JP6716620B2 - Sensor device and displacement determination system - Google Patents

Description

The present invention relates to a sensor device that eliminates the influence of minute vibration transmitted from the installation environment of a sensor and a displacement determination system that determines the presence or absence of minute displacement of a target object using the device.

It is known that ultrasonic waves are suitable for detecting a reflective object and determining a state by utilizing its acoustic characteristics. Therefore, the reflection type ultrasonic sensor is widely used as an ultrasonic echo device in a medical field, a fish finder in a fishery, a nondestructive inspection device for a building in the construction field, a human sensor for an automatic door, and the like. The reflection type ultrasonic sensor outputs an ultrasonic pulse and receives a reflected wave reflected by a person or an object. The presence or movement of a person or an object is detected by measuring the time difference (TOF (Time Of Flight)) from the output of this pulse to the reception and the distance from the propagation velocity to the reflector and its change.

In Patent Document 1, an ultrasonic sensor is installed in an incubator for a newborn baby, and by observing the state of reflection of the ultrasonic wave output toward the newborn baby, it is possible to detect minute fluctuations due to the heartbeat and respiration of the newborn baby. A sound wave type living body monitoring apparatus is disclosed. This ultrasonic sensor is intended to detect minute fluctuations from the time from the output of ultrasonic waves to the reception of reflected waves.

However, for example, in the case of detecting small body movements due to respiration in not only a newborn baby but also a sleeping adult in a general household, pulsed ultrasonic waves are transmitted as in the method of Patent Document 1 to measure the TOF. It is difficult. The reason is that the movement of the rib cage due to the respiration of the human body has a difference of at most about 1 cm between inspiration and expiration, and the difference in TOF using ultrasonic waves corresponds to about 30 [μs]. In general burst waves, the burst width is often several hundred [μs], and in order to capture the difference in TOF of about 30 [μs] from the burst length, extremely high accuracy is required for the distance measuring device. Because.

Therefore, a method using a pulse-modulated wave as described in Patent Document 2 is adopted to detect a fine movement due to breathing or the like. In this method, when a modulated wave having a bandwidth of 8 [kHz] is used, for example, a distance resolution of about 2 [cm] (about 1 [cm] when considering the round trip from transmission to reception) is obtained, but still It is not enough to detect the movement of the rib cage as a concrete change in distance. Therefore, in Patent Document 2, the presence or absence of slight movement is determined by detecting the movement of the rib cage as a specific change in distance from the time variation of the waveform of the reflected wave.

JP, 2010-158517, A JP, 2016-193020, A

By the way, in the fine motion sensing technology as disclosed in Patent Document 2, the sensor unit itself may vibrate due to vibration transmitted from a wall, a ceiling, or the like, and its accuracy may be deteriorated.

Although the vibration of the sensor unit itself is so small that it cannot be visually confirmed (for example, the amplitude is less than 1 [mm] and the cycle is around 1 [Hz]), it is inevitable to suppress the vibration by using some fixing means. Such a minute vibration may appear as a time variation of the waveform of the reflected wave regardless of whether the reflector (target object) is a living body or a non-living body, and may cause an error in fine movement detection. In other words, if the sensor unit itself is affected by vibration, it is very difficult to accurately detect the minute movement of the target object.

The present invention is intended to solve the above problems, and performs an appropriate state detection by eliminating the influence of minute vibration transmitted from a wall or ceiling to a device that detects a minute displacement of a target object such as a person. It is an object of the present invention to provide a sensor device capable of performing the above and a displacement determination system that determines the presence or absence of a minute displacement of a target object using the sensor device.

In order to achieve the above-mentioned object, the sensor device according to the present invention is a transmitter that intermittently transmits a transmission wave toward a target object and a reference object that is present at a known position at a certain distance or more from the target object. Department,
A reflection wave receiving unit that receives a reflection wave reflected by the target object and the reference object,
A portion corresponding to the reflection from the reference object by applying a time window that is set in common to the reflected wave data based on the reflected wave for each of the transmitted waves with reference to the transmission time of each of the transmitted waves. A partial data extraction unit for extracting waveform data,
From the difference between the phase characteristics of the partial waveform data for one of the partial waveform data for the plurality of transmission waves and the phase characteristics of the partial waveform data for the other transmission waves, the other transmission waves A waveform correction unit that corrects the frequency characteristics of the reflected wave data with respect to
A displacement information calculation unit that obtains the corrected reflected wave data from the frequency characteristics of each of the corrected reflected wave data after the correction, and calculates displacement information of the target object from the time change of the corrected reflected wave data.
And an output unit for outputting the displacement information to an external device.

Further, the sensor device according to the present invention, a wave transmission unit that intermittently transmits the transmission wave toward the target object,
A reflected wave receiving unit that receives the reflected wave reflected by the target object,
A reference wave receiving unit that receives the transmission wave transmitted from the wave transmitting unit as a direct wave at a position apart from the target object by a certain amount or more,
Partial waveform data corresponding to the transmission wave is applied to each of the direct wave data based on the direct wave of each of the transmission waves by applying a time window that is commonly determined in time based on the transmission time of each of the transmission waves. A partial data extraction unit to be extracted,
From the difference between the phase characteristics of the partial waveform data for one of the partial waveform data for the plurality of transmission waves and the phase characteristics of the partial waveform data for the other transmission waves, the other transmission waves A waveform correction unit that corrects the frequency characteristics of the reflected wave data with respect to
A displacement information calculation unit that calculates corrected reflected wave data from the frequency characteristics of each of the corrected reflected wave data after the correction, and calculates displacement information of the target object from the time change of the corrected reflected wave data.
An output unit that outputs the displacement information to an external device,
It is characterized by having.

Furthermore, a displacement determination system according to the present invention is a displacement determination system including the above-described sensor device and at least a control device including an input unit for inputting the displacement information,
When the displacement information falls below a stop determination threshold value for a predetermined time, the control device determines that the target object is inactive, and outputs an alarm.

Further, in the displacement determination system according to the present invention, the target object may be a person in a recumbent state on a reference plane, and the displacement information may be a change in the distance from the sensor device to the rib cage due to the breathing of the person.

According to the sensor device of the present invention, it is possible to eliminate the influence of the vibration of the sensor device itself due to the vibration transmitted from the wall or ceiling where the sensor device is installed. However, it is possible to accurately detect a minute displacement such as a movement of the chest due to the respiration of the human body.

Further, according to the displacement determination system of the present invention, the sensor device can detect a minute displacement of the target object to be detected with high accuracy by canceling the vibration transmitted from the installed wall, ceiling, or the like. The displacement information obtained by the device is highly reliable. Therefore, by performing the stop determination of the target object based on the displacement information, the activity stop state of the target object can be determined with high accuracy.

(A), (b) is a conceptual diagram which shows the outline of the displacement determination system which concerns on 1st Embodiment which concerns on this invention. (A) is a functional block diagram of the sensor unit according to the first embodiment, and (b) is a functional block diagram of a demodulated wave processing unit. It is a wave form diagram which shows an example of the ultrasonic wave (sweep signal) transmitted as a transmission wave. It is a wave form diagram which showed typically the reflected wave which made a certain transmission time the origin. FIG. 7 is a waveform diagram schematically showing demodulated waves obtained by demodulating reflected waves received at different times. 7 is a flowchart showing the contents of processing performed by an initial setting unit. 6 is a graph of phase characteristics with respect to angular frequency for explaining the concept of group delay. FIG. 6 is a schematic diagram in which demodulated wave data of received reflected waves and demodulated wave data after phase component correction by the waveform correction unit are superimposed. It is a flow chart explaining a series of processing operations of a sensor unit of a 1st embodiment. (A), (b) is a conceptual diagram which shows the outline of the displacement determination system which concerns on 2nd Embodiment which concerns on this invention. (A) is a functional block diagram of a sensor unit according to the second embodiment, and (b) is a functional block diagram of a demodulated wave processing unit. (A) is a waveform diagram schematically showing a state in which a reflected wave received by a measurement microphone is demodulated, and (b) is a state in which a direct wave received by a reference microphone is demodulated It is the waveform diagram shown. It is a flowchart explaining a series of processing operations of the sensor unit of the second embodiment.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.

It should be noted that the drawings attached to the present specification may be schematically represented by changing the actual scales, vertical/horizontal dimensional ratios, shapes, etc., for convenience of illustration and understanding, but are only examples. However, this does not limit the interpretation of the present invention. Therefore, the present invention is not limited to the embodiments described with reference to the accompanying drawings, and all other possible embodiments, examples, operational techniques, and the like that can be conceived by those skilled in the art based on this embodiment are the present invention. Shall be included in the category of.

Further, in the following description with reference to the accompanying drawings in this specification, when the terms up, down, left, and right are used to indicate directions and positions, this is as illustrated by the user. If you look at the top, bottom, left, right matches.

Hereinafter, as preferred embodiments of the present invention, two embodiments (first embodiment and second embodiment) in which the sensor device according to the present invention is applied to a living body detection technique for detecting a state of a person will be described.

[First Embodiment]
The displacement determination system 1 according to the first embodiment of the present invention will be described with reference to FIGS.
1A and 1B are diagrams schematically showing the displacement determination system 1 in the first embodiment. As shown in each drawing, the displacement measurement system 1 includes a sensor unit mounted above (ceiling or wall surface) in an observation space (room) in which a target object and a reference object arranged in the vicinity of the target object exist. (Corresponding to the sensor device in the claims) 10 and a signal from the sensor unit 10 are received wirelessly or by wire and, for example, when there is no movement in the vicinity of the rib cage, there is a possibility that breathing may be stopped, and a predetermined notification not shown. It is composed of a control device 20 for notifying a security company or the like.

In the present embodiment, the target object whose displacement is detected by the sensor unit 10 is the human body 12 in bed lying on the bed 11 in the supine direction, and the minute displacement to be detected is the movement of the rib cage associated with respiration.
Further, the reference object is furniture or a floor arranged in the vicinity of the bed 11, and is conditioned on being always stationary. In the present embodiment, the existence and position (distance from the sensor unit 10) are known.

The distance from the sensor unit 10 to the desk 13 and the floor 14 is input from a setting input unit (not shown) including a keyboard and a mouse and stored in a setting condition storage unit (not shown). Alternatively, it may be automatically measured by the later-described initial setting unit 110c and stored in the setting condition storage unit.

Further, the sensor unit 10 is installed at a position where the transmission wave is transmitted to the target object and the reference object and the reception wave is surely received. In the first embodiment, the sensor unit 10 is directed downward to the ceiling almost directly above the person who is lying down. Although it is inevitable that the sensor unit 10 receives a minute vibration from an installation location such as a ceiling or a wall, the present invention can eliminate the influence of the vibration.

Next, the configuration of the sensor unit 10 will be described with reference to FIG.
Outside the housing of the sensor unit 10, a speaker 101 that functions as a transmitting unit that transmits a transmission wave, and a reception wave that is a reflection wave that is a transmission wave that is transmitted from the speaker 101 and is reflected by a target object and a reference object A microphone 102 that functions as a wave receiving unit that receives the wave is provided. As shown in FIG. 2A, the transmitting portion of the speaker 101 and the receiving portion of the microphone 102 are located below the sensor unit 10 (the surface facing the installation surface) in a state of facing the target object and the reference object, respectively. It is arranged.

The internal configuration of the sensor unit 10 includes a modulated wave storage unit 103, a D/A conversion unit 104, a speaker amplifier 105, a microphone amplifier 106, an A/D conversion unit 107, a transmission/reception control unit 108, and a reception/reception control unit. The wave demodulation unit 109, the demodulation wave processing unit 110, the demodulation wave storage unit 111, and the output unit 112 are provided.

The modulated wave storage unit 103 stores digital signals such as pulsed modulated waves and burst waves in the ultrasonic band, and is composed of, for example, a semiconductor memory or a hard disk drive. Here, the pulse-like modulated wave refers to a frequency-modulated wave in which the frequency is linearly changed or a phase-modulated wave using an M-sequence, which is highly accurate by demodulating and capturing the position of the object in a pulsed manner. You can measure the distance. A burst wave is a signal that outputs a signal of a single frequency (for example, 40 [kHz]) in a very short time (less than 1 [ms]). In demodulation processing, the envelope detection is performed and its peak is detected. You can measure distance by position.

The modulated wave storage unit 103 of this embodiment stores in advance digital data of a sweep signal that is a pulsed modulated wave. The graph 30 of FIG. 3 illustrates the waveform of the sweep signal, and the graph 31 illustrates the time-frequency characteristic of the time of the sweep signal. The sweep signal is a signal having a property that the frequency changes temporally even though the amplitude is constant, and in the example of FIG. 3, the frequency gradually decreases with the passage of time. It is known that by using such a signal, the reception power is secured and the resolution of the distance measurement result is improved rather than the output of a simple pulse signal. For example, by changing the frequency in the range of 32 [kHz] to 24 [kHz], the resolution from the sensor unit 10 can be about 2 cm.

Hereinafter, in the present embodiment, since the sweep signal outside the audible range is adopted as the transmission wave, the transmission wave transmitted from the speaker 101 is described as “ultrasonic wave”.

The D/A conversion unit 104 reads the digital data of the sweep signal from the modulated wave storage unit 103 at the timing according to the output instruction of the transmission/reception control unit 108, and D/A converts the read digital data.

The speaker amplifier 105 drives the speaker 101 by amplifying the analog data output from the D/A conversion unit 104. As a result, ultrasonic waves are transmitted from the speaker 101 toward the target object and the reference object. The transmitted ultrasonic wave is reflected by the target object and the reference object, and the reflected wave reflected is received by the microphone 102. The reflected wave received by the microphone 102 is converted into an electric signal (analog signal).

The microphone amplifier 106 amplifies the analog signal converted by the microphone 102.

The A/D conversion unit 107 converts the analog signal amplified by the microphone amplifier 106 into a digital signal and outputs the digital signal to the reception wave demodulation unit 109 according to the output instruction of the transmission/reception control unit 108.

The transmission/reception control unit 108 has a function of controlling the timing of transmitting ultrasonic waves and a function of associating ultrasonic waves with reflected waves.
In the present embodiment, the transmission timing of ultrasonic waves is every 200 [ms]. Further, in the present embodiment, the number of times of measurement L required to determine the presence or absence of movement of the rib cage due to breathing of the human body 12 is 15.
The number of transmitted waves can be appropriately set according to the type of displacement to be detected.

In the present embodiment, the time length of the sweep signal (reference numeral 30) shown in FIG. 3 is set to 128 [ms], and the sensor unit 10 shown in FIG. 1 is attached to a position approximately 2 [m] directly above the human body 12. To do.

The reception wave demodulation unit 109 demodulates the digital signal output by the A/D conversion unit 107 and outputs the demodulated digital data as reflected wave data. A pulsed waveform appears in the reflected wave data obtained by demodulating the sweep signal.

In FIG. 4, the reflected wave data 40 is schematically shown. In the reflected wave data 40, a peak 41 is a component corresponding to the reflection from the desk 13, a peak 42 is a component corresponding to the reflection from the human body 12, and a peak 43 is a component corresponding to the reflection from the floor 14.
In FIG. 4, the horizontal axis represents time. The origin of the reflected wave data 40 is included in the demodulated reflected wave data by the partial data extraction unit 110a, which will be described later, and is matched with the peak of the wraparound wave (not shown). The wraparound wave that wraps around from the speaker 101 to the microphone 102 and is directly received is not affected by the vibration of the sensor unit 10. Therefore, the origin of the reflected wave data is always a certain time after the transmission time of the transmission wave. Further, the peak time almost represents the round trip time of the ultrasonic wave, and the long round trip time indicates that the distance from the sensor unit 10 to the object reflecting the ultrasonic wave is long, and the short time indicates that the distance is short. In this embodiment, the length of the reflected wave data is 128 [ms].

The demodulation wave processing unit 110 corrects the reflected wave data demodulated by the reception wave demodulation unit 109 to eliminate the influence of vibration of the sensor unit 10 itself, obtains displacement information regarding a minute displacement of the target object, and outputs the output unit. Output to 112.
The demodulated wave processing unit 110 includes a partial data extraction unit 110a, a frequency analysis unit 110b, an initial setting unit 110c, a waveform correction unit 110d, and a displacement information calculation unit 110e.

Here, the influence when the sensor unit 10 is subjected to vibration and the outline of the countermeasure method according to the present invention will be described.
FIG. 5 schematically shows reflected wave data of three times of reflected waves received while the sensor unit 10 is vibrating. Note that, in FIG. 5, the state of actual fluctuation is greatly exaggerated for easy understanding.

FIG. 5B is a case where the sensor unit 10 vibrates and approaches the human body 12, the desk 13 and the floor 14, and the peak time thereof is the reflected wave data of FIG. 5A indicated by the alternate long and short dash line in the figure. It can be seen that the peaks are detected earlier than the peak time by shifting to the left as indicated by the arrow in the figure. Further, FIG. 5C shows a case where the sensor unit 10 vibrates and moves away from the human body 12, the desk 13 and the floor 14, and the peak time thereof is the reflected wave of FIG. It can be seen that the data is detected later than the peak time of the data by shifting to the right as shown by the arrow in the figure.

When the sensor unit 10 vibrates, the peak time change due to the vibration of the sensor unit 10 is superimposed on the peak time change due to the slight movement of the human body 12, and therefore the minute movement of the human body 12 cannot be simply determined from the peak time change. On the other hand, since the desk 13 or the floor 14 is immobile at any time, it can be considered that the fluctuation of the peak time related to the reflection of both is due to the vibration of the sensor unit 10.

Therefore, in the present invention, the desk 13 or the floor 14 that is a stationary object is used as a reference object, and the peak time of the human body 12 that is the target object is corrected on the basis of the peak time of the reference object so that the sensor unit 10 vibrates in a pseudo manner. If not, the peak time change is obtained. That is, it means that the reflected wave data of FIGS. 5A to 5C are shifted in the time direction and aligned with the peak time of the reference object as a reference. As a result, it becomes possible to accurately determine even a slight displacement of the target object.

The partial data extraction unit 110a is a unit that extracts (cuts out) data of a predetermined time width around the peak time from the reflected wave data output by the received wave demodulation unit 109. Therefore, the partial data extraction unit 110a initializes a time window for clipping for each object in a predetermined period during which the operation is stable after the power is turned on.
That is, the partial data extraction unit 110a defines a search section based on the transmission time of ultrasonic waves and the distance to each object in the reflected wave data, obtains the absolute value of the amplitude value in the search section, and A peak time is searched for in a time section whose value is equal to or greater than a predetermined threshold value, and a time window having a predetermined time width centered on the peak time is determined. That is, for each object, the time from the origin of the reflected wave data to the beginning of the time window and the time from the origin to the end of the time window are determined. The width of the time window can be set to 10 [ms], for example. The threshold value is set so that noise components can be eliminated.
Then, the determined time window becomes a common setting for the reflected wave data output thereafter. As described above, the partial data extraction unit 110a applies, to each of the output reflected wave data, a time window that is commonly set for each object at a time based on the transmission time point of each corresponding transmission wave. The waveform data corresponding to the reflection from the object is extracted.

For example, when the reflected wave data shown in FIG. 4 is output, the partial data extraction unit 110a applies the time windows for the desk 13, the human body 12, and the floor 14, respectively, and the partial waveform data related to each object from the reflected wave data. Cut out. Then, the amplitude is set to 0 except the cut-out time.

The frequency analysis unit 110b performs a Fourier transform process on the reflected wave data input from the received wave demodulation unit 109 and the partial waveform data of each object cut out by the partial data extraction unit 110a to obtain the obtained frequency characteristic (phase characteristic or phase characteristic The amplitude characteristics) are stored in the demodulated wave storage unit 111, respectively.

After the measurement process is started, the reflected wave data obtained by the i-th measurement _{h i (n) (n =} 0, ..., N-1) and _{then, h} i (n) from the cut-out partial waveform data _g i ( The equation of the Fourier transform processing of n) is as shown in the following Expression 1.

Here, N is the number of sampling points for one measurement obtained by multiplying the time length (for example, 128 [ms]) of the reflected wave data obtained by one measurement by the sampling interval (for example, 8 [kHz]). It becomes 1024 (=128 [ms]×8 [kHz]).

Further, the frequency characteristic of the partial waveform data for one reference object cut out by the partial data extraction unit 110a is represented by φ _i (ω) of the following Expression 2 rewriting the above Expression 1.

The subscript i in the equation is the measurement index, that is, when the reflected wave is received after the ultrasonic wave is transmitted by the wave transmission/reception control unit 108 with reference to an appropriate time after the operation starts, for example, the time when the time window is determined. Is an identification number given to each of the reflected waves, and represents the latest time (current time). Further, the phase term φ _i (ω) is assumed to have been subjected to unwrap processing without a 2π jump, and the phase unit φ _i (ω) is set to the sensor unit 10 and the floor 14 set as the reference object. The information on the distance to and is held.

In addition, the frequency analysis unit 110b performs the frequency characteristic H _i (ω) (phase characteristic, amplitude characteristic) obtained by performing the Fourier transform of the above Expression 1 on the reflected wave data, and the partial waveform corresponding to the selected reference object. The frequency characteristic φ _i (ω) (phase characteristic) obtained by performing the Fourier transform on the data is stored in the demodulated wave storage unit 111.

The initial setting unit 110c compares the peaks of the partial waveform data cut out by the partial data extraction unit 110a to determine which peak is the desk 13 (or floor 14) that is the reference object and which peak is the target object. The human body 12 is determined.

Here, the content of the processing performed by the initial setting unit 110c will be described with reference to the flowchart of FIG.
First, ultrasonic waves are transmitted/received at each time (time corresponding to the above-described measurement index) (ST1), the reflected wave received by the microphone 102 is demodulated, and the demodulated digital data is output as reflected wave data. (ST2).

Next, after the power is turned on, the partial data extraction unit 110a cuts out partial waveform data corresponding to each object from the reflected wave data using a predetermined time window determined at the time when the operation is stable (ST3), and the following mathematical formula 3 is used. The partial waveform data of each object cut out using is subjected to Fourier transform, and the obtained result is stored in the demodulated wave storage unit 111 (ST4). In addition, in each Fourier-transformed partial waveform data, the amplitude value other than the portion cut out by the time window is 0, and the time length is 128 [ms].

The subscript i in the formula is the same as the above-mentioned equation 2. The subscript k is the number of the peak cut out in the demodulated wave having the measurement index represented by the subscript i. That is, referring to FIG. 4, the peak 41 is 0, the peak 42 is 1, and the peak 43 is 2.

Next, it is determined whether or not the result obtained by Equation 3 is stored in the demodulated wave storage unit 111 for a predetermined number of times (ST5). In other words, in the present embodiment, the determination is made by performing 15 times of measurement, so in ST5, it is determined whether or not 15 times of measurement are performed.

At this time, if not stored for a predetermined number of times (ST5-No), the process returns to S1 again and the processes of S1 to S4 are performed.
In addition, when stored for a predetermined number of times (ST5-Yes), next, for the same measurement index i, two peaks are sequentially selected and the phases φ _i,k (ω) are stored for a predetermined number of times. Is obtained by brute force and stored in the demodulation storage unit 111 (ST6).

However, the "phase difference" in the processing of ST6 does not simply involve the subtraction of φ _i,k (ω), but introduces the concept of group delay in which the distance information can be extracted from the phase characteristics as follows.
FIG. 7 shows a graph of the phase characteristic φ with respect to the angular frequency ω. When an ideal impulse is obtained by demodulating the reflected wave, the phase characteristic graph 51 has a linear shape, but it does not actually become an impulse, and the phase characteristic graph has a curved shape as shown in FIG. .. Further, it is known that the inverse sign (−Δφ/Δω) of the slope of the phase characteristic 51 corresponds to the distance of the pulse from the time origin (time width from the time origin). Therefore, the initial setting unit 110c obtains the approximate straight line 52 indicated by the dotted line in the figure by the least square method for the section of ω except for the constant width ε _{ω in the} vicinity of 0 and π of ω(0 to π), and the inverse of the slope. The value of the group delay that is the code is obtained. Note that ε _ω is appropriately set to π/10 or the like as a design parameter.

Further, in the following description, for the measurement timing i, the group delay for the k-th pulse is represented by τ _i,k . In the present embodiment, since there are three partial waveform data to be cut out, the combinations of the differences are Δτ _i,0 =τ _i,0 −τ _i,1 , Δτ _i,1 =τ _i,1 −τ _i,2 , Δτ _i,2 =τ _i,2 −τ _i,0 . Therefore, in the process of ST6, when Δτ _i,p for a predetermined number of hours is referred to and a time change when i is changed while fixing p is obtained,
_{p = 0: Δτ -14,0, Δτ} -13,0 ... Δτ -1,0, Δτ 0,0
p=1: Δτ _-14,1 , Δτ _-13,1 ... Δτ _-1,1 , Δτ _0,1
p=2: Δτ _-14,2 , Δτ _-13,2 ... Δτ _-1,2 , Δτ _0,2
Becomes

Further, the initial setting unit 110c stores the difference (Δτ _i,p ) between the group delays in the demodulated wave storage unit 111 for a predetermined number of times (15 points), but the difference between the group delays for the new measurement index is stored. When asked, I try to remove the oldest group delay difference. Therefore, the demodulated wave storage unit 111 always stores the difference between the group delays for 15 points including the latest data for each of p=0, p=1, and p=2.

Returning to the flowchart of FIG. 6, when the difference Δτ _i,p between the group delays τ _{i,k in the} brute force is calculated for the same measurement index i in ST6, the calculated Δτ _i,p (p=0,1) is obtained. , 2) with time is judged to be less than a predetermined threshold value (ST7).

The threshold value used in the process of ST7 is a value that is appropriately set based on the minute displacement that is the detection target. Therefore, for example, when the movement of the rib cage of the human body 12 that is the target object is detected, the rib cage of the lying human body 12 is displaced by about 1 [cm] in the vertical direction (vertical direction). In other words, a value empirically obtained based on the standard amount of displacement to be detected (for example, a value corresponding to 1 [mm] which is 1/10 of 1 [cm]) may be set. If the threshold value is set in this way, the combination including at least the human body 12 has a time change larger than that of the combination of the stationary desk 13 and the floor 14, and the threshold value is definitely exceeded. Therefore, the human body 12 is included. The combination can be easily discriminated.

In the process of ST7, when it is determined that the time change is less than the threshold value (ST7-Yes), it is determined that the objects corresponding to these partial waveform data both have little time change and do not move (ST8). It is stored in the demodulated wave storage unit 111 as motion information (information as to whether or not a moving object is included in the combination) (ST10). That is, when the comparison target with the threshold value is p=2, the difference between the past 14 Δτ _−14,2 , Δτ _−13,2 ... Δτ _−1, and the latest Δτ _0,2 is less than the threshold value. Therefore, it is determined that all the objects are stationary, that is, the combination of the desk 13 and the floor 14.
On the other hand, when it is determined that the temporal change is equal to or more than the threshold value (ST7-No), it is determined that one of the objects corresponding to these partial waveform data includes an object having a movement (displacement) (ST9). ), and stores this result in the demodulated wave storage unit 111 as motion information (ST10). In other words, half of the difference between the compared with threshold when the p = 0, the last of the 14 .DELTA..tau _-14,0, and Δτ _{-13,0 ...} Δτ _-1,0 the latest .DELTA..tau _0,0 Since the above is the threshold value or more, it is determined that the human body 12 is included in this combination. The same applies to p=1.

After the processing of ST10 is finished, it is next determined whether or not all combinations of partial waveform data have been compared (ST11).
At this time, if all combinations are not compared (ST11-No), the process returns to ST6 again and the processes of ST6 to ST10 are appropriately performed.
On the other hand, when all combinations are compared (ST11-Yes), as a final process, based on the motion information stored in the demodulated wave storage unit 111, a stationary object is identified from the results of p=0, 1, and 2 and the stationary object is stopped. Of the objects, one of the stationary objects is selected as a reference object that serves as a reference for the correction processing in the waveform correction section 110d (ST12). In the present embodiment, the objects corresponding to the peaks 41 and 43 are the desk 13 and the floor 14 which are stationary objects, and the object corresponding to the peak 42 is determined to be the human body 12 which is a moving object. Is selected as the reference object. Of course, the desk 13 may be selected as the reference object.

Note that, in step ST12, .DELTA..tau _i corresponding to one of _k, in determining whether that set of _p corresponding to the stationary object, the time change is large .DELTA..tau _i as described _above, set the time variation of _p is The condition is that the pair is divided into small Δτ _i,p . This is because if all the objects that reflected the ultrasonic waves are stationary objects, or if they are all moving bodies and have different moving directions, it will be difficult to determine and a request to the user to manually set the reference object will be displayed. Is required. Therefore, it is assumed that there are a total of three or more objects existing in the observation space, one target object and two or more stationary objects that can be reference objects.

The waveform correction unit 110d corrects the reflected wave data using the result of the Fourier transform processing performed by the frequency analysis unit 110b. That is, the frequency characteristic of the reflected wave data is corrected by the phase characteristic of the frequency characteristic of the reflection component from the reference object.

The waveform correction unit 110d uses the phase information obtained by Fourier transforming the partial waveform data of the reference object stored in the demodulated wave storage unit 111 as φ _i-L+1 (ω),..., φ _i (ω), that is, φ _i-14 (ω),..., φ _i (ω) and the result obtained by Fourier transforming the reflected wave data are H _i-L+1 (ω),..., H _i (ω), that is, H _i-14 As (ω),..., H _i (ω), the correction process is performed using the following Expression 4. As a result, it is possible to determine how much vibration has an influence on a past time based on the current time.

Then, the waveform correction unit 110d causes the demodulated wave storage unit 111 to store X _i,m (ω) obtained by the above Equation 4 as the corrected reflected wave data at the current time.

FIG. 8 is a schematic diagram in which the reflected wave data before correction by the waveform correction unit 110d and the reflected wave data after correction are superimposed. In the figure, the solid line is the reflected wave data after correction, and the dotted line is the reflected wave data before correction, and the difference in the waveform of the reflected wave reflected from each object at each reception time can be understood. By performing the correction by the waveform correction unit 110d, the vibration received by the sensor unit 10 is canceled, and the original waveform indicating the movement of the rib cage of the human body 12 can be obtained as shown by the peak 61.

The reference object is selected by the initial setting unit 110c, but at the same time, the target object can be specified from the reflected wave data. Therefore, the waveform correction unit 110d corrects the phase characteristic of the reflected wave data based on the phase characteristic of the selected reference object, but the present invention is not limited to this, and at least the human body 12 is reflected in the reflected wave data. The corresponding partial waveform data may be cut out in a time window, and the phase characteristic of this partial waveform data may be corrected by the phase characteristic of the partial waveform data of the selected reference object.

The displacement information calculation unit 110e reads the corrected reflected wave data stored in the demodulated wave storage unit 111 for the number of times of measurement L (15 times), calculates displacement information, and outputs the displacement information to the output unit 112.

The displacement information calculation unit 110e performs an inverse Fourier transform process on the read X _i,m (ω) using the following equation 5, and the corrected reflected wave data obtained as a result is x _i,m (n), m=0, ..., 14 (=L-1). Here, n represents a (discrete) time index for the reflected wave, and the larger n is, the farther from the sensor unit 10. This result is a result in which the peak times of the reflections of the reference objects are aligned and shifted in the time direction.

Further, the displacement information calculation unit 110e uses the corrected reflected wave data obtained by the above equation 5 to calculate the displacement information of the target object (that is, the rib cage of the human body 12 from the time change of the corrected reflected wave data for a predetermined number in the past from the current time). Displacement) is calculated. Assuming that the human body 12 is completely stationary, the range N _{0 of} n corresponding to the human body 12 in the L series x _i,m (n), m=0,..., 14 (=L−1). ≦n≦N ₁ will have the same value.
Therefore, it is possible to determine the movement of the rib cage due to the respiration of the human body 12 by evaluating the degree of variation of the latest L series including the current frame.

That is, the following 15 (=L) average response sequences of x _i,m (n) are calculated using the following equation 6.

Then, the displacement information E _1,i (or E _2,i ) is calculated and output from the average response sequence y _i (n) and the time-domain signal x _i,m (n) using the following Equation 7 or Equation 8. It is output to the unit 112.

The demodulated wave storage unit 111 stores information related to the processing of the demodulated wave processing unit 110. For example, the frequency characteristics of the reflected wave data and the partial waveform data obtained by the frequency analysis unit 110b, the difference between the group delays, the movement information of the object, and the waveform correction unit 110d are used as information related to the initial setting of the initial setting unit 110c. The reflected wave data is stored.

The output unit 112 outputs the displacement information E _1,i (or E _2,i ) calculated by the displacement information calculation unit 115e to the control device 20.

The control device 20 is connected to the sensor unit 10 in a wired or wireless communicable manner. The control device 20 communicates various kinds of information (whether wired or wireless) with the sensor unit 10 and with a predetermined notification destination, and the displacement information obtained at each time. From the communication unit 21 and the control unit 23 that controls the communication unit 21 and the determination unit 22 that is received from the communication unit 21 and is determined to be equal to or less than a preset threshold value (stop determination threshold value) for a predetermined time. It has and.

The displacement determination system 1 of the present embodiment observes the displacement (movement) of the chest of the human body 12 that is the detection target, and the stop determination that can determine that the breathing of the human body 12 is stopped as a preset threshold value. The threshold is set. Therefore, when the determination unit 22 determines that the displacement information E _1,i (or E _2,i ) is below the stop determination threshold value for a predetermined time, the control device 20 determines that the human body 12 is not breathing. It is determined that there is a possibility that it has stopped, and a process of notifying a predetermined notification destination via the communication unit 21 is performed.

Next, the processing operation of the sensor unit 10 of the first embodiment described above will be described with reference to FIG.
Here, in the observation space shown in FIG. 1, it is assumed that the human body 12 as the target object lies on the bed 11, and the desk 13 and the floor 14 exist as stationary objects that can be the reference object. In the present embodiment, the floor is used as the reference object. It is assumed that 14 is selected.

First, two initial settings are performed when detecting the movement of the thorax accompanying the breathing of the human body 12 using the sensor unit 10. Since the first initial setting (ST21) is a process according to the process (the flowchart shown in FIG. 6) described in the configuration of the initial setting unit 110c, the description thereof is omitted here.

Next, as the second initial setting (ST22), the ultrasonic wave stored in the modulated wave storage unit 108 is transmitted from the speaker 101, the reflected wave received by the microphone 102 is demodulated, and the time window is determined. To do. In this process, the time window determined in the process of the initial setting of ST21 (flowchart shown in FIG. 6) described above may be used as it is. In addition, the time window for the reference object may be determined again according to the procedure described in the description of the partial data extraction unit 110a.

Next, ultrasonic waves are transmitted toward the target object and the reference object existing in the observation space, and the reflected waves reflected from each object are received (ST23). That is, in the transmission/reception control unit 108, the digital data of the ultrasonic wave to be transmitted is read from the modulated wave storage unit 103, converted into analog data by the D/A converter 104, and then converted from the speaker 101 to the target object through the speaker amplifier 105. Transmit to the reference object. Also, the reflected wave from each object is received by the microphone 102, the analog signal is amplified by the microphone amplifier 106, and then the analog signal is converted into a digital signal by the A/D converter 107.

Next, demodulation processing of the reflected wave converted into the digital signal is performed (ST24). That is, the received wave demodulation unit 109 demodulates the digital signal converted by the A/D converter 107 and outputs reflected wave data.

Next, the frequency analysis unit 110b performs a Fourier transform on the reflected wave data demodulated by the received wave demodulation unit 109 using the above Equation 1 to obtain the frequency characteristic H _i (ω) (ST25). The obtained H _i (ω) is due to the latest wave transmission, so that it is stored in the demodulation wave storage unit 111, and at the same time, the already stored H _{i −L} (ω) (that is, L times before). (Due to transmission) is deleted and updated (ST26).

Further, in parallel with the processing of ST25 and ST26, the partial data extraction unit 110a corresponds to the reference object selected from the reflected wave data demodulated by the received wave demodulation unit 109 using the time window set in ST22. Cut out partial waveform data. Then, in the frequency analysis unit 110b, the reflected wave data of the cut-out reference object is subjected to Fourier transform according to the above-mentioned equation 2 to obtain the phase characteristic φ _i (ω) (ST27). Since the obtained φ _i (ω) is due to the latest wave transmission, it is stored in the demodulated wave storage unit 111, and at the same time, φ _i−L (ω) (that is, L times before) is stored. This is deleted and updated (ST28).

The processes of ST29 to 31 below are repeated for 15 frames by 15 (=L) transmissions. However, in order to reduce the processing amount, the reusable processing result is stored in the demodulated wave storage unit 111 each time. It is configured to be updated and stored and to be read at a later time. Below, it demonstrates as a process reused as needed.

The waveform correction unit 110d reads the frequency characteristic H _i (ω) of the reflected wave data and the phase information φ _i (ω) of the partial waveform data of the reference object stored in the demodulated wave storage unit 111 (ST29). These will be the latest frames.

Next, the waveform correction section 110d corrects the reflected wave data with respect to the phase component according to the equation 4 to obtain X _i,m (ω), and stores it in the demodulated wave storage section 111 (ST30). In the case of the latest frame, m=0, so the parentheses of the exponent component are zero, and X _i,0 (ω)=H _i (ω).

Next, the displacement information calculation unit 110e performs an inverse Fourier transform on the X _i,m (ω) corrected by the waveform correction unit 110d by using the above Equation 5, and the time domain signal x _i,m (n). (ST31). Since the past frame has already been stored, it is not necessary to repeat ST29 to ST31 L times as described above.

Next, the displacement information calculation unit 110e calculates the latest L number of average response series y _i (n) including the current time from x _i,m (n) obtained through the processes of ST29 to ST31 by the above formula 6. , The displacement information E _1,i (or E _2,i ) is obtained from the obtained average response sequence y _i (n) and the time-domain signal x _i,m (n) using the equation 7 or the equation 8 ( ST32).

Then, the obtained displacement information E _1,i (or E _2,i ) is output to the output unit 112 (ST33). In this embodiment, it outputs to the control device 20 shown in FIG. When the process of ST33 is completed, the process returns to ST23 again along the line A in the figure to process the next frame.

Further, the control device 20 determines whether or not the movement of the thorax accompanying the breathing of the human body 12 is normal based on the displacement information input from the sensor unit 10, and if there is an abnormality, that is, breathing stops. If it is determined that there is a warning, a warning is output to a predetermined notification destination.

[Second Embodiment]
Next, a displacement determination system according to the second embodiment of the present invention will be described with reference to FIGS.

The displacement determination system 1 of the second embodiment is different from that of the first embodiment in that a microphone installed near the bed 11 is used as a wave receiving unit instead of a known stationary reference object. Therefore, in the description of the second embodiment, the same components as those in the above-described first embodiment will be denoted by the same reference numerals, and the description of their functions will be omitted, and only the differences from the first embodiment will be described. ..

As shown in FIG. 10A or FIG. 10B, the displacement determination system 1 according to the second embodiment includes the microphone 102 provided in the sensor unit (corresponding to the sensor device in the claims) 10 and a stationary state thereof. A reference microphone 15 whose position is known is provided.
Hereinafter, the microphone 102 provided in the sensor unit 10 will be referred to as a “measurement microphone 102” in order to distinguish it from the reference microphone 15.

In the second embodiment, since the correction is performed based on the ultrasonic wave received by the reference microphone 15, the arrangement position of the reference microphone 15 is not in a positional relationship where the sound waves are aligned with the speaker 101 and the target object in a straight line. That is the condition. In the following description, since the reference microphone 15 directly receives the ultrasonic wave transmitted from the speaker 101, the ultrasonic wave received by the reference microphone 15 is described as a “direct wave”.

FIG. 12A schematically shows reflected wave data obtained by demodulating the reflected wave received by the measurement microphone 102. Assuming that there is no body other than the human body 12 in the measurement range, the peak 71 corresponds to the human body 12.
Further, FIG. 12B schematically shows direct wave data obtained by demodulating the direct wave received by the reference microphone 15. Assuming that there is no object between the speaker 101 and the reference microphone 15, the peak 73 represents the received direct wave.

The reflected wave data 70 shown in FIG. 12A has the origin of the peak time (not shown) of the sneak wave from the speaker 101 to the measurement microphone 102 as described with reference to FIG. .. Further, since the A/D converter 107 digitizes the reflected wave and the direct wave in synchronization with each other, the direct wave data 72 in FIG. 12B also has the same time as the origin.
A peak 71 in FIG. 12A is a result of the ultrasonic waves transmitted from the speaker 101 of the sensor unit 10 being reflected from the human body 12 and being received by the measurement microphone 102. Therefore, in the reflected wave data 70, the ultrasonic waves appear at the time required for the ultrasonic waves to travel back and forth from the speaker 101 to the measurement microphone 102.
On the other hand, a peak 73 in FIG. 12B is a result of the reference microphone 15 directly receiving the ultrasonic wave from the speaker 101. Therefore, the time required for the reference microphone 15 to receive the wave is about half that of the reflected wave. Therefore, the peak 73 in the direct wave data 72 appears on the left side of the peak 71 in the reflected wave data 70 in FIG.

FIG. 11 is a functional block diagram of the sensor unit 10 according to the second embodiment. As shown in FIG. 11, the reference microphone 15 includes a microphone amplifier 15a. The microphone amplifier 15 a converts the ultrasonic wave received by the reference microphone 15 into an analog signal, amplifies the analog signal, and outputs the analog signal to the A/D conversion unit 107.

The received wave demodulation unit 109 demodulates the digital signal of the reflected wave received by the measurement microphone 102 and outputs the demodulated digital data as reflected wave data. Further, the received wave demodulation unit 109 demodulates the direct wave digital signal received by the reference microphone 15 and outputs the demodulated digital data as direct wave data.

The partial data extraction unit 110a determines the absolute value of the amplitude value in the search section in the direct wave data based on the ultrasonic wave transmission time and the distance to the reference microphone 15 at the time when the operation is stable after the power is turned on. The peak time is searched for in a time section in which the value is equal to or greater than a predetermined threshold value, and a predetermined time width is determined as a time window with the peak time as the center. This threshold value is set so that noise components can be eliminated. Then, the partial data extraction unit 110a cuts out the partial waveform data of the direct wave using the determined time window. The determined time window is used in common for each of the direct wave data with the same time and time width in the direct wave data for the correction processing of the reflected wave data described below.

The frequency analysis unit 110b performs a Fourier transform on the reflected wave data input from the received wave demodulation unit 109 and the partial waveform data of the direct wave cut out by the partial data extraction unit 110a by using the above formula 1 or formula 2. The obtained frequency characteristics (phase characteristics and amplitude characteristics) are stored in the demodulated wave storage unit 111, respectively.

The waveform correction unit 110d corrects the reflected wave data using the result of the Fourier transform processing by the frequency analysis unit 110b.

The waveform correction unit 110d uses the phase information obtained by performing Fourier transform on the partial waveform data cut out from the direct wave data stored in the demodulated wave storage unit 111 using the time window as φ _i−L+1 (ω),... , Φ _i (ω), that is, φ _i-14 (ω),..., φ _i (ω), and the result obtained by Fourier transforming the reflected wave data is H _i−L+1 (ω),..., H _i (Ω), that is, H _i−14 (ω),..., H _i (ω), the correction process is performed using the following Expression 9. It should be noted that L=15 as in the first embodiment.

Comparing Expression 9 with Expression 4 used in the waveform correction unit 110d of the first embodiment, the exponent term is doubled. This is because the influence of the vibration of the sensor unit 10 is superposed on the measurement microphone 102 by twice the vibration measured by the reference microphone 15 because the ultrasonic wave reciprocates.

Next, the processing operation of the displacement determination system 1 of the first embodiment described above will be described with reference to FIG.
Regarding the same processing as the processing (the flowchart shown in FIG. 9) in the first embodiment, the corresponding step numbers are shown and the description thereof is omitted or simplified.

First, the ultrasonic wave stored in the modulated wave storage unit 108 is transmitted from the speaker 101, the direct wave received by the reference microphone 15 is demodulated, and the time window is determined (ST41).

The process of ST42 is the same as the process of ST23 in the first embodiment, except that the transmission wave for displacement measurement is transmitted to the reference microphone 15. That is, in ST42, in addition to the processing in ST23, the ultrasonic wave transmitted from the speaker 101 is received by the reference microphone 15, amplified by the microphone amplifier 15a, and then converted into a digital signal by the A/D converter 107. Also do.

The following ST43 to ST45 are the same as the processes of ST24 to ST26 in the first embodiment. That is, in the processing of ST43 to ST45, after demodulating the digital signal of the reflected wave received by the measurement microphone 102, the Fourier transform processing is performed by the above mathematical expression 1 to obtain the frequency characteristic H _i (ω) of the reflected wave data. The demodulated wave storage unit 111 is updated and stored.
Further, in parallel with the processing of ST43 to ST45, the received wave demodulation unit 109 demodulates the direct wave digital signal (ST46), and the partial data extraction unit 110a extracts the direct wave data output from the received wave demodulation unit 109. , ST41 is used to cut out the partial waveform data, and the frequency analysis unit 110b performs a Fourier transform process on the cut out partial waveform data according to the equation 2 to obtain a phase characteristic φ _i (ω) (ST47). ). Since the obtained φ _i (ω) is due to the latest wave transmission, it is stored in the demodulated wave storage unit 111, and at the same time, φ _i−L (ω) (that is, 15(=L) is already stored. ) Deleted (before transmission) and updated (ST48).

The processes of ST49 and 50 below are repeated for 15 frames by the latest 15 transmissions, as in the processes of ST29 and 30 in the first embodiment. Further, the processing of ST51 is the same as the processing of ST30 in the first embodiment.

In ST49, the waveform correction unit 110d reads the frequency characteristic H _i (ω) of the reflected wave data and the phase information φ _i (ω) of the partial waveform data stored in the demodulated wave storage unit 111. These will be the latest frames.

Next, the waveform correction section 110d corrects the phase component of the reflected wave data to obtain X _i,m (ω) according to the above-mentioned equation 9, and stores it in the demodulated wave storage section 111 (ST50). In the case of the latest frame, i=0. Therefore, the parentheses of the exponent component are zero, and X _i,0 (ω)=H _i (ω).

Further, regarding the displacement information calculation processing (ST52, 53) based on the corrected reflected wave data X _i,m (ω) obtained by the inverse Fourier transform in ST51, the processing of ST32, ST33 in the first embodiment. Is the same as.

Further, as in the first embodiment, the control device 20 determines whether or not the movement of the thorax accompanying the respiration of the human body 12 is normal based on the displacement information input from the sensor unit 10, and there is an abnormality. In this case, that is, when it is determined that breathing is stopped, an alarm is output to a predetermined notification destination.

[Operation and effect of the present invention]
As described above, in the displacement determination system 1 according to the first embodiment, the target object to be detected is the human body 12 lying on the bed 11 and serves as a reference object that is placed in a stationary state near the target object. On condition that there are two or more desks 13 and floors 14 in the observation space, ultrasonic waves that are transmission waves are transmitted from the speaker 101 of the sensor unit 10 to the target object and the reference object, and the reflected waves are transmitted to the microphone 102. Receive at. The partial waveform data corresponding to the reflection from the reference object is extracted by applying a time window that is commonly set for the time based on the transmission time of each transmitted wave to each of the reflected wave data based on the received reflected wave. To obtain the phase characteristics. Then, from the difference between the phase characteristic of one partial waveform data of the partial waveform data for a plurality of transmission waves and the phase characteristic of the partial waveform data for another transmission wave, the frequency characteristic of the reflected wave data for the other transmission wave is obtained. The corrected reflected wave data is obtained from the frequency characteristics of the corrected reflected wave data after correction, and the displacement information of the target object is calculated from the time change of the corrected reflected wave data.

In the second embodiment, the reference microphone 15 is arranged in the vicinity of the target object in the observation space instead of the reference object, and ultrasonic waves are transmitted from the speaker 101 of the sensor unit 10 to the target object and the reference microphone 15. The reference microphone 15 directly receives the ultrasonic wave, and the microphone 102 receives the reflected wave from the target object. Next, the partial wave data corresponding to the transmission wave is applied to each of the direct wave data based on the direct wave received by the reference microphone 15 by applying a time window commonly set in the time with the transmission time of each transmission wave as a reference. To obtain the phase characteristic. Then, from the difference between the phase characteristic of one partial waveform data of the partial waveform data for a plurality of transmission waves and the phase characteristic of the partial waveform data for another transmission wave, the frequency characteristic of the reflected wave data for the other transmission wave is obtained. The corrected reflected wave data is obtained from the frequency characteristics of the corrected reflected wave data after correction, and the displacement information of the target object is calculated from the time change of the corrected reflected wave data.

As a result, it is possible to eliminate the influence of the vibration of the sensor unit 10 itself due to the vibration transmitted from the wall or ceiling where the sensor unit 10 is installed. Can be accurately detected.

[Other Embodiments]
By the way, the present invention is not limited to the above-described embodiment, and may be carried out by appropriately changing it according to a use environment and the like, for example, as shown below.

In the above-described first embodiment, it is assumed that at least two of the desk 13 and the floor 14 are present as reference objects, but as the installation condition of the sensor unit 10 according to the present invention, the sensor unit 10 is connected to the human body. If the distance to 12 and the distance to the reference object (for example, the floor 14) are generally known, and the user can manually set and input the sensor unit 10, even one reference object has the same effect.
That is, by referring to the reflected wave data and manually inputting which peak corresponds to the target object or the reference object, the automatic determination process described with reference to FIG. 6 can be omitted. It is possible to significantly reduce the processing amount. In this case, ST21 is omitted in FIG.

Further, in each of the above-described embodiments, the partial data extraction unit 110a has been described as determining the time window at a time when the operation is stable after the power is turned on, but is not limited to this.
For example, when the desk 13 is selected as the reference object instead of the floor 14 in the first embodiment, moving the desk 13 makes it difficult to detect the movement of the thorax accompanying the breathing of the person 12, and thus the reflected wave data is obtained. It is preferable to continuously refer to the peak intensity of the reference object in 1) and perform the time window determination process again when the intensity falls below a certain level.
In addition, in the second embodiment, when the reference microphone 15 is moved, it becomes difficult to detect the movement of the rib cage associated with the breathing of the person 12, so that the intensity of the peak 73 in the direct wave data is continuously referred to. Then, when it falls below a certain level, it is preferable to perform the time window determination process again.

Furthermore, in each of the above-described embodiments, the example in which the waveform correction unit 110d corrects the reflected wave data in the same number as the number of times of measurement L is shown as a unit, but the unit of correction is 2 or more and the number M different from L is used. You can also
However, when M<L, the displacement information calculation unit 110e calculates displacement information in units of M pieces of reflected wave data, and integrates the pieces of displacement information of the reflected wave data.
Further, when M>L, the displacement information calculation unit 110e calculates the displacement information by using L pieces of the M pieces of reflected wave data corrected by the common reference.

Further, in each of the above-described embodiments, the configuration has been described in which the respiratory arrest is detected as an abnormal state by being installed in a public facility (hospital, nursing facility, etc.) or general home, but the present invention is not limited to this. As another application example, for example, the sensor unit 10 is installed in an unattended bank ATM booth, a toilet installed in a station or a commercial facility, and used as a living body detection system for detecting a suspicious person such as a drunken person. You can also

For example, when it is adopted in an unmanned bank ATM, it can be detected that a suspicious person enters a bank ATM booth and lays down on the floor (reference object) as it is. At this time, in addition to the fact that the suspicious individual has stopped breathing, when it is determined that the person is lying down and resting, it is possible to notify the outside to that effect. Further, if the activity state is maintained after entering the room and the user exits the room as it is, the notification processing is not particularly performed, so that unnecessary alarm output can be suppressed.

Furthermore, in each of the above-described embodiments, the ultrasonic sensor is attached at a high place and is directed substantially directly below, but the present invention is not limited to this. For example, in the case of detecting a suspicious person leaning against a wall and getting drunk, such a suspicious person can be detected by the same determination method even when the ultrasonic sensor is directed obliquely downward or sideways.
In this way, the present invention can be realized in a form that does not exceed the scope of the present invention.

1... Displacement determination system 10... Sensor unit 11... Bed 12... Human body 13... Desk 14... Floor 15... Reference microphone (15a... Microphone amplifier)
20... Control device (21... Communication unit, 22... Judgment unit, 23... Control unit)
101... Speaker 102... Microphone 103... Modulated wave storage section 104... D/A conversion section 105... Speaker amplifier 106... Microphone amplifier 107... A/D conversion section 108... Transmission/reception control section 109... Reception wave demodulation section 110... Demodulation wave Processing unit (110a... Partial data extraction unit, 110b... Frequency analysis unit, 110c... Initial setting unit, 110d... Waveform correction unit, 110e... Displacement information calculation unit)
111... Demodulated wave storage unit 112... Output unit

Claims (4)

A transmission unit that intermittently transmits a transmission wave toward a target object and a reference object existing at a known position apart from the target object by a certain amount or more,
A reflection wave receiving unit that receives a reflection wave reflected by the target object and the reference object,
A portion corresponding to the reflection from the reference object by applying a time window that is commonly set in the time based on the transmission time of each transmission wave to each of the reflection wave data based on the reflection wave of each transmission wave. A partial data extraction unit for extracting waveform data,
From the difference between the phase characteristics of the partial waveform data for one of the partial waveform data for the plurality of transmission waves and the phase characteristics of the partial waveform data for the other transmission waves, the other transmission waves a waveform correcting unit that corrects the frequency characteristics of the reflected wave data against the,
A displacement information calculation unit that obtains the corrected reflected wave data from the frequency characteristics of each of the corrected reflected wave data after the correction, and calculates displacement information of the target object from the time change of the corrected reflected wave data.
An output unit that outputs the displacement information to an external device. A wave transmission unit that intermittently transmits a transmission wave toward a target object,
A reflected wave receiving unit that receives the reflected wave reflected by the target object,
A reference wave receiving unit that receives the transmission wave transmitted from the wave transmitting unit as a direct wave at a position apart from the target object by a certain amount or more,
Partial waveform data corresponding to the transmission wave is applied to each of the direct wave data based on the direct wave of each of the transmission waves by applying a time window that is commonly determined in time based on the transmission time of each of the transmission waves. A partial data extraction unit to be extracted,
From the difference between the phase characteristic of the partial waveform data for one of the partial waveform data for the plurality of transmission waves and the phase characteristic of the partial waveform data for the other transmission wave, the other transmission wave A waveform correction unit that corrects the frequency characteristics of the reflected wave data with respect to
A displacement information calculation unit that obtains the corrected reflected wave data from the frequency characteristics of each of the corrected reflected wave data after the correction, and calculates displacement information of the target object from the time change of the corrected reflected wave data.
An output unit that outputs the displacement information to an external device,
A sensor device comprising: A displacement determination system comprising the sensor device according to claim 1 or 2, and at least a control device including an input unit for inputting the displacement information,
The displacement determination system, wherein the control device determines that the target object is inactive and outputs an alarm when the displacement information falls below a stop determination threshold value for a predetermined time. The displacement determination system according to claim 3, wherein the target object is a person in a recumbent state on a reference plane, and the displacement information is a change in distance from the sensor device to the rib cage due to breathing of the person. ..