JP2019158364A - Sensor device and displacement determination system - Google Patents

Abstract

To highly accurately detect the minute displacement of a target object to be detected after eliminating the effect of vibration transmitted from the point of installation.SOLUTION: An ultrasonic wave which is a transmission wave is sent to a target object and a reference object from a speaker 101 of a sensor unit 10, and its reflected wave is received by a microphone 102. A demodulated wave processing unit 110 cuts out, by a common time window, partial waveform data that corresponds to the reference object from reflected wave data derived by demodulating the received reflected wave and obtains phase characteristics by frequency analyzing the cut-out data. Then the demodulated wave processing unit 110 corrects the frequency characteristics of the reflected wave data at other reception times from a difference in phase characteristics between the partial waveform data at a reference time and the partial waveform data at other reception times, finds corrected reflected wave data from the frequency characteristics of the reflected wave data after the correction, and calculates the displacement information of the target object from a temporal change of the corrected reflected wave data for a prescribed past portion from the current time.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a sensor device that eliminates the influence of minute vibrations transmitted from a sensor installation environment, 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 the detection of reflection objects and state determination using their acoustic characteristics. For this reason, the reflection type ultrasonic sensor is widely used, such as an ultrasonic echo device in a medical field, a fish finder in a fishery industry, a nondestructive inspection device for a building in a building field, and a human sensor for an automatic door. The reflective ultrasonic sensor outputs an ultrasonic pulse and receives a reflected wave reflected by a person or an object. The time difference (TOF (Time Of Flight)) from the output of this pulse to the wave reception and the distance from the propagation speed to the reflector and its change are measured to detect the presence and movement of a person or an object.

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

  However, for example, when detecting minute body movements due to breathing, etc., not only for newborns but also for sleeping adults in general households, TOF is measured by transmitting pulsed ultrasonic waves as in the method of Patent Document 1. It is difficult. The reason is that the movement of the thorax due to the breathing of the human body is a difference of about 1 cm at the time of inspiration and the expiration, and the difference in TOF using ultrasonic waves is equivalent to about 30 [μs]. In general burst waves, the burst width is often set to several hundreds [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.

  For this reason, a method using a pulse-modulated wave as described in Patent Document 2 is employed to detect fine movement due to respiration. In this method, for example, when a modulated wave with a bandwidth of 8 [kHz] is used, a distance resolution of about 2 [cm] (about 1 [cm] when considered from a round trip from a transmission to a reception) can be obtained. It is not enough to detect the movement of the rib cage as a concrete distance change. Therefore, in Patent Document 2, the presence or absence of fine movement is determined by detecting the movement of the thorax as a specific change in distance from the time variation of the waveform of the reflected wave.

JP 2010-158517 A JP, 2006-193020, A

  By the way, in the fine motion sensing technique 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 the accuracy may deteriorate.

The vibration of the sensor unit itself is so fine that it cannot be visually confirmed (for example, the amplitude is less than 1 [mm] and the period is around 1 [Hz]), but even if some fixing means is used, the vibration suppression is unavoidable. Such minute vibrations may appear as temporal fluctuations in 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 judge by capturing the fine movement of the target object.

  The present invention is intended to solve the above-described problem, and performs an appropriate state detection by eliminating the influence of minute vibrations transmitted from walls, ceilings, etc., on a device that detects minute displacement of a target object such as a person. It is an object of the present invention to provide a sensor device that can be used, and a displacement determination system that determines the presence or absence of a minute displacement of a target object using the device.

In order to achieve the above-described object, a sensor device according to the present invention transmits a transmission wave intermittently toward a target object and a reference object existing at a known position at a certain distance from the target object. And
A reflected wave receiving unit for receiving a reflected wave reflected by the target object and the reference object;
A portion corresponding to reflection from the reference object by applying a time window defined in common to each of the reflected wave data based on the reflected wave for each transmission wave in a time based on the transmission time of each transmission wave A partial data extraction unit for extracting waveform data;
Of the partial waveform data for the plurality of transmission waves, the other transmission wave is determined from the difference between the phase characteristic of the partial waveform data for the transmission wave and the phase characteristic of the partial waveform data for the other transmission wave. A waveform correction unit for correcting the frequency characteristics of the reflected wave data with respect to
A displacement information calculation unit that obtains corrected reflected wave data from the frequency characteristics of each of the reflected wave data after correction, and calculates displacement information of the target object from a time change of the plurality of 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 includes a wave transmission unit that intermittently transmits a transmission wave toward the target object,
A reflected wave receiving unit for receiving a reflected wave reflected by the target object;
A reference receiving unit that receives a transmission wave transmitted from the transmission unit as a direct wave at a position apart from the target object by a certain distance;
The partial waveform data corresponding to the transmission wave is applied to each of the direct wave data based on the direct wave for each transmission wave by applying a time window defined in common with respect to the transmission time of each transmission wave. A partial data extraction unit to be extracted;
Of the partial waveform data for the plurality of transmission waves, the other transmission wave is determined from the difference between the phase characteristic of the partial waveform data for the transmission wave and the phase characteristic of the partial waveform data for the other transmission wave. A waveform correction unit for correcting the frequency characteristics of the reflected wave data with respect to
A displacement information calculation unit that obtains corrected reflected wave data from the frequency characteristics of each of the reflected wave data after correction, and calculates displacement information of the target object from a time change of the plurality of corrected reflected wave data;
An output unit for outputting the displacement information to an external device;
It is characterized by having.

Furthermore, the displacement determination system according to the present invention is a displacement determination system having at least a control device that includes the sensor device described above and includes an input unit that inputs the displacement information.
When the displacement information falls below a stop determination threshold for a predetermined time, the control device determines that the activity of the target object is stopped and outputs an alarm.

  In the displacement determination system according to the present invention, the target object may be a person lying on the reference plane, and the displacement information may be a change in distance from the sensor device to the thorax accompanying the person's breathing.

  According to the sensor device of the present invention, it is possible to eliminate the influence of vibration of the sensor device itself due to vibration transmitted from the wall or ceiling on which the sensor device is installed. Therefore, the sensor device is not necessarily an ideal environment. However, it is possible to accurately detect a minute displacement such as the movement of the thorax accompanying the breathing of the human body.

  Further, according to the displacement determination system of the present invention, the sensor device can detect a minute displacement of a target object to be detected by canceling vibration transmitted from a wall or ceiling to be installed with high accuracy. 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, it is possible to determine the state of the activity stop of the target object with high accuracy.

(A), (b) is a conceptual diagram which shows the outline | summary 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 which concerns on 1st Embodiment, (b) is a functional block diagram of a demodulation wave process part. It is a wave form diagram which shows an example of the ultrasonic wave (sweep signal) transmitted as a transmission wave. It is the wave form diagram which showed typically the reflected wave which made a certain transmission time the origin. It is the wave form diagram which showed typically the demodulated wave which demodulated the reflected wave received at different time. It is the flowchart which showed the processing content implemented by the initial setting part. It is a graph of the phase characteristic with respect to the angular frequency for demonstrating the concept of group delay. FIG. 6 is a schematic diagram in which demodulated wave data of a received reflected wave and demodulated wave data after phase component correction by a waveform correction unit are superimposed. It is a flowchart explaining a series of processing operations of the sensor unit of the first embodiment. (A), (b) is a conceptual diagram which shows the outline | summary of the displacement determination system which concerns on 2nd Embodiment which concerns on this invention. (A) is a functional block diagram of the sensor unit which concerns on 2nd Embodiment, (b) is a functional block diagram of a demodulation wave process part. (A) is a waveform diagram schematically showing how the reflected wave received by the measurement microphone is demodulated, and (b) schematically shows how the direct wave received by the reference microphone is demodulated. It is the shown waveform diagram. It is a flowchart explaining a series of process operation | movement of the sensor unit of 2nd Embodiment.

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

  Note that the drawings attached to the present specification may be schematically expressed by appropriately changing the scale, vertical / horizontal dimension ratio, shape, etc. from the actual one for convenience of illustration and easy understanding. However, the interpretation of the present invention is not limited. Therefore, the present invention is not limited by the embodiment described with reference to the accompanying drawings, and all other forms, examples, operation techniques, and the like that can be considered by those skilled in the art based on this embodiment are included in the present invention. It shall be included in the category.

  In this specification, in the following description with reference to the accompanying drawings, when the words “up”, “down”, “left”, and “right” are used to indicate directions and positions, this is indicated by the user as shown in the drawings. Matches top, bottom, left, and right.

Hereinafter, as a preferred embodiment 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 the state of a person will be described.

[First Embodiment]
A displacement determination system 1 according to a first embodiment of the present invention will be described with reference to FIGS.
FIGS. 1A and 1B are diagrams schematically illustrating a displacement determination system 1 according to the first embodiment. As shown in each figure, the displacement measurement system 1 is a sensor unit that is attached above (ceiling or wall surface) in an observation space (room) where 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. For example, when there is no movement near the thorax, there is a possibility that the breathing may stop and a predetermined notification not shown It is comprised with the control apparatus 20 which reports to the security company etc. which are ahead.

In this embodiment, the target object whose displacement is detected by the sensor unit 10 is the sleeping human body 12 lying on the bed 11 in a supine position, and the minute displacement to be detected is the movement of the thorax accompanying breathing.
The reference object is furniture or a floor arranged in the vicinity of the bed 11 and is required to be stationary at all times. In the present embodiment, the existence and position (distance from the sensor unit 10) are assumed to be known.

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

In addition, the sensor unit 10 is installed at a position where a transmission wave is transmitted to the target object and the reference object and the reception wave can be reliably received. In the first embodiment, the sensor unit 10 is directed downward on the ceiling almost directly above the person who lies. Although it is inevitable that the sensor unit 10 receives 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 transmission unit that transmits a transmission wave, and a reception wave that is a reflected wave reflected from the target object and the reference object by the transmission wave transmitted from the speaker 101. A microphone 102 that functions as a wave receiving unit is provided. As shown in FIG. 2 (a), 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) while facing the target object and the reference object. Has been placed.

  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 wave control unit 108, and a reception. A wave demodulation unit 109, a demodulation wave processing unit 110, a demodulation wave storage unit 111, and an 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 pulsed modulation wave refers to a frequency modulation wave whose frequency is linearly changed or a phase modulation wave using an M-sequence, etc., and demodulates and captures the position of the object in a high accuracy. Can measure the distance. The burst wave is a signal having a single frequency (for example, 40 [kHz]) that is output in a very short time (less than 1 [ms]). In the demodulation process, the envelope is detected and the peak is obtained. You can measure distance by position.

  The modulated wave storage unit 103 of this embodiment stores digital data of a sweep signal that is a pulsed modulated wave in advance. A graph 30 in FIG. 3 illustrates a waveform of the sweep signal, and a graph 31 illustrates a time-frequency characteristic of time of the sweep signal. The sweep signal is a signal having the property that the frequency changes with time although the amplitude is constant. In the example of FIG. 3, the frequency gradually decreases with time. By using such a signal, it is known that the reception power is ensured and the resolution of the distance measurement result is improved compared to outputting 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, a sweep signal outside the audible range is adopted as a transmission wave, and thus the transmission wave transmitted from the speaker 101 is expressed 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 a timing according to the output instruction of the transmission / reception wave control unit 108, and D / A converts the read digital data.

  The speaker amplifier 105 amplifies the analog data output from the D / A conversion unit 104 and drives the speaker 101. Thereby, 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 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 in accordance with an output instruction from the transmission / reception control unit 108.

The transmission / reception wave control unit 108 has a function of controlling the timing of transmitting an ultrasonic wave and a function of associating an ultrasonic wave with a reflected wave.
In the present embodiment, the ultrasonic wave transmission timing is every 200 [ms]. In the present embodiment, the number of measurements L required to determine the presence or absence of thorax movements associated with breathing of the human body 12 is fifteen.
Note that the number of transmissions can be set as appropriate 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 128 [ms], and the sensor unit 10 shown in FIG. 1 is attached at a position about 2 [m] directly above the human body 12. To do.

  The reception wave demodulator 109 demodulates the digital signal output from the A / D converter 107 and outputs the demodulated digital data as reflected wave data. A pulse waveform appears in the reflected wave data obtained by demodulating the sweep signal.

FIG. 4 schematically shows reflected wave data 40. The peak 41 in the reflected wave data 40 is a component corresponding to the reflection from the desk 13, the peak 42 is a reflection from the human body 12, and the 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 the one that is included in the demodulated reflected wave data by the partial data extraction unit 110a described later and matches the peak of a sneak wave (not shown). Since the sneak wave directly sunk from the speaker 101 to the microphone 102 is not affected by the vibration of the sensor unit 10, the origin of the reflected wave data is always after a certain time from the transmission time of the transmission wave. Further, the peak time substantially represents the round trip time of the ultrasonic wave. When the round trip time is long, the distance from the sensor unit 10 to the object reflecting the ultrasonic wave is long, and when the round trip time is short, the distance is short. In the present embodiment, the length of the reflected wave data is 128 [ms].

The demodulated wave processing unit 110 corrects the reflected wave data demodulated by the received wave demodulating unit 109 to eliminate the influence of vibration of the sensor unit 10 itself, and obtains displacement information related to minute displacement of the target object to output the output unit. 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 receives 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 reflected waves received while the sensor unit 10 is vibrating. In FIG. 5, for easy understanding, the actual variation is greatly exaggerated.

  FIG. 5 (b) shows 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 of the reflected wave data of FIG. 5 (a) indicated by a one-dot chain line in the figure. It can be seen that the detection is earlier than the peak time, shifted to the left as indicated by the arrow in the figure. FIG. 5C shows the 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 is the reflected wave of FIG. 5A indicated by a one-dot chain line in the figure. As shown by the arrows in the figure, it can be seen that the data is detected later than the peak time of the data.

  When the sensor unit 10 vibrates, the peak time variation due to the vibration of the sensor unit 10 is superimposed on the peak time variation due to the fine motion of the human body 12, and therefore the fine motion of the human body 12 cannot be simply determined from the peak time variation. On the other hand, since the desk 13 or the floor 14 does not move 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, the peak time related to the human body 12 that is the target object is corrected based on the peak time related to the reference object, and the sensor unit 10 vibrates in a pseudo manner. The peak time change when not doing so is obtained. That is, it means that the reflected wave data of FIGS. 5A to 5C are shifted in the time direction so as to align the peak time with respect to the reference object. Thereby, even a slight displacement of the target object can be accurately determined.

The partial data extracting unit 110a is a means for extracting (cutting out) data having a predetermined time width centered on the peak time from the reflected wave data output from the received wave demodulating unit 109. Therefore, the partial data extraction unit 110a initially sets a time window for clipping for each object in a predetermined period in which the operation is stabilized after the power is turned on.
That is, the partial data extraction unit 110a determines a search section based on the ultrasonic wave transmission time and the distance to each object in the reflected wave data, obtains the absolute value of the amplitude value in the search section, A peak time is searched in a time interval 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, 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 for each object. 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.
The determined time window is a common setting for the reflected wave data output thereafter. As described above, the partial data extraction unit 110a applies the time window defined in common for each object to each of the output reflected wave data at a time based on the transmission time point of each corresponding transmission wave. Waveform data corresponding to reflection from an object is extracted.

For example, when the reflected wave data shown in FIG. 4 is output, the partial data extraction unit 110a applies time windows for the desk 13, the human body 12, and the floor 14, and the partial waveform data relating to each object from the reflected wave data. Cut out. The amplitude is set to 0 except for 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 extracted by the partial data extraction unit 110a, and the obtained frequency characteristics (phase characteristics and phase characteristics). (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 expression of the Fourier transform process of n) is as shown in the following formula 1.

  Here, N is the number of sampling points for one measurement obtained by multiplying the time length (for example, 128 [ms]) of reflected wave data obtained by one measurement by a sampling interval (for example, 8 [kHz]). 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 expressed by φ _i (ω) of the following formula 2 obtained by rewriting the above formula 1.

The subscript i in the expression is a measurement index, that is, an appropriate time after the start of operation, for example, when a reflected wave is received after transmitting an ultrasonic wave by the transmission / reception control unit 108 based on 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) as appropriate. The phase term φ _i (ω) is assumed to have been subjected to an unwrapping process without a jump of 2π. The phase term φ _i (ω) has a floor 14 set as a sensor unit 10 and a reference object. And distance information is held.

In addition, the frequency analysis unit 110b performs the frequency characteristics H _i (ω) (phase characteristics and amplitude characteristics) obtained by performing the Fourier transform of Equation 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 subjecting the data to Fourier transform 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 and determines which peak is the desk 13 (or floor 14) which is the reference object, which peak is the target object. The human body 12 is determined.

Here, the contents of processing performed by the initial setting unit 110c will be described with reference to the flowchart of FIG.
First, ultrasonic waves are transmitted and 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, 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 stabilized after the power is turned on (ST3), 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). Note that each partial waveform data subjected to Fourier transform has an amplitude value of 0 other than the portion cut out by the time window, and the time length is 128 [ms].

  The subscript i in the formula is the same as the above formula 2. The subscript k is the number of the peak extracted in the demodulated wave having the measurement index represented by the subscript i. That is, in 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 hours (ST5). That is, in the present embodiment, the determination is performed by performing 15 measurements, and therefore it is determined in ST5 whether or not 15 measurements have been performed.

At this time, if only a predetermined number of hours have not been stored (ST5-No), the process returns to S1 again and the processes of S1 to S4 are performed.
If only the predetermined number of hours are stored (ST5-Yes), next, for the same measurement index i, two peaks are sequentially selected and stored for a predetermined number of hours φ _{i, k} (ω). Is obtained by brute force and stored in the demodulation storage unit 111 (ST6).

However, the “phase difference” in the process of ST6 is not simply subtraction of φ _{i, k} (ω), but introduces the concept of group delay that can extract distance information 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 actually does not become an impulse, and the phase characteristic graph has a curved shape as shown in FIG. . Further, it is known that the reverse sign (−Δφ / Δω) of the slope of the phase characteristic 51 corresponds to the distance from the time origin of the pulse (time width from the time origin). Therefore, the initial setting unit 110c obtains an approximate straight line 52 indicated by a dotted line in the figure by the least square method for a section of ω excluding ω (0 to π) near 0 and a constant width ε _ω near π, and reverses the slope. The value of the group delay which is a sign is obtained. Incidentally, the epsilon _omega, and the like [pi / 10 as appropriate design parameters.

In the following description, for the measurement timing i, the group delay for the kth pulse is represented as τ _{i, k} . In this embodiment, since there are three partial waveform data to be cut out, the combinations of 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 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
It becomes.

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 hours (for 15 time points). When asked, the oldest group delay difference is deleted. Therefore, the demodulated wave storage unit 111 always stores the difference between the group delays for 15 time 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} is determined for the same measurement index i in ST6, next, Δτ _{i, p} (p = 0, 1) , 2) is determined whether or not the time change is 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 a minute displacement that is a detection target. Therefore, for example, when the movement of the thorax accompanying the breathing of the human body 12 that is the target object is a detection target, the thorax of the lying human body 12 is displaced by about 1 [cm] in the vertical direction (vertical direction). That is, a value empirically obtained based on a standard amount of displacement to be detected (for example, a value corresponding to 1 [mm] corresponding to 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 the combination of the stationary desk 13 and the floor 14 and surely exceeds the threshold value, so the human body 12 is included. The combination can be easily determined.

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 both of the objects corresponding to the partial waveform data have a small time change and no movement (ST8), and this result is obtained. It is memorize | stored in the demodulation wave memory | storage part 111 as motion information (information whether the moving object is contained in the combination) (ST10). That is, when compared with the threshold value of p = 2, past fourteen Δτ _-14,2, Δτ _{-13,2 ...} Δτ _-1,2 the difference is less than the threshold with the latest .DELTA..tau _{0, 2} Therefore, it is determined that any object is stationary, that is, a combination of the desk 13 and the floor 14.
On the other hand, when it is determined that the time change is equal to or greater than the threshold value (ST7-No), it is determined that one of the objects corresponding to the partial waveform data includes an object with movement (displacement) (ST9). The result is stored 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 equal to or greater than the threshold value, it is determined that the human body 12 is included in this combination. The same applies to p = 1.

When the process of ST10 is completed, it is next determined whether or not all combinations of partial waveform data have been compared (ST11).
At this time, if not all combinations are compared (ST11-No), the process returns to ST6 again and the processes from ST6 to ST10 are performed as appropriate.
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, 2, and stationary. Among the objects, any stationary object is selected as a reference object to be used as a correction processing standard in the waveform correction unit 110d (ST12). In this embodiment, the object corresponding to the peak 41 and the peak 43 is 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 a reference object. Of course, the desk 13 may be selected as the reference object.

In step ST12, when determining which set of Δτ _{i, p} corresponding to which k corresponds to a stationary object, the set of Δτ _{i, p} having a large time change and the time change are as described above. The condition is that it is divided into a small set of Δτ _{i, p} . If all the objects that reflected the ultrasonic waves are stationary objects, or if they are all moving objects and move in different directions, it will be difficult to make a decision and a message will be displayed to request the user to manually set the reference object. Because is required. Accordingly, it is assumed that there are three or more objects in the observation space, that is, one target object and two or more stationary objects that can serve as 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 among the frequency characteristics of the reflected 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 transform of the reflected wave data are H _{i−L + 1} (ω),..., H _i (ω), that is, H _i-14. As (ω),..., H _i (ω), correction processing is performed using the following equation (4). As a result, it is possible to determine how much vibration has an effect on a past time with the current time as a reference.

Then, the waveform correcting unit 110d stores the X _{i, m} (ω) obtained in the above equation 4 in the demodulated wave storage unit 111 as the reflected wave data after correction at the current time.

FIG. 8 is a schematic diagram in which the reflected wave data before correction by the waveform correcting unit 110d and the reflected wave data after correction are overlapped. 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 it is in a state in which the difference in waveform at each reception time of the reflected wave reflected from each object can be grasped. By performing the correction by the waveform correction unit 110d, the vibration received by the sensor unit 10 is canceled, and an original waveform indicating the movement of the thorax of the human body 12 as indicated by the peak 61 can be obtained.

  The reference object is selected by the initial setting unit 110c. 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 is not limited to this, and at least the human body 12 is selected from the reflected wave data. Corresponding partial waveform data may be cut out with a time window, and the phase characteristics of the partial waveform data may be corrected with the phase characteristics 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 measurement count L (for 15 time points), calculates the displacement information, and outputs it 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 formula 5, and the corrected reflected wave data as a result is converted to x _{i, m} (n), m = 0, ..., 14 (= L-1). Here, n represents a (discrete) time index for the reflected wave, and a larger n represents a position farther from the sensor unit 10. This result is a result obtained by aligning the reflection peak times with respect to the reference object 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 thorax of the human body 12) from the time change of the corrected reflected wave data for the past predetermined number from the current time. Displacement). Assuming that the human body 12 is completely stationary, an n range N ₀ corresponding to the human body 12 in the L sequences x _{i, m} (n), m = 0,..., 14 (= L−1). ≦ n ≦ N ₁ has the same value.
Therefore, it is possible to determine the movement of the thorax due to the respiration of the human body 12 by evaluating the degree of variation of the last L sequences including the current frame.

That is, the nearest 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 from the average response sequence y _i (n) and the time domain signal x _{i, m} (n) using the following equation 7 or 8, and output. 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 partial waveform data obtained by the frequency analysis unit 110b, the information relating to the initial setting of the initial setting unit 110c, the difference between group delays, the object motion information, and the waveform correction unit 110d are corrected. 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 115 e to the control device 20.

  The control device 20 is connected to the sensor unit 10 so that wired or wireless communication is possible. The control device 20 communicates various information with the sensor unit 10 and with a predetermined notification destination (whether wired or wireless), and the displacement information obtained at each time is transmitted to the sensor unit 10. And a control unit 23 that controls the communication unit 21 and the determination unit 22 to determine whether or not it has continued for a predetermined time that it is below a preset threshold value (stop determination threshold value). And.

The displacement determination system 1 according to the present embodiment observes the displacement (movement) of the thorax of the human body 12 that is the detection target, and can determine that the human body 12 has stopped breathing as a preset threshold. A threshold is set. Therefore, if the control unit 20 determines that the state where the displacement information E _{1, i} (or E _{2, i} ) is below the stop determination threshold continues for a predetermined time by the determination unit 22, the human body 12 is not breathing. It is determined that there is a possibility of stopping, 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 a human body 12 as a target object lies on the bed 11 and a desk 13 and a floor 14 exist as stationary objects that can serve as reference objects. In the present embodiment, a floor is used as a reference object. 14 is selected.

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

  Next, as the second initial setting (ST22), the ultrasonic wave stored in the modulation wave storage unit 108 is transmitted from the speaker 101, and the reflected wave received by the microphone 102 is demodulated to determine the time window. To do. In this process, the time window determined in the process of the initial setting of ST21 described above (the flowchart shown in FIG. 6) may be used as it is. Further, 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, an ultrasonic wave is transmitted toward a target object and a reference object existing in the observation space, and a reflected wave reflected from each object is received (ST23). That is, in the transmission / reception control unit 108, ultrasonic digital data to be transmitted is read from the modulation wave storage unit 103, converted into analog data by the D / A converter 104, and then the target object from the speaker 101 through the speaker amplifier 105. Transmit to the reference object. In addition, 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, the demodulation process 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 analyzing unit 110b performs Fourier transform on the reflected wave data demodulated by the received wave demodulating unit 109 using Equation 1 to obtain a frequency characteristic H _i (ω) (ST25). Since the obtained H _i (ω) is based on the latest transmission, it is stored in the demodulated wave storage unit 111, and at the same time, H _i−L (ω) already stored (that is, the Lth previous transmission). Delete (updated by transmission) and update (ST26).

In parallel with the processing in ST25 and ST26, partial data extraction section 110a corresponds to the reference object selected from the reflected wave data demodulated by received wave demodulation section 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 formula 2 to obtain the phase characteristic φ _i (ω) (ST27). Since the obtained φ _i (ω) is based on the latest 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) Delete (updated by transmission) and update (ST28).

  The processing of ST29 to ST31 described below is 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. The configuration is such that it is updated and stored and 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 stored in the demodulated wave storage unit 111 and the phase information φ _i (ω) of the partial waveform data of the reference object (ST29). These are the latest frames.

Next, the waveform correcting unit 110d corrects the reflected wave data with respect to the phase component in accordance with Equation 4 to obtain X _{i, m} (ω), and stores it in the demodulated wave storage unit 111 (ST30). Since m = 0 in the case of the latest frame, the parenthesis of the exponent component is zero, and X _{i, 0} (ω) = H _i (ω).

Next, the displacement information calculation unit 110e performs inverse Fourier transform on the X _{i, m} (ω) corrected by the waveform correction unit 110d using the above equation 5 to perform the time domain signal x _{i, m} (n). (ST31). Since the past frames have already been stored, it is not actually necessary to repeat ST29 to ST31 L times as described above.

Next, the displacement information calculation unit 110e calculates the average response sequence y _i (n) for the latest L times including the current time from x _{i, m} (n) obtained through the processes of ST29 to ST31, using the above equation (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 above equation 7 or 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 apparatus 20 shown in FIG. When the process of ST33 is completed, the process returns to ST23 again along A in the figure, and the next frame is processed.

  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, the breathing stops. If it is determined that the alarm is detected, an alarm is output to a predetermined notification destination.

[Second Embodiment]
Next, a displacement determination system according to a 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 the first embodiment in that a microphone installed in the vicinity of the bed 11 is used as a wave receiving unit instead of a known reference object that is stationary. Therefore, in the description of the second embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the functional description thereof is omitted, and only the differences from the first embodiment will be described. .

As shown in FIG. 10 (a) or (b), the displacement determination system 1 according to the second embodiment includes a microphone 102 provided in a sensor unit (corresponding to a sensor device in the claims) 10 in a stationary state. A reference microphone 15 having a known position 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 made based on the ultrasonic wave received by the reference microphone 15, the arrangement position of the reference microphone 15 is not a positional relationship in which the sound wave that is aligned with the speaker 101 and the target object is blocked. On 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 expressed as “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 human body 12 in the measurement range, the peak 71 corresponds to the human body 12.
FIG. 12B schematically shows direct wave data obtained by demodulating the direct wave received by the reference microphone 15. Assuming that no object exists between the speaker 101 and the reference microphone 15, the peak 73 represents the received direct wave.

Note that the reflected wave data 70 shown in FIG. 12A has a peak time (not shown) of the sneak wave from the speaker 101 to the measurement microphone 102 as the origin, as described with reference to FIG. . Since the A / D converter 107 digitizes the reflected wave and the direct wave in synchronism, the direct wave data 72 in FIG. 12B also uses the same time as the origin.
A peak 71 in FIG. 12A is a result of the ultrasonic wave transmitted from the speaker 101 of the sensor unit 10 being reflected from the human body 12 and received by the measurement microphone 102. Therefore, the reflected wave data 70 appears 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, the 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 of the reflected wave data 70 in FIG.

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

  The received wave demodulator 109 demodulates the reflected wave digital signal received by the measurement microphone 102 and outputs the demodulated digital data as reflected wave data. The reception wave demodulator 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 calculates 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 in a time section in which the value is equal to or greater than a predetermined threshold, and a predetermined time width is determined as a time window around the peak time. This threshold value is set so that a noise component can be excluded. 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 in the same time and time width in the direct wave data for the correction process of the reflected wave data described below.

  The frequency analyzing unit 110b performs Fourier transform on the reflected wave data input from the received wave demodulating unit 109 and the partial waveform data in the direct wave extracted by the partial data extracting unit 110a using the above Equation 1 or Equation 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 performed by the frequency analysis unit 110b.

The waveform correction unit 110d obtains φ _{i−L + 1} (ω), phase information obtained by Fourier transforming partial waveform data cut out from the direct wave data stored in the demodulated wave storage unit 111 using a time window. , Φ _i (ω), that is, φ _i-14 (ω),..., Φ _i (ω), and the result obtained by performing Fourier transform on the reflected wave data is H _{i−L + 1} (ω) _,. (Ω), that is, H _i-14 (ω),..., H _i (ω), correction processing is performed using the following equation (9). Note that L = 15 as in the first embodiment.

When the formula 9 is compared with the formula 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 superimposed on the measurement microphone 102 by twice the vibration measured by the reference microphone 15 as the ultrasonic waves reciprocate.

Next, the processing operation of the displacement determination system 1 of the first embodiment described above will be described with reference to FIG.
In addition, regarding the process similar to the process (flowchart shown in FIG. 9) in 1st Embodiment, a corresponding step number is described and the description is abbreviate | omitted or simplified.

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

  The process of ST42 is the same as the process of ST23 in the first embodiment, except that a 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 next ST43 to ST45 are the same as the processing 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 process is performed by the above equation 1 to obtain the frequency characteristic H _i (ω) of the reflected wave data. The demodulated wave storage unit 111 is updated and stored.
In parallel with the processing of ST43 to ST45, the reception wave demodulation unit 109 demodulates the direct wave digital signal (ST46), and the partial data extraction unit 110a uses the direct wave data output from the reception wave demodulation unit 109. The partial waveform data is cut out by using the time window set in ST41, and the phase analysis φ _i (ω) is obtained by subjecting the cut-out partial waveform data to Fourier transform processing according to the above equation 2 in the frequency analysis unit 110b (ST47). ). Since the obtained φ _i (ω) is based on the latest transmission, it is stored in the demodulated wave storage unit 111 and at the same time, φ _i−L (ω) (that is, 15 (= L ) Delete the previous transmission) and update (ST48).

  The processes of ST49 and 50 below are repeated for 15 frames by the latest 15 transmissions, similarly to the processes of ST29 and 30 in the first embodiment. Further, the process of ST51 is the same as the process 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 stored in the demodulated wave storage unit 111 and the phase information φ _i (ω) of the partial waveform data. These are the latest frames.

Next, the waveform correction unit 110d corrects the phase component of the reflected wave data according to the above equation 9, obtains X _{i, m} (ω), and stores it in the demodulated wave storage unit 111 (ST50). Since i = 0 in the case of the latest frame, the parenthesis of the exponent component is zero, and X _{i, 0} (ω) = H _i (ω).

In addition, regarding displacement information calculation processing (ST52, 53) based on X _{i, m} (ω) that is the corrected reflected wave data obtained by inverse Fourier transform in ST51, the processing of ST32 and ST33 in the first embodiment. It is the same.

  Further, as in the first embodiment, 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 there is an abnormality. In this case, that is, when it is determined that breathing has stopped, an alarm is output to a predetermined notification destination.

[Operation and effect of the present invention]
As described above, the displacement determination system 1 according to the first embodiment is a reference object placed in a stationary state near the target object, with the target object to be detected as the human body 12 lying on the bed 11. On the condition that there are two or more desks 13 and floors 14 in the observation space, ultrasonic waves as 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. Partial waveform data corresponding to reflection from the reference object is extracted by applying a time window defined in common to each of the reflected wave data based on the received reflected wave in the time based on the transmission time of each transmission wave. To obtain phase characteristics. Then, the frequency characteristic of the reflected wave data for the other transmission wave is obtained from the difference between the phase characteristic of the partial waveform data of the partial waveform data for the plurality of transmission waves and the phase characteristic of the partial waveform data for the other transmission waves. Correction is performed, corrected reflected wave data is obtained from the frequency characteristics of each of the plurality of corrected reflected wave data, and displacement information of the target object is calculated from a time change of the plurality of corrected reflected wave data.

  In the second embodiment, the reference microphone 15 is disposed 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 ultrasonic wave is directly received by the reference microphone 15 and the reflected wave from the target object is received by the microphone 102. Next, partial waveform 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 defined in common with respect to the transmission time of each transmission wave. To obtain the phase characteristics. Then, the frequency characteristic of the reflected wave data for the other transmission wave is obtained from the difference between the phase characteristic of the partial waveform data of the partial waveform data for the plurality of transmission waves and the phase characteristic of the partial waveform data for the other transmission waves. Correction is performed, corrected reflected wave data is obtained from the frequency characteristics of each of the plurality of corrected reflected wave data, and displacement information of the target object is calculated from a time change of the plurality of corrected reflected wave data.

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

[Other embodiments]
By the way, this invention is not limited to embodiment mentioned above, For example, as shown below, it can also implement by changing suitably according to a use environment etc., for example.

In the first embodiment described above, the description is based on the assumption that at least two of the desk 13 and the floor 14 exist as reference objects. However, as an installation condition of the sensor unit 10 according to the present invention, the sensor unit 10 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 to the sensor unit 10, the same effect can be obtained with one reference object.
That is, the user can manually input which peak corresponds to the target object or the reference object with reference to the reflected wave data, so that the automatic discrimination process described with reference to FIG. 6 can be omitted. As a result, the amount of processing can be greatly reduced. In this case, ST21 is omitted in FIG.

Further, in each of the above-described embodiments, the partial data extraction unit 110a determines that the time window is determined at a time when the operation after power-on is stable, but is not limited thereto.
For example, when the desk 13 is selected instead of the floor 14 as the reference object in the first embodiment, it is difficult to detect the movement of the thorax accompanying the breathing of the person 12 when the desk 13 is moved. It is preferable to continuously refer to the peak intensity of the reference object in the above and perform the time window determination process again when the peak intensity falls below a certain level.
In the second embodiment, if the reference microphone 15 is moved, it becomes difficult to detect the movement of the thorax accompanying the breathing of the person 12 as well. Therefore, the intensity of the peak 73 in the direct wave data is continuously referred to. Thus, it is preferable to perform the time window determination process again when the value falls below a certain level.

Further, in each of the above-described embodiments, the example in which the waveform correction unit 110d corrects the reflected wave data having the same number as the number of times of measurement L as a unit has been described. 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 displacement information for L pieces of reflected wave data.
When M> L, the displacement information calculation unit 110e calculates the displacement information using L pieces of the M pieces of reflected wave data corrected with the common reference.

  Moreover, although each embodiment mentioned above demonstrated by the structure which installs in a public facility (a hospital, a nursing care facility, etc.) and a general household, and detects a respiratory stop as an abnormal state, it is not limited to this. As another application example, for example, the sensor unit 10 is installed in an unmanned bank ATM booth, a toilet installed in a station premises or a commercial facility, and used as a living body detection system for detecting a suspicious person such as a drunk person. You can also.

For example, when employed in an unattended bank ATM, it can be detected that a suspicious person has entered a bank ATM booth and lies on the floor (reference object) as it is. At this time, in addition to the fact that the suspicious person has stopped breathing, if it is determined that the person has laid down and is in a resting state, it can be notified to the outside. Further, if the user keeps the active state after entering the room and leaves the room as it is, the alarm processing can be suppressed if the notification process is not performed.

Further, in each of the above-described embodiments, the ultrasonic sensor is attached at a high place and is directed almost directly below, but is not limited thereto. For example, when detecting a suspicious person who gets drunk by leaning against a wall, such a suspicious person can be detected by the same determination method even if the ultrasonic sensor is inclined downward or horizontally.
In this way, it can be realized in a form not exceeding the scope of the present invention.

DESCRIPTION OF SYMBOLS 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 ... Determination unit, 23 ... Control unit)
DESCRIPTION OF SYMBOLS 101 ... Speaker 102 ... Microphone 103 ... Modulated wave memory | storage part 104 ... D / A converter 105 ... Speaker amplifier 106 ... Microphone amplifier 107 ... A / D converter 108 ... Transmission / reception wave control part 109 ... Received wave demodulation part 110 ... Demodulated 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 distance;
A reflected wave receiving unit for receiving a reflected wave reflected by the target object and the reference object;
A portion corresponding to reflection from the reference object by applying a time window defined in common to each of the reflected wave data based on the reflected wave for each transmission wave in a time based on the transmission time of each transmission wave A partial data extraction unit for extracting waveform data;
Of the partial waveform data for the plurality of transmission waves, the other transmission wave is determined from the difference between the phase characteristic of the partial waveform data for the transmission wave and the phase characteristic of the partial waveform data for the other transmission wave. A waveform correction unit for correcting the frequency characteristics of the reflected wave data with respect to
A displacement information calculation unit that obtains corrected reflected wave data from the frequency characteristics of each of the reflected wave data after correction, and calculates displacement information of the target object from a time change of the plurality of corrected reflected wave data;
An output unit that outputs the displacement information to an external device. A transmission unit that intermittently transmits a transmission wave toward the target object;
A reflected wave receiving unit for receiving a reflected wave reflected by the target object;
A reference receiving unit that receives a transmission wave transmitted from the transmission unit as a direct wave at a position apart from the target object by a certain distance;
The partial waveform data corresponding to the transmission wave is applied to each of the direct wave data based on the direct wave for each transmission wave by applying a time window defined in common with respect to the transmission time of each transmission wave. A partial data extraction unit to be extracted;
Of the partial waveform data for the plurality of transmission waves, the other transmission wave is determined from the difference between the phase characteristic of the partial waveform data for the transmission wave and the phase characteristic of the partial waveform data for the other transmission wave. A waveform correction unit for correcting the frequency characteristics of the reflected wave data with respect to
A displacement information calculation unit that obtains corrected reflected wave data from the frequency characteristics of each of the reflected wave data after correction, and calculates displacement information of the target object from a time change of the plurality of corrected reflected wave data;
An output unit for outputting 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 comprising at least a control device including an input unit for inputting the displacement information.
The said control apparatus is a displacement determination system which determines the activity stop of the said target object, and outputs a warning, if the said displacement information falls below a stop determination threshold value over predetermined time.   The displacement determination system according to claim 3, wherein the target object is a person who is lying on the reference plane, and the displacement information is a change in distance from the sensor device to the thorax accompanying breathing of the person. .