Sensor control device, sensor system, and sensor control method

Abstract

To provide a sensor control device capable of accurately detecting driver's biological information regardless of the driver's position.SOLUTION: A sensor control device 100 for acquiring biological information from a detection target using a sensor comprises a transmission reception control unit 111, a signal reception unit 112, a near field determination unit 113, and a measurement processing unit 114. The transmission reception control unit 111 performs control for transmitting and receiving a transmission signal to be transmitted to the detection target and a reception signal to be received from the detection target. The signal reception unit 112 receives a reference signal and a reflection signal that are included in the transmission signal and a transfer signal included in the reception signal. The near field determination unit 113 determines whether or not the detection target is positioned in a near field region, on the basis of delay time information on the reception signal and a reflection characteristic of the transmission signal that is determined on the basis of the reference signal and the reflection signal. The measurement processing unit 114 performs measurement processing on the biological information on the detection target depending on a determination result of the near field determination unit 113.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a sensor control device, a sensor system, and a sensor control method. [Background technology]

[0002] A device has been proposed that uses a sensor to detect the heart rate and breathing of a driver operating a vehicle. Patent Document 1 discloses a condition detection system that uses a millimeter wave sensor to detect the driver's heart rate and brain waves. The condition detection system disclosed in Patent Document 1 transmits millimeter waves from a millimeter wave sensor installed in the roof position toward the driver and detects the driver's biological information from the millimeter waves returned from the driver. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-75208 Summary of the Invention [Problem to be solved by the invention]

[0004] When detecting biological information using a millimeter wave sensor, if the distance between the millimeter wave sensor and the object (detection target) is short, accurate biological information may not be detected due to a phase error or the like. For example, the millimeter wave sensor used in the condition detection system disclosed in Patent Document 1 can detect biological information when the millimeter wave sensor and the driver are located farther than a predetermined position, but cannot accurately acquire biological information when the distance between the millimeter wave sensor and the driver is short. The position of a vehicle driver fluctuates depending on the driving situation, etc. In other words, the distance between the millimeter wave sensor and the driver changes as the position of the vehicle driver fluctuates. Therefore, a sensor system is needed that can accurately detect biological information even when the distance between the millimeter wave sensor and the driver (detection target) is short.

[0005] The present invention has been made in consideration of the problems inherent in the prior art, and an object of the present invention is to provide a sensor control device that can accurately detect the driver's biological information regardless of the driver's position. [Means for solving the problem]

[0006] A sensor control device according to an aspect of the present invention is a sensor control device that acquires biometric information from a detection target using a sensor, and includes a transmission / reception control unit that controls the transmission and reception of a transmission signal to be transmitted to the detection target and a reception signal received from the detection target, a signal receiving unit that receives a reference signal and a reflected signal included in the transmission signal and a transmission signal included in the reception signal, a near-field determination unit that determines whether the detection target is located in a near-field region based on delay time information of the reception signal and the reflection characteristics of the transmission signal determined based on the reference signal and the reflected signal, and a measurement processing unit that performs measurement processing of the biometric information of the detection target depending on the determination result of the near-field determination unit.

[0007] A sensor system according to another aspect of the present invention is a sensor system comprising: a sensor control device that acquires biometric information from a detection target using a sensor; an antenna unit having a plurality of antenna elements; and a switching unit that switches between transmitting and receiving of the plurality of antenna elements based on control from the sensor control device. The sensor control device comprises: a transmission / reception control unit that controls the transmission and reception of a transmission signal to be transmitted to the detection target and a reception signal received from the detection target; a signal receiving unit that receives a reference signal and a reflected signal included in the transmission signal and a transmission signal included in the reception signal; a near-field determination unit that determines whether the detection target is located in a near-field region based on delay time information of the reception signal and the reflection characteristics of the transmission signal determined based on the reference signal and the reflected signal; and a measurement processing unit that performs measurement processing of the biometric information of the detection target based on the determination result of the near-field determination unit.

[0008] A sensor control method according to another aspect of the present invention is a sensor control method that is executed by a computer and acquires biometric information from a detection target using a sensor, and controls the sending and receiving of a transmission signal to be sent to the detection target and a reception signal to be received from the detection target, receives a reference signal and a reflected signal contained in the transmission signal and a transmission signal contained in the reception signal, determines whether the detection target is located in a near-field region based on delay time information of the reception signal and the reflection characteristics of the transmission signal determined based on the reference signal and the reflected signal, and performs measurement processing of the biometric information of the detection target depending on the determination result. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a sensor control device that can accurately detect the driver's biological information regardless of the driver's position. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating a configuration of a sensor system according to an embodiment of the present invention. [Figure 2] 2 is a diagram showing the configuration of an antenna unit according to the present embodiment; FIG. [Figure 3] FIG. 2 is a diagram illustrating a configuration of a switching unit according to the present embodiment. [Figure 4] FIG. 2 is a diagram illustrating a functional configuration of the sensor control device according to the present embodiment. [Figure 5] 3A and 3B are diagrams for explaining near fields and far fields processed by the sensor control device according to the present embodiment. [Figure 6] FIG. 10 is a diagram illustrating a delay profile according to the present embodiment. [Figure 7A] 10 is a diagram for explaining a transmission characteristic parameter S21 supported by the sensor control device according to the present embodiment. FIG. [Figure 7B] 10 is a diagram for explaining a reflection characteristic parameter S11 supported by the sensor control device according to the present embodiment. FIG. [Figure 8] 4 is a flowchart illustrating an example of processing of the sensor control device according to the present embodiment. [Figure 9] 10 is a flowchart illustrating an example of a near-field determination process in the processing of the sensor control device according to the present embodiment. [Figure 10] 10 is a flowchart illustrating an example of a near-field measurement process in the processing of the sensor control device according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] The sensor control device 100 according to this embodiment will be described in detail below with reference to the drawings. Note that the dimensional proportions in the drawings are exaggerated for the sake of explanation and may differ from the actual proportions. In addition, in the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0012] (Overview of Sensor System 10) FIG. 1 is a diagram showing the configuration of a sensor system 10 including a sensor control device 100 according to this embodiment.

[0013] The sensor system 10 is installed, for example, inside a vehicle for the purpose of safe driving of the vehicle, etc. In this embodiment, the sensor system 10 is installed, for example, near on-board devices such as meters and an instrument panel inside the vehicle.

[0014] The sensor system 10 uses sensors to acquire biometric information from the driver and detect the driver's state. Among the driver's biometric information, for example, heart rate is closely related to the driver's level of alertness, and the lower the level of alertness, the lower the driver's heart rate. Furthermore, the driver's level of alertness decreases due to the driver's level of fatigue, stress, drowsiness, and the like. For example, it is known that the lower the heart rate, the more drowsy the driver feels. In other words, by acquiring the driver's biometric information and detecting the driver's state using the sensor system 10, it is possible to detect that the driver's level of alertness is low. Based on the information detected by the sensor system 10, for example, if the driver's level of alertness is low, an alarm or the like can be output, which can be useful for safe driving.

[0015] The sensor used in the sensor system 10 according to this embodiment uses millimeter waves (extremely high frequencies). Millimeter waves are radio waves with a wavelength of 1 to 10 mm and a frequency of 30 to 300 GHz. The sensor system 10 uses these millimeter waves to measure the driver's heart rate and blood flow. Because millimeter waves have a short wavelength, they can observe minute movements.

[0016] Here, a millimeter wave sensor can accurately detect biometric information when the sensor and the detection target are far apart. On the other hand, when the sensor and the detection target are close together, the millimeter wave sensor may not be able to accurately detect biometric information due to a phase error or the like. For example, when a sensor for detecting biometric information is installed in a vehicle, the sensor is not always far away from the driver, who is the detection target, and the distance between the sensor and the driver may become close depending on the driver's condition.

[0017] The sensor system 10 according to this embodiment realizes a system that can accurately detect the driver's biological information even when the sensor and the driver, who is the detection target, are located close to each other. (Configuration of sensor system 10)

[0018] Next, a description will be given of the configuration of the sensor system 10. As shown in Fig. 1, the sensor system 10 includes a sensor control device 100, a transmitter 130, a receiver 140, directional couplers 150 (150a, 150b, 150r), a switch 160, and an antenna unit 200.

[0019] The sensor system 10 transmits millimeter wave transmission signals from the antenna unit 200 shown in Fig. 1 and acquires the driver's biometric information from the received signals returned from the target. As shown in Fig. 1, the sensor system 10 includes the antenna unit 200 that can be switched by a switching unit 160. That is, the switching unit 160 switches between transmitting millimeter waves from the antenna unit 200 and receiving millimeter waves via the antenna unit 200.

[0020] In this embodiment, the antenna unit 200 is configured as an array antenna having a plurality of antenna elements as shown in Fig. 2. In this embodiment, the plurality of antenna elements are configured as nine antenna elements, namely, first antenna element 201a to ninth antenna element 201i. The array antenna of the antenna unit 200 in this embodiment is configured as a patch antenna. Note that the configuration of the antenna unit 200 using a patch antenna is not intended to limit the configuration of this embodiment, and for example, the antenna unit 200 may be configured as a probe antenna or a dipole antenna.

[0021] The first to ninth antenna elements 201a to 201i are connected to the switching unit 160 via antenna lines AL1 to AL9, respectively. Hereinafter, when there is no need to distinguish between the first to ninth antenna elements 201a to 201i, they will be simply referred to as "antenna elements 201."

[0022] 1, the components of the sensor system 10 will be described. The sensor control device 100 will be described in detail later.

[0023] The transmitter 130 transmits a transmission signal, which is a millimeter wave, via the antenna unit 200. The signal processing method of the sensor system 10 in this embodiment may be a direct conversion method. In the case of the direct conversion method, the transmitter 130 emits a radio wave having the same frequency as the baseband signal via the first antenna element 201a of the antenna unit 200.

[0024] The signal processing method of the sensor system 10 in this embodiment may be a superheterodyne method. In the case of the superheterodyne method, the transmitter 130 separately generates a predetermined coherent frequency signal and similarly emits radio waves of a frequency mixed with the baseband signal. Note that in this embodiment, the signal processing method used in the sensor system 10 does not limit the configuration of the embodiment.

[0025] In this embodiment, the transmission from the transmitting unit 130 is not a continuous signal but has transmission pause periods. The transmitting unit 130 also has a local oscillator (not shown).

[0026] The receiving unit 140 receives a reception signal, which is a millimeter wave, received via the antenna unit 200. Specifically, the receiving unit 140 receives radio waves reflected by an object via the antenna unit 200. The receiving unit 140 receives the reception wave during a transmission pause period. In this embodiment, the receiving unit 140 may also include a local oscillator (not shown). Note that the local oscillator of the receiving unit 140 may be shared with the local oscillator of the transmitting unit 130 described above.

[0027] The sensor system 10 includes, as directional couplers 150, a directional coupler 150r for the reference signal Sr, a directional coupler 150a for the reflected signal Sa, and a directional coupler 150b for the transmission signal Sb. That is, the directional couplers 150 extract signals from and to the antenna unit 200, and obtain a reflection characteristic parameter S11 and a transmission characteristic parameter S21. Hereinafter, when there is no need to distinguish between the directional couplers 150r, 150a, and 150b, they will be simply referred to as "directional couplers 150."

[0028] The reference signal Sr is the forward wave power of the transmission signal extracted by the directional coupler 150r. Due to high isolation, the reference signal Sr is not mixed with reflected wave power. The reflected signal Sa is the reflected wave power of the transmission signal extracted by the directional coupler 150a. Like the reference signal Sr, the reflected signal Sa is also not mixed with forward wave power. The transmission signal Sb is the power of the reception signal extracted by the directional coupler 150b.

[0029] FIG. 3 is a diagram illustrating the switching unit 160 in detail. As shown in FIG. 3, the switching unit 160 includes a transmission switching unit 161 and a reception switching unit 162. The transmission switching unit 161 and the reception switching unit 162 switch between transmitting a transmission signal and receiving a reception signal based on a control signal (not shown) from the control unit 110 of the sensor control device 100. In this embodiment, the transmission signal is transmitted by the first antenna element 201a. Therefore, the transmission switching unit 161 is connected to the first antenna element 201a via the antenna line AL1. Furthermore, the reception wave of the reception signal is received by the first antenna element 201a to the ninth antenna element 201i. Therefore, the reception switching unit 162 is connected to the first antenna element 201a to the ninth antenna element 201i via the antenna lines AL1 to AL9. For example, the example illustrated in FIG. 3 illustrates a case where a reception signal is received from the third antenna element 201c.

[0030] (Configuration of sensor control device 100) Next, a description will be given of the configuration of the sensor control device 100. The sensor control device 100 includes a control unit 110 and a storage unit 120.

[0031] The control unit 110 may be configured as, for example, a general-purpose microcomputer. In this case, a computer program for causing the microcomputer to function as the sensor control device 100 may be installed in the microcomputer. By executing the computer program, the microcomputer functions as multiple information processing circuits provided in the sensor control device 100. The control unit 110 may also realize the multiple information processing circuits provided in the sensor control device 100 by software, or it is also possible to provide dedicated hardware to configure the information processing circuits. The multiple information processing circuits may also be configured as separate hardware.

[0032] The storage unit 120 may be a read-only memory (ROM), a random access memory (RAM), a hard disk, etc. The storage unit 120 may also store various data such as input data, output data, and intermediate data for the sensor control device 100 to execute processing.

[0033] The storage unit 120 also has an area for storing the delay profile of the received signal, the results of each calculation, etc. The storage unit 120 for storing each of these data may be one or more. For example, a single storage unit 120 may be configured to store the data in separate areas. Alternatively, the data may be stored in a distributed manner in multiple storage devices installed in physically separate locations. The delay profile corresponds to delay time information.

[0034] (Functions of the sensor control device 100) 4 is a block diagram showing the functions of the control unit 110. The control unit 110 has, as its functions, a transmission / reception control unit 111, a signal receiving unit 112, a near-field determination unit 113, and a measurement processing unit 114. The control unit 110 may also have, as its function, a measurement result output unit 115.

[0035] The transmission / reception control unit 111 controls the transmission and reception of a transmission signal to be transmitted to the driver and a reception signal sent from the driver via the antenna unit 200.

[0036] The signal receiving unit 112 includes a reference signal receiving unit 112a, a reflected signal receiving unit 112b, and a transmission signal receiving unit 112c. The signal receiving unit 112 receives a reference signal Sr and a reflected signal Sa included in the transmission signal, and a transmission signal Sb included in the reception signal. Specifically, the signal receiving unit 112 receives the forward wave power of the transmission signal extracted by directional coupler 150r as the reference signal Sr. The signal receiving unit 112 also receives the reflected wave power of the transmission signal extracted by directional coupler 150a as the reflected signal Sa. The signal receiving unit 112 also receives the power of the reception signal extracted by directional coupler 150b as the transmission signal Sb.

[0037] In determining the distance to the object, near-field determination unit 113 determines whether the object is in the near field when the distance between antenna unit 200 and the object is close, or whether the object is in the far field when the distance between antenna unit 200 and the object is far. Specifically, near-field determination unit 113 determines whether the object is located in the near-field region or the far-field region based on the reflection characteristics of the transmitted signal determined based on the reference signal and the reflected signal, and the transmission characteristics of the received signal determined based on the reference signal and the transmitted signal.

[0038] Figure 5 is a diagram for explaining whether an object is in the near field or far field based on the distance from the antenna to the object. If the maximum diameter, which is the aperture dimension of the antenna, is D, the far field is defined as a position (area C) that is at least a distance R that satisfies the following equation (1). Here, λ is the free space wavelength. The far field defined by area C in Figure 5 is an area where directivity does not change depending on the distance from the antenna aperture. R>2D 2 / λ (1)

[0039] Furthermore, among the regions of the electromagnetic field radiated from the antenna aperture, region A close to the antenna aperture is a reactive near-field region (region A) where electromagnetic field components that do not contribute to radiation are predominant. In this embodiment, region C, which satisfies the condition of the above-mentioned formula (1), is defined as the far field, and regions A and B, which do not satisfy the condition of the above-mentioned formula (1), are defined as the near field.

[0040] Generally, when measuring the electromagnetic field radiated from an antenna, the spherical wave radiated from the antenna becomes a plane wave when it is far enough away, and this state is the far field. For example, the area immediately adjacent to the antenna becomes a spherical wave, and this area is defined as the near field. When these spherical waves are superimposed, their envelope becomes a plane wave, and according to the Huygens-Fresnel principle, the 2D wave shown in Figure 5 is generated. 2 The area C farther than / λ is the far field.

[0041] On the other hand, in the near field, the coupling product between antennas and the radiated electromagnetic field are spherical waves, so data on the amplitude and phase of the near field are acquired at the required sampling intervals, and the phase error is accumulated to calculate the near field.

[0042] Further, the near field determination unit 113 determines the near field and the far field based on a delay profile (delay time information) indicating the arrival time of the first arriving wave of the received signal. Specifically, as shown in Fig. 6, the near field determination unit 113 determines the near field and the far field on the time axis using a predetermined time to as a threshold.

[0043] Here, the threshold used to determine near field and far field based on the delay profile is given by the following equation (2), where c is the speed of light. In other words, if the delay time is greater than to, it is the far field, and if it is smaller, it is the near field. to=(1 / c)×(2D 2 / λ) (2)

[0044] Note that when the delay profile is near the threshold value to, which is the boundary condition, the near field and far field determination based on the delay profile alone may not be accurate. FIG. 7A is a diagram showing the characteristics of the transmission characteristic parameter S21. This transmission characteristic parameter S21 is determined by the transmission signal Sb / reference signal Sr. In the delay time information shown in FIG. 6 and the transmission characteristic parameter S21 shown in FIG. 7A, the boundary between the near field and the far field is not clear, and the boundary condition tends to gradually approach the far field from the near field depending on the transmission characteristics. Therefore, the determination of the near field and the far field based on the delay time information in FIG. 6 or the transmission characteristic parameter S21 shown in FIG. 7A is possible when it is clear that the field is the near field or the far field, but may not be accurate near the boundary. Note that in this embodiment, the vicinity of the boundary is defined as a range of several hundred picoseconds around to.

[0045] In this embodiment, when the delay time information is near the boundary between the near field and the far field, the polarity of the reflection characteristic parameter S11 shown in Fig. 7B is used to determine whether it is in the near field or the far field. Here, the reflection characteristic parameter S11 is determined by the reflection signal Sa / reference signal Sr.

[0046] That is, in this embodiment, when it is determined that the delay time information indicates the vicinity of a boundary, the near-field determination unit 113 determines that the object is in the near field if the polarity of the reflection characteristic parameter S11 is positive based on the reflection characteristic parameter S11 shown in Fig. 7B. On the other hand, when it is determined that the delay time information indicates the vicinity of a boundary, the near-field determination unit 113 determines that the object is in the far field if the polarity of the reflection characteristic parameter S11 is negative based on the reflection characteristic parameter S11 shown in Fig. 7B. Note that when it is determined that the delay time information does not indicate the vicinity of a boundary, the near-field determination unit 113 determines whether the object is located in the near field or the far field based on the delay time information.

[0047] The measurement processing unit 114 is configured to include, as functions, a near-field measurement processing unit 114a and a far-field measurement processing unit 114b. Specifically, the measurement processing unit 114 performs measurement processing of the biological information of the object by performing near-field measurement processing or far-field measurement processing according to the determination result of the near-field determination unit 113.

[0048] The near-field measurement processing unit 114a is executed when the near-field determining unit 113 determines that the object is located in the near field.

[0049] The near-field measurement processing unit 114a first obtains the phase at each measurement position in the near field using a commonly known planar scanning method. Specifically, the near-field measurement processing unit 114a receives received waves reflected from the target in a spiral pattern, starting from the first antenna element 201a at the center of the antenna unit 200 shown in FIG. 2. The near-field measurement processing unit 114a then calculates the phase difference between the received antenna elements 201, such as the phase difference between the first antenna element 201a and the second antenna element 201b, and the phase difference between the second antenna element 201b and the third antenna element 201c. The near-field measurement processing unit 114a also stores amplitude information of each received signal in the storage unit 120.

[0050] Furthermore, the near-field measurement processing unit 114a performs a process of converting the near field to the far field based on the calculated phase difference. Specifically, the near-field measurement processing unit 114a calculates the electric field intensity distribution of the far field using position information of the antenna elements 201, amplitude information of the received signals received by each antenna element 201, and the above-mentioned phase difference information. In this embodiment, the near-field measurement processing unit 114a estimates the electric field intensity distribution of the far field by performing numerical calculations using a known near-field / far-field conversion method, and calculates the measurement results as the far field. The position information of the antenna elements 201 is position information of each antenna element 201 in the antenna unit 200, and is assumed to be stored in advance in the storage unit 120. In this embodiment, the amplitude information of the received signals received by each antenna element 201 may be calculated by calculating the average value of the amplitudes of the received signals received by each antenna element 201.

[0051] The far-field measurement processing unit 114b is executed when it is determined that the object is located in the far field by the near-field determination unit 113. In this embodiment, the far-field measurement processing unit 114b calculates the average received power and the like using the measured delay profile, and acquires biological information of the detection object.

[0052] The measurement result output unit 115 outputs the measurement result based on the result of the measurement processing unit 114. Specifically, the measurement result may be output to a device (not shown) such as an ECU (Electronic Control Unit) provided outside the sensor system 10, and processing for safe driving support may be performed in the ECU. Alternatively, the measurement result output unit 115 of the sensor control device 100 may have a function to output an alarm or the like based on the measurement result of the measurement processing unit 114.

[0053] (Outline of processing flow of sensor control device 100) Next, the flow of processing in the sensor control device 100 will be shown using the flowcharts shown in Figures 8 to 10. The series of operations of the sensor control device 100 shown in the flowcharts of Figures 8 to 10 begins when the sensor control device 100 is started, and ends when the work is completed. The processing in the flowcharts shown in Figures 8 to 10 also ends when the power is turned off or an interrupt occurs to end the processing. In the following explanation of the flowcharts, the same content as that described above in the explanation of the sensor control device 100 will be omitted or simplified.

[0054] In step S801, the transmission / reception control unit 111 transmits a transmission signal for measurement via the antenna unit 200.

[0055] In step S802, the reference signal receiving unit 112a, the reflected signal receiving unit 112b, and the transmission signal receiving unit 112c of the signal receiving unit 112 receive the reference signal Sr, the reflected signal Sa, and the transmission signal Sb, respectively, via the directional coupler 150 and store them in the memory unit 120.

[0056] In step S803, the near-field determining unit 113 performs a near-field determination process based on the delay profile. Specifically, a subroutine process of the near-field determination process shown in Fig. 9 is executed. The subroutine process of the near-field determination process in Fig. 9 will be described.

[0057] (Subroutine processing of near-field determination processing) In step S901, the near-field determining unit 113 initializes the number of measurements. Specifically, the near-field determining unit 113 sets the values of a counter for the number of near-field measurements and a counter for the number of far-field measurements to 0.

[0058] In step S902, the near-field determining unit 113 acquires a delay profile (delay time information) from the received signal via the receiving unit 140. The delay profile is the arrival time of the first arriving wave shown in FIG.

[0059] In step S903, the near-field determination unit 113 determines whether the delay time information is near the boundary between the near field and the far field based on the delay profile. In step S903, if the near-field determination unit 113 determines that the delay time information is near the boundary (step S903: YES), the process proceeds to step S906. On the other hand, in step S903, if the near-field determination unit 113 determines that the delay time information is not near the boundary (step S903: NO), the process proceeds to step S904. In this embodiment, the vicinity of the boundary is defined as a range of several hundred ps around to.

[0060] In step S904, the near-field determination unit 113 determines whether the delay time information is in the far field or not based on the delay profile. Since it is determined in step S903 that the delay time information is not near the boundary, it is possible to clearly determine in step S904 whether it is in the near field or the far field. In step S904, if the near-field determination unit 113 determines that the delay time information is in the far field (step S904: YES), the process proceeds to step S907. On the other hand, in step S904, if the near-field determination unit 113 determines that the delay time information is not in the far field (step S904: NO), the process proceeds to step S905.

[0061] In step S905, the near-field determining unit 113 adds 1 to the value of the counter for the number of near-field measurements. Then, the process proceeds to step S909.

[0062] In step S906, the near-field determination unit 113 determines whether the polarity of the reflection characteristic parameter S11 is negative. Specifically, the near-field determination unit 113 determines whether the value of the corresponding reflection characteristic parameter S11 is positive or negative in the graph showing the reflection characteristics of the reflection characteristic parameter S11 shown in FIG. 7B. In step S906, if the near-field determination unit 113 determines that the polarity of the reflection characteristic parameter S11 is negative (step S906: YES), the process proceeds to step S907. On the other hand, in step S906, if the near-field determination unit 113 determines that the polarity of the reflection characteristic parameter S11 is not negative (step S906: NO), the process proceeds to step S908.

[0063] In step S907, the near-field determining unit 113 adds 1 to the value of the counter for the number of far-field measurements. After that, the process proceeds to step S909.

[0064] In step S908, the near-field determining unit 113 adds 1 to the value of the counter for the number of near-field measurements. Then, the process proceeds to step S909.

[0065] In step S909, the near-field determination unit 113 determines whether the cumulative number of measurements is greater than 2. Here, the cumulative number of measurements is the sum of the value of the counter for the number of near-field measurements and the value of the counter for the number of far-field measurements.

[0066] In step S909, if the near-field determining unit 113 determines that the cumulative number of measurements is greater than two (step S909: YES), the process proceeds to step S910. That is, in step S909, if the cumulative number of measurements is three, the process proceeds to step S910. On the other hand, in step S909, if the near-field determining unit 113 determines that the cumulative number of measurements is two or less (step S909: NO), the process returns to step S902, and the process from step S902 is repeated.

[0067] In step S910, the near-field determination unit 113 determines whether the value of the counter for the number of near-field measurements is greater than the value of the counter for the number of far-field measurements. That is, the near-field determination unit 113 determines, as a determination result, which of the number of near-field measurements and the number of far-field measurements has been measured more.

[0068] In step S910, if the near-field determination unit 113 determines that the value of the counter for the number of near-field measurements is greater than the value of the counter for the number of far-field measurements (step S910: YES), the process proceeds to step S911. On the other hand, in step S910, if the near-field determination unit 113 determines that the value of the counter for the number of near-field measurements is equal to or less than the value of the counter for the number of far-field measurements (step S910: NO), the process proceeds to step S912. Note that in this embodiment, since the cumulative number of measurements is three (an odd number) in the determination in step S910, the value of the counter for the number of near-field measurements and the value of the counter for the number of far-field measurements will not be the same.

[0069] In step S911, the near field determination unit 113 determines that the position of the object is in the near field, stores this in the storage unit 120, and returns to step S803 in the flowchart shown in Fig. 8. Thereafter, the process proceeds to step S804.

[0070] In step S912, the near-field determining unit 113 determines that the position of the object is in the far field, stores this in the storage unit 120, and returns to step S803 in the flowchart shown in Fig. 8. Thereafter, the process proceeds to step S804.

[0071] Returning to the flowchart of FIG. 8, the explanation will be continued.

[0072] In step S804, the near-field determination unit 113 performs a selection process based on the result of the near-field determination process performed in step S803. In step S804, if the near-field determination unit 113 determines that the position of the object is in the near field (step S804: YES), On the other hand, in step S804, if the near-field determining unit 113 determines that the position of the object is not in the near field (step S804: NO), the process proceeds to step S805. If so, the process proceeds to step S806.

[0073] In step S805, the near-field measurement processing unit 114a performs measurement processing in the near field. Specifically, a subroutine process of the near-field measurement processing shown in Fig. 10 is executed. The subroutine process of the near-field measurement processing shown in Fig. 10 will be described.

[0074] (Subroutine processing of near-field measurement processing) In step S1001, the near-field measurement processing unit 114a sets a counter value n for measurement processing to 1. Here, the counter value n for measurement processing in the flow shown in Fig. 10 is a value corresponding to the reception order of the antenna elements 201 of the antenna unit 200, and in the example of the antenna unit 200 shown in Fig. 2, it is a value corresponding to the first to ninth antenna elements 201.

[0075] In step S1002, the near-field measurement processing unit 114a performs measurement of the antenna element (n). Specifically, the near-field measurement processing unit 114a performs measurement processing by transmitting a transmission signal from the first antenna element 201a and receiving a reception signal at the antenna element 201 having a value corresponding to the counter value n for measurement processing.

[0076] In step S1003, the near-field measurement processing unit 114a determines whether there is data from the measurement in step S1002. For example, when the sensor system 10 of this embodiment is used in a vehicle, radio waves may be blocked by passengers or the like, or radio wave strength may drop due to multipath fading (interference caused by radio wave reflection). Furthermore, the position of the target object may be in the near field before getting in the vehicle, but may become in the far field due to a change in the situation, causing the reflection path to become longer, resulting in a decrease in signal strength and exceeding the measurement limit. In such cases, measurement processing is performed again using the corresponding antenna element 201.

[0077] In step S1003, if the near-field measurement processing unit 114a determines that there is data at the time of measurement (step S1003: YES), the process proceeds to step S1004. On the other hand, in step S1003, if the near-field measurement processing unit 114a determines that there is no data at the time of measurement (step S1003: NO), the process returns to step S1002, and the process from step S1002 is repeated.

[0078] In step S1004, the near-field measurement processing unit 114a stores the measurement data in the storage unit 120. After that, the process proceeds to step S1005.

[0079] In step S1005, the near-field measurement processing unit 114a adds 1 to the counter value n for measurement processing. Then, the process proceeds to step S1006.

[0080] In step S1006, the near-field measurement processing unit 114a determines whether the counter value n for the measurement process is equal to or greater than 10. That is, in step S1006, it determines whether measurement data has been stored for the number of antenna elements 201 in the antenna unit 200. It is assumed that the value in step S1006 (10 in the example of FIG. 10) varies depending on the number of antenna elements 201 in the antenna unit 200. For example, if the number of antenna elements 201 is 25, which is an additional one spiral addition to the example shown in FIG. 2, the near-field measurement processing unit 114a determines in step S1006 whether the counter value n for the measurement process is equal to or greater than 26. It is assumed that the value according to the antenna elements 201 determined in step S1006 is stored in advance in the storage unit 120 in accordance with the configuration of the antenna unit 200.

[0081] In step S1007, the near-field measurement processing unit 114a compares the measurement results of each antenna element 201 with those of the reference antenna (the antenna element 201 measured immediately before) based on the stored data, and stores the comparison results in the memory unit 120. Specifically, the near-field measurement processing unit 114a obtains the phase at each measurement position in the near field using a commonly known planar scanning method. That is, the near-field measurement processing unit 114a receives the received waves reflected from the target in a spiral pattern, starting from the first antenna element 201a at the center of the antenna unit 200 shown in FIG. 2. The near-field measurement processing unit 114a then calculates the phase difference between the received antenna elements 201, such as the phase difference between the first antenna element 201a and the second antenna element 201b, and the phase difference between the second antenna element 201b and the third antenna element 201c. The near-field measurement processing unit 114a also stores amplitude information of each received signal in the memory unit 120.

[0082] In step S1008, the near-field measurement processing unit 114a uses the comparison result to convert the planar measurement result into a spherical measurement result. Specifically, the near-field measurement processing unit 114a converts the near field to the far field based on the calculated phase difference. The near-field measurement processing unit 114a calculates the far-field electric field strength distribution using position information of the antenna elements 201, amplitude information of the received signals received by each antenna element 201, and the above-mentioned phase difference information. In this embodiment, the near-field measurement processing unit 114a estimates the far-field electric field strength distribution by performing numerical calculations using a known near-field / far-field conversion method, and calculates the far-field measurement result. The position information of the antenna elements 201 is position information of each antenna element 201 in the antenna unit 200, and is assumed to be stored in advance in the storage unit 120. In this embodiment, the amplitude information of the received signals received by each antenna element 201 may be calculated by averaging the amplitudes of the received signals received by each antenna element 201.

[0083] Thereafter, the process returns to step S805 shown in FIG. 8, and the process proceeds to step S807.

[0084] Returning to the flowchart of FIG. 8, the explanation will be continued.

[0085] In step S806, the far-field measurement processing unit 114b performs measurement processing on the far field. In this embodiment, the far-field measurement processing unit 114b calculates average received power and the like using the measured delay profile, and acquires biological information of the detection target.

[0086] In step S807, the measurement result output unit 115 outputs the measurement result. The measurement result is output based on the result of the measurement processing unit 114. Specifically, the measurement result output unit 115 may output the measurement result to a device (not shown) such as an ECU (Electronic Control Unit) provided outside the sensor system 10, and the ECU may perform processing for safe driving support. Alternatively, the measurement result output unit 115 of the sensor control device 100 may have a function to output an alarm or the like based on the measurement result of the measurement processing unit 114.

[0087] As described above, the sensor control device 100 in this embodiment is a sensor control device that acquires biological information from a detection target using a sensor, and includes a transmission / reception control unit 111, a signal receiving unit 112, a near-field determination unit 113, and a measurement processing unit 114. The transmission / reception control unit 111 controls the transmission and reception of a transmission signal to be transmitted to the detection target and a reception signal received from the detection target. The signal receiving unit 112 receives a reference signal and a reflected signal included in the transmission signal, and a transmission signal included in the reception signal. The near-field determination unit 113 determines whether the detection target is located in a near-field region based on delay time information of the reception signal and the reflection characteristics of the transmission signal determined based on the reference signal and the reflected signal. The measurement processing unit 114 performs measurement processing of the biological information of the detection target according to the determination result of the near-field determination unit 113.

[0088] This enables the sensor control device 100 to accurately detect biometric information whether the detection target is in the near field or the far field. That is, the sensor control device 100 can accurately detect the driver's biometric information regardless of the position of the detection target (driver).

[0089] Furthermore, when the near-field determination unit 113 of the sensor control device 100 determines that the detection target is located near a predetermined boundary based on the delay time information, if the polarity of the reflection characteristics is negative, the near-field determination unit 113 may determine that the detection target is located in the far field. This enables the sensor control device 100 to more accurately determine whether the detection target is located in the near field or the far field.

[0090] Furthermore, when the determination result of the near-field determiner 113 is determined to be the near field, the measurement processor 114 of the sensor control device 100 may calculate the near-field measurement processing result as the far-field measurement processing result. That is, the measurement processor 114 may calculate the near-field measurement processing result as the far-field measurement processing result based on amplitude information of the received signal and phase difference information of the multiple antenna elements 201. This enables the sensor control device 100 to perform measurement processing even when the detection target is located in the near field, and to detect the driver's biological information more accurately.

[0091] (Other embodiments) Although the embodiments have been described in detail with reference to the drawings, the present embodiments are not limited to the contents described in the above embodiments. Furthermore, the components described above include those that can be easily imagined by a person skilled in the art and those that are substantially the same. Furthermore, the configurations described above can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configurations can be made without departing from the spirit of the embodiments.

[0092] Furthermore, the scope of this embodiment includes a computer program (sensor control program) that causes a computer to execute the processing (sensor control method) in the sensor control device 100 described above, and a computer-readable recording medium on which the program is recorded. Any type of computer-readable recording medium may be used. Furthermore, the computer program is not limited to being recorded on the recording medium, but may be transmitted via a telecommunications line, a wireless or wired communication line, a network such as the Internet, or the like.

[0093] The following describes the features of the sensor control device 100, the sensor system 10, and the sensor control method.

[0094] The sensor control device 100 according to the first aspect is a sensor control device that acquires biological information from a detection target using a sensor, and includes a transmission / reception control unit 111 that controls transmission and reception of a transmission signal to be transmitted to the detection target and a reception signal received from the detection target. The sensor control device 100 also includes a signal receiving unit 112 that receives a reference signal and a reflected signal included in the transmission signal and a transmission signal included in the reception signal. The sensor control device 100 also includes a near-field determination unit 113 that determines whether the detection target is located in a near-field region based on delay time information of the reception signal and reflection characteristics of the transmission signal determined based on the reference signal and the reflected signal. The sensor control device 100 also includes a measurement processing unit 114 that performs measurement processing of the biological information of the detection target in accordance with the determination result of the near-field determination unit 113.

[0095] According to the above configuration, the sensor control device 100 can accurately detect biological information whether the detection target is in the near field or the far field. That is, the sensor control device 100 can accurately detect the driver's biological information regardless of the position of the detection target (driver).

[0096] The near-field determination unit 113 of the sensor control device 100 according to the second aspect may determine that the detection target is located in the far field if the polarity of the reflection characteristics is negative when the near-field determination unit 113 determines that the detection target is located near a predetermined boundary based on the delay time information.

[0097] According to the above configuration, the sensor control device 100 can more accurately determine whether the detection target is located in the near field or the far field.

[0098] The measurement processing unit 114 of the sensor control device 100 according to the third aspect may calculate the near-field measurement processing result as the far-field measurement processing result when the near-field determination unit 113 determines that the result is the near field. That is, the measurement processing unit 114 may calculate the near-field measurement processing result as the far-field measurement processing result based on amplitude information of signals received by multiple antenna elements provided in the sensor and phase difference information of the multiple antenna elements.

[0099] According to the above configuration, the sensor control device 100 can perform measurement processing even when the detection target is located in the near field, and can detect more accurate biological information of the driver.

[0100] A sensor system 10 according to a fourth aspect includes a sensor control device that acquires biometric information from a detection target using a sensor, an antenna unit with multiple antenna elements, and a switching unit that switches between transmitting and receiving the multiple antenna elements based on control from the sensor control device. The sensor control device 100 includes a transmission / reception control unit 111 that controls the transmission and reception of a transmission signal to be transmitted to the detection target and a reception signal received from the detection target. The sensor control device 100 also includes a signal receiving unit 112 that receives a reference signal and a reflected signal included in the transmission signal and a transmission signal included in the reception signal. The sensor control device 100 also includes a near-field determination unit 113 that determines whether the detection target is located in a near-field region based on delay time information of the reception signal and reflection characteristics of the transmission signal determined based on the reference signal and the reflected signal. The sensor control device 100 also includes a measurement processing unit 114 that performs measurement processing of the biometric information of the detection target based on the determination result of the near-field determination unit 113.

[0101] According to the above configuration, the sensor system 10 can accurately detect biometric information whether the detection target is in the near field or the far field. That is, the sensor system 10 can accurately detect the driver's biometric information regardless of the position of the detection target (driver), and can be realized as a safe driving support system.

[0102] A sensor control method according to a fifth aspect is a sensor control method executed by a computer and for acquiring biometric information from a detection target using a sensor. The sensor control method controls transmission and reception of a transmission signal to be transmitted to the detection target and a reception signal to be received from the detection target. The sensor control method also receives a reference signal and a reflected signal included in the transmission signal, and a transmission signal included in the reception signal. The sensor control method also determines whether the detection target is located in a near-field region based on delay time information of the reception signal and reflection characteristics of the transmission signal determined based on the reference signal and the reflected signal. The sensor control method also performs a measurement process of the biometric information of the detection target depending on the determination result.

[0103] According to the above configuration, by causing a computer to execute the sensor control method, accurate detection of biological information becomes possible regardless of whether the detection target is in the near field or the far field. In other words, by causing a computer to execute the sensor control method, accurate detection of the driver's biological information becomes possible regardless of the position of the detection target (driver). [Explanation of symbols]

[0104] 100 Sensor control device 110 control section 111 Transmission and reception control section 112 Signal receiving unit 113 Near-field determination unit 114 Measurement processing section 115 Measurement result output section 120 Storage section 200 Antenna section 201, 201a to 209i antenna elements

Claims

1. A sensor control device that acquires biological information from a detection target via an antenna unit having a plurality of antenna elements, a transmission / reception control unit that controls transmission and reception of a transmission signal to be transmitted to the detection target and a reception signal received from the detection target; a signal receiving unit that receives a reference signal and a reflected signal included in the transmission signal and a transmission signal included in the reception signal; a near-field determination unit that determines whether the detection target is located in a near-field region based on delay time information of the received signal and reflection characteristics of the transmitted signal determined based on the reference signal and the reflected signal; a measurement processing unit that performs measurement processing of the biological information of the detection target in accordance with a determination result of the near-field determination unit; Equipped with when it is determined based on the delay time information that the detection target is located near a boundary between a near field and a far field, if the polarity of the reflection characteristics is negative, the near field determination unit determines that the detection target is located in the far field, and if the polarity of the reflection characteristics is positive, determines that the detection target is located in the near field; when it is determined, based on the delay time information, that the detection target is not located near a boundary between the near field and the far field, the near field determination unit determines, based on the delay time information, whether the detection target is located in the near field or the far field; When the judgment result of the near field judgment unit is judged to be the near field, the measurement processing unit calculates the near field measurement processing result as the far field measurement processing result based on amplitude information of the received signals received by the plurality of antenna elements and phase difference information of the plurality of antenna elements.

2. an antenna unit including a plurality of antenna elements; a sensor control device that acquires biological information from a detection target via the antenna unit; a switching unit that switches between transmission and reception of the plurality of antenna elements based on control from the sensor control device, The sensor control device a transmission / reception control unit that controls transmission and reception of a transmission signal to be transmitted to the detection target and a reception signal received from the detection target; a signal receiving unit that receives a reference signal and a reflected signal included in the transmission signal and a transmission signal included in the reception signal; a near-field determination unit that determines whether the detection target is located in a near-field region based on delay time information of the received signal and reflection characteristics of the transmitted signal determined based on the reference signal and the reflected signal; a measurement processing unit that performs measurement processing of the biological information of the detection target in accordance with a determination result of the near-field determination unit, when it is determined based on the delay time information that the detection target is located near a boundary between a near field and a far field, if the polarity of the reflection characteristics is negative, the near field determination unit determines that the detection target is located in the far field, and if the polarity of the reflection characteristics is positive, determines that the detection target is located in the near field; when it is determined, based on the delay time information, that the detection target is not located near a boundary between the near field and the far field, the near field determination unit determines, based on the delay time information, whether the detection target is located in the near field or the far field; when the determination result of the near field determination unit is determined to be the near field, the measurement processing unit calculates the near field measurement processing result as the far field measurement processing result based on amplitude information of the received signals received by the plurality of antenna elements and phase difference information of the plurality of antenna elements. Sensor system.

3. A sensor control method executed by a computer, for acquiring biological information from a detection target via an antenna unit having a plurality of antenna elements, comprising: performing control for transmitting and receiving a transmission signal to be transmitted to the detection target and a reception signal received from the detection target; receiving a reference signal and a reflected signal included in the transmission signal and a transmission signal included in the reception signal; When it is determined based on delay time information of the received signal that the detection target is located near the boundary between the near field and the far field, if the polarity of the reflection characteristic of the transmission signal determined based on the reference signal and the reflected signal is negative, it is determined that the detection target is located in the far field, and if the polarity of the reflection characteristic is positive, it is determined that the detection target is located in the near field; when it is determined based on the delay time information that the detection target is not located near the boundary between the near field and the far field, determining whether the detection target is located in the near field or the far field based on the delay time information; When the judgment result is determined to be the near field, the sensor control method calculates the near field measurement processing result as the far field measurement processing result based on amplitude information of the received signals received by the plurality of antenna elements and phase difference information of the plurality of antenna elements.

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