JP6465827B2 - Biological state acquisition device, biological state acquisition program, device provided with biological state acquisition device, and air conditioner - Google Patents

Description

  The present invention relates to a biological state acquisition device, a biological state acquisition program, a device including the biological state acquisition device, and an air conditioner that acquire a state of a living body such as a human (hereinafter referred to as a biological state).

  2. Description of the Related Art Conventionally, a technique has been proposed in which a biological signal of a sleeping person is acquired in a non-contact and non-restraint manner and a state is determined. For example, the living body state acquisition device disclosed in Patent Document 1 includes a transmission / reception unit that transmits electromagnetic waves to the body surface of a living body during sleep and receives reflected waves, and performs quadrature detection of the reflected waves to obtain I signals and Q signals. And a signal processing unit that determines the state of the living body from the locus of the signal on the IQ plane. Here, the signal processing unit obtains a respiration signal by calculating the norm of the velocity vector of the IQ signal on the IQ plane, and calculates the respiration frequency by setting the threshold value and counting this increase / decrease. .

  Such a method is characterized in that even if there is signal degradation (origin deviation on the IQ plane, etc.) that occurs when analog processing of the received signal, the respiratory frequency is easily detected without using frequency analysis. Yes.

JP 2011-15887 A

  However, the norm of the velocity vector of the IQ signal obtained on the IQ plane is affected by the distance between the electromagnetic wave transmitting / receiving unit and the reflecting surface, the reflection intensity, and the like. Therefore, in this conventional example, it is necessary to adjust the threshold value in order to count the increase / decrease of the norm of the velocity vector.

  An object of the present invention is to solve the above-described problems and to provide a biological state acquisition apparatus that can obtain a respiratory signal by a simpler method compared to the prior art.

The biological state acquisition device according to one aspect of the present invention includes:
Signal receiving and transmitting means for transmitting electromagnetic waves to the body surface of the living body and receiving reflected waves reflected by the body surface of the living body as received signals;
Quadrature detection means for quadrature detection of the received signal to generate an I signal and a Q signal;
IQ signal acquisition means for sequentially acquiring the generated I signal and Q signal in time series;
Signal processing means for generating, as biological information, a respiration signal indicating a change in respiration of the living body based on a direction change of the I signal acquired at a predetermined time point and a velocity vector of the Q signal on the IQ plane over a certain period of time. Prepared ,
The signal processing means changes the direction change of the acquired velocity vector on the IQ plane in a certain period, the velocity vector on the IQ plane at a predetermined time point, the IQ signal acquired in a certain period in the past and the IQ of the Q signal. It is calculated as a cosine of an angle formed by a velocity vector on a plane .

  According to the present invention, it is possible to obtain a time series signal that fluctuates within a fixed range as a respiratory signal. As a result, the threshold value can be easily set and the respiration frequency can be calculated with high accuracy.

It is a block diagram which shows the structure of the biological condition acquisition apparatus which concerns on Embodiment 1 of this invention. It is a graph which shows the behavior of IQ signal acquired in the living body state acquisition device of FIG. 2 is a graph of an IQ signal for explaining a method of calculating a velocity vector on an IQ plane of the IQ signal in the biological state acquisition device of FIG. 1. It is a graph of IQ signal which shows the method of calculating the change of a velocity vector in the biological condition acquisition apparatus of FIG. FIG. 3 is a waveform diagram of a respiratory signal showing an example of calculating a respiratory curve and determining a respiratory state in the biological state acquisition device of FIG. 1. It is a graph which shows the moisture retention amount with respect to respiration frequency which shows the utilization example of respiration frequency in the biological condition acquisition apparatus of FIG. It is a block diagram which shows the structure of the biological condition acquisition apparatus which concerns on Embodiment 2 of this invention. It is a wave form diagram of the respiration signal which shows the example of correction | amendment of the respiration curve in the biological condition acquisition apparatus of FIG. It is a graph which shows the input-output voltage characteristic of the hysteresis filter 12 used in the biological condition acquisition apparatus of FIG. FIG. 8 is a waveform diagram of a respiratory signal showing an example of a respiratory curve after filtering by the hysteresis filter 12 in the biological state acquisition device of FIG. 7. It is a block diagram which shows the structure of the biological condition acquisition apparatus which concerns on Embodiment 3 of this invention. 12 is a graph of an IQ signal showing a method for determining a direction of change of a velocity vector in the biological state acquisition device of FIG. 11. 12 is a graph showing an expiration / inhalation determination method using a respiratory signal and an expiration / inspiration determination curve in the biological state acquisition device of FIG.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In addition, in each following embodiment, the same code | symbol is attached | subjected about the same component.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a biological state acquisition apparatus according to Embodiment 1 of the present invention. In FIG. 1, the biological state acquisition apparatus according to the present embodiment is an apparatus that acquires the biological state of a living body 20 that is, for example, a human or an animal. The frequency represents the number of breaths per unit time.

  In FIG. 1, the biological state acquisition apparatus includes a Doppler radar sensor 1, a quadrature detection circuit 2, a bandpass filter 3, an AD converter 4, an arithmetic device 5, and a display device 11. Here, the arithmetic device 5 includes an IQ signal acquisition circuit 6, a signal processing circuit 7, and a respiration determination circuit 10. The signal processing circuit 7 includes a velocity vector change detection circuit 8 and a respiratory signal generation circuit 9.

  The Doppler radar sensor 1 is provided as a signal transmission / reception means, and the antenna of the Doppler radar sensor 1 is directed to the body surface (preferably the chest surface) of the living body 20, and electromagnetic waves are irradiated toward the body surface of the living body 20, It is installed so that a reflected wave, which is an electromagnetic wave reflected from the body surface, can be received as a received signal. The quadrature detection circuit 2 performs quadrature detection on the received signal to generate an IQ signal composed of an I signal and a Q signal and outputs the IQ signal to the bandpass filter 3. The band pass filter 3 has a frequency pass characteristic set in advance to remove components other than the Doppler shift component due to respiration, and outputs the filtered IQ signal to the AD converter 4. The AD converter 4 converts the input analog IQ signal into a digital IQ signal having an AD conversion value and outputs it to the arithmetic unit 5.

  The IQ signal acquisition circuit 6 of the arithmetic unit 5 has a signal buffer memory, and sequentially receives digital IQ signals in a time series, discretely at a predetermined cycle, and stores the digital IQ signals for a predetermined period in the signal buffer memory. Used for signal processing in the signal processing circuit 7. The velocity vector change detection circuit 8 calculates the cosine of the angle formed by the velocity vector on the IQ plane of the IQ signal at an arbitrary time point and the velocity vector on the IQ plane of the IQ signal acquired in the past for a certain period. The respiration signal generation circuit 9 outputs the calculated cosine to the respiration determination circuit 10 as a respiration signal. The respiration determining circuit 10 determines respiration from the increase / decrease of the respiration signal, calculates respiration frequency (hereinafter referred to as respiration frequency), and displays the calculation result on the display device 11 or outputs it to an output device such as a printer.

  Next, the calculation of the velocity vector performed by the velocity vector change detection circuit 8 will be described below.

  FIG. 2 is a graph showing the behavior of an IQ signal acquired for a human in the biological state acquisition apparatus of FIG. As shown in FIG. 2, when the coordinates of the IQ signal, which is a set of the I signal and the Q signal output from the AD converter 4, are plotted on the IQ plane, for example, a body when a human breathes as an example of the living body 20. A trajectory as illustrated is drawn according to the movement of the surface. Here, the coordinates of the IQ signal draw a locus counterclockwise when the body surface approaches the Doppler radar sensor 1 and clockwise when the body surface moves away from the Doppler radar sensor 1. The Doppler radar sensor 1 is preferably installed at a position where the expansion and contraction of the thorax of the living body can be accurately captured.

  The movement of the body surface during breathing reaches its peak during inhalation after the inhalation starts and the speed gradually increases. Then, the velocity decreases this time toward the end point of breathing (when exhalation and inspiration are switched), and becomes substantially zero at the end point of breathing. Also, the velocity vector is in the opposite direction before and after the end point of respiration.

  FIG. 3 is a graph of an IQ signal for explaining a method of calculating a velocity vector on the IQ plane of the IQ signal in the biological state acquisition apparatus of FIG. In FIG. 3, when the coordinate on the IQ plane at time t is P (t), and the coordinate at time t−Δt that is a fixed time (Δt) past from time t is P (t−Δt), The velocity vector at t is calculated as:

V (t) = P (t) −P (t−Δt)

  If the velocity vector at time t is V (t), the cosine of the angle formed by V (t) and the velocity vector V (t−Δtv) at time t−Δtv in the past is calculated for a certain time (Δtv). By doing so, it is possible to obtain a change in the direction of the velocity vector V (t) from V (t−Δtv).

  FIG. 4 is a graph of an IQ signal showing a method for calculating a change in velocity vector in the biological state acquisition apparatus of FIG. That is, FIG. 4 simulates the transition of the velocity vector on the IQ plane of the IQ signal during the human breathing motion. In FIG. 4, V (t1), V (t1−Δtv), and V (t2−Δtv) represent velocity vectors during intake, and V (t2), V (t3−Δtv), and V (t3). Represents a velocity vector during expiration. “◯” indicates switching from inspiration to expiration, and “□” indicates switching from expiration to inspiration.

  In FIG. 4, the angle formed by the velocity vector V (t1) during intake with V (t1−Δtv) is smaller than π / 2, and these cosines are close to +1. The angle formed by the velocity vector V (t3) during expiration with V (t3−Δtv) is smaller than π / 2, and these cosines are also close to +1. At the time of switching from inspiration to expiration, the velocity vector V (t2) is in the opposite direction to V (t2−Δtv), so the cosine is a value close to −1.

  When the cosine of the angle formed by the velocity vector V (t) and the velocity vector V (t−Δtv) at time t−Δtv, which is a certain time in the past, is calculated and this time series change is defined as a respiratory signal, The respiratory signal changes as shown in FIG.

  FIG. 5 is a waveform diagram of a respiratory signal showing an example of calculating a respiratory curve and determining a respiratory state in the biological state acquisition apparatus of FIG. In this embodiment, the respiration signal generation circuit 9 outputs the value output from the velocity vector change detection circuit 8 as it is as a respiration signal. Note that the sampling period of the IQ signal in the AD converter 4 is, for example, 50 samples / second, and the difference times Δt and Δtv are both about 1 second, for example, but the required measurement accuracy, required cost, etc. In consideration, it can be set appropriately. If calculation by the above method is performed, it is possible to obtain a respiration signal in which the fluctuation is within ± 1 even when one respiration operation is long and rotates several times on the IQ plane.

  When calculating the respiration frequency per unit time from the obtained respiration signal, it is not necessary to adjust the threshold value, and the intersection point may be counted with the threshold value set to zero. Specifically, since zero passes four times for each breath, the number obtained by dividing the number of intersections counted per unit time by four may be used as the breathing frequency.

  According to the above embodiment, it is possible to obtain a time series signal that fluctuates within a fixed range as a respiratory signal. As a result, the threshold value can be easily set and the respiration frequency can be calculated with high accuracy. Moreover, the fluctuation range of the respiratory signal can be kept within a known limited range, and the threshold value adjustment for detecting the switching between the expiration and the inspiration becomes unnecessary. That is, if the threshold value is an angle, it always passes through π / 2, and this may be used as the threshold value.

  Furthermore, since the direction change is calculated as the cosine of the angle formed by the velocity vector on the IQ plane at an arbitrary point in time and the velocity vector on the IQ plane acquired in the past for a certain period, the fluctuation range of the respiratory signal is set to ± 1. Thus, it is not necessary to adjust the threshold value for detecting switching between expiration and inspiration.

  The respiration frequency output from the arithmetic device 5 may be input to another arithmetic device and used for device control.

  FIG. 6 is a graph showing the moisturizing amount with respect to the respiration frequency, showing an example of use of the respiration frequency in the biological state acquisition apparatus of FIG. For example, in a humidifier for assisting breathing during sleep, a control of sequentially adjusting the amount of humidified air released (moisturizing amount) according to the breathing frequency as shown in FIG. 6 can be considered. By this control, excessive water supply to the air can be suppressed by supplying water mainly when the absorption frequency is high and the mucous membrane of the nasal cavity is easy to dry. In FIG. 6, the respiration frequency and the moisturizing amount are represented by a proportional relationship. However, the present invention is not limited to this, and any relationship may be used as long as the respiration frequency increases. Therefore, as a result, the occurrence of dew condensation in the room where the humidifier is installed can be prevented, and the capacity of the water supply tank incorporated in the humidifier can be reduced.

Embodiment 2. FIG.
FIG. 7 is a block diagram showing a configuration of the biological state acquisition apparatus according to Embodiment 2 of the present invention. 7, the biological state acquisition device according to the second embodiment is different from the biological state acquisition device of FIG. 1 in the following points.
(1) The respiration determining circuit 10 determines respiration by setting two threshold values A and B (FIG. 8) as will be described later.
(2) A hysteresis filter 12 is inserted between the respiration signal generation circuit 9 and the respiration determination circuit 10.

  FIG. 8 is a waveform diagram of a respiration signal showing an example of correction of a respiration curve in the biological state acquisition apparatus of FIG. FIG. 9 is a graph showing input / output voltage characteristics of the hysteresis filter 12 used in the biological state acquisition apparatus of FIG. Further, FIG. 10 is a waveform diagram of a respiration signal showing an example of a respiration curve after the filtering process by the hysteresis filter 12 in the biological state acquisition apparatus of FIG.

  As shown in FIG. 8, when noise having a frequency close to that of the respiration signal is superimposed, it is difficult to remove it with the bandpass filter 3 or the like, and when the respiration frequency is calculated by the method shown in the first embodiment, Many breaths are counted. In such a case, as shown in FIG. 8, two threshold values A and B (for example, a positive threshold value A between the maximum value and 0 of the respiratory signal and a negative value between the minimum value and 0) And the respiratory frequency may be calculated by detecting that the respiratory signal has passed both thresholds A and B in the same direction.

  In FIG. 8, there are a threshold value A and a threshold value B, and the point at which the respiratory signal has passed is indicated by an arrow. When the threshold A is passed from the bottom to the top, UA is shown, when the threshold A is passed from the top to the bottom, DA, and the threshold B is shown near the arrows as UB and DB, respectively. When UB and UA are detected consecutively and only DA and DB are detected continuously, the portion indicated by x is not counted.

  Such processing is realized by using, for example, a hysteresis filter 12 having hysteresis characteristics as shown in FIG. By applying the hysteresis filter 12 having the hysteresis characteristic of FIG. 9, the respiration signal shown in FIG. 8 becomes a waveform as shown in FIG. Respiration can be detected with higher accuracy than in the prior art.

  In the present embodiment described above, for example, by detecting the section indicated by the double-sided arrow line in FIG. 8 as one breath, the respiration frequency can be calculated with higher accuracy than in the prior art. In addition, by setting two thresholds A and B and detecting that the respiratory signal has passed through both thresholds in the same direction, noise with a frequency close to that of the respiratory signal is multiplied. Even if it is, accurate respiration rate count becomes possible.

Embodiment 3 FIG.
FIG. 11 is a block diagram showing a configuration of a biological state acquisition apparatus according to Embodiment 3 of the present invention. In FIG. 11, the biological state acquisition apparatus according to Embodiment 3 includes a respiration determination circuit 10 </ b> A that determines the change direction of the velocity vector on the IQ plane of the IQ signal, instead of the respiration determination circuit 10 of FIG. 1. It is characterized by that.

  When discriminating between expiration and inspiration, it is effective to calculate the change direction (rotation angle) of the velocity vector when the IQ signal is away from the breathing end. The change direction of the velocity vector can be realized by calculating the outer product of the velocity vector at an arbitrary time and the past velocity vector.

  FIG. 12 is a graph of an IQ signal showing a method for determining the direction of change of the velocity vector in the biological state acquisition apparatus of FIG.

  In FIG. 12, the speed vector at the time of intake is represented as V (t1), but it rotates counterclockwise as compared with the speed vector V (t1−Δtv) (the rotation angle is θ1). On the contrary, the velocity vector at the time of exhalation is expressed as V (t3), but rotates clockwise compared with the velocity vector V (t3-Δtv) (the rotation angle is θ3). For example, the outer product V (t1) × V (t1−Δtv) is a three-dimensional vector of the following equation.

  Here, when away from the end point of respiration, | V (t1) || V (t1−Δt) | sin θ1 in Expression (1) is a positive value. Similarly, when calculating the outer product V (t3) × V (t3−Δtv) at the time of exhalation, | V (t3) || V (t3−Δt) | sin θ3 is negative when it is away from the end point of respiration. Value. These are defined as expiration and inhalation determination curves. Here, being away from the end point of respiration is that a predetermined threshold is set for the respiration curve calculated in the first and second embodiments, and the end point of respiration is larger than the above threshold. Can be judged.

  FIG. 13 is a graph showing an expiration / inhalation determination method using a breathing signal and an expiration / inspiration determination curve in the biological state acquisition apparatus of FIG. In FIG. 13, when the threshold value C is set for the respiratory signal shown in FIG. 5 and the respiratory signal and the respiratory signal is larger than the threshold value C, the expiration and inhalation determination curves described above are displayed at the same time. Expressed on the axis. The determination result is shown below the graph of FIG. In this example, expiration, inspiration, expiration, and inspiration are sequentially determined from the left.

  As described above, according to the present embodiment, it is possible to determine expiration or inspiration with higher accuracy than in the prior art by determining the change direction of the velocity vector of the IQ signal.

Modified example.
In the above embodiment, the circuits 6 to 10 in the arithmetic device 5 are configured by hardware, for example. However, the present invention is not limited to this, and the arithmetic device is configured by a computer such as one digital computer, Each calculation may be configured by a software program executed by a computer. The IQ signal acquisition circuit 6 includes a memory that temporarily stores IQ signals.

  The respiration signal and the expiration and inhalation determination results output from the arithmetic device 5 according to the first to third embodiments can be input to another control device and used for device control and the like. For example, in a humidifier for assisting breathing during sleep, it is possible to release humidified air in accordance with the timing of inspiration. As a result, excessive water supply to the air can be suppressed, condensation in the room where the humidifier is installed can be prevented, and the capacity of the water supply tank incorporated in the humidifier can be reduced.

  The device provided with the biological state acquisition device includes a control unit that controls the operation of the device main body based on the biological state acquired by the biological state acquisition device. For example, in addition to an alarm clock and an air conditioner, for example, Equipment that stimulates the five senses such as lighting and fragrance functions, or AV equipment such as TVs and music players, hot water bottles, humidifiers, dehumidifiers, air purifiers, and other air conditioning equipment. The air conditioner may include a state acquisition device, an air conditioning unit that air-conditions the space, and a control unit that controls the air conditioning unit based on the biological information acquired by the biological state acquisition device.

  As described above in detail, according to the present invention, it is possible to obtain a time series signal that fluctuates within a fixed range as a respiratory signal. As a result, the threshold value can be easily set and the respiration frequency can be calculated with high accuracy.

  1 Doppler radar sensor, 2 quadrature detection circuit, 3 band pass filter, 4 AD converter, 5 arithmetic unit, 6 IQ signal acquisition circuit, 7 signal processing circuit, 8 speed vector change detection circuit, 9 respiratory signal generation circuit, 10, 10A Respiration determination circuit, 11 Display device, 12 Hysteresis filter, 20 Living body.

Claims (9)

Signal receiving and transmitting means for transmitting electromagnetic waves to the body surface of the living body and receiving reflected waves reflected by the body surface of the living body as received signals;
Quadrature detection means for quadrature detection of the received signal to generate an I signal and a Q signal;
IQ signal acquisition means for sequentially acquiring the generated I signal and Q signal in time series;
Signal processing means for generating, as biological information, a respiration signal indicating a change in respiration of the living body based on a direction change of the I signal acquired at a predetermined time point and a velocity vector of the Q signal on the IQ plane over a certain period of time. Prepared ,
The signal processing means changes the direction change of the acquired velocity vector on the IQ plane in a certain period, the velocity vector on the IQ plane at a predetermined time point, the IQ signal acquired in a certain period in the past and the IQ of the Q signal. A biological state acquisition apparatus that calculates a cosine of an angle formed by a velocity vector on a plane . The signal processing means sets a first and a second threshold value different from each other for the respiration signal when detecting a change in direction of the velocity vector on the IQ plane over a certain period of time. It signals the first and second both biological condition acquisition device according to claim 1, wherein the detecting that has passed through the same direction threshold. The generated respiratory signals biological condition acquisition device according to claim 1, wherein further comprising a hysteresis filter to filter using a predetermined hysteresis characteristic with respect. Signal receiving and transmitting means for transmitting electromagnetic waves to the body surface of the living body and receiving reflected waves reflected by the body surface of the living body as received signals;
Quadrature detection means for quadrature detection of the received signal to generate an I signal and a Q signal;
IQ signal acquisition means for sequentially acquiring the generated I signal and Q signal in time series;
Signal processing means for generating, as biological information, a respiration signal indicating a change in respiration of the living body based on a direction change of the I signal acquired at a predetermined time point and a velocity vector of the Q signal on the IQ plane over a certain period of time. Prepared ,
The signal processing means sets a first and a second threshold value different from each other for the respiration signal when detecting a change in direction of the velocity vector on the IQ plane over a certain period of time. A biological state acquisition apparatus, characterized in that it detects that a signal has passed through both the first and second threshold values in the same direction . Signal receiving and transmitting means for transmitting electromagnetic waves to the body surface of the living body and receiving reflected waves reflected by the body surface of the living body as received signals;
Quadrature detection means for quadrature detection of the received signal to generate an I signal and a Q signal;
IQ signal acquisition means for sequentially acquiring the generated I signal and Q signal in time series;
Signal processing means for generating, as biological information, a respiration signal indicating a change in respiration of the living body based on a direction change of the I signal acquired at a predetermined time point and a velocity vector of the Q signal on the IQ plane over a certain period of time ;
A biological state acquisition apparatus comprising: a hysteresis filter that filters the generated respiratory signal using a predetermined hysteresis characteristic . 2. The apparatus according to claim 1, further comprising a breath determination unit that determines the expiration and inhalation of the living body by determining a change direction of a velocity vector based on the generated I signal and Q signal. The biological state acquisition device according to any one of 5 . Computer
IQ signal acquisition means according to any one of claims 1 to 6 ,
The signal processing means according to any one of claims 1 to 6 ,
The biological condition acquisition program for functioning as a breath determination means of Claim 6 . The biological state acquisition device according to any one of claims 1 to 6 ,
A device comprising control means for controlling the operation of the device main body based on the biological state acquired by the biological state acquisition device. The biological state acquisition device according to any one of claims 1 to 6 ,
Air-conditioning means for air-conditioning the space;
An air conditioning apparatus comprising control means for controlling the air conditioning means based on the biological information acquired by the biological state acquisition device.

Images