Sensor system

Abstract

The sensor system Al includes a first sensor 11 that converts a first physical quantity of a measurement object into a first signal V1 and outputs it, a second sensor 12 that converts a second physical quantity of the measurement object into a second signal V2 and outputs it, and a control section 2. The second physical quantity has relevance to whether or not the measurement object is in a state suitable for detection by the first sensor 11. The control section 2 performs: a first judgment process that judges whether or not the measurement object is in a state suitable for detection by the first sensor 11 based on the second signal V2; a measurement process that measures first information of the measurement object using the first signal V1 in the case where it is judged in the first judgment process that the measurement object is in a suitable state; a second judgment process that judges whether or not the measurement object is in a state suitable for detection by the first sensor 11 based on the first signal V1; and a correction process that corrects a judgment criterion of the first judgment process using a judgment result of the second judgment process and the second signal V2 at the time of making the judgment. With such a configuration, it is possible to improve the accuracy of measurement by combining two kinds of sensors.

Description

Technical Field

[0001] This invention relates to sensor systems. Background Technology

[0002] To measure vital signs indicating a person's life, systems combining multiple sensors have been proposed, for example. Patent Document 1 discloses an example of a conventional sensor system. The sensor system disclosed in this document includes a fabric sensor and a signal processing device. The fabric sensor has two sensor elements. One sensor element is a piezoelectric sensor, and the other sensor element is a capacitive sensor. The fabric sensor is disposed, for example, in a chair, bed, etc. It can detect whether the subject is sitting in a chair or lying in a bed based on the signal from the capacitive sensor. Furthermore, by processing the signal from the piezoelectric sensor at this time, it is possible to measure vital signs such as the subject's pulse and respiration.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-129318 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] Besides the presence of the subject, capacitive sensors can be affected by various other factors. In cases where the signal of a capacitive sensor rises or falls unexpectedly due to factors other than the subject's presence, it becomes difficult to properly detect the subject's presence, and it may be possible to measure vital signs based on the signal of a piezoelectric sensor at an inappropriate time.

[0008] The present invention was conceived under the above circumstances, and its objective is to provide a sensor system capable of improving the accuracy of measurements performed by combining two sensors.

[0009] Technical solutions for solving the problem

[0010] The sensor system provided by the present invention includes: a first sensor that converts a first physical quantity of a measured object into a first signal and outputs it; a second sensor that converts a second physical quantity of the measured object into a second signal and outputs it; and a control unit electrically connected to the first sensor and the second sensor, wherein the second physical quantity is correlated with whether the measured object is in a state suitable for detection by the first sensor, and the control unit performs the following processing: a first judgment processing, which determines whether the measured object is in a state suitable for detection by the first sensor based on the second signal; a measurement processing, which, if the first judgment processing determines that the measured object is in a state suitable for detection by the first sensor, measures first information of the measured object using the first signal; a second judgment processing, which determines whether the measured object is in a state suitable for detection by the first sensor based on the first signal; and a correction processing, which corrects the judgment criteria of the first judgment processing using the judgment result of the second judgment processing and the second signal at the time of the judgment.

[0011] In a preferred embodiment of the present invention, in the correction process, the first signal, which is determined in the second judgment process to be not in a state suitable for detection by the first sensor, is used to correct the judgment criterion of the first judgment process.

[0012] In a preferred embodiment of the present invention, in the correction process, when it is determined in the second judgment process that the state is not suitable for detection by the first sensor for a specified time, the first signal within the specified time is used to correct the judgment criterion of the first judgment process.

[0013] In a preferred embodiment of the present invention, the first physical quantity is a physical quantity corresponding to the vital signs of the person being measured, and the second physical quantity is related to whether the person being measured is located in a position that can be detected by the first sensor.

[0014] In a preferred embodiment of the present invention, the first sensor is a piezoelectric sensor and the second sensor is a capacitive sensor.

[0015] Invention Effects

[0016] According to the present invention, the accuracy of measurements performed by combining two sensors can be improved.

[0017] Other features and advantages of the invention will become clearer from the detailed description following with reference to the accompanying drawings. Attached Figure Description

[0018] Figure 1 This is a system configuration diagram illustrating the sensor system according to the first embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram illustrating the sensor system according to the first embodiment of the present invention.

[0020] Figure 3 This is a partial cross-sectional perspective view showing an example of a sensor unit of a sensor system according to the first embodiment of the present invention.

[0021] Figure 4 This is a flowchart illustrating an example of a measurement method for a sensor system according to the first embodiment of the present invention.

[0022] Figure 5 This is a graph illustrating an example of the measurement method of the sensor system according to the first embodiment of the present invention.

[0023] Figure 6 This is a graph illustrating another example of the measurement method of the sensor system according to the first embodiment of the present invention.

[0024] Figure 7 This is a flowchart illustrating an example of a measurement method for a sensor system according to a second embodiment of the present invention.

[0025] Figure 8 This is a graph illustrating an example of the measurement method of the sensor system according to the second embodiment of the present invention. Detailed Implementation

[0026] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0027] The terms “first”, “second”, etc., used in this disclosure are for identification purposes only and are not intended to assign order to the objects.

[0028] <First Implementation>

[0029] Figures 1-3 This describes a sensor system according to a first embodiment of the present invention. The sensor system A1 of this embodiment includes a first sensor 11, a second sensor 12, and a control unit 2. The specific application of the sensor system A1 is not limited in any way. For example, the sensor system A1 is used to measure specified measurement items of various measurement objects at a suitable time.

[0030] The prescribed measurement items for the object of measurement can be, for example, human vital signs. Vital signs are represented by, for example, pulse, respiration, body temperature, and blood pressure. The environment for measuring vital signs can be, for example, beds and chairs in hospitals, nursing homes, hotels, and residences, or chairs in offices, beauty salons, cinemas, cars, airplanes, and trains.

[0031] The first sensor 11 is a sensor used to measure first information about a measurement item, which is the object of measurement. The first sensor 11 converts a first physical quantity of the object of measurement into a first electrical signal and outputs it. The specific configuration of the first sensor 11 is not limited. The first sensor 11 can be configured to convert various types of first physical quantities into first signals, and can have various sensor elements. It may also include a processing unit or amplifier for processing the output of the sensor element as a first signal. Examples of first sensors 11 include piezoelectric sensors, force sensors, accelerometers, gyroscopes, microphone sensors, ultrasonic sensors, Doppler sensors, fiber optic sensors, proximity sensors, displacement sensors, image sensors, magnetic sensors, current sensors, voltage sensors, capacitive sensors, optical sensors, temperature sensors, pressure sensors, acoustic sensors, humidity sensors, moisture sensors, color sensors, and pyroelectric sensors. When the first information is, for example, a vital sign such as pulse, respiration, body temperature, or blood pressure, the first physical quantity is acceleration, vibration, or pressure corresponding to these vital signs. When the first information is a vital sign, the first sensor 11 may employ a piezoelectric sensor, accelerometer, gyroscope, microphone sensor, ultrasonic sensor, Doppler sensor, pressure sensor, acoustic sensor, moisture sensor, pyroelectric sensor, etc. When the rate of change of the first physical quantity is detected or output by the first sensor 11, the first sensor 11 may employ a piezoelectric sensor, accelerometer, gyroscope, microphone sensor, Doppler sensor, fiber optic sensor, acoustic sensor, pyroelectric sensor, etc. When the quantity of change of the first physical quantity is detected or output by the first sensor 11, the first sensor 11 may employ a force sensor, ultrasonic sensor, Doppler sensor, fiber optic sensor, proximity sensor, displacement sensor, temperature sensor, pressure sensor, humidity sensor, moisture sensor, color sensor, capacitive sensor, etc. In the following description, unless otherwise specified, the case where the first sensor 11 is a piezoelectric sensor will be used as an example.

[0032] The specific configuration of the piezoelectric sensor 11 is not limited in any way. For example, the configuration disclosed in Japanese Patent No. 6501958 can be adopted, which includes: a core wire formed by spirally winding a metal foil on a resin wire, an organic piezoelectric layer covering the core wire, and a conductive layer covering the organic piezoelectric layer.

[0033] The second sensor 12 converts a second physical quantity of the measured object into a second electrical signal and outputs it. The second physical quantity is related to whether the measured object is in a state suitable for detection by the first sensor 11. Whether the measured object is in a state suitable for detection by the first sensor 11 can be categorized in ways such as: whether the measured object is in a position where the first sensor 11 can function; whether the measured object is in a state or posture where the first sensor 11 can function; and whether the measured object is under conditions such as temperature, pressure, and noise level where the first sensor 11 can function. The specific configuration of the second sensor 12 is not limited. The second sensor 12 can be configured to convert various types of second physical quantities into second signals, and can include various sensor elements, as well as a processing unit or amplifier for processing the output of the sensor elements as a second signal. Examples of second sensors 12 include capacitive sensors, optical sensors, temperature sensors, pressure sensors, acoustic sensors, force sensors, accelerometers, gyroscopes, microphone sensors, ultrasonic sensors, Doppler sensors, fiber optic sensors, proximity sensors, displacement sensors, image sensors, magnetic sensors, current sensors, voltage sensors, humidity sensors, moisture sensors, color sensors, pyroelectric sensors, and piezoelectric sensors. When the rate of change of a second physical quantity is detected or output by the second sensor 12, the second sensor 12 may be a piezoelectric sensor, accelerometer, gyroscope, microphone sensor, Doppler sensor, fiber optic sensor, acoustic sensor, or pyroelectric sensor. When the quantity of change of a second physical quantity is detected or output by the second sensor 12, the second sensor 12 may be a force sensor, ultrasonic sensor, Doppler sensor, fiber optic sensor, proximity sensor, displacement sensor, temperature sensor, pressure sensor, humidity sensor, moisture sensor, color sensor, or capacitive sensor. The first sensor 11 and the second sensor may be the same type of sensor or different types of sensors. When the first sensor 11 and the second sensor 12 are the same type of sensor, their installation locations can be different, and their detection or output ranges, sampling rates, etc., can also be different. When the first sensor 11 and the second sensor 12 are different types of sensors, it is advantageous to detect the first physical quantity and the second physical quantity more accurately. Furthermore, it is preferable to adopt a configuration in which the first sensor 11 outputs a data signal of the first physical quantity as a rate of change, and the second sensor 12 outputs a data signal of the second physical quantity as a change quantity. In the following description, unless otherwise specified, the case where the second sensor 12 is a capacitive sensor will be used as an example. The specific configuration of the capacitive sensor as the second sensor 12 is not limited in any way; for example, it can be a configuration consisting of a combination of copper foil and an insulating layer.

[0034] The first sensor 11 and the second sensor 12 can be configured as separate units and installed separately on the object being measured. Alternatively, the first sensor 11 and the second sensor 12 can be configured as a single unit and installed together on the object being measured. In this embodiment, the sensor system A1 includes a sensor unit 10. Figure 3 As shown, in sensor unit 10, first sensor 11 and second sensor 12 are integrally formed via substrate 19. Substrate 19 is, for example, a fabric-like strip. Multiple cavities extending along the length direction are provided in substrate 19. The first sensor 11 is housed in the central cavity in the width direction. The second sensor 12 is housed in cavities on both sides of the width direction. Furthermore, the portion of substrate 19 housing the first sensor 11 and second sensor 12 may have a slightly bulging shape along the length direction. For example, an anti-slip portion (not shown) may be provided in this portion.

[0035] exist Figure 2 In the example shown, sensor unit 10 is disposed on the seat of chair 91. This allows for the measurement of vital signs of a person sitting on chair 91.

[0036] A first signal from the first sensor 11 and a second signal from the second sensor 12 are input to the control unit 2. The control unit 2 uses the first and second signals to perform vital sign processing, which measures the vital signs as first information. The specific configuration of the control unit 2 is not limited in any way; for example, it may include a CPU, memory, various interfaces, etc. Furthermore, the control unit 2 may also include dedicated processing circuitry for processing signals from either or both of the first sensor 11 and the second sensor 12. The first sensor 11 and the second sensor 12 are electrically connected to the control unit 2. The electrical connection can be wired or wireless.

[0037] Next, refer to Figure 4 and Figure 5 The measurement method performed by sensor system A1 will be described below.

[0038] Figure 4 This is a flowchart illustrating an example of a measurement method performed by sensor system A1. When the measurement method begins in step S0, signals are output from the first sensor 11 and the second sensor 12. Figure 5This is a graph showing an example of the output of the first signal V1 from the first sensor 11 and the second signal V2 from the second sensor 12. The horizontal axis represents time, the upper part of the vertical axis represents the first signal V1, and the lower part represents the second signal V2. In this graph, the measurement method of this embodiment starts from time t1. Furthermore, the first signal V1 of the first sensor 11 is set to be able to take both positive and negative values, and the second signal V2 of the second sensor 12 is set to be able to take 0 or a positive value. Moreover, these settings for the first signal V1 and the second signal V2 are only one example; the first threshold Vth1 and the second threshold Vth2, described later, are appropriately set according to the numerical range of the first signal V1 and the second signal V2.

[0039] Figure 4 Step S1 is the first judgment process. In the first judgment process, it is determined whether the object to be measured is in a state suitable for detection by the first sensor 11 based on the second signal V2. In this embodiment, a reference is set as the basis for the judgment. Figure 5 The second threshold Vth2 is shown. For example, when the second sensor 12 is a capacitive sensor, when a person is not sitting on the chair 91, that is, in a state unsuitable for measurement by the first sensor 11, the second signal V2 is almost 0. On the other hand, when a person is sitting on the chair 91, that is, in a state suitable for measurement by the first sensor 11, the second signal V2 rises to a predetermined value. The second threshold Vth2 is set to a value lower than the predetermined value when a person is sitting on the chair 91.

[0040] From time t1 to time t6, the second signal V2 is less than the second threshold Vth2. Therefore, Figure 4 If step S1 is "No", then the measurement process in step S2 will not be performed. On the other hand, in Figure 5 At time t7, the second signal V2 exceeds the second threshold Vth2. This can be attributed to the change caused by the person sitting on chair 91. In this case, Figure 4 If step S1 is "yes", proceed to step S2 for measurement processing.

[0041] In the measurement processing of step S2, the control unit 2 uses the first signal V1 to measure, for example, the pulse, which is the first piece of information of the measurement object. The specific signal processing in the control unit 2 used to implement the pulse measurement is not limited in any way. For example, various conventionally known methods such as various filtering processes and FFT analysis can be used.

[0042] The measurement processing in step S2 is performed during the period when the second signal V2 exceeds the second threshold Vth2. At time t8, since the second signal V2 is below the second threshold Vth2, the measurement processing in step S2 ends. The measurement result (pulse) of the measurement processing (step S2) from time t7 to time t8 can be stored in the storage unit of the control unit 2, and can also be further sent from the control unit 2 to other devices.

[0043] Between time t1 and time t6, since the second signal V2 is less than the second threshold Vth2 in the first judgment process of step S1 (step S1: no), the measurement process is not performed (step S2), and the second judgment process of step S3 is performed instead.

[0044] The second judgment process determines whether the object being measured is in a state suitable for detection by the first sensor 11 based on the first signal V1. In this embodiment, a criterion is set as the basis for the judgment. Figure 5 The first threshold Vth1 is shown. In this embodiment, since the first sensor 11 is a piezoelectric sensor, when a person sits on the chair 91, the first signal V1 becomes a waveform signal with a relatively large amplitude by detecting vibrations such as pulse. On the other hand, when a person is not sitting on the chair 91, the first signal V1 becomes a signal that does not exhibit a significant waveform and displays an approximately constant value. The first threshold Vth1 is, for example, set to a positive value that the absolute value of the first signal V1 can exceed when a person is sitting on the chair 91.

[0045] In this embodiment, when the absolute value of the first signal V1 exceeds the first threshold Vth1, it is assumed that a person is sitting on the chair 91, and vibrations, equivalent to the person's pulse or other physical quantities, are being detected by the first sensor 11. Therefore, when the absolute value of the first signal V1 exceeds the first threshold Vth1, it can be determined that the person is in a state suitable for measurement by the first sensor 11. On the other hand, when the absolute value of the first signal V1 is below the first threshold Vth1, in this embodiment, it can be determined that the person is not sitting on the chair 91 and is not in a state suitable for measurement by the first sensor 11.

[0046] Furthermore, in the second judgment process (step S3), when comparing the absolute value of the first signal V1 with the first threshold Vth1, various signal processing methods can be appropriately performed to achieve a more appropriate judgment. For example, the standard deviation of the first signal V1 can be calculated and compared with the first threshold Vth1 that matches the standard deviation. Alternatively, the coefficient of variation of the first signal V1 can be calculated and compared with the first threshold Vth1 that matches the coefficient of variation. Alternatively, an FFT analysis can be performed on the first signal V1, and if the peak frequency obtained by the FFT analysis is below a preset threshold frequency, it can be determined that it is in a state suitable for measurement by the first sensor 11. Alternatively, the maximum amplitude value, integral value, or effective value (RMS: root mean square) of the first signal V1 can also be used. In addition, these comparison methods can be appropriately combined. Furthermore, for the purpose of noise removal, these comparisons can also be performed using the first signal V1 that has undergone filtering processing such as a low-pass filter.

[0047] As a preferred example of the method for comparing the first signal V1 with the first threshold Vth1, the coefficient of variation of the first signal V1, which has undergone low-pass filtering, is calculated. The value corresponding to the coefficient of variation is preset as the first threshold Vth1. When the state in which the coefficient of variation of the first signal V1 is lower than the first threshold Vth1 persists for a predetermined time, it is determined that the state is suitable for measurement by the first sensor 11.

[0048] In this embodiment, when the second judgment process determines that the state is not suitable, that is, when the absolute value of the first signal V1 is less than the first threshold Vth1 (step S3: yes), the correction process of step S4 is performed.

[0049] The correction process is a process of correcting the judgment criteria of the first judgment process (step S1) using the judgment result of the second judgment process (step S3) and the second signal V2 at the time of the judgment. In this embodiment, when the state has lasted for a specified time from the point (time t1) when the absolute value of the first signal V1 is lower than the first threshold Vth1, the judgment criteria are corrected in the correction process.

[0050] exist Figure 5In this context, the specified time is denoted as time ta. When the absolute value of the first signal V1 at time t1 is lower than the first threshold Vth1, and the duration of this state is ta, the control unit 2 corrects the judgment criteria of the first judgment process (step S1) at time t2. The specific method for correcting this judgment criteria is not limited. For example, zero-point correction can be performed on the second signal V2, or the second threshold Vth2 can be corrected. In the case of zero-point correction of the second signal V2, the control unit 2, for example, temporarily stores the second signal V2 from time t1 to time t2 in advance. Then, using the values ​​of the second signal V2 from time t1 to time t2, zero-point correction is performed on the second signal V2.

[0051] The specific method for using the values ​​of the second signal V2 from time t1 to time t2 is not limited in any way. Examples of possible values ​​for the second signal V2 from time t1 to time t2 include the mean, median, standard deviation, coefficient of variation, maximum amplitude, energy (integral value), mode, RMS (effective value), norm (when considered as a vector), and slope between two points. These values ​​can be calculated after applying various filtering processes. Various filtering processes can be employed, such as moving average, low-pass filter, high-pass filter, band-pass filter, truncated average, missing value handling, outlier handling, median filter, Kalman filter, regression analysis, and frequency analysis. For example, when using the mean value, the mean value of the second signal V2 from time t1 to time t2 is calculated as a correction value V2r. Then, the value of the correction value V2r is set as the zero point of the second signal V2 after time t2. Figure 5 In the above, at time t2, the dashed arrow extending from the first signal V1 (upper side) to the second signal V2 (lower side) indicates that correction has been performed through the correction process (step S4). Thus, the correction process in step S4 is complete.

[0052] If the process does not end in step S5, the sequence from time t2 to time t3 is: Step S1: No → Step S3: Yes, and correction processing is performed at time t3 (Step S4). Alternatively, if the sequence from time t3 is: Step S1: No → Step S3: Yes, but before time ta has elapsed from time t3, the absolute value of the first signal V1 exceeds the first threshold Vth1 at time t4 (Step S3: No). In this case, since the second signal V2 is lower than the second threshold Vth2, it is assumed that although no one is sitting on chair 91, there is an object on chair 91 that emits unexpected vibrations. Therefore, correction processing in step S4 is not performed. Alternatively, measurement processing (Step S2) can be performed from time t4 to time t5.

[0053] Subsequently, in the illustrated example, for instance at time t5, the absolute value of the first signal V1 is lower than the first threshold Vth1, and a correction process is performed at time t6 after time ta (step S4). Additionally, a measurement process is performed between times t7 and t8 (step S2), a correction process is performed at time t9 after time ta from time t8 (step S4), and a measurement process is performed between times t10 and t11 (step S2).

[0054] If the process related to the measurement method is not terminated (step S5: No), the process after step S1 is executed again. If the process related to the measurement method is terminated (step S5: Yes), the process related to the measurement method ends (step S6).

[0055] Next, the function of sensor system A1 will be explained.

[0056] In sensor system A1, the judgment criteria of the first judgment process (step S1) are corrected using the judgment result of the second judgment process (step S3) and the second signal V2 at the time of the judgment. Therefore, when the state of the measured object changes unexpectedly, the misjudgment of the first judgment process caused by such change can be reduced.

[0057] For example, in Figure 6 In the example shown, the value of the second signal V2 gradually increases after the measurement method begins at time t1. This could be conceivable, for example, if water accidentally spills onto chair 91, affecting the detection of the second sensor 12.

[0058] The second signal V2' in this figure differs from that in this embodiment. It is represented by an imaginary line as the output signal of the second sensor 12 when no judgment processing (step S3) and correction processing (step S4) are performed. From time t1, the second signal V2' gradually increases and exceeds the second threshold Vth2 at time t7. Therefore, the control unit 2 determines that the object being measured is in a state suitable for measurement by the first sensor 11 (step S1: Yes) and performs measurement processing (step S2). At time t7, since the person is not sitting on the chair 91 or lying on the bed that is the object, the measurement result obtained from the measurement processing is recorded as an inappropriate result.

[0059] In this embodiment, a correction process is performed at time t2 after time ta from time t1 (step S4). Therefore, for the second signal V2 after time t2, a correction process such as zero-point correction is performed using the second signal V2 from time t1 to time t2. In the illustrated example, a zero-point correction is performed on the second signal V2 at time t2, causing the second signal V2 to drop to a value close to 0. Similarly, correction processes are performed at each time when the condition is met from time t3 to time t9 (step S4). As a result, even if the value of the second signal V2 gradually increases, an appropriate judgment can be made in the first judgment process (step S1: No) from time t1 to time t9 when no one is sitting on the chair 91, thereby avoiding erroneous execution of the measurement process (step S2). Furthermore, when someone is indeed sitting on the chair 91 at time t10, the value of the second signal V2 increases significantly and exceeds the second threshold Vth2. Therefore, during the period from time t10 to time t11, the first determination process determines that the state is suitable for measurement by the first sensor 11 (step S1: Yes), and the measurement process is executed appropriately (step S2). Therefore, according to the sensor system A1, the accuracy of measurement by combining the two sensors can be improved.

[0060] like Figure 4 As shown, in this embodiment, when the object to be measured is not in a state suitable for measurement by the first sensor 11 during the second determination process (step S3: Yes), a correction process (step S4) is performed. In this case, the second signal V2 used for the correction process is, for example, the value under conditions such as when no one is sitting on the chair 91. Therefore, zero-point correction can be performed on the second signal V2 during the correction process. This correction has the advantage that it can more accurately determine, based on the value of the second signal V2, that the object to be measured, such as when no one is sitting on the chair 91, is not in a state suitable for measurement by the first sensor 11. In addition, as Figure 5 As shown, the correction process and measurement process can be separated and executed at different times, which helps to reduce the processing load of the control unit 2.

[0061] like Figure 5 As shown, in this embodiment, when the absolute value of the first signal V1 is lower than the first threshold Vth1, i.e. Figure 4 When the state of "yes" in step S3 continues for a specified time ta, correction processing is performed (step S4). Therefore, in cases where the absolute value of the first signal V1 falls below the first threshold Vth1 for only a very short time due to a sudden event that should not be considered, unnecessary correction processing can be avoided, and unintended reduction in measurement accuracy can be prevented.

[0062] Figure 7 and Figure 8Other embodiments of the present invention are shown. Furthermore, in these figures, elements that are the same as or similar to those in the above embodiments are labeled with the same reference numerals as those in the above embodiments. Moreover, without causing technical inconsistencies, the configurations of the various modifications and parts in each embodiment can be appropriately combined with each other.

[0063] Figure 7 This describes a measurement method for a sensor system according to a second embodiment of the present invention. In this embodiment, when the result of the second determination process (step S3) indicates that the object to be measured is in a state suitable for measurement by the first sensor 11, a correction process (step S4) is performed.

[0064] In this embodiment, if the second signal V2 exceeds the second threshold Vth2 during the first determination process and the object being measured is in a state suitable for measurement by the first sensor 11 (step S1: Yes), the measurement process (step S2) (times t2 to t4, times t5 to t7) is performed in the same way as in the first embodiment, and the second determination process (step S3) is also performed.

[0065] In the second determination process, when it is determined that the absolute value of the first signal V1 exceeds the first threshold Vth1, or that the object being measured is in a state suitable for measurement by the first sensor 11 (step S3: Yes), the control unit 2 performs a correction process (step S4). In this embodiment, when the correction process (step S4) is performed, for example, in the state of a person sitting on a chair 91, and as... Figure 8 As shown, the second signal V2 is in an upward state (time t2 to time t4). When the absolute value of the first signal V1 exceeds the state of the first threshold Vth1 for a specified time tb, the control unit 2 uses the second signal V2 from time t2 to time t3 to correct the judgment criteria of the first judgment process.

[0066] In this embodiment, the case where the second signal V2 from time t2 to time t3 is used to correct the second threshold Vth2 will be described. For example, the average value of the second signal V2 from time t2 to time t3 is compared with the second threshold Vth2, and the difference is calculated. When the calculated difference is less than a preset appropriate difference, it is conceivable that the second threshold Vth2 is set to be larger. Therefore, the control unit 2 reduces the second threshold Vth2 according to a predetermined ratio. From time t3 onwards, the reduced second threshold Vth2 is used.

[0067] Furthermore, at time t5, as a result of the second judgment process, it is determined that the object being measured is in a state suitable for measurement by the first sensor 11 (step S3: Yes). In the illustrated example, the difference between the second signal V2 and the second threshold Vth2 is still less than a pre-set appropriate difference. Therefore, at time t6, the second threshold Vth2 is reduced. From time t6 onwards, the reduced second threshold Vth2 is used.

[0068] This embodiment also improves the accuracy of measurements when combining two sensors. Furthermore, as can be seen from this embodiment, in this invention, the value of the second signal V2 used for correction processing can be either the second signal V2 when the object being measured is in a state suitable for measurement by the first sensor 11, or the second signal V2 when the object being measured is not in a state suitable for measurement by the first sensor 11.

[0069] The sensor system of the present invention is not limited to the embodiments described above. Various design changes can be freely made to the specific configuration of each part of the sensor system of the present invention. In the above embodiments, when the first sensor 11 detects vital signs, etc., a threshold value equivalent to a lower limit can be applied to the first sensor 11 to avoid erroneously outputting signals caused by noise, etc., as detection signals for vital signs, etc. Furthermore, processing to correct the threshold value of the first sensor 11 using the output of the second sensor 12 can be further added.

[0070] Explanation of reference numerals in the attached figures

[0071] A1: Sensor system, 2: Control unit, 10: Sensor unit, 11: First sensor, 12: Second sensor, 19: Substrate, 91: Chair, V1: First signal, V2: Second signal, V2r: Correction value, Vth1: First threshold, Vth2: Second threshold.

Claims

1. A sensor system, characterized in that, include: A first sensor that converts the first physical quantity of the measured object into a first signal and outputs it; A second sensor that converts the second physical quantity of the measured object into a second signal and outputs it; and The control unit is electrically connected to the first sensor and the second sensor. The second physical quantity is related to whether the object being measured is in a state suitable for detection by the first sensor. The control unit performs the following processing: The first judgment process determines, based on the second signal, whether the object being measured is in a state suitable for detection by the first sensor; Measurement processing: If, in the first determination processing, it is determined that the object is in a state suitable for detection by the first sensor, the first information of the object being measured is measured using the first signal; The second judgment process involves determining, based on the first signal, whether the object being measured is in a state suitable for detection by the first sensor. as well as The correction process uses the judgment result of the second judgment process and the second signal at the time of the judgment to correct the judgment criteria of the first judgment process.

2. The sensor system according to claim 1, characterized in that: In the correction process, the first signal, which is determined in the second judgment process to be in a state unsuitable for detection by the first sensor, is used to correct the judgment criterion of the first judgment process.

3. The sensor system according to claim 2, characterized in that: In the correction process, when it is determined in the second judgment process that the state is not suitable for detection by the first sensor for a specified time, the first signal within the specified time is used to correct the judgment criterion of the first judgment process.

4. The sensor system according to any one of claims 1 to 3, characterized in that: The first physical quantity is a physical quantity corresponding to the vital signs of the person being measured. The second physical quantity is related to whether the object being measured is located in a position that can be detected by the first sensor.

5. The sensor system according to claim 4, characterized in that: The first sensor is a piezoelectric sensor. The second sensor is a capacitive sensor.

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