Ballistocardiogram detection device having noise reduction function and ballistocardiogram measurement system

Abstract

To provide a ballistocardiogram detection device having a noise reduction function, and a ballistocardiogram measurement system.SOLUTION: A ballistocardiogram detection device having a noise reduction function includes a pressure reception device, a force sensor, a vibration sensor, and a signal processing module. The pressure reception device is arranged directly or indirectly in a lower part or a back of a body of a subject. The force sensor and the vibration sensor are provided in the pressure reception device. A distance between the vibration sensor and the force sensor is less than 20 cm. The signal processing module electrically connects the force sensor and the vibration sensor and receives a signal output by the force sensor and the vibration sensor.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a ballistocardiogram detection device and a ballistocardiogram measurement system, and more particularly to a ballistocardiogram detection device and a ballistocardiogram measurement system having a noise reduction function. [Background technology]

[0002] A ballistocardiogram (BCG) is a physiological signal generated by the heart. The waveform of the ballistocardiogram shows the regular motion displacements caused by the action force of the cardiac output from the heart to the aorta impacting the vascular walls of the ascending and descending aorta. The ballistocardiogram can effectively reflect the health status of the cardiovascular system of the human body. The ballistocardiogram may be applied in different fields, such as heart rate monitoring systems, for example, heart rate monitoring, cardiac function (systolic and diastolic) evaluation, and physiological signal analysis (respiratory rate and blood pressure change). The ballistocardiogram may be combined with a wearable device to remotely monitor the cardiac health of patients with chronic diseases, or to analyze cardiac activity during sleep to help diagnose sleep disorders.

[0003] In the current technology, many bed monitoring devices or instruments for measuring ballistocardiogram have been developed and produced. However, ballistocardiogram signals (also called BCG signals) are minute vibrations of the body caused by the contraction and expansion of the heart (i.e., the BCG signal itself is a minute signal), and are easily affected by other body movements or interference signals caused by the mattress itself when detected. Therefore, the signal-to-noise ratio (SNR) of the BCG signal detected by the current devices is not good. Therefore, how to improve it to overcome the above-mentioned shortcomings is one of the important problems that the field is trying to solve. Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention has been made in consideration of the shortcomings of the prior art, and is to provide a ballistocardiogram detection device and a ballistocardiogram measurement system having a noise reduction function that can accurately measure the BCG signal of a subject and achieve a noise reduction effect. [Means for solving the problem]

[0005] In order to solve the above problems, the means adopted in the present invention is a ballistocardiogram detection device with a noise reduction function. The ballistocardiogram detection device with a noise reduction function includes a pressure receiving device, a force sensor, a vibration sensor, and a signal processing module. The pressure receiving device is directly or indirectly placed under or on the back of the subject's body. The force sensor and the vibration sensor are provided on the pressure receiving device. The distance between the vibration sensor and the force sensor is less than 20 cm. The signal processing module electrically connects the force sensor and the vibration sensor, and receives the signals output by the force sensor and the vibration sensor.

[0006] In order to solve the above problems, another means adopted in the present invention is a ballistocardiogram measurement system. The ballistocardiogram measurement system includes a soft protective pad, a plurality of measurement devices, and a signal processing module. The plurality of measurement devices are respectively arranged in a plurality of regions of the soft protective pad. Each measurement device includes a force sensor and a vibration sensor, and measures the force and vibration received by the soft protective pad in the region where the measurement device is located, so that the force sensor outputs a force measurement signal and the vibration sensor outputs a vibration measurement signal. The signal processing module electrically connects the plurality of force sensors and the plurality of vibration sensors in the plurality of measurement devices. The signal processing module receives a plurality of vibration measurement signals from the plurality of vibration sensors, generates a plurality of ballistocardiogram waveforms based on the plurality of vibration measurement signals, and further captures a plurality of peak points from the plurality of ballistocardiogram waveforms and obtains a plurality of heartbeat interval data from the plurality of peak points. Effect of the Invention

[0007] The present invention has the following beneficial effects: The ballistocardiogram detection device and ballistocardiogram measurement system with noise reduction function provided by the present invention can locate the vibration sensor and the force sensor in close proximity with each other less than 20 cm, so that the force sensor and the vibration sensor can be located in the same measurement area. Thus, the signal processing module receives a plurality of vibration measurement signals from a plurality of vibration sensors, generates a plurality of ballistocardiogram waveforms according to the plurality of vibration measurement signals, and obtains a plurality of heartbeat interval data from the plurality of ballistocardiogram waveforms. Furthermore, the signal processing module screens or weights the plurality of heartbeat interval data according to the force measurement signals, so that the accuracy and signal-to-noise ratio of the obtained heartbeat interval data are improved, and noise countermeasure effect and noise reduction effect are achieved.

[0008] In order to further understand the features and technical contents of the present invention, please refer to the following detailed description of the present invention and the drawings. The drawings provided are for reference and explanation only, and are not intended to limit the present invention. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a ballistocardiogram detection device of the present invention. [Diagram 2] FIG. 2 is another schematic diagram of the ballistocardiogram detection device of the present invention. [Diagram 3] 1 is a schematic diagram of a pressure receiving device, a force sensor, and a vibration sensor according to the present invention. [Figure 4] FIG. 2 is a vibration waveform diagram obtained by using the ballistocardiogram detection device of the present invention. [Diagram 5] FIG. 2 is another vibration waveform diagram obtained by using the ballistocardiogram detection device of the present invention. [Figure 6] FIG. 1 is a diagram of beat-to-beat data captured from a oscillogram. [Figure 7] FIG. 2 is a curve diagram of downward force obtained using the ballistocardiogram detection device of the present invention. [Figure 8] FIG. 11 is a moving average curve diagram obtained without removing noise signals from heartbeat interval data. [Figure 9]FIG. 11 is a moving average curve diagram obtained by removing noise signals from heartbeat interval data. [Figure 10] FIG. 1 is a schematic side view of a ballistocardiogram measurement system according to the present invention. [Figure 11] FIG. 1 is a top schematic view of a ballistocardiogram measurement system of the present invention. [Figure 12] FIG. 2 is a vibration waveform diagram obtained by using a plurality of ballistocardiogram detection devices in the ballistocardiogram measurement system of the present invention. [Figure 13] FIG. 2 is a curve diagram of multiple downward forces obtained using multiple ballistocardiogram detection devices in the ballistocardiogram measurement system of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The following is an implementation manner for explaining the "ballistocardiogram detection device and ballistocardiogram measurement system having noise reduction function" disclosed by the present invention through a specific specific embodiment, and those skilled in the art can understand the advantages and effects of the present invention from the contents disclosed in this specification. The present invention may be implemented or applied through other specific embodiments, and each detail in this specification may be variously modified and changed based on different perspectives and applications without departing from the concept of the present invention. In addition, it should be noted in advance that the drawings of the present invention are only for simple and schematic explanation and do not represent actual size. In the following implementation manner, the related technical contents of the present invention will be described in more detail, but the disclosed contents do not limit the protection scope of the present invention. In addition, in this specification, various members may be described using terms such as "first" and "second", but it should be understood that these members should not be limited by these terms. These terms are mainly used to distinguish one member from another member. In addition, the term "or" used in this specification may include any one or more combinations of related listed items according to actual circumstances.

[0011] [Example] As shown in Fig. 1, the present invention provides a ballistocardiogram detection device. The ballistocardiogram detection device includes a pressure receiving device 1, a force sensor 2, a vibration sensor 3, and a signal processing module 4. The pressure receiving device 1 is directly or indirectly disposed under or on the back of a subject U. For example, the subject U is a human body or other animals, but the present invention does not limit the type of the subject U. In the present invention, the subject U is described as a human body.

[0012] The force sensor 2 and the vibration sensor 3 are provided in the pressure receiving device 1, and the vibration sensor 3 is located near the force sensor 2. Preferably, the distance between the vibration sensor 3 and the force sensor 2 is less than 20 cm, so that the vibration sensor 3 and the force sensor 2 are located within the same measurement range, and the phases of the signals output by the vibration sensor 3 and the force sensor 2 are compatible (i.e., the phases of the signals are close or equivalent). The signal processing module 4 electrically connects the force sensor 2 and the vibration sensor 3, and receives the signals output by the force sensor 2 and the vibration sensor 3.

[0013] The subject U (i.e., the human body) can be a force source and a vibration source. For example, when the pressure receiving device 1 is placed directly or indirectly on the back of the body of the subject U, the subject U applies a downward force to the pressure receiving device 1, and the force sensor 2 measures the force received by the pressure receiving device 1 and outputs a force measurement signal. Also, the vibration sensor 3 measures the body vibration of the subject U due to heartbeat and outputs a vibration measurement signal. In another embodiment, as shown in FIG. 2, when the subject U changes his / her position, the measurement areas of the force sensor 2 and the vibration sensor 3 are separated from the back of the subject U, so that the pressure receiving device 1 does not receive any force (downward force=0), and the force sensor 2 does not measure the force received by the pressure receiving device 1. However, since the measurement sensitivity of the vibration sensor 3 is higher than that of the force sensor 2, the vibration sensor 3 may measure other vibration signals from different measurement areas (e.g., the lower limbs of the subject U or other objects nearby).

[0014] As shown in FIG. 3, the present invention further provides a specific embodiment of the ballistocardiogram detection device. For example, the ballistocardiogram detection device may include a pressure receiving device 1, a force sensor 2, and a vibration sensor 3. The pressure receiving device 1 may include a first pressure receiving plate 11 and a second pressure receiving plate 12. The first pressure receiving plate 11 and the second pressure receiving plate 12 are basically the same in shape and size, and the first pressure receiving plate 11 is located above the second pressure receiving plate 12. The force sensor 2 is provided between the first pressure receiving plate 11 and the second pressure receiving plate 12. The vibration sensor 3 is provided on the first pressure receiving plate 11. The vibration sensor 3 is provided on the upper surface of the first pressure receiving plate 11 and is located directly above the first pressure receiving plate 11. In addition, the pressure receiving device 1 may further include two limit rivets S movably fixed to both sides of the pressure receiving plates (the first pressure receiving plate 11 and the second pressure receiving plate 12). The limit rivet S limits the deformation on the first pressure plate 11 side to within the allowable range of the corresponding limit rivet S, thereby preventing the first pressure plate 11 from being deformed excessively.

[0015] Furthermore, the signal processing module 4 is not limited to a specific location, and may be integrated inside the pressure receiving device 1, or may be provided as a separate component outside the pressure receiving device 1. The signal processing module 4 may include, but is not limited to, a signal amplifier, a filter, and an analog-to-digital signal converter to receive, filter, convert, and perform subsequent analysis processing of the detected signal.

[0016] For example, the force sensor 2 is a load cell including an electric resistance strain gauge. When in use, the electric resistance strain gauge is attached to the object to be measured. The resistance value of the electric resistance strain gauge changes as the object to be measured expands and contracts, and the strain is estimated from the change in resistance value. Therefore, when the first pressure receiving plate 11 is deformed by receiving a force, the vibration sensor 3 measures the deformation caused by the first pressure receiving plate 11 receiving the force and outputs a force measurement signal.

[0017] For example, the vibration sensor 3 may be a piezoelectric sensor. When a piezoelectric sensor receives mechanical stress, it generates an electric signal due to the piezoelectric effect. In the present invention, the vibration sensor 3 measures the minute vibrations generated when the first pressure receiving plate 11 receives a force, and outputs a vibration measurement signal.

[0018] As shown in Figures 1 and 4, for example, when the vibration sensor 3 measures the body vibration of the subject U caused by heartbeat and outputs a vibration measurement signal, the signal processing module 4 receives the vibration measurement signal and generates a vibration waveform shown in Figure 4, i.e., a ballistocardiogram waveform. The signal processing module 4 captures multiple peak points from the ballistocardiogram waveform and can obtain multiple heartbeat interval data P from the multiple peak points. Similarly, as shown in Figures 2 and 5, the vibration sensor 3 also measures a ballistocardiogram waveform generated by a vibration measurement signal (considered to be an interference signal or noise) from another measurement region, and the signal processing module 4 captures multiple peak points from the ballistocardiogram waveform and can obtain multiple heartbeat interval data Q from the multiple peak points.

[0019] In other words, in the detection process of the vibration sensor 3, the detected vibration waveform is a comprehensive waveform including a waveform caused by vibration from its own measurement area (FIG. 4) and a waveform caused by vibration from other measurement areas (FIG. 5). Therefore, as shown in FIG. 6, the signal processing module 4 simultaneously captures multiple heartbeat interval data P, Q. Next, the signal processing module 4 performs moving average calculation on the multiple heartbeat interval data P, Q to obtain the moving average curve diagram of FIG. 8. Statistically, the moving average is usually used in conjunction with a time series to eliminate short-term fluctuations and emphasize long-term trends or cycles. Therefore, the ballistocardiogram obtained by the moving average calculation (see FIG. 8) can more accurately reflect the heart rate of the subject U.

[0020] However, as described above, in the detection process of the vibration sensor 3, the detected vibration waveform is a comprehensive waveform, and strictly speaking, Fig. 8 cannot actually reflect the heartbeat of the subject U (because it contains noise caused by the vibration of other objects). Therefore, the signal processing module 4 receives the force measurement signal from the force sensor 2, and based on the force measurement signal, screens a plurality of heartbeat interval data, thereby removing the heartbeat interval data Q and leaving the heartbeat interval data P.

[0021] For details, refer to the force / time curve diagram (FIG. 7) generated when the signal processing module 4 receives the force measurement signal from the force sensor 2, shown in FIG. 6 and FIG. 7. The force sensor 2 and the vibration sensor 3 are located in the same measurement area, and the downward force measured by the force sensor 2 corresponds to the heartbeat interval data. For example, in FIG. 7, the section where the downward force measured by the force sensor 2 is F (F is a preset fixed value) corresponds to the distribution of the heartbeat interval data P in FIG. 6. In FIG. 7, the section where the downward force measured by the force sensor 2 is 0 corresponds to the distribution of the heartbeat interval data Q in FIG. 6. Therefore, the signal processing module 4 can determine that the heartbeat interval data Q is data caused by noise and delete it. That is, by arranging the force sensor 2 and the vibration sensor 3 to be located in the same measurement area, the signal processing module 4 can determine whether the vibration measured by the vibration sensor 3 is from the same measurement area or not, thereby reducing the calculation error of the heart rate. Next, the screened heartbeat interval data P is calculated to obtain the moving average value of the heartbeat interval shown in FIG. 9. FIG. 9 is a ballistocardiogram obtained after noise reduction and moving average calculation, which can actually reflect the heart rate of subject U.

[0022] The present invention further provides a ballistocardiogram measuring system. As shown in Fig. 10 and Fig. 11, the ballistocardiogram measuring system includes a plurality of measuring devices D and a soft protective pad 5. The plurality of measuring devices D are arranged in a plurality of regions of the soft protective pad 5. The soft protective pad 5 is directly or indirectly arranged under or on the back of the body of a subject U. For example, as shown in Fig. 10, the soft protective pad 5 is arranged under a mattress 6, and a user (subject U) lies on the mattress 6.

[0023] Each measuring device D is the ballistocardiogram detection device mentioned above and includes a force sensor 2 and a vibration sensor 3 (see FIG. 1). Each measuring device D measures the forces and vibrations experienced by the soft protective pad 5 in the area where the measuring device D is located, such that the force sensor 2 outputs a force measurement signal and the vibration sensor 3 outputs a vibration measurement signal. The signal processing module 4 electrically connects the multiple force sensors 2 and the multiple vibration sensors 3 in the multiple measuring devices D.

[0024] As shown in FIG. 11, three measuring devices in a ballistocardiogram measuring system are taken as an example. These three measuring devices are referred to as measuring devices D1 to D3. In FIG. 11, a user (subject U) is lying on his / her side. From the relative positions, the gravity acting on the measuring device D1 is the largest, which indicates that the signal measured by the measuring device D1 can better reflect the user's heart rate for the measuring devices D2 and D3. As shown in FIG. 1, FIG. 11 and FIG. 12, the signal processing module 4 receives a plurality of vibration measurement signals from the vibration sensors 3 in the measuring devices D1 to D3, and generates a plurality of ballistocardiogram waveforms as shown in FIG. 12 based on the plurality of vibration measurement signals. The upper waveform in FIG. 12 is obtained from the measuring device D1, the middle waveform is obtained from the measuring device D2, and the lower waveform is obtained from the measuring device D3.

[0025] The signal processing module 4 further acquires a plurality of peak points from each ballistocardiogram waveform, and obtains a plurality of heartbeat interval data from the plurality of peak points. As shown in FIG. 12, the heartbeat interval data A1, A2,..., A n represents the data obtained from the ballistocardiogram waveform of the measuring device D1, and the heartbeat interval data B1, B2...B n represents the data obtained from the ballistocardiogram waveform of the measuring device D2, and the heartbeat interval data C1, C2...C n represents what can be obtained from the ballistocardiogram waveform of measuring device D3.

[0026] Next, as shown in Fig. 13, the signal processing module 4 receives a plurality of force measurement signals from the force sensors 2 in the measuring devices D1 to D3, and generates a plurality of force / time curves based on the plurality of force measurement signals. As shown in Fig. 12 and Fig. 13, the downward force F1 in Fig. 13 corresponds to the ballistocardiogram waveform of the measuring device D1 in Fig. 12, the downward force F2 in Fig. 13 corresponds to the ballistocardiogram waveform of the measuring device D2 in Fig. 12, and the downward force F3 in Fig. 13 corresponds to the ballistocardiogram waveform of the measuring device D3 in Fig. 12.

[0027] As can be seen from the relative position distribution between the measuring devices D1-D3 and the user's body in FIG. 11, the closer the measuring device is to the user, the greater the force the pressure receiving device 1 receives, and the vibration waveform obtained by the measuring device can reliably reflect the ballistocardiogram caused by the user's heartbeat. Therefore, the signal processing module 4 receives a plurality of force measurement signals from a plurality of force sensors 2, and gives a corresponding weight to each force measurement signal, and the greater the downward force, the greater the weight given. As shown in FIG. 13, for example, the weight of the downward force F1 is set to W1, the weight of the downward force F2 is set to W2, and the weight of the downward force F3 is set to W3. Next, the signal processing module 4 performs weighted calculation of these heartbeat interval data based on the obtained weights to obtain a weighted average value of the heartbeat interval data. As shown in FIG. 12 and FIG. 13, a weighted average calculation is performed on the heartbeat interval data in the same time segment. For example, a first weighted average value obtained by performing a weighted average calculation on the heartbeat interval data A1, B1, and C1 in the first time segment is equal to ((A1×W1)+(B1×W2)+(C1×W3)) / (W1+W2+W3). A second weighted average value obtained by performing a weighted average calculation on the heartbeat interval data A2, B2, and C2 in the second time segment is equal to ((A2×W1)+(B2×W2)+(C2×W3)) / (W1+W2+W3). n , B n , C n The nth weighted average value obtained by performing a weighted average calculation is ((A n ×W1) + (B n ×W2) + (C n ×W3)) / (W1+W2+W3), where n is a natural number greater than 3.

[0028] Through the weighted average calculation, the proportion of the vibration signal of the measuring device D1 close to the user becomes larger, that is, the proportion of the vibration signal of the measuring device D1 farther from the user becomes lower (because the further away from the user, the weaker and noisier the vibration measurement signal measured becomes), thus achieving a noise reduction effect.Therefore, the noise is reduced and the ballistocardiogram obtained after the weighted average calculation can actually reflect the heart rate of the user (subject U).

[0029] The contents disclosed above are merely preferred and possible embodiments of the present invention, and are not intended to limit the scope of the claims of the present invention. Any equivalent technical modifications made using the contents of the specification and drawings of the present invention are within the scope of the claims of the present invention. [Explanation of symbols]

[0030] D, D1 to D3: Measuring equipment 1: Pressure receiving device 2: Force sensor 3: Vibration sensor 4: Signal processing module 5: Soft protective pad 6: Mattress 11: First pressure plate 12: Second pressure plate U: Subject F, F1~F3: Downward force P, Q, A1, A2, A n , B1, B2, B n , C1, C2, C n : Heart rate data S: Limit rivet

Claims

1. A pressure receiving device that is placed directly or indirectly under or on the back of the subject's body; A force sensor provided in the pressure receiving device; a vibration sensor provided on the pressure receiving device, the distance between the vibration sensor and the force sensor being less than 20 cm; and a signal processing module electrically connecting the force sensor and the vibration sensor and receiving signals output by the force sensor and the vibration sensor.

2. 2. The ballistocardiogram detection device with noise reduction function according to claim 1, wherein the force sensor is a load cell, which measures the force received by the pressure receiving device and outputs a force measurement signal.

3. 3. The ballistocardiogram detection device with noise reduction function according to claim 2, wherein the vibration sensor is a piezoelectric sensor, which measures the vibration of the pressure receiving device and outputs a vibration measurement signal.

4. The ballistocardiogram detection device with noise reduction function according to claim 3, wherein the signal processing module receives the vibration measurement signal, generates a ballistocardiogram waveform based on the vibration measurement signal, and further extracts a plurality of peak points from the ballistocardiogram waveform, and obtains a plurality of heartbeat interval data from the plurality of peak points.

5. 5. The ballistocardiogram detection device with noise reduction function according to claim 4, wherein the signal processing module receives the force measurement signal, screens a plurality of the heartbeat interval data based on the force measurement signal, and calculates the screened plurality of the heartbeat interval data to obtain a moving average value of the heartbeat interval data.

6. A soft protective pad to be placed directly or indirectly on the underside or back of the subject's body; A plurality of measuring devices each including a force sensor and a vibration sensor and disposed in a plurality of regions of the soft protection pad, the force sensor outputs a force measurement signal and the vibration sensor outputs a vibration measurement signal by measuring the force and vibration received by the soft protection pad in the region where the measuring device is located; a signal processing module electrically connecting the force sensors and the vibration sensors in the measurement devices; The signal processing module receives a plurality of vibration measurement signals from a plurality of the vibration sensors, generates a plurality of ballistocardiogram waveforms based on the plurality of vibration measurement signals, and further captures a plurality of peak points from the plurality of ballistocardiogram waveforms and obtains a plurality of cardiac interval data from the plurality of peak points.

7. 7. The ballistocardiogram measurement system according to claim 6, wherein the signal processing module receives a plurality of the force measurement signals from a plurality of the force sensors, assigns a corresponding weight to each of the force measurement signals, and calculates a plurality of the cardiac interval data based on the obtained weights to obtain a weighted average value of the cardiac interval data.

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