Biological information detection system, biological information detection method, and program

Abstract

A biological information generating system, a biological information generating method, and a program are provided that can accurately measure biological information such as the respiratory rate and heart rate of a subject while reducing the processing load. [Solution] A Doppler sensor selection unit (26) selects at least one Doppler sensor from among a plurality of Doppler sensors with different measurement areas based on the measurement results of the loads applied to each of a plurality of load sensors identified based on load data. An operation control unit (30) suppresses the operation of Doppler sensors other than the selected at least one Doppler sensor. A biometric information generation unit (40) generates biometric information of the subject based on Doppler data indicating the measurement results of each of the selected at least one Doppler sensor.

Description

[Technical Field]

[0001] The present invention relates to a biological information detection system, a biological information detection method, and a program, and more particularly to a system for detecting biological information of a subject based on a Doppler signal. [Background technology]

[0002] Various systems for measuring biological information such as the respiratory rate or heart rate of a person in bed have been studied. As an example of such a system, Patent Document 1 describes a monitoring device that determines the respiratory rate and heart rate of a person in bed in a non-contact manner using a microwave Doppler sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-134795 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology described in Patent Document 1, if the subject moves, for example, by turning over in bed, it may not be possible to accurately measure biological information such as the subject's respiratory rate and heart rate.

[0005] Here, in order to enable accurate measurement of biological information even when the subject moves, it is conceivable to increase the number of Doppler sensors that operate to measure the biological information.

[0006] However, the greater the number of Doppler sensors that operate to measure biological information, the higher the processing load on the entire system including these Doppler sensors.

[0007] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a biometric information generation system, a biometric information generation method, and a program that can accurately measure biometric information such as the respiratory rate and heart rate of a subject while reducing the processing load. [Means for solving the problem]

[0008] (1) The biometric information detection system of the present invention includes a load data acquisition means for acquiring load data indicating the measurement results of the load acting on each of a plurality of load sensors located below the position of the subject when the subject is on a bed; a Doppler sensor selection means for selecting at least one Doppler sensor from a plurality of Doppler sensors having different measurement areas based on the measurement results of the load acting on each of the plurality of load sensors identified based on the load data; an operation suppression means for suppressing the operation of the Doppler sensors other than the at least one selected Doppler sensor; and a biometric information generation means for generating biometric information of the subject based on Doppler data indicating the measurement results of each of the at least one selected Doppler sensor.

[0009] (2) In the biometric information detection system described in (1), the system further includes a ratio calculation means for calculating a ratio for each of the plurality of load sensors by dividing the measurement result of the load acting on that load sensor by the sum of the measurement results of the load acting on each of the plurality of load sensors, and the Doppler sensor selection means selects the at least one Doppler sensor based on the ratio calculated for each of the plurality of load sensors.

[0010] (3) In the biometric information detection system described in (1) or (2), the plurality of Doppler sensors are arranged in a line along the width direction of the bed, and the system further includes a position estimation means for estimating the position of the subject along the width direction of the bed based on the measurement results of the load acting on each of the plurality of load sensors, and the Doppler sensor selection means selects at least one Doppler sensor based on the estimated position of the subject.

[0011] (4) In the biometric information detection system described in any one of (1) to (3), a body axis direction estimation means is further included which estimates the body axis direction of the subject based on the measurement results of the load applied to each of the plurality of load sensors, and the Doppler sensor selection means selects the at least one Doppler sensor based on the estimated body axis direction.

[0012] (5) In the biological information detection system according to any one of (1) to (4), the load sensor is provided on each of the four legs of the bed.

[0013] (6) In the biometric information detection system described in any one of (1) to (5), the Doppler sensor selection means further includes an operation suppression release means that repeatedly selects the Doppler sensor based on the latest load measurement result, and releases the suppression of the operation of the Doppler sensor that was not selected in the previous selection but was selected in the latest selection, depending on the selection of the Doppler sensor based on the latest load measurement result.

[0014] (7) In the biometric information detection system described in any one of (1) to (5), the Doppler sensor selection means repeatedly selects the Doppler sensor based on the latest load measurement result, and the operation suppression means further includes a start-up means that stops the Doppler sensor that was selected in the previous selection but not in the latest selection in accordance with the selection of the Doppler sensor based on the latest load measurement result, and starts the Doppler sensor that was not selected in the previous selection but selected in the latest selection in accordance with the selection of the Doppler sensor based on the latest load measurement result.

[0015] (8) In the biometric information detection system described in any one of (1) to (7), the system further includes a body movement determination means for determining whether or not the subject is moving based on the magnitude of fluctuation in the total value of the measurement results of the loads applied to each of the plurality of load sensors, and a generation suppression means for suppressing the generation of the biometric information when it is determined that the subject is moving.

[0016] (9) In the biometric information detection system described in any one of (1) to (7), a body movement determination means is further included which determines whether or not the subject is moving based on the magnitude of fluctuation in the total value of the measurement results of the load applied to each of the plurality of load sensors, and the movement suppression means suppresses the movement of all of the plurality of Doppler sensors when it is determined that the subject is moving.

[0017] (10) In the presence / absence determining system according to any one of (1) to (9), the Doppler sensor selecting means selects a predetermined number of the Doppler sensors.

[0018] (11) The biometric information detection method of the present invention includes the steps of acquiring load data indicating the measurement results of the load acting on each of a plurality of load sensors located below the position of the subject when the subject is lying on a bed, selecting at least one Doppler sensor from a plurality of Doppler sensors having different measurement areas based on the measurement results of the load acting on each of the plurality of load sensors identified based on the load data, suppressing the operation of the Doppler sensors other than the at least one selected Doppler sensor, and generating biometric information of the subject based on Doppler data indicating the measurement results of each of the at least one selected Doppler sensor.

[0019] (12) A program according to the present invention causes a computer to execute the following steps: acquiring load data indicating a measurement result of a load applied to each of a plurality of load sensors located below a position of a subject lying on a bed; selecting at least one Doppler sensor from a plurality of Doppler sensors having different measurement areas based on the measurement result of the load applied to each of the plurality of load sensors identified based on the load data; suppressing operation of the Doppler sensors other than the at least one selected Doppler sensor; and generating biometric information of the subject based on Doppler data indicating the measurement result of each of the at least one selected Doppler sensor. This program may be stored in a computer-readable information storage medium. [Effects of the Invention]

[0020] According to the present invention, it is possible to accurately measure biological information such as the respiratory rate and heart rate of a subject while suppressing the processing load. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a configuration diagram of a biological information detection system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of the bed shown in FIG. [Figure 3] 1 is a functional block diagram of a signal processing device according to an embodiment of the present invention. [Figure 4] FIG. 10 is a flowchart showing an example of the flow of a Doppler sensor selection process performed in the signal processing device according to the embodiment of the present invention. [Figure 5] 10A and 10B are diagrams illustrating an example of processing by a Doppler data acquisition unit. [Figure 6] FIG. 4 is a flowchart showing an example of the flow of a frequency spectrum selection process performed in the signal processing device according to the embodiment of the present invention. [Figure 7] FIG. 10 is a diagram illustrating an example of generating an aggregate spectrum. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0023] FIG. 1 is a configuration diagram of a biological information detection system 1 according to an embodiment of the present invention. As shown in the figure, the biological information detection system 1 includes a signal processing device 10, a Doppler sensor unit 12, and a plurality of load sensors 14. The Doppler sensor unit 12 includes a plurality of Doppler sensors. Here, for example, it is assumed that the Doppler sensor unit 12 includes six Doppler sensors (first to sixth Doppler sensors). Furthermore, as shown in FIG. 1, the biological information detection system 1 includes four load sensors 14 (14a to 14d).

[0024] In the example of FIG. 1, the Doppler sensor unit 12 is attached to the headboard of the bed 16. Here, the Doppler sensor unit 12 may be provided symmetrically with respect to the center line L1 of the bed 16 (a line passing through the center of the width direction of the bed 16 and extending in the length direction of the bed 16). Also, multiple Doppler sensors may be provided lined up perpendicular to the length direction of the bed 16 (a direction along the center line L1 of the bed 16). That is, multiple Doppler sensors may be provided lined up along the width direction of the bed 16. Also, multiple Doppler sensors may be provided lined up at equal intervals in a row. Note that the position and orientation of the Doppler sensor are not limited to the example described above. For example, the Doppler sensor may be attached to the ceiling. Also, the number of Doppler sensors is not limited to six.

[0025] The Doppler sensors are all arranged to face the length (longitudinal direction) of the bed 16 and emit microwaves in the lengthwise direction of the bed 16. The microwaves are reflected by the chest of the person being measured sleeping on the bed 16, and the reflected waves are received by each Doppler sensor. Each Doppler sensor generates a Doppler signal from the reflected waves that indicates chest movement associated with breathing, and outputs Doppler data by digitizing this Doppler signal. The microwaves emitted from each Doppler sensor have slightly different frequencies, which prevents mutual interference.

[0026] The reflected wave is frequency shifted due to the Doppler effect, and by observing this, the breathing rate of the subject can be obtained. The reflected wave is detected by quadrature detection as a Doppler signal containing an I signal, which is an in-phase component with the transmitted wave, and a Q signal, which is a quadrature component, and output in digital form to the signal processing device 10. The Doppler signal input to the signal processing device 10 is time-series data, indicating the amplitude (I component and Q component) at each time.

[0027] FIG. 2 is a plan view of the bed 16 shown in FIG. 1. FIG. 2 shows measurement areas 18 (18a to 18f) respectively associated with six Doppler sensors. The measurement areas 18 of the Doppler sensors may be substantially rectangular parallelepiped areas forward in the direction of microwave emission from the Doppler sensors. When a person to be measured is present in the measurement areas 18 of the Doppler sensors, the Doppler sensors are configured to accurately detect reflected waves from the person to be measured. Adjacent measurement areas 18 may partially overlap each other. However, adjacent measurement areas 18 do not have to overlap each other.

[0028] Load sensor 14 is positioned below the position of the person being measured when the person is on bed 16. As shown in Fig. 1, load sensor 14 may be provided on each of the four legs of bed 16. Note that the positions and number of load sensors 14 are not limited to those shown in Fig. 1.

[0029] Then, each load sensor 14 outputs load data indicating the measurement result of the load applied to that load sensor 14 .

[0030] The signal processing device 10 may be configured by a known computer including, for example, a CPU, a memory, an input device, and a display. The signal processing device 10 generates the respiration rate of the subject based on the Doppler signal output from the Doppler sensor.

[0031] 3 is a functional block diagram of a signal processing device 10 according to an embodiment of the present invention. As shown in the figure, the signal processing device 10 includes a load data acquisition unit 20, a ratio calculation unit 22, a position / body axis estimation unit 24, a Doppler sensor selection unit 26, a body movement determination unit 28, a movement control unit 30, a Doppler data acquisition unit 32, a frequency spectrum generation unit 34, a frequency spectrum selection unit 36, an aggregate spectrum generation unit 38, and a biometric information generation unit 40. These functional blocks are realized by executing a signal processing program in the signal processing device 10, which is a computer. The signal processing program may be stored in various computer-readable information storage media such as semiconductor memory and loaded into the signal processing device 10 from the medium. Alternatively, the signal processing program may be downloaded to the signal processing device 10 via a data communication line such as the Internet.

[0032] The load data acquisition unit 20 acquires load data indicating the measurement results of the load acting on each of a plurality of load sensors 14 located below the position of the person being measured when the person is on a bed 16, for example.

[0033] In the following description, it is assumed that the load data acquiring unit 20 acquires load data indicating the latest load measurement results from each of the four load sensors 14 (load sensors 14a to 14d) at predetermined time intervals. It is also assumed that the load measurement timings of the four load sensors 14 are synchronized.

[0034] The ratio calculation unit 22 calculates a ratio by, for example, dividing the measurement result of the load applied to each of the multiple load sensors 14 by the total value of the measurement results of the loads applied to each of the multiple load sensors 14. Hereinafter, the ratio calculated in this manner will be referred to as the load ratio.

[0035] The position / body axis estimator 24 estimates the position of the person being measured along the width direction of the bed 16, for example, based on the measurement results of the loads applied to each of the multiple load sensors 14. The position / body axis estimator 24 may estimate the position of the person being measured along the width direction of the bed 16 based on the above-mentioned load ratio.

[0036] Furthermore, the position and body axis estimation unit 24 estimates the body axis direction of the subject based on, for example, the measurement results of the loads applied to each of the multiple load sensors 14. The position and body axis estimation unit 24 may estimate the body axis direction of the subject based on the above-mentioned load ratio.

[0037] The Doppler sensor selection unit 26 selects at least one Doppler sensor from among a plurality of Doppler sensors having different measurement areas 18, for example, based on the measurement results of the load acting on each of a plurality of load sensors 14 identified based on the load data.

[0038] Here, the Doppler sensor selection unit 26 may select at least one Doppler sensor based on the above-described load ratio calculated for each of the multiple load sensors 14. The Doppler sensor selection unit 26 may also select at least one Doppler sensor based on an estimation result of the position of the person being measured along the width direction of the bed 16. The Doppler sensor selection unit 26 may also select at least one Doppler sensor based on an estimated body axis direction.

[0039] Here, an example of the flow of the Doppler sensor selection process that is executed in response to acquisition of the latest load data will be described with reference to the flow diagram shown in FIG.

[0040] First, the ratio calculation unit 22 calculates a load ratio based on the latest load measurement result indicated by the load data (S101). For example, the latest load measurement results by the load sensors 14a, 14b, 14c, and 14d are assumed to be a1, b1, c1, and d1, respectively. In this case, the ratio calculation unit 22 calculates the values ​​of a1 / (a1+b1+c1+d1), b1 / (a1+b1+c1+d1), c1 / (a1+b1+c1+d1), and d1 / (a1+b1+c1+d1) as the load ratio a2 of the load sensor 14a, the load ratio b2 of the load sensor 14b, the load ratio c2 of the load sensor 14c, and the load ratio d2 of the load sensor 14d, respectively.

[0041] Then, the position body axis estimation unit 24 estimates the position of the person being measured along the width direction of the bed 16 (for example, the position of the center of gravity of the person being measured) based on the load ratio calculated in the process shown in S101 (S102). Hereinafter, the position of the center of gravity of the person being measured along the width direction of the bed 16 will be referred to as the width-direction center of gravity position. The position body axis estimation unit 24 calculates, for example, a value calculated using the formula (-a2 + b2 - c2 + d2) as the width-direction center of gravity position value. In this case, the range of values ​​that the width-direction center of gravity position value can take is from -1 to 1.

[0042] Then, the Doppler sensor selection unit 26 determines whether the estimated widthwise center of gravity position is shifted to the left (S103). Here, for example, if the calculated widthwise center of gravity position value is less than a predetermined value (e.g., less than −0.5), it may be determined that the widthwise center of gravity position is shifted to the left, and if the calculated widthwise center of gravity position value is equal to or greater than the predetermined value (e.g., equal to or greater than −0.5), it may be determined that the widthwise center of gravity position is not shifted to the left.

[0043] If it is determined that the widthwise center of gravity position is shifted to the left (S103: Y), the Doppler sensor selector 26 selects the four Doppler sensors from the left (S104).

[0044] If it is determined that the widthwise center of gravity position is not shifted to the left (S103: N), the Doppler sensor selection unit 26 determines whether the estimated widthwise center of gravity position is shifted to the right (S105). Here, for example, if the widthwise center of gravity position value is equal to or greater than a predetermined value (e.g., 0.5 or greater), it may be determined that the widthwise center of gravity position is shifted to the right, and if it is less than the predetermined value (e.g., less than 0.5), it may be determined that the widthwise center of gravity position is not shifted to the right.

[0045] If it is determined that the widthwise center of gravity position is shifted to the right (S105: Y), the Doppler sensor selector 26 selects four Doppler sensors from the right (S106).

[0046] If it is determined that the widthwise center of gravity position is not shifted to the right (S105: N), the position and body axis estimation unit 24 estimates the body axis direction of the subject (S107). The position and body axis estimation unit 24 calculates, for example, a value calculated by the formula (-a2 + b2 + c2 - d2) as the body axis direction value. In this case, the range of values ​​that the body axis direction value can take is from -1 to 1.

[0047] Then, the Doppler sensor selection unit 26 determines whether the estimated body axis direction is from the upper left to the lower right (S108). Here, for example, if the body axis direction value is less than a predetermined value (e.g., less than −0.5), it may be determined that the body axis direction is from the upper left to the lower right, and if the body axis direction value is equal to or greater than the predetermined value (e.g., −0.5 or greater), it may be determined that the body axis direction is not from the upper left to the lower right.

[0048] If it is determined that the body axis direction is from the upper left to the lower right (S108: Y), the Doppler sensor selector 26 selects the four Doppler sensors from the left (S104).

[0049] If it is determined that the body axis direction is not from the upper left to the lower right (S108: N), the Doppler sensor selector 26 determines whether the estimated body axis direction is from the upper right to the lower left (S109). Here, for example, if the body axis direction value is equal to or greater than a predetermined value (e.g., 0.5 or greater), it may be determined that the body axis direction is from the upper right to the lower left, and if the body axis direction value is less than the predetermined value (e.g., less than 0.5), it may be determined that the body axis direction is not from the upper right to the lower left.

[0050] If it is determined that the body axis direction is from the upper right to the lower left (S109: Y), the Doppler sensor selector 26 selects the four Doppler sensors from the right (S106).

[0051] If it is determined that the body axis direction is not from the upper right to the lower left (S109: N), the Doppler sensor selector 26 selects the four central Doppler sensors (S110).

[0052] In this way, at least one Doppler sensor is selected. As shown in the above processing example, the Doppler sensor selector 26 may select a predetermined number of Doppler sensors (four Doppler sensors in the above processing example).

[0053] 4 may be executed each time the latest load data is acquired. That is, the Doppler sensor selector 26 may repeatedly select a Doppler sensor based on the latest load measurement results.

[0054] The body movement determining section 28 determines whether or not the subject is moving, for example, based on the magnitude of the fluctuation in the total value of the measurement results of the loads applied to each of the plurality of load sensors 14.

[0055] Here, for example, the body movement determination unit 28 may calculate the sum of the measurement results of the loads indicated by the respective load data each time the load data is acquired.Then, the body movement determination unit 28 may determine whether or not the subject is moving each time a determination timing arrives, which arrives at a time interval longer than the time interval at which the load data is acquired.

[0056] Here, the period between two consecutive determination timings is referred to as a body movement determination period. The maximum or minimum value of the total value calculated during a specific body movement determination period may be specified. The average value of the total value calculated during the body movement determination period immediately preceding the specific body movement determination period may be specified. If the difference between the maximum value specified for the specific body movement determination period and the average value specified for the body movement determination period immediately preceding the specific body movement determination period is equal to or greater than a predetermined value, it may be determined that the subject's body movement has occurred during the body movement determination time. If the difference between the minimum value specified for the specific body movement determination period and the average value specified for the body movement determination period immediately preceding the specific body movement determination period is equal to or greater than a predetermined value, it may be determined that the subject's body movement has occurred during the body movement determination time. If neither of these conditions is met, it may be determined that the subject's body movement has not occurred during the body movement determination time. Note that the method for determining whether the subject's body movement has occurred is not limited to this method.

[0057] For example, the operation control unit 30 suppresses the operation of Doppler sensors other than at least one Doppler sensor selected by the Doppler sensor selection unit 26. For example, the operation control unit 30 may stop a Doppler sensor that was selected in the immediately preceding selection but not in the latest selection, in accordance with the selection of a Doppler sensor based on the latest load measurement result.

[0058] Furthermore, the operation control unit 30 may cancel the suppression of the operation of a Doppler sensor that was not selected in the previous selection but was selected in the latest selection, in accordance with the selection of a Doppler sensor based on the latest load measurement result. For example, the operation control unit 30 may activate a Doppler sensor that was not selected in the previous selection but was selected in the latest selection.

[0059] For example, if the four leftmost Doppler sensors were selected in the previous selection and the four central Doppler sensors were selected in the latest selection, the operation control unit 30 may activate the second rightmost Doppler sensor and deactivate the leftmost Doppler sensor. Alternatively, if the four central Doppler sensors were selected in the previous selection and the four leftmost Doppler sensors were selected in the latest selection, the operation control unit 30 may activate the leftmost Doppler sensor and deactivate the second rightmost Doppler sensor.

[0060] Furthermore, for example, if the four central Doppler sensors were selected in the previous selection and the four rightmost Doppler sensors were selected in the latest selection, the operation control unit 30 may activate the rightmost Doppler sensor and deactivate the second-from-the-left Doppler sensor. Alternatively, if the four rightmost Doppler sensors were selected in the previous selection and the four central Doppler sensors were selected in the latest selection, the operation control unit 30 may activate the second-from-the-left Doppler sensor and deactivate the rightmost Doppler sensor.

[0061] Furthermore, for example, if the four Doppler sensors from the left were selected in the immediately preceding selection and the four Doppler sensors from the right were selected in the most recent selection, the operation control unit 30 may activate the rightmost Doppler sensor and the second-from-the-right Doppler sensor and deactivate the leftmost Doppler sensor and the second-from-the-left Doppler sensor. Furthermore, if the four Doppler sensors from the right were selected in the immediately preceding selection and the four Doppler sensors from the left were selected in the most recent selection, the operation control unit 30 may activate the leftmost Doppler sensor and the second-from-the-left Doppler sensor and deactivate the rightmost Doppler sensor and the second-from-the-right Doppler sensor.

[0062] Furthermore, when it is determined that the subject is moving, the operation control unit 30 may suppress the operation of all of the Doppler sensors. For example, when it is determined that the subject is moving, the operation control unit 30 may stop all of the Doppler sensors.

[0063] The Doppler data acquisition unit 32 acquires Doppler data indicating the measurement results of the Doppler sensor over a certain period of time for each of at least one Doppler sensor selected by the Doppler sensor selection unit 26. Here, the Doppler data acquisition unit 32 may acquire Doppler data from an operating Doppler sensor.

[0064] In the following explanation, it is assumed that the four Doppler sensors from the left are selected by the Doppler sensor selection unit 26, and that the four Doppler sensors from the left (here, for example, the first Doppler sensor, the second Doppler sensor, the third Doppler sensor, and the fourth Doppler sensor) are operating.

[0065] For each of a plurality of periods (a plurality of time windows), the Doppler data acquisition unit 32 extracts a portion of the Doppler data indicating the measurement results of the Doppler sensor selected by the Doppler sensor selection unit 26, the portion indicating the measurement results for that period, as shown in FIG. 5, for example.

[0066] For example, Doppler data D(1,1), D(2,1), D(3,1), D(4,1), ... indicating measurement results in a first time window, a second time window, a third time window, a fourth time window, ... are extracted from the first Doppler data acquired from the first Doppler sensor. Also, Doppler data D(1,2), D(2,2), D(3,2), D(4,2), ... indicating measurement results in a first time window, a second time window, a third time window, a fourth time window, ... are extracted from the second Doppler data acquired from the second Doppler sensor.

[0067] Similarly, Doppler data indicating measurement results in each time window is extracted from the third Doppler sensor and the fourth Doppler sensor. For example, Doppler data D(1,3), D(2,3), D(3,3), D(4,3), and so on are extracted from the third Doppler data acquired from the third Doppler sensor, indicating measurement results in the first time window, the second time window, the third time window, the fourth time window, and so on. Similarly, Doppler data D(1,4), D(2,4), D(3,4), D(4,4), and so on are extracted from the fourth Doppler data acquired from the fourth Doppler sensor, indicating measurement results in the first time window, the second time window, the third time window, the fourth time window, and so on.

[0068] The length of each time window is constant (e.g., 60 seconds), and the start timing of each time window is shifted by a predetermined time (here, for example, 2 seconds). The same time window is applied to all of the first to fourth Doppler data. That is, for all of the first to fourth Doppler data, the period corresponding to, for example, the first time window is the same, and the period corresponding to the second time window is also the same.

[0069] For example, the frequency spectrum generating unit 34 generates a frequency spectrum for each of the selected Doppler sensors based on Doppler data indicating the measurement results of the Doppler sensor.

[0070] The frequency spectrum generation unit 34 converts the input Doppler data into a frequency spectrum by, for example, performing a fast Fourier transform (FFT) on the Doppler data. Here, for example, the I signal data and the Q signal data may each be converted into a frequency spectrum.

[0071] The frequency spectrum selection unit 36 ​​selects a plurality of frequency spectra from among those generated for each of the selected Doppler sensors, based on, for example, the peak frequencies in the frequency spectra generated for each of the selected Doppler sensors.

[0072] An example of the flow of the frequency spectrum selection process performed by the frequency spectrum selector 36 will now be described with reference to the flow diagram shown in Fig. 6. Here, for example, the process of selecting a plurality of frequency spectra from among those generated for the I signal data and Q signal data of each of the four Doppler data D(1,1), D(1,2), D(1,3), and D(1,4) extracted for the first time window will be described.

[0073] First, the frequency spectrum selection unit 36 ​​identifies the peak frequency, which is the frequency of the maximum amplitude in the frequency spectrum generated for the I signal data and Q signal data of each of the four Doppler data D(1,1), D(1,2), D(1,3), and D(1,4), as the respiratory rate corresponding to that frequency spectrum (S201).

[0074] Then, the frequency spectrum selection unit 36 ​​calculates a representative value (here, for example, an average value) of the respiratory rate identified in the process shown in S201 (S202).

[0075] Then, the frequency spectrum selection unit 36 ​​checks whether there is a frequency spectrum corresponding to a respiratory rate (i.e., an outlier respiratory rate) whose difference from the representative value calculated in the process shown in S202 is a predetermined value (e.g., 5) or more (S203).

[0076] If there is an outlier respiratory rate (S203: Y), the frequency spectrum selection unit 36 ​​excludes the frequency spectrum corresponding to the outlier respiratory rate (S204), and returns to the process shown in S202.

[0077] If there is no outlier respiratory rate (S203: N), the process shown in this example is terminated. Note that in the process shown in this example, none of the frequency spectra may be excluded, and all frequency spectra may be selected.

[0078] The frequency spectra that remain after the above-described processing correspond to the frequency spectra selected from the frequency spectra generated for the I signal data and Q signal data of each of the four Doppler data extracted for the first time window. The above-described processing is performed for each of the multiple time windows.

[0079] The aggregate spectrum generation unit 38 generates an aggregate spectrum based on, for example, some or all of the frequency spectra generated for each selected Doppler sensor. As shown in FIG. 7 , for the first time window, aggregate spectrum (1) may be generated by adding, for each frequency, the amplitudes (intensities) of the frequency spectrum of the I signal data of D(1,1), the frequency spectrum of the Q signal data of D(1,1), the frequency spectrum of the I signal data of D(1,2), the frequency spectrum of the Q signal data of D(1,2), the frequency spectrum of the I signal data of D(1,3), the frequency spectrum of the Q signal data of D(1,3), ..., the frequency spectrum of the Q signal data of D(1,4). Aggregate spectrum (1) corresponds to the aggregate spectrum for the first time window. In this way, the aggregate spectrum generation unit 38 may generate an aggregate spectrum that is a frequency spectrum obtained by adding up some or all of the frequency spectra generated for each of the multiple Doppler sensors.

[0080] Furthermore, the aggregate spectrum generating unit 38 may generate an aggregate spectrum, which is a frequency spectrum obtained by averaging some or all of the frequency spectra generated for each of the multiple Doppler sensors.

[0081] Furthermore, the aggregate spectrum generation unit 38 may generate an aggregate spectrum based on multiple frequency spectra selected by the frequency spectrum selection unit 36. For example, assume that the frequency spectrum of the I signal data of D(1,4) and the frequency spectrum of the Q signal data of D(1,4) are excluded and other frequency spectra are selected. In this case, an aggregate spectrum (1) may be generated, which is a frequency spectrum obtained by summing the frequency spectrum of the I signal data of D(1,1), the frequency spectrum of the Q signal data of D(1,1), the frequency spectrum of the I signal data of D(1,2), the frequency spectrum of the Q signal data of D(1,2), the frequency spectrum of the I signal data of D(1,3), and the frequency spectrum of the Q signal data of D(1,3). In this way, the influence of outliers on the generated aggregate spectrum can be reduced.

[0082] Figure 7 shows aggregate spectrum (1), which is the aggregate spectrum for the first time window. Similarly, aggregate spectrum (2), which is the aggregate spectrum for the second time window, aggregate spectrum (3), which is the aggregate spectrum for the third time window, etc. are generated.

[0083] The biological information generating unit 40 generates biological information of the subject based on, for example, Doppler data indicating the measurement results of at least one selected Doppler sensor. The biological information generating unit 40 may generate biological information of the subject for the period based on the aggregate spectrum. Here, the biological information generating unit 40 may generate the respiratory rate of the subject for the period based on the peak frequency in the aggregate spectrum. For example, the frequency of the maximum amplitude in the aggregate spectrum may be identified as the peak frequency. Then, the peak frequency in the aggregate spectrum may be generated as the respiratory rate.

[0084] The biometric information generation unit 40 may also identify the maximum amplitude and the second largest amplitude in the aggregate spectrum, and then generate an amplitude ratio by dividing the maximum amplitude by the second largest amplitude.

[0085] Furthermore, the biological information generating unit 40 may generate an amplitude ratio for each of the aggregate spectra calculated for a plurality of time windows (e.g., the first to thirtieth time windows). Then, the biological information generating unit 40 may extract aggregate spectra whose amplitude ratios are equal to or greater than a predetermined threshold (e.g., 1.5). Then, the biological information generating unit 40 may generate an average value of the respiratory rates generated for each of the aggregate spectra whose amplitude ratios are equal to or greater than a predetermined threshold (e.g., 1.5) as the respiratory rate for a period (e.g., one minute) associated with the plurality of time windows.

[0086] Furthermore, the biological information generating unit 40 may generate, as the reliability, the ratio of the number of aggregate spectra whose amplitude ratio is equal to or greater than a predetermined threshold (for example, 1.5) to the number of aggregate spectra calculated for a plurality of time windows.

[0087] In this embodiment, the frequency spectrum may not be selected by the frequency spectrum selector 36. The aggregate spectrum generator 38 may generate an aggregate spectrum for a certain period of time by using all frequency spectra for that period of time generated by the frequency spectrum generator 34.

[0088] Alternatively, the frequency spectrum selector 36 may select a frequency spectrum for each Doppler sensor. That is, the frequency spectrum selector 36 may select multiple Doppler sensors based on the peak frequency in the frequency spectrum generated for each of the multiple Doppler sensors. The aggregate spectrum generator 38 may then generate an aggregate spectrum based on the frequency spectrum generated for each of the selected Doppler sensors.

[0089] Furthermore, it is not necessary to convert each of the I signal data and the Q signal data into a frequency spectrum. For example, complex signal data with the I component as the real part and the Q component as the imaginary part may be converted into a frequency spectrum. Then, an aggregate spectrum may be generated based on the frequency spectrum.

[0090] When measuring the biological information of a subject using multiple Doppler sensors, depending on the subject's position and posture, some of the measurement results obtained from these multiple Doppler sensors may be low in accuracy.

[0091] Therefore, if biometric information is measured using each of these multiple Doppler sensors and a representative value such as the average value of the measured biometric information is used as the value of the subject's biometric information, the value of the biometric information obtained in this way may not be a valid value.

[0092] As described above, in this embodiment, the biological information is generated based on the aggregate spectrum. Therefore, according to this embodiment, the biological information of the subject can be measured more accurately than when a representative value such as an average value of the measured biological information is used as the value of the biological information of the subject.

[0093] Furthermore, for example, since each Doppler sensor is at a different angle relative to the subject, the peak frequencies of the frequency spectrum based on the measurement results may be slightly different. Here, when multiple Doppler sensors are arranged in a line perpendicular to the length of bed 16, when multiple Doppler sensors are arranged symmetrically with respect to the center line of bed 16, when multiple Doppler sensors are arranged in a line at equal intervals, or the like, an aggregate spectrum is generated in which the frequency spectra corresponding to each Doppler sensor are appropriately averaged, and as a result, it becomes possible to measure the subject's biological information with higher accuracy.

[0094] In this embodiment, at least one Doppler sensor is selected based on the load data. Then, biological information of the subject is generated based on Doppler data indicating the measurement results of each of the selected Doppler sensors. Therefore, in this embodiment, the biological information of the subject can be measured accurately even when the subject moves, such as when the subject turns over in bed.

[0095] Furthermore, in this embodiment, operation of Doppler sensors other than the selected Doppler sensor is suppressed. Therefore, in this embodiment, it is possible to prevent the processing load of the entire system including these Doppler sensors from becoming high due to the operation of many Doppler sensors. In particular, by selecting a predetermined number of Doppler sensors, it is possible to keep the processing load of the entire system including these Doppler sensors relatively constant.

[0096] As described above, according to this embodiment, it is possible to accurately measure biological information such as the respiratory rate of a subject while suppressing the processing load.

[0097] Furthermore, when body movement occurs, there is a high possibility that the respiratory rate cannot be detected accurately. In light of this, as described above, when it is determined that the subject is moving, the operation of all of the multiple Doppler sensors may be suppressed. In this way, it is possible to reduce the processing load when there is a high possibility that the respiratory rate cannot be detected accurately.

[0098] Furthermore, in this embodiment, when it is determined that the subject is moving, instead of suppressing the operation of the Doppler sensor, the operation control unit 30 may suppress the generation of biological information by the biological information generation unit 40. For example, when it is determined that the subject is moving, the generation of biological information may be inhibited. This also makes it possible to reduce the processing load when it is highly likely that the respiratory rate cannot be accurately detected.

[0099] In this embodiment, the Doppler sensors may be arranged side by side along the length of the bed 16. The position body axis estimation unit 24 may estimate the position of the person being measured along the length of the bed 16 based on the measurement results of the loads applied to each of the multiple load sensors 14. The Doppler sensor selection unit 26 may then select at least one Doppler sensor based on the estimated position of the person being measured.

[0100] The present invention is not limited to the above embodiment, and various modifications are possible. For example, although the respiratory rate is generated as biological information of the subject in the above description, the heart rate can also be generated in a similar manner.

[0101] For the heart rate, for example, the following processes (1) to (4) may be executed for each of at least one Doppler sensor selected by the Doppler sensor selection unit 26.

[0102] (1) The Doppler data acquisition unit 32 acquires Doppler data indicating the measurement results by the Doppler sensor in each of a plurality of time windows (e.g., the first to thirtieth time windows). (2) The frequency spectrum generation unit 34 generates a frequency spectrum based on the acquired Doppler data for each of the plurality of time windows. (3) The biometric information generation unit 40 identifies the maximum amplitude and the second largest amplitude in the generated frequency spectrum for each of the plurality of time windows, and generates an amplitude ratio by dividing the maximum amplitude by the second largest amplitude. (4) The biometric information generation unit 40 generates, as a reliability, the ratio of the number of frequency spectra whose amplitude ratio is equal to or greater than a predetermined threshold (e.g., 1.5) to the number of frequency spectra generated for the plurality of time windows.

[0103] The biometric information generating unit 40 may then identify the Doppler sensor with the largest reliability value.The biometric information generating unit 40 may then identify the frequency spectrum having an amplitude ratio equal to or greater than a predetermined threshold (e.g., 1.5) from among the frequency spectra generated by the process shown in (2) above for the identified Doppler sensor.The biometric information generating unit 40 may then identify the frequency of the maximum amplitude for each of the frequency spectra having an amplitude ratio equal to or greater than the predetermined threshold.The biometric information generating unit 40 may then generate, as the heart rate for a period (e.g., one minute) associated with the plurality of time windows, the average value of the frequency of the maximum amplitude identified for each of the frequency spectra having an amplitude ratio equal to or greater than the predetermined threshold. [Explanation of symbols]

[0104] 1 Biometric information detection system, 10 signal processing device, 12 Doppler sensor unit, 14, 14a, 14b, 14c, 14d load sensor, 16 bed, 18, 18a, 18b, 18c, 18d, 18e, 18f measurement area, 20 load data acquisition unit, 22 ratio calculation unit, 24 position body axis estimation unit, 26 Doppler sensor selection unit, 28 body movement determination unit, 30 movement control unit, 32 Doppler data acquisition unit, 34 frequency spectrum generation unit, 36 frequency spectrum selection unit, 38 aggregate spectrum generation unit, 40 biological information generation unit.

Claims

1. a load data acquisition means for acquiring load data indicating a measurement result of a load acting on each of a plurality of load sensors positioned below the position of the subject when the subject is lying on the bed; a Doppler sensor selection means for selecting at least one Doppler sensor from a plurality of Doppler sensors having different measurement areas based on a measurement result of the load acting on each of the plurality of load sensors specified based on the load data; an operation suppression means for suppressing the operation of the Doppler sensors other than the at least one selected Doppler sensor; a biological information generating means for generating biological information of the subject based on Doppler data indicating the measurement results of each of the selected at least one Doppler sensor; A biological information detection system comprising:

2. 2. The biological information detection system according to claim 1, a ratio calculation means for calculating a ratio obtained by dividing a measurement result of a load applied to each of the plurality of load sensors by a total value of the measurement results of the loads applied to each of the plurality of load sensors; The Doppler sensor selection means selects the at least one Doppler sensor based on the ratio calculated for each of the plurality of load sensors.

3. 2. The biological information detection system according to claim 1, The plurality of Doppler sensors are arranged side by side along the width direction of the bed, a position estimation unit that estimates a position of the person being measured along a width direction of the bed based on a measurement result of the load applied to each of the plurality of load sensors, The Doppler sensor selection means selects the at least one Doppler sensor based on the estimated position of the subject.

4. 2. The biological information detection system according to claim 1, and a body axis direction estimation means for estimating a body axis direction of the subject based on a measurement result of the load applied to each of the plurality of load sensors, The Doppler sensor selection means selects the at least one Doppler sensor based on the estimated body axis direction.

5. 2. The biological information detection system according to claim 1, A biological information detection system, wherein the load sensor is provided on each of the four legs of the bed.

6. 2. The biological information detection system according to claim 1, the Doppler sensor selection means repeatedly selects the Doppler sensor based on the latest load measurement result; The biological information detection system further includes an operation suppression release means for releasing the suppression of the operation of the Doppler sensor that was not selected in the previous selection but is selected in the latest selection, in accordance with the selection of the Doppler sensor based on the latest load measurement result.

7. 2. The biological information detection system according to claim 1, the Doppler sensor selection means repeatedly selects the Doppler sensor based on the latest load measurement result; the operation suppression means, in response to the selection of the Doppler sensor based on the latest load measurement result, stops the Doppler sensor that was selected in the immediately preceding selection but not in the latest selection; The biological information detection system further includes an activation means for activating the Doppler sensor that was not selected in the previous selection but was selected in the latest selection in response to the selection of the Doppler sensor based on the latest load measurement result.

8. 2. The biological information detection system according to claim 1, a body movement determining means for determining whether or not a body movement of the subject is occurring based on the magnitude of fluctuation in the total value of the measurement results of the loads applied to the plurality of load sensors; A biological information detection system further comprising: a generation suppression means for suppressing generation of the biological information when it is determined that a body movement of the person being measured is occurring.

9. 2. The biological information detection system according to claim 1, and a body movement determining means for determining whether or not a body movement of the subject is occurring based on the magnitude of a change in the total value of the measurement results of the loads applied to each of the plurality of load sensors. The motion suppressing means suppresses the motion of all of the plurality of Doppler sensors when it is determined that the subject is moving.

10. 2. The biological information detection system according to claim 1, The Doppler sensor selection means selects a predetermined number of the Doppler sensors.

11. acquiring load data indicating a measurement result of a load acting on each of a plurality of load sensors positioned below the position of the subject when the subject is lying on the bed; selecting at least one Doppler sensor from a plurality of Doppler sensors having different measurement areas based on a measurement result of the load acting on each of the plurality of load sensors identified based on the load data; inhibiting operation of the Doppler sensors other than the at least one selected Doppler sensor; generating biological information of the subject based on Doppler data indicating the measurement results of each of the selected at least one Doppler sensor; A biological information detection method comprising:

12. acquiring load data indicating a measurement result of a load acting on each of a plurality of load sensors positioned below the position of the subject when the subject is lying on the bed; selecting at least one Doppler sensor from a plurality of Doppler sensors having different measurement areas based on a measurement result of the load acting on each of the plurality of load sensors identified based on the load data; inhibiting operation of the Doppler sensors other than the at least one selected Doppler sensor; generating biological information of the subject based on Doppler data indicating the measurement results of each of the selected at least one Doppler sensor; A program that causes a computer to execute the following.

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