detection method according to the comparative example determines that a human body is present in the detection range 50 of the sensor devices 1a and 1b when any of the sensor values of the sensor devices 1a and 1b exceeds a fixed threshold. This is a method for determining that no human body is present in the detection range 50 of the sensor devices 1a and 1b when both the sensor values 1a and 1b are below the fixed threshold value.

  FIG. 4 is a diagram for explaining problems that may occur in the human body detection method according to the comparative example.

  FIG. 4A is a view similar to FIG. 2 (the arrangement positions of the sensor devices 1a and 1b and the movement direction of the person are the same). Here, as shown in FIG. 4A, a case is considered where illumination 51 (sunlight or the like) as a heat source exists at the corner of the detection range 50a of the sensor device 1a. Further, since the temperature of the illumination 51 is higher than the surface temperature of the human body, when the illumination 51 is turned on, the temperature difference between the surface temperature of the human body and the background temperature becomes large. When the illumination 51 is turned off, the surface temperature of the human body It is assumed that the temperature difference from the background temperature is small (in this case, the air temperature is close to the surface temperature of the human body). Therefore, the level of the sensor value output from the sensor devices 1a and 1b is changed by turning on / off the illumination 51. Specifically, when the illumination 51 is turned on, a relatively high level of sensor value is output from the sensor devices 1a and 1b, and when the illumination 51 is turned off, the sensor devices 1a and 1b A relatively low level sensor value is output.

  FIG. 4B shows an example of a result obtained by the human body detection method according to the comparative example. FIG. 4B shows time on the horizontal axis and sensor values on the vertical axis. Graphs 61a and 61b show examples of sensor values of the sensor devices 1a and 1b when the illumination 51 is turned on, respectively. When sensor values as shown in FIG. 4 (b) are obtained, it is determined that no human body exists since none of the sensor values of the sensor devices 1a and 1b exceed the fixed threshold A until time t11. From time t11 to time t12, since at least one sensor value of the sensor devices 1a and 1b exceeds the fixed threshold A, it is determined that a human body exists. And after time t12, since both sensor values of sensor device 1a and 1b are less than fixed threshold A, it is judged that a human body does not exist.

  It can be said that the determination of “detection” and “non-detection” as shown in FIG. 4B is an appropriate determination according to the movement of the person as shown in FIG. The reason why the determination can be made appropriately is that when the illumination 51 is turned on, the temperature difference between the surface temperature of the human body and the background temperature is large, so that the sensor values at a relatively high level from the sensor devices 1a and 1b. (Specifically, it is considered that this is because a sensor value at a level at which the presence / absence of the human body can be appropriately determined using the fixed threshold A) is output.

  FIG. 4C shows another example of the result obtained by the human body detection method according to the comparative example. In FIG. 4C, the horizontal axis indicates time, and the vertical axis indicates sensor value. Graphs 62a and 62b show examples of sensor values of the sensor devices 1a and 1b when the illumination 51 is turned off, respectively. From this, it can be seen that the sensor value levels of the graphs 62a and 62b are smaller than the sensor value levels of the graphs 61a and 61b when the illumination 51 is turned on as shown in FIG. This is because when the illumination 51 is turned off, the temperature difference between the human body surface temperature and the background temperature is small, and thus sensor values of a relatively low level are output from the sensor devices 1a and 1b.

  When sensor values as shown in FIG. 4C are obtained, it is determined that no human body exists because none of the sensor values of the sensor devices 1a and 1b exceed the fixed threshold A until time t21. From time t21 to time t22, since the sensor value of the sensor device 1a exceeds the fixed threshold A, it is determined that a human body exists. From time t22 to time t23, since both sensor values of the sensor devices 1a and 1b are below the fixed threshold A, it is determined that no human body exists. Thereafter, since the sensor value of the sensor device 1b exceeds the fixed threshold A from time t23 to time t24, it is determined that a human body exists, and after time t24, both sensor values of the sensor devices 1a and 1b are determined. Since it is below the fixed threshold A, it is determined that no human body exists.

  As shown in FIG. 4C, in the human body detection method according to the comparative example, when the illumination 51 is turned off, in the period from the time t22 to the time t23, the person specifically detects the detection range 50 of the sensor devices 1a and 1b. It can be said that it is erroneously determined that the human body does not exist in the middle of passing through (the overlap region 50c in detail). Such a misjudgment is that when the illumination 51 is turned off, the temperature difference between the human body surface temperature and the background temperature is small, so that a relatively low level sensor value is output from the sensor devices 1a and 1b. It is thought that it occurred. That is, when the illumination 51 is turned off, the sensor value has not reached a level at which the presence / absence of the human body can be appropriately determined using the fixed threshold A, and it is considered that an erroneous determination has occurred.

  As described above, in the comparative example in which the presence / absence of the human body is determined using only the fixed threshold A, the presence / absence of the human body is appropriately determined when the sensor value level fluctuates due to the change in the background temperature. It may not be possible. Therefore, in this embodiment, the presence / absence of a human body is determined by a method capable of suppressing the influence of fluctuations in the sensor value level due to changes in the background temperature.

  Specifically, in this embodiment, the human body detection determination unit 24 in the human body detection device 2 determines that no human body exists in the detection ranges 50 of the sensor devices 1a and 1b (that is, the detection state holding unit). In the state where the flag 25 is set to “non-detection”), a determination is made using a fixed threshold value, whereas in the state where it is determined that a human body is present in the detection range 50 of the sensor device 1a, 1b. (In other words, the state where the flag of the detection state holding unit 25 is set to “detection”), the determination is performed using the dynamic threshold. That is, the human body detection determination unit 24 switches the determination method between the “detection” state and the “non-detection” state. Specifically, in the “non-detection” state, the human body detection determination unit 24 moves the human body to the detection range 50 of the sensor devices 1a and 1b when any sensor value of the sensor devices 1a and 1b exceeds a fixed threshold. (In this case, the flag is changed to “detection”). On the other hand, in the “detection” state, the attenuation amount (the amount attenuated from the maximum value) in the sensor values of the sensor devices 1a and 1b. ) Both exceed the dynamic threshold value, it is determined that no human body exists in the detection ranges 50 of the sensor devices 1a and 1b (at this time, the flag is changed to “non-detection”).

  In the present embodiment, the dynamic threshold value comparison unit 23 in the human body detection device 2 sets the dynamic threshold value used for the above determination based on the sensor values of the sensor devices 1a and 1b. Specifically, the dynamic threshold value comparison unit 23 determines the dynamic threshold value used for each sensor value of the sensor devices 1a and 1b according to the maximum value of each sensor value of the sensor devices 1a and 1b. Set. In this case, the dynamic threshold value comparison unit 23 monitors each sensor value of the sensor devices 1a and 1b by monitoring the rising sensor value after any sensor value of the sensor devices 1a and 1b exceeds the fixed threshold value. The maximum threshold value is sequentially obtained, and the finally obtained maximum value is multiplied by a predetermined attenuation rate, thereby obtaining a dynamic threshold to be used for each sensor value of the sensor devices 1a and 1b. . Specifically, the dynamic threshold value comparison unit 23 is used in the previous detection state when the flag of the detection state holding unit 25 is changed from “non-detection” to “detection”, that is, when the detection state shifts to a new detection state. The existing dynamic threshold is cleared and a dynamic threshold for use in a new detection state is obtained.

  In one example, the dynamic threshold value comparison unit 23 uses “25%” as the attenuation rate, and obtains the dynamic threshold value by multiplying the maximum value of the sensor value by “25%”. In this example, when the maximum value of the sensor value of the sensor device 1a is “5000” and the maximum value of the sensor value of the sensor device 1b is “3000”, the dynamic threshold value comparison unit 23 determines that the sensor device 1a The dynamic threshold used for the sensor value of “5000 × 0.25 = 1250” is set, and the dynamic threshold used for the sensor value of the sensor device 1b is set to “3000 × 0.25 = 750”. .

  The sensor devices 1a and 1b are not limited to using the same attenuation rate, and different attenuation factors may be used for the sensor devices 1a and 1b. For example, the attenuation rate can be set for each of the sensor devices 1a and 1b in consideration of variations in sensor values of the sensor devices 1a and 1b.

  FIG. 5 is a diagram for specifically explaining the human body detection method according to the present embodiment. FIG. 5 shows time on the horizontal axis and sensor values on the vertical axis. Graphs 63a and 63b show examples of sensor values of the sensor devices 1a and 1b, respectively. The graphs 63a and 63b are obtained when the sensor devices 1a and 1b are arranged as shown in FIG. 2 and a person moves as shown in FIG.

  In the example illustrated in FIG. 5, the human body detection determination unit 24 determines that no human body is present until the time t <b> 31 because none of the sensor values of the sensor devices 1 a and 1 b exceed the fixed threshold A, and maintains the detection state. The flag of the unit 25 is continuously set to “non-detection”. Then, since the sensor value of the sensor device 1a exceeds the fixed threshold A at time t31, the human body detection determination unit 24 determines that a human body is present, and changes the flag of the detection state holding unit 25 from “non-detection” to “detection”. Change to Thereafter, the sensor value of the sensor device 1a reaches the maximum value Max1a at time t32, and the sensor value of the sensor device 1a starts to attenuate from time t32. The dynamic threshold value comparison unit 23 obtains a dynamic threshold value α1 used for the sensor value of the sensor device 1a by multiplying the maximum value Max1a by a predetermined attenuation rate at time t32. At time t33 after time t32, the amount of attenuation in the sensor value of the sensor device 1a (the amount attenuated from the maximum value Max1a) exceeds the dynamic threshold α1, but the amount of attenuation in the sensor value of the other sensor device 1b does not move. The threshold is not exceeded. Therefore, the human body detection determination unit 24 maintains the flag of the detection state holding unit 25 at “detection” even after the time t33.

  Then, at time t34 after time t33, the sensor value of the sensor device 1b reaches the maximum value Max1b, and from time t34, the sensor value of the sensor device 1b starts to attenuate. The dynamic threshold value comparison unit 23 obtains a dynamic threshold value β1 used for the sensor value of the sensor device 1b by multiplying the maximum value Max1b by a predetermined attenuation rate at time t34. At time t35 after time t34, the amount of attenuation at the sensor value of the sensor device 1b (the amount attenuated from the maximum value Max1b) exceeds the dynamic threshold value β1, so the amount of attenuation at each sensor value of the sensor devices 1a and 1b is The dynamic threshold values α1 and β1 are exceeded. Therefore, the human body detection determination unit 24 determines that no human body exists at time t35, and changes the flag of the detection state holding unit 25 from “detection” to “non-detection”.

  Next, with reference to FIG.6 and FIG.7, the effect | action and effect of the human body detection method based on a present Example are demonstrated. Here, it demonstrates, comparing with the human body detection method concerning the above-mentioned comparative example.

  FIG. 6 is a diagram for explaining the operation and effect of the human body detection method according to the present embodiment when the level of the sensor value changes due to the change of the background temperature. 6 (a) and 6 (b), an example of the result when the illumination 51 shown in FIG. 4 (a) is turned off will be described. That is, the sensor values (graphs 62a and 62b) of the sensor devices 1a and 1b illustrated in FIG. 4C will be described as an example.

  FIG. 6A shows an example of a result obtained by the human body detection method according to the comparative example, similar to FIG. As described above, in the comparative example, it is erroneously determined that the human body does not exist while the person is passing the detection range 50 (period from time t22 to time t23).

  FIG. 6B shows an example of a result obtained by the human body detection method according to the present embodiment. In the present embodiment, the human body detection determination unit 24 determines that no human body exists because none of the sensor values of the sensor devices 1a and 1b exceed the fixed threshold A until time t41, and the sensor is detected at time t41. Since the sensor value of the device 1a exceeds the fixed threshold A, it is determined that a human body exists. Thereafter, at time t42, the attenuation amount in the sensor value of the sensor device 1a exceeds the dynamic threshold value α2, and further, at time t43 after time t42, the attenuation amount in the sensor value of the sensor device 1b exceeds the dynamic threshold value β2. . Therefore, the human body detection determination unit 24 determines that a human body exists from time t41 to time t43, and determines that no human body exists after time t43.

  6B, according to the human body detection method according to the present embodiment, unlike the human body detection method according to the comparative example, it can be appropriately determined that a person exists while the person is passing through the detection range 50. You can see that Therefore, according to the present embodiment, it can be said that the presence / absence of the human body can be appropriately determined without being affected by the fluctuation of the sensor value level due to the change of the background temperature.

  FIG. 7 is a diagram for explaining the operation and effect of the human body detection method according to the present embodiment when the sensor values of the sensor devices 1a and 1b vary. 7A and 7B, graphs 65a and 65b show examples of sensor values of the sensor devices 1a and 1b, respectively. Here, a case where the sensor value level of the sensor device 1a is considerably smaller than the sensor value level of the sensor device 1b is taken as an example.

  FIG. 7A shows an example of a result obtained by the human body detection method according to the comparative example. In the human body detection method according to the comparative example, no sensor value of the sensor devices 1a and 1b exceeds the fixed threshold A until time t51, so it is determined that no human body exists, and from time t51 to time t52, Since the sensor value of the sensor device 1a exceeds the fixed threshold A, it is determined that a human body exists. From time t52 to time t53, since both sensor values of the sensor devices 1a and 1b are below the fixed threshold A, it is determined that there is no human body. Thereafter, from time t53 to time t54, since the sensor value of the sensor device 1b exceeds the fixed threshold A, it is determined that a human body exists, and after time t54, both sensor values of the sensor devices 1a and 1b are Since it is below the fixed threshold A, it is determined that no human body exists.

  From FIG. 7A, in the human body detection method according to the comparative example, in the period from time t52 to time t53, specifically, a person sets the detection range 50 (specifically, the overlap region 50c) of the sensor devices 1a and 1b. In the middle of passing, it can be said that it is erroneously determined that the human body does not exist. Such an erroneous determination is considered to have occurred because the sensor value of the sensor device 1a did not reach a level at which the presence / absence of the human body can be appropriately determined using the fixed threshold A.

  FIG. 7B shows an example of a result obtained by the human body detection method according to the present embodiment. In the present embodiment, the human body detection determination unit 24 determines that no human body exists because none of the sensor values of the sensor devices 1a and 1b exceed the fixed threshold A until time t61, and the sensor is detected at time t61. Since the sensor value of the device 1a exceeds the fixed threshold A, it is determined that a human body exists. Thereafter, at time t62, the amount of attenuation at the sensor value of the sensor device 1a exceeds the dynamic threshold value α3, and at time t63 after time t62, the amount of attenuation at the sensor value of the sensor device 1b exceeds the dynamic threshold value β3. . Therefore, the human body detection determination unit 24 determines that a human body exists from time t61 to time t63, and determines that no human body exists after time t63.

  7B, according to the human body detection method according to the present embodiment, unlike the human body detection method according to the comparative example, it can be appropriately determined that a person is present while the person is passing through the detection range 50. You can see that Therefore, according to the present embodiment, it can be said that the presence / absence of a human body can be appropriately determined without being affected by variations in sensor values in the sensor devices 1a and 1b.

  As described above, according to the human body detection method according to the present embodiment, the influence due to the change in the level of the sensor value due to the change in the background temperature, the influence due to the variation in the sensor value in the sensor devices 1a and 1b, and the like are suppressed. The presence or absence of the human body can be determined appropriately. Specifically, in this embodiment, the dynamic threshold value used for each sensor value of the sensor devices 1a and 1b is set according to the sensor value of the sensor devices 1a and 1b, and the sensor devices 1a and 1b Since the dynamic threshold is set according to the maximum value of the sensor value every time, it is possible to appropriately determine the presence / absence of a human body without being affected by changes in the background temperature, variations in sensor values, and the like.

  In the technique described in Patent Document 1 described above, the presence / absence of a human body is determined using a threshold adjusted in accordance with variations in background temperature and changes in temperature. Specifically, the background temperature is measured by providing a shutter (chopper) that periodically opens and closes in front of the sensor, and the threshold used for the determination is updated. However, in this technique, if the output of the sensor for an area where no human body exists does not change, the threshold used for the determination is not updated, and thus it may not be possible to appropriately determine the presence or absence of the human body. On the other hand, in the present embodiment, as described above, because the dynamic threshold set according to the maximum value of each time in the sensor value is used, even if the output of the sensor for an area where no human body exists does not change, The presence or absence of the human body can be determined appropriately.

[Human body detection processing]
Next, a human body detection process according to the present embodiment will be described with reference to FIG. FIG. 8 is a flowchart illustrating human body detection processing according to the present embodiment. This flow is repeatedly executed by the human body detection device 2 at a predetermined cycle.

  First, in step S101, the signal acquisition unit 21 in the human body detection device 2 acquires sensor values from the sensor devices 1a and 1b. Specifically, the signal acquisition unit 21 acquires the sensor value processed (smoothing process or the like) by each of the signal processing units 12a and 12b in the sensor devices 1a and 1b. Then, the process proceeds to step S102.

  In step S102, the human body detection determination unit 24 in the human body detection device 2 determines whether or not the flag of the detection state holding unit 25 is set to “non-detection”. That is, the human body detection determination unit 24 determines whether or not it is determined that no human body exists in the detection ranges 50 of the sensor devices 1a and 1b. When the flag of the detection state holding unit 25 is set to “non-detection” (step S102: Yes), the process proceeds to step S103.

  In step S103, the fixed threshold value comparison unit 22 in the human body detection device 2 determines whether one of the sensor values of the sensor devices 1a and 1b acquired in step S101 exceeds the fixed threshold value. When the sensor value of any of the sensor devices 1a and 1b exceeds the fixed threshold value (step S103: Yes), the process proceeds to step S104. In this case, the human body detection determination unit 24 in the human body detection device 2 determines that a human body exists in the detection range 50 of the sensor devices 1a and 1b, and the flag of the detection state holding unit 25 is changed from “non-detection” to “detection”. Change (step S104). Then, the process ends. On the other hand, when none of the sensor values of the sensor devices 1a and 1b exceed the fixed threshold value (step S103: No), the process ends.

  On the other hand, when the flag of the detection state holding unit 25 is not set to “non-detection” (step S102: No), that is, when the flag of the detection state holding unit 25 is set to “detection”, the process is step. The process proceeds to S105. In step S105, the dynamic threshold value comparison unit 23 in the human body detection device 2 determines whether attenuation has occurred in which the sensor values of the sensor devices 1a and 1b acquired in step S101 both exceed the dynamic threshold value. That is, the dynamic threshold value comparison unit 23 determines whether or not the attenuation amount (amount attenuated from the maximum value) in the sensor values of the sensor devices 1a and 1b exceeds the dynamic threshold value. The dynamic threshold is set by a method as described in the section [Human Body Detection Method] above.

  When the amount of attenuation in the sensor values of the sensor devices 1a and 1b exceeds the dynamic threshold (step S105: Yes), the process proceeds to step S106. In this case, the human body detection determination unit 24 in the human body detection device 2 determines that no human body exists in the detection ranges 50 of the sensor devices 1a and 1b, and the flag of the detection state holding unit 25 is changed from “detection” to “non-detection”. (Step S106). Then, the process ends. On the other hand, when both the attenuation values of the sensor values of the sensor devices 1a and 1b do not exceed the dynamic threshold (step S105: No), the process ends.

[Modification]
Below, the modification suitable for said Example is demonstrated. It should be noted that the following modifications can be applied to the above-described embodiments in any combination.

(Modification 1)
In the system shown in FIG. 1, the human body detection device 2 and the sensor devices 1a and 1b are connected by wire. However, the communication device such as Wi-Fi (wireless fidelity) is used to connect the sensor device and the human body detection device. May be connected. FIG. 9 shows a schematic configuration of a system according to such a modification. 9, components having the same reference numerals as those in FIG. 1 are assumed to have the same configuration, and the description thereof is omitted.

  As shown in FIG. 9, in the system according to the modification, the sensor devices 1 xa and 1 xb and the human body detection device 2 x are connected via a network 4. In this configuration, the sensor devices 1xa and 1xb transmit the sensor values processed by the signal processing units 12a and 12b by the signal transmission units 13a and 13b, and the human body detection device 2x is transmitted from the signal transmission units 13a and 13b. The sensor value is received by the signal receiving unit 26. The signal receiving unit 26 is an example of the “acquiring unit” in the present invention.

(Modification 2)
Although the example using two sensor devices 1a and 1b has been described above, the application of the present invention is not limited to this. The present invention can also be applied to a configuration using only one sensor device. That is, the human body detection device can determine whether or not a human body exists within the detection range of the sensor device based on the sensor value of one sensor device. In this case, the human body detection device determines that a human body exists when the sensor value of the sensor device exceeds a fixed threshold (first threshold), and after the determination, the attenuation in the sensor value is the dynamic threshold (first threshold). 2), it is determined that no human body exists. The dynamic threshold is set according to the maximum value of the sensor value every time, as in the above-described embodiment. Thus, even in a configuration using only one sensor device, by making a determination based on the dynamic threshold, the influence of fluctuations in the sensor value level due to changes in the background temperature is suppressed, and the presence / absence of a human body can be determined. It can be judged appropriately.

  In yet another example, the present invention can be applied to a configuration using three or more sensor devices. That is, the human body detection device can determine whether or not a human body exists within the detection range of the sensor device based on the sensor values of three or more sensor devices. In this case, the human body detection device determines that a human body exists when any one of the three or more sensor devices exceeds a fixed threshold (first threshold), and after the determination, three or more When the attenuation amount of all the sensor values of the sensor device exceeds the dynamic threshold (second threshold), it is determined that no human body exists. The dynamic threshold is set for each sensor value of each sensor device according to the maximum value of each sensor value of each of the three or more sensor devices, as in the above-described embodiment. Even in a configuration using three or more sensor devices in this way, by making a determination based on the dynamic threshold, the influence of the change in the level of the sensor value due to the change in the background temperature, or in the three or more sensor devices It is possible to appropriately determine the presence / absence of a human body by suppressing the influence of variations in sensor values. When three or more sensor devices are used, it is preferable to arrange the sensor devices so that detection ranges of two or more sensors among the three or more sensor devices overlap.

  FIG. 10 shows a configuration example when four sensor devices 1ya to 1yd are used. As shown in FIG. 10, the four sensor devices 1ya to 1yd are arranged at the four corners of the space, and are arranged so that the respective detection ranges overlap.

(Modification 3)
In the above, an example in which the dynamic threshold is obtained based on the attenuation rate has been shown. Specifically, an example in which the dynamic threshold is obtained by multiplying the maximum sensor value by a predetermined attenuation rate has been shown. Thus, the determination of the dynamic threshold is not limited. In another example, the dynamic threshold can be set using a table in which the dynamic threshold to be set according to the maximum value of the sensor value is defined. For example, in the table, a dynamic threshold having a larger value is determined as the maximum value of the sensor value is increased, and a dynamic threshold having a smaller value is determined as the maximum value of the sensor value is decreased. A threshold is defined in stages.

(Modification 4)
In the above, an example in which a fixed threshold is used when determining whether or not a human body exists in the state of “non-detection” has been shown, that is, an example in which a fixed threshold is used as the “first threshold” in the present invention has been shown. However, it is not limited to using such a fixed threshold value. In another example, a value obtained by adding a predetermined value to the minimum value of the sensor values of each sensor device in the “non-detection” state is used as a first threshold value for determining whether or not a human body exists. be able to. In this example, a different first threshold value is set for each sensor value of each sensor device, and a different first threshold value is set according to the minimum value of each sensor value.

(Modification 5)
INDUSTRIAL APPLICABILITY The present invention can be used for acoustic equipment that aims to provide an optimal sound field according to a human body position in an acoustic space, home appliances such as an air conditioner that adjusts control according to the human body position, and lighting. it can.

  As described above, the embodiments are not limited to the above-described embodiments, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification.

DESCRIPTION OF SYMBOLS 1a, 1b Sensor apparatus 2 Human body detection apparatus 11a, 11b Sensor part 12a, 12b Signal processing part 21 Signal acquisition part 22 Fixed threshold value comparison part 23 Dynamic threshold value comparison part 24 Human body detection determination part 25 Detection state holding part

Claims (10)

A human body detection device that determines the presence or absence of a human body using a plurality of sensors that detect the movement of the human body and output an electrical signal,
Obtaining means for obtaining an output value corresponding to the electrical signal output by the plurality of sensors;
Determination means for determining whether or not a human body exists within a detection range of the sensor based on the output values of the plurality of sensors,
The determination means includes
When the output value of any one of the plurality of sensors exceeds a first threshold, it is determined that the human body exists,
A human body detection apparatus, wherein after determining that the human body exists, when the attenuation amount of all the output values of the plurality of sensors exceeds a second threshold, it is determined that the human body does not exist.   The human body detection apparatus according to claim 1, wherein the determination unit sets the second threshold value for each of the plurality of sensors according to the output value of each of the plurality of sensors.   The human body detection apparatus according to claim 2, wherein the determination unit sets the second threshold according to a maximum value of the output values of each of the plurality of sensors.   The human body detection apparatus according to claim 3, wherein the determination unit obtains the second threshold value by multiplying a maximum value of the output values of each of the plurality of sensors by a predetermined attenuation rate.   5. The human body detection apparatus according to claim 2, wherein the determination unit sequentially updates the second threshold value in accordance with the output value of each of the plurality of sensors.   The human body detection according to any one of claims 1 to 5, wherein the plurality of sensors are arranged so that detection ranges of two or more of the plurality of sensors overlap each other. apparatus.   The acquisition means acquires the signal after the smoothing process is performed on the electrical signals output from the plurality of sensors as the output value. The human body position detecting device according to one item. A human body detection method performed by a human body detection device that determines the presence or absence of a human body using a plurality of sensors that detect the movement of the human body and output an electrical signal,
An acquisition step of acquiring an output value corresponding to the electrical signal output by the plurality of sensors;
A determination step of determining whether or not a human body exists within a detection range of the sensor based on the output values of the plurality of sensors,
The determination step includes
When the output value of any one of the plurality of sensors exceeds a first threshold, it is determined that the human body exists,
A human body detection method comprising: determining that the human body does not exist when it is determined that the human body is present and attenuation values of all the output values of the plurality of sensors exceed a second threshold. A program that is executed in a human body detection device that has a computer and determines the presence or absence of a human body using a plurality of sensors that detect movement of the human body and output an electrical signal,
The computer,
Obtaining means for obtaining an output value corresponding to the electrical signal output by the plurality of sensors;
Based on the output values of the plurality of sensors, function as a determination unit that determines whether a human body exists within the detection range of the sensors,
The determination means includes
When the output value of any one of the plurality of sensors exceeds a first threshold, it is determined that the human body exists,
After determining that the human body exists, the program determines that the human body does not exist when the attenuation amount of all the output values of the plurality of sensors exceeds a second threshold value. A human body detection device that determines the presence or absence of a human body using a sensor that detects the movement of the human body and outputs an electrical signal,
Obtaining means for obtaining an output value corresponding to the electrical signal output by the sensor;
Determination means for determining whether or not a human body exists within a detection range of the sensor based on the output value of the sensor,
The determination means includes
When the output value of the sensor exceeds a first threshold, it is determined that the human body exists,
After determining that the human body exists, the human body detection apparatus determines that the human body does not exist when an attenuation amount in the output value of the sensor exceeds a second threshold value.

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