Information processing device, biological data measurement system, information processing method, and program

Abstract

[Problem] To provide an information processing device, a biological data measurement system, an information processing method, and a program which are capable of acquiring biological data having improved accuracy. [Solution] An information processing device according to the present technology comprises a body movement noise prediction unit and a control unit. The body movement noise prediction unit predicts that a body movement noise is added to a detected biological signal detected from a subject by a biological sensor on the basis of a reference signal which is body movement information of the subject detected by a reference signal sensor. The control unit controls signal processing of the detected biological signal on the basis of the result of prediction by the body movement noise prediction unit.

Description

[Technical field]

[0001] The present technology relates to an information processing device, a biological data measurement system, an information processing method, and a program used for acquiring biological data by a biological sensor. [Background technology]

[0002] In measuring biodata using a biosensor, an analog detected biosignal detected by a bioelectrode attached to a subject is digitized by an analog-to-digital converter. During measurement, body movement noise caused by the subject's body movements may be added to the detected biosignal. If the detected biosignal with added body movement noise exceeds the effective input range of the analog-to-digital converter, it may be impossible to obtain biodata during the body movements.

[0003] Patent Document 1 discloses a biological condition detection device that detects pulse rate as biological data. After detecting the occurrence of body movement, this biological condition detection device determines whether the pulse wave signal exceeds the A / D input range, and if so, adjusts the light intensity and offset by the amount of light intensity adjustment, and then controls the pulse wave signal to fall within the A / D input range by following the offset. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-208467 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the biological condition detection device of Patent Document 1, the control to keep the pulse wave signal within the A / D input range is performed after the pulse wave signal has exceeded the A / D input range, so it is not possible to avoid the pulse wave signal exceeding the A / D input range, making it difficult to improve the accuracy of the acquired biological data.

[0006] In view of the above circumstances, an object of the present technology is to provide an information processing device, a biological data measurement system, an information processing method, and a program that can improve the accuracy of acquired biological data. [Means for solving the problem]

[0007] In order to achieve the above object, an information processing device according to the present technology includes a body movement noise prediction unit and a control unit. The body movement noise prediction unit predicts that body movement noise will be added to the detected bio-signal detected from the measurement subject by the bio-sensor based on a reference signal, which is body movement information of the measurement subject detected by a reference signal sensor. The control unit controls signal processing of the detected biological signal based on a result of the prediction by the body movement noise prediction unit.

[0008] In order to achieve the above object, a biological data measurement system according to the present technology includes a reference signal sensor, a biological sensor, a body movement noise prediction unit, and a control unit. The reference signal sensor detects a reference signal that is body movement information of the subject. The biosensor detects a biosignal of the measurement subject. The body movement noise prediction unit predicts, based on the reference signal, that body movement noise will be added to the detected biological signal. The control unit controls signal processing of the detected biological signal based on a result of the prediction by the body movement noise prediction unit.

[0009] In order to achieve the above object, an information processing method according to the present technology includes: predicting, based on a reference signal which is body movement information of a measurement subject detected by a reference signal sensor, that body movement noise will be added to a detected biosignal detected from the measurement subject by a biosensor; Based on the predicted result, signal processing of the detected biological signal is controlled.

[0010] In order to achieve the above-mentioned objective, the program related to the present technology causes an information processing device to execute processing including a step of predicting, based on a reference signal which is body movement information of the measurement subject detected by a reference signal sensor, that body movement noise will be added to a detected bio-signal detected from the measurement subject by a bio-sensor, and a step of controlling signal processing of the detected bio-signal based on the predicted result. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic diagram of a biological data measurement system according to an embodiment of the present technology. [Diagram 2] FIG. 2 is a block diagram showing a functional configuration of the biological data measuring system. [Diagram 3] FIG. 11 is an image diagram for explaining offset control in a normal state. [Figure 4] FIG. 4 is a diagram for explaining an outline of the operation of the biological data measurement system in an offset / gain control state. [Diagram 5] FIG. 13 is an image diagram illustrating a change in an offset control threshold value. [Figure 6] FIG. 13 is an image diagram illustrating a change in gain. [Figure 7] 11 is a diagram for explaining an outline of the operation when restoring the normal state from the offset / gain control state in the above-mentioned biological data measurement system. FIG. [Figure 8] 4 is a sequence diagram showing communication between the biosensor, the system microcomputer, and the terminal in the biodata measurement system. FIG. [Figure 9] 1 is a diagram illustrating an information processing method in a biosensor. [Figure 10] FIG. 2 is a diagram for explaining an information processing method in a system unit microcomputer. [Figure 11] 11 is a diagram for explaining that body movement noise caused by a body movement appears in a detected biosignal with a time delay from the detection of the body movement by a reference signal sensor. FIG. [Figure 12] 11C and 11D, which are partially enlarged views of FIG. 11, and are diagrams for explaining that body movement noise appears in a detected biosignal with a time delay. [Figure 13] 11A and 11B are diagrams illustrating an example of a change in the number of times the effective input range of an analog-to-digital converter is exceeded due to a change in the offset control threshold value. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] When measuring biometric data using a biosensor, body movement noise caused by the body movement of the subject may be added to the detected biometric signal, causing the detected biometric signal to suddenly fluctuate. When the detected biometric signal with added body movement noise is processed by an analog front-end circuit (hereinafter referred to as an AFE circuit) and input to an analog-to-digital converter (hereinafter referred to as an ADC), it may exceed the effective input range (hereinafter referred to as a dynamic range (DR)) of the ADC, making it impossible to obtain biometric data during the occurrence of body movement. The AFE circuit performs signal processing such as amplification and offset control of the detected biometric signal.

[0013] The inventor discovered that body movement noise caused by the body movement of the subject appears in the detected bio-signal detected by the bio-sensor with a delay from the time when the body movement of the subject occurs, which can be read from the detection results of a reference signal sensor that detects the body movement information of the subject, and thus completed the present technology. That is, in this technology, based on the detection result of the reference signal sensor, it is predicted in advance that the detected biosignal detected by the biosensor will be abruptly changed due to the addition of body movement noise. Then, the AFE circuit is controlled based on this prediction result, and the detected biosignal predicted to have body movement noise added thereto is signal-processed by the AFE circuit. More specifically, when it is predicted that the detected biosignal will have body movement noise added thereto, at least one of the offset control threshold value used when determining whether or not to activate offset control and the gain of the detected biosignal (hereinafter, sometimes referred to as the amplification factor) is changed, and the detected biosignal is signal-processed. As a result, the detected biosignal is offset-controlled using the changed offset control threshold value, or the detected biosignal is amplified with the changed gain. This prevents the signal-processed detected biosignal from exceeding the dynamic range. This makes it possible to improve the accuracy of the acquired biodata even during the occurrence of body movement. The details are explained below.

[0014] FIG. 1 is a schematic diagram of a biological data measuring system according to an embodiment of the present technology. In the biological data measurement system 1, biological data of a measurement subject is obtained using a biological sensor. In this embodiment, an electroencephalogram sensor that detects brain waves is taken as an example of the biological sensor, and an electroencephalogram signal is measured as the biological data. In this specification, the biosignal detected by the biosensor from the subject before signal processing is called the detected biosignal. Also, the detected biosignal is processed by the AFE circuit and then digitally converted by the ADC is called the output biosignal. The output biosignal may also be called the A / D value or biodata.

[0015] [Outline of the biomedical data measurement system] 1, the biological data measurement system 1 includes a head fixing support 14, a biological sensor module 7, a system microcomputer 2, a reference signal sensor 9, and a terminal 12. The head fixing support 14, the biological sensor module 7, the system microcomputer 2, and the reference signal sensor 9 constitute a measuring device main body 10.

[0016] The head fixing support 14 supports the biosensor module 7, the system microcomputer 2, and the reference signal sensor 9, and is configured to be wearable on the head of the subject 13. The bioelectrodes 5 of the biosensor 4, which will be described later, are fixed to the head fixing support 14, and are configured so that the bioelectrodes 5 are positioned at predetermined positions on the head when the subject 13 wears them.

[0017] In this embodiment, the biosensor module 7 is an electroencephalogram sensor module. The biosensor module 7 has a plurality of biosensors (brain wave sensors) 4A, 4B, . . . 4N. The biosensors 4A, 4B, . . . 4N have the same basic configuration, and when there is no need to particularly distinguish between them, they will be referred to as biosensors 4. The number of biosensors is one or more.

[0018] The biosensor 4 has a bioelectrode 5, a reference electrode 6, a sensor control unit 41, a detected biosignal acquisition unit 42, an ADC 47, and an AFE circuit 48. The biosensor module 7 has a plurality of bioelectrodes 5A, 5B...5N, and biosensors 4A, 4B...4N are provided corresponding to the respective bioelectrodes 5A, 5B...5N. When there is no need to particularly distinguish between the respective bioelectrodes 5A, 5B...5N, they will be referred to as bioelectrodes 5.

[0019] The reference electrode 6 is configured so as to be attachable to, for example, the ear of the measurement subject 13. One reference electrode 6 is provided in the biosensor module 7, and one reference electrode 6 is shared by a plurality of biosensors 4. The bioelectrodes 5 as a detection section are detection electrodes that acquire biosignals of the subject 13. The bioelectrodes 5 are biocontact sections configured to be able to come into contact with body parts of the subject 13. When the head fixing support 14 is worn, each bioelectrode 5 comes into contact with a plurality of different body parts of the head of the subject 13 and acquires biosignals of each body part. A detected biosignal (detected brain wave signal) is detected from the potential difference between each bioelectrode 5 and the reference electrode 6. The analog detected biosignal, which is the potential difference between each bioelectrode 5 and the reference electrode 6, is processed by the AFE circuit 48, and then input to the ADC 47 and digitized to become an output biosignal. The output biosignal is transmitted to the system microcomputer 2. In the biosensor 4, the AFE circuit 48 is controlled based on the instruction received from the system microcomputer 2. The detected biosignal that has been subjected to signal processing by the controlled AFE circuit 48 is input to the ADC 47 and digitized. The biosensor 4 will be described in detail later.

[0020] The reference signal sensor 9 detects body movements of the subject 13. In this embodiment, a three-axis acceleration sensor is used as the reference signal sensor. The three-axis acceleration sensor as the reference signal sensor 9 is attached to the head of the subject 13 via the head fixing support 14, and detects acceleration when the head moves. The body movement information of the subject 13 detected by the reference signal sensor 9 is called a reference signal.

[0021] The system microcomputer 2 as an information processing device predicts, based on the reference signal detected by the reference signal sensor 9, that body movement noise caused by the body movement of the subject 13 will appear in the detected biosignal detected by the biosensor 4. Then, based on the prediction result, the system microcomputer 2 transmits to each biosensor 4 an instruction to control the AFE circuit 48 of each biosensor 4. In addition, the system microcomputer 2 transmits the acquired reference signal and the output biosignal transmitted from each biosensor 4 to the terminal 12. Details of the system microcomputer 2 will be described later.

[0022] The terminal 12 presents the output biosignal transmitted from the system microcomputer 2 to the user as biodata. The terminal 12 also presents the reference signal data transmitted from the system microcomputer 2 to the user as body movement information of the subject 13. The system microcomputer 2 and the terminal 12 are connected to each other by wire or wirelessly.

[0023] [Details of each configuration] FIG. 2 is a block diagram showing a functional configuration of the biological data measuring system. As shown in Figure 2, the biodata measurement system 1 has a system section microcontroller 2, a data input / output interface (hereinafter referred to as data input / output I / F) 3, a biosensor module 7, a reference signal sensor 9, a data input / output interface (hereinafter referred to as data input / output I / F) 11, and a terminal 12. The data input / output I / F 3 is an I / F for inputting and outputting various data between the system microcomputer 2 and the biosensor module 7 . The data input / output I / F 11 is an I / F for inputting and outputting various data between the system microcomputer 2 and the terminal 12. The communication between the system microcomputer 2 and the terminal 12 may be wired or wireless.

[0024] (System microcomputer configuration) The system microcomputer 2 as an information processing device has a memory 8 , a system control unit 20 as a control unit, a reference signal acquisition unit 21 , and a body movement noise prediction unit 22 .

[0025] The program stored in the memory 8 causes the system unit microcomputer 2 to execute processing including a step of predicting that body movement noise will be added to the detected bio-signal detected from the subject by the bio-sensor 4 based on a reference signal, which is body movement information of the subject detected by the reference signal sensor 9, and a step of controlling signal processing of the detected bio-signal based on the prediction result.

[0026] The reference signal acquisition unit 21 acquires the reference signal detected by the reference signal sensor 9 . The body movement noise prediction unit 22 predicts, based on the acquired reference signal, that body movement noise caused by the body movement of the measurement subject 13 will be added to the detected bio-signal detected by the bio-sensor 4 with a time delay from when the body movement is detected by the reference signal sensor 9. In this embodiment, the body movement noise prediction unit 22 determines a body movement noise level as a prediction result based on the reference signal. The system control unit 20 transmits an instruction for controlling the AFE circuit 48 of the biosensor 4 to the biosensor 4 based on the prediction result by the body movement noise prediction unit 22, i.e., the determined body movement noise level. The instruction content is set in association with the body movement noise level.

[0027] The body motion noise prediction unit 22 determines the body motion noise level by calculating a reference signal variation value by using the acquired reference signal value and comparing the reference signal variation value with a threshold value associated with a body motion noise level that is prepared in advance. In this embodiment, the reference signal variation is an acceleration signal variation.

[0028] The reference signal fluctuation value can be calculated using the following formula: That is, in the time domain, the difference between the current value and the previous value of each reference signal is calculated, and the reference signal fluctuation is calculated by taking the square root of the sum of the squares of the differences for each reference signal.

[0029]

number

[0030] In the above formula, N represents the number of types of reference signals. In this embodiment, an example is given in which a three-axis acceleration sensor is used as the reference signal sensor, so three types of reference signals, namely, X-axis acceleration, Y-axis acceleration, and Z-axis acceleration, are acquired, so N=3. In the above formula, r1 indicates the X-axis acceleration, r2 indicates the Y-axis acceleration, and r3 indicates the Z-axis acceleration. The reference signal fluctuation value calculated by the above formula is sometimes called reference signal fluctuation value 1.

[0031] In addition, in the above formula, an example has been given in which the reference signal fluctuation is calculated by taking the square root, but the reference signal fluctuation value may be calculated by the sum of the squares of the differences between each reference signal without taking the square root, as in the following formula. The reference signal fluctuation value calculated by the following formula is sometimes referred to as reference signal fluctuation value 2.

[0032]

number

[0033] The system microcomputer 2 manages two states: the "normal state" and the "offset / gain control state" as the control state. The default state is the "normal state." The offset / gain control state is a state in which the body movement of the measurement subject 13 is detected from the reference signal, and body movement noise is predicted to be added to the detected biosignal. In the offset / gain control state, the system microcomputer 2 instructs the biosensor 4 to change the offset control threshold value used to control the offset of the detected biosignal in controlling the AFE circuit 48, or to change the gain. The normal state is a state in which the subject 13 is at rest, no significant body movement by the subject 13 is detected by the reference signal sensor 9, and it is predicted that no significant body movement noise will be added to the detected biosignal. In the normal state, no instruction to change the offset control threshold value or gain is given in the control of the AFE circuit 48 of each biosensor 4. The operation of the biological data measurement system 1 in each state will be described later.

[0034] In detail, the body movement noise level can be determined as follows, for example. When the reference signal variation value calculated by the above formula is greater than the first threshold and equal to or less than the second threshold, the body movement noise level is determined to be A. When the reference signal variation value is greater than the second threshold, the body movement noise level is determined to be B. The second threshold is greater than the first threshold. When the reference signal variation value is equal to or less than the first threshold, the body movement noise level is determined to be C. In this embodiment, the first threshold value to be compared with the reference signal fluctuation value (reference signal fluctuation value 1) calculated using the square root of the sum of the squares of the differences between each of the above reference signals is set to 0.07 G, and the second threshold value is set to 1 G, but the numerical values ​​are not limited to these.

[0035] The body motion noise level A and the body motion noise level B correspond to the offset / gain control states. The body motion noise level C corresponds to the normal state. When the calculated reference signal fluctuation value is greater than 0.07 G and equal to or less than 1 G, the system microcomputer 2 determines that the body movement noise level is A, and transmits an instruction to the biosensor 4 to set the offset control threshold to a value different from that in the normal state. More specifically, the system microcomputer 2 transmits an instruction to narrow the range of the offset control threshold by moving the offset control threshold to the center of the dynamic range. When the calculated reference signal fluctuation value is greater than 1 G, the system microcomputer 2 determines that the body movement noise level is B, and transmits an instruction to the biosensor 4 to set the gain to a value different from that in the normal state. More specifically, the system microcomputer 2 transmits an instruction to lower the gain. If the calculated reference signal fluctuation value is 0.07 G or less, the system microcomputer 2 determines that the body movement noise level is C. If the system microcomputer 2 is currently in a normal state, it does not instruct the biosensor 4 to change the offset control threshold and gain.

[0036] Furthermore, the system microcomputer 2 starts a 500 msec timer at the same time as transitioning from the normal state to the offset / gain control state. After the 500 msec timer expires, it transmits a restoration instruction (hereinafter sometimes referred to as an offset / gain restoration instruction) to the biosensor 4 to return the changed offset control threshold or gain to the normal state. In this way, in this embodiment, the period during which the offset / gain control state is maintained is adjusted by setting the timer. Details will be described later.

[0037] The system microcomputer 2 also receives output bio-signals output from each bio-sensor 4 of the bio-sensor module 7, and outputs the same to the terminal 12 via the data input / output I / F 11. The system microcomputer 2 outputs the acquired reference signal data to the terminal 12 via the data input / output I / F 11.

[0038] In this technology, the calculation of the fluctuation value of the reference signal used to predict the occurrence of body movement noise is not complicated as it only uses two-point differences in the time domain, and real-time prediction of the occurrence of body movement noise through calculation is guaranteed.

[0039] (Biosensor configuration) The biosensor 4 performs signal processing on the detected biosignal, which is the potential difference between the bioelectrode 5 and the reference electrode 6, converts it into a digital signal, and outputs an output biosignal. In the biosensor 4, the AFE circuit 48 is controlled based on an instruction sent from the system microcomputer 2. In the biosensor 4, the detected biosignal is processed by the controlled AFE circuit 48, then digitized and output as an output biosignal.

[0040] The biosensor 4, like the system microcomputer 2, manages two states: a "normal state" and an "offset / gain control state." The default state is the "normal state."

[0041] As shown in FIG. 2, the biosensor 4 includes a bioelectrode 5, a reference electrode 6, a sensor control unit 41 which is a microcomputer in the sensor unit, a detected biosignal acquisition unit 42, an offset digital-to-analog converter (hereinafter referred to as offset DAC) 43, an offset control unit 44, an amplifier gain register 45, a programmable gain amplifier 46, and an ADC 47. The offset DAC 43, the offset control unit 44, the amplifier gain register 45, and the programmable gain amplifier 46 constitute an AFE circuit 48.

[0042] The detected biosignal acquiring section 42 acquires the potential difference between the bioelectrode 5 and the reference electrode 6 (detected biosignal). The ADC 47 digitally converts the detected biosignal, which is analog waveform data that has been offset-controlled and gain-adjusted by the AFE circuit 48. In this embodiment, for example, a low-bit 14-bit ADC can be used, which enables miniaturization and low power consumption of the biosensor 4. Increasing the signal resolution with a low-bit ADC such as 14 bits reduces the dynamic range, but offset control can be used to apply an offset to the dynamic range, so that the obtainable range of the detected biosignal can be expanded to the offset controllable range.

[0043] The sensor control unit 41 controls the AFE circuit 48 based on an instruction sent from the system microcomputer 2 . When the sensor control unit 41 receives an instruction from the system unit microcomputer 2 to change the range of the offset control threshold from the normal state, more specifically, to narrow the offset control threshold, it takes the offset / gain control state. The sensor control unit 41 updates the threshold so as to narrow the range of the offset control threshold. In the two states of the normal state and the offset / gain control state, if the A / D value obtained by signal processing and digitally converting the detected biosignal exceeds the offset control threshold, the sensor control unit 41 adjusts the offset amount using the offset DAC 43. When the sensor control unit 41 receives an instruction from the system microcomputer 2 to change the gain from the normal state, more specifically, to lower the gain, the sensor control unit 41 enters an offset / gain control state. The sensor control unit 41 sets the amplifier gain register 45 of the AFE circuit 48 to lower the amplification factor of the programmable gain amplifier 46. When the sensor control unit 41 receives an offset / gain restoration instruction from the system unit microcomputer 2, it transitions to a normal state and controls the AFE circuit 48 to return the changed offset control threshold value or gain to the normal state. The analog detected biosignal that has been signal-processed by the AFE circuit 48 is converted into a digital output biosignal by the ADC 47. The sensor control unit 41 transmits the output biosignal to the system unit microcomputer 2 via the data input / output I / F 3.

[0044] The offset DAC 43 adjusts the offset amount during offset control. The offset control unit 44 is capable of adjusting the offset amount programmably. The offset control unit 44 offsets the detected biological signal based on the offset amount set by the offset DAC 43.

[0045] The amplifier gain register 45 sets the gain (amplification factor) of the programmable gain amplifier 46 in accordance with an instruction from the sensor control unit 41 . The programmable gain amplifier 46 adjusts and amplifies the offset-controlled detected biological signal by switching to a gain set by the amplifier gain register 45. This makes it possible to vary the dynamic range width.

[0046] In this manner, in the biosensor 4, the signal processing of the detected biosignal is controlled based on an instruction to change the offset control threshold or gain based on the body movement noise predicted by the system microcomputer 2.

[0047] [Explanation of the operation of the system microcontroller and biosensor] (Offset control) The offset control will now be described. FIG. 3 is an image diagram for explaining offset control in a normal state. In FIG. 3, a line graph 30 shows an example of time-dependent change in A / D value obtained by signal processing and digital conversion of a detected biological signal of a sample. The horizontal axis indicates the time axis, and the vertical axis indicates the A / D value. Two dashed dotted lines 31, 31 indicate the dynamic range of the ADC 47. One long dashed line 33 indicates the center of the dynamic range. Two short dashed lines 32, 32 indicate the range of the offset control threshold.

[0048] The sensor control unit 41 sequentially samples the A / D values ​​and compares the A / D values ​​with the offset control threshold. If the comparison shows that the A / D value exceeds the offset control threshold, the dynamic range is offset so that the A / D value at the time of the exceeding is at the center of the dynamic range indicated by the dashed line 33, as shown in FIG. 3. The offset amount at this time is used to perform offset control of the detected biological signal. In the example shown in FIG. 3, since the A / D value exceeds the offset control threshold at the time of plotted point 15, the dynamic range is offset so that point 15 is at the center of the dynamic range.

[0049] In this way, the range of the offset control threshold is set to a range narrower than the dynamic range. When the offset control threshold is exceeded, an offset is applied to the detected biological signal to perform offset control, thereby preventing the A / D value from exceeding the dynamic range of the ADC 47, and improving the accuracy of the acquired biological data. Here, if there is no significant body movement of the measurement subject 13, there is no sudden change in the biological signal, and therefore the dynamic range is not exceeded when the offset control threshold is exceeded.

[0050] In the signal processing in the AFE circuit 48 under normal conditions, in addition to the offset control described above, the detected vital signs signal is amplified with a predetermined gain.

[0051] (Operation in offset / gain control state) When the biosensor 4 receives an offset control threshold change instruction or a gain change instruction from the system microcomputer 2, it transitions from the normal state to the offset / gain control state.

[0052] FIG. 4 is a schematic diagram for explaining an outline of the operation of the biological data measurement system 1 in the offset / gain control state. As shown in Fig. 4, a reference signal 38 detected by a reference signal sensor 9 is input to the system microcomputer 2. In the example shown in Fig. 4, a sudden change due to the body movement of the subject 13 appears in a portion of the reference signal 38 surrounded by a dashed rectangle 34. Based on the input reference signal 38, the system microcomputer 2 predicts that body movement noise caused by the body movement of the measurement subject 13 will be added to the detected biosignals detected by each biosensor 4. In this embodiment, the above formula is used to determine the body movement noise level as the body movement noise prediction result. The system microcomputer 2 transmits instructions related to signal processing linked to the determined body movement noise level to the sensor control unit 41. Specifically, at the body movement noise level A, the system microcomputer 2 transmits to the sensor control unit 41 of the biosensor 4 an instruction to narrow the offset control threshold value more than in the normal state. At the body movement noise level B, the system microcomputer 2 transmits to the sensor control unit 41 an instruction to lower the gain. At body movement noise level C, the system microcomputer 2 does not issue an instruction to change the offset control threshold and the gain.

[0053] When the sensor control unit 41 receives an instruction to change the offset control threshold or the gain from the system microcomputer 2, the biosensor 4 transitions from the normal state to the offset / gain control state. The sensor control unit 41 controls the AFE circuit 48 in accordance with instructions from the system microcomputer 2 . More specifically, the sensor control unit 41 changes the offset control threshold based on the change instruction to narrow the offset control threshold, and controls the AFE circuit 48 to perform offset control using the changed offset control threshold. In this case, the detected biological signal is amplified in the AFE circuit 48 by a gain set in a normal state. The sensor control unit 41 changes the gain based on a change instruction to decrease the gain, and controls the AFE circuit 48 to perform signal processing with the changed gain. In this case, in the AFE circuit 48, the detected biological signal is offset-controlled based on an offset control threshold value set in a normal state.

[0054] 4, the detected biosignal 40 detected by the biosensor 4 is signal-processed by the AFE circuit 48 based on the set offset control threshold and gain. As a result, although body movement noise appears in the area surrounded by the dashed rectangle 35 as shown in FIG. 4, the detected biosignal 39 after signal processing by the AFE circuit 48 can be kept within the dynamic range 37 of the ADC 47. The detected biosignal 39 input to the ADC 47 is digitally converted by the ADC 47 and output to the sensor control unit 41.

[0055] (Change in offset control threshold) The change of the offset control threshold value will be described. When the sensor control unit 41 receives an instruction to change the offset control threshold from the system unit microcomputer 2, it updates the threshold so as to narrow the range of the offset control threshold. 5(A) and (B) are conceptual diagrams for explaining offset control when body movement occurs. Fig. 5(A) is a diagram showing a case where the offset control threshold is not changed, and Fig. 5(B) is a diagram showing a case where the offset control threshold is changed based on the predicted body movement noise according to the present technology. 5, a line graph 30 indicates the change over time in the A / D value of a sample. Two dashed lines 31, 31 indicate the dynamic range of the ADC 47. Two broken lines 32, 32 indicate the range of the offset control threshold.

[0056] As explained above with reference to Figure 3, offset control is also performed in the normal state. In the normal state, there is no sudden change in the A / D value, so the dynamic range is not exceeded when the A / D value exceeds the range of the offset control threshold, and even if offset control is performed based on the time when the offset control threshold is exceeded, the A / D value is prevented from exceeding the dynamic range. In this way, in the normal state with no body movement, the offset control prevents the A / D value from exceeding the dynamic range.

[0057] On the other hand, when body movement occurs and body movement noise is added, causing a sudden change in the A / D value, the dynamic range may be exceeded at the point where the offset control threshold range is exceeded, as shown by point 17 in line graph 30 in Fig. 5(A). In this case, even if offset control is performed based on the point where the offset control threshold is exceeded, there is a point where the dynamic range has already been exceeded, and so the biological data of that point cannot be acquired.

[0058] In contrast, in this embodiment, it is possible to predict in advance from the reference signal that body movement noise will be added to the detected biosignal, and if it is predicted that body movement noise will be added, an instruction is given to change the range of the offset control threshold. Specifically, as shown in FIG. 5B, an instruction is given to narrow the range of the offset control threshold value more than in the normal state so that the offset control threshold value is brought closer to the center of the dynamic range.

[0059] As shown in FIG. 5(A), when the offset control threshold is not changed, the offset control threshold is set so that the +offset control threshold (-offset control threshold) is located, for example, at a position of 85% from the center of the dynamic range indicated by the dashed line 33, when the range from the center to +DR (-DR) is set to 100%. In contrast, as shown in FIG. 5(B), when the offset control threshold is changed, the offset control threshold is set so that the +offset control threshold (-offset control threshold) is located, for example, at a position of 20% from the center of the dynamic range when the range from the center of the dynamic range to +DR (-DR) is set to 100%. Thus, in this embodiment, the offset control threshold is set to 85% in the normal state, and is set to 20% in the offset / gain control state.

[0060] As shown in Fig. 5(B), by changing the range of the offset control threshold to be narrower, the offset control threshold is exceeded at point 16, which is before point 17, so offset control is performed so that the detected biological signal of the sample at point 16 is at the center of the dynamic range. As shown in Fig. 5(B), point 16 does not exceed the dynamic range. This reduces the risk that the A / D value of the sample at the next point 17 will exceed the dynamic range. In this way, by changing the offset control threshold to the center of the dynamic range before body movement noise appears in the detected vital sign, the offset control is activated more frequently. This makes it possible to reduce the possibility that the detected vital sign after signal processing will be outside the dynamic range, even if a sudden change appears in the detected vital sign due to the addition of body movement noise. This makes it possible to improve the accuracy of the acquired vital sign data.

[0061] The offset / gain control state lasts from the time the offset control threshold is changed until 500 msec has elapsed. When the offset / gain control state transitions to the normal state after 500 msec has elapsed, the range of the offset control threshold is set to be wider than when in the offset / gain control state.

[0062] (Gain change) The gain change will be described. When the sensor control unit 41 receives a gain change instruction from the system unit microcomputer 2, it transitions from a normal state to an offset / gain control state, and controls the AFE circuit 48 to lower the gain (programmable gain). FIG. 6(A) is an image diagram showing an example of transitioning from a normal state to an offset / gain control state to reduce the gain. FIG. 6(B) is an image diagram showing an example in which the gain is returned to the original state by transitioning from the offset / gain control state to the normal state, i.e., the gain is increased. Fig. 6(C) is an image diagram for explaining the operation of the biosensor 4 in this embodiment. Fig. 6(C) shows an example in which the addition of body movement noise is predicted, the gain is changed, and the state transitions from the normal state to the offset / gain control state, and then the state transitions to the normal state 500 msec after the transition to the offset / gain control state. A line graph 30 shows the change over time in the A / D value of the sample.

[0063] As shown in Figs. 6(A) and (C), when the gain (amplification factor) is reduced, a detected vital signal with less amplification is input to the ADC 47. Therefore, the detected vital signal is input with a margin relative to the dynamic range of the ADC 47, and the dynamic range is expanded. This makes it possible to prevent the detected vital signal from falling outside the dynamic range of the ADC 47 even when a sudden change appears in the detected vital signal due to the addition of body movement noise. In the example shown in Fig. 6(C), body movement noise is included in the samples at points 18 and 19. In this embodiment, since it is possible to predict in advance that body movement noise will be added to the detected vital signal based on the reference signal, the gain can be changed at the point 53 before point 18, that is, before the body movement noise appears in the detected vital signal. This makes it possible to prevent the detected vital signal from falling outside the dynamic range of the ADC 47 at the points 18 and 19.

[0064] As shown in Figure 6 (C), the offset-gain control state lasts from point 50 when the gain is changed to point 51, 500 msec later. As shown in Figures 6 (B) and (C), when the offset-gain control state transitions to the normal state after 500 msec has elapsed, the gain is set to be higher than in the offset-gain control state. This increases the amplification factor of the detected biosignal, and the dynamic range is narrower than in the offset-gain control state.

[0065] By lowering the gain in this manner, it is possible to prevent the detected biological signal from falling outside the dynamic range.

[0066] (Changes in offset control threshold and gain) In this embodiment, an example is given in which the gain is changed when the body movement is large, and the offset control threshold is changed when the body movement is small. This is because a gain change that lowers the programmable gain results in coarse biosignal resolution, and in this embodiment, the gain change is performed only when it is predicted that the body movement noise is not sufficient to be addressed by changing the offset control threshold. For example, when a 14-bit ADC is used for the ADC 47, if the gain is lowered and the dynamic range is expanded as shown in Fig. 6(A), this range is represented by the 14-bit ADC, and the signal resolution per LSB becomes coarse. On the other hand, if the gain is increased and the dynamic range is reduced as shown in Fig. 6(B), this range is represented by the 14-bit ADC, and the signal resolution per LSB becomes fine. For this reason, in this embodiment, the gain is changed only when it is predicted that the noise is body movement noise that cannot be handled by changing the offset control threshold.

[0067] As described above, in this embodiment, it is possible to predict in advance that body movement noise will be added to the detected biosignal detected by the biosensor 4, based on the reference signal detected by the reference signal sensor 9. Therefore, the detected biosignal in which body movement noise appears can be signal-processed with an offset control threshold and an amplification factor that are preset based on the body movement noise level, and then input to the ADC 47. This makes it easier to prevent the detected biosignal after signal processing from falling outside the dynamic range of the ADC 47. This makes it possible to improve the accuracy of the acquired biodata.

[0068] (Transition from timer and offset / gain control state to normal state) As described above, the body movement noise caused by the body movement of the measurement subject, which can be read from the reference signal, appears in the detected biosignal detected by the biosensor with a delay from the time when the body movement occurs. In this embodiment, this delay is estimated at 400 msec. In the biodata measurement system 1, after the body movement noise prediction unit 22 detects an excess of the threshold associated with the body movement noise level, it predicts that a sudden change will occur in the detected biosignal for a period of 500 msec with some time margin, and sets the timer to 500 msec. After 500 msec has elapsed since the offset / gain control state transition, the system microcomputer 2 transmits an instruction to restore the normal state to the biosensor 4. The instruction to restore the normal state is an offset control threshold restoration instruction to restore the offset control threshold to the offset control threshold in the normal state, or a gain restoration instruction to restore the gain to the normal state. Hereinafter, a description will be given with reference to FIG. 7.

[0069] FIG. 7 is a schematic diagram for explaining an outline of the operation of the biological data measurement system 1 when transitioning from the offset / gain control state to the normal state. 7, a reference signal 38 detected by a reference signal sensor 9 is input to the system microcomputer 2. The system microcomputer 2 transitions to the offset / gain control state and at the same time starts a 500 msec timer. When the system microcomputer 2 detects that 500 msec has elapsed using the timer, it transmits an offset control threshold recovery instruction or a gain recovery instruction to the sensor control unit 41. After receiving the offset control threshold restoration instruction or the gain restoration instruction, the sensor control unit 41 transitions to a normal state. The sensor control unit 41 controls the AFE circuit 48 in accordance with the instruction from the system unit microcomputer 2. More specifically, the sensor control unit 41 controls the AFE circuit 48 to restore the offset control threshold to the original value, or to restore the gain to the original value. The detected biosignal 40 detected by the biosensor 4 is signal-processed by the AFE circuit 48 based on the set offset control threshold and gain, converted into digital form by the ADC 47 , and output to the sensor control unit 41 .

[0070] In this way, by issuing a restoration instruction to return to the normal state a predetermined time after transitioning to the offset / gain control state, it is possible to suppress an increase in power consumption and avoid degradation of biosignal resolution. That is, by providing a timer, the period of the offset / gain control state can be adjusted, and adjustments can be made so that the offset control threshold and the gain are changed mainly under circumstances in which body movement noise is added to the detected biosignal. As a result, by narrowing the offset control threshold, offset control is frequently performed and power consumption increases, but by providing a timer, the period during which power consumption increases can be limited, and the increase in power consumption in periods when no body movement noise is predicted can be suppressed. In addition, a change to lower the gain causes degradation of biosignal resolution, but by providing a timer, the period during which biosignal resolution deteriorates can be limited, and degradation of biosignal resolution in periods when no body movement noise is predicted can be avoided.

[0071] After transmitting an instruction to restore the offset control threshold or an instruction to restore the gain to the biosensor 4, the system microcomputer 2 transitions to a normal state and causes the body movement noise prediction unit 22 to resume observing the reference signal fluctuation. The observation of the reference signal fluctuation continues even during the offset / gain control state, and if a reference signal fluctuation exceeding the threshold is observed during the offset / gain control state, a new 500 msec timer is restarted from that point.

[0072] After receiving the offset control threshold restoration instruction or the gain restoration instruction, the biosensor 4 transitions to a normal state, restores the offset control threshold to its original value, or restores the programmable gain to its original value, and continues to acquire the detected biosignal, process the signal, and perform digital conversion processing.

[0073] [Information processing method] (Processing flow in the biological data measurement system) FIG. 8 is a sequence diagram showing communication between the biosensor 4, the system microcomputer 2, and the terminal 12 in the biodata measurement system 1. As shown in FIG. In Figure 8, the left side of the white arrow shows a sequence diagram in the normal state, and the right side shows a sequence diagram in the offset / gain control state. The white arrow indicates the transition to a different state. In the sequence diagram for the normal state on the left side of the drawing, the upper side shows the operation when the reference signal variation value in the body movement noise level judgment is equal to or less than the first threshold, and the lower side shows the operation when the reference signal variation value is greater than the first or second threshold. In the sequence diagram for the offset / gain control state on the right side of the drawing, the upper side shows the operation performed during the period up to 500 msec after transition to the offset / gain control state, and the lower side shows the operation performed 500 msec after transition to the offset / gain control state.

[0074] 8, the biosensor 4 acquires a detected biosignal (S1). The biosensor 4 processes and digitally converts the acquired detected biosignal into an output biosignal (biological data), and transmits it to the system microcomputer 2. The system microcomputer 2 acquires a reference signal (S2), and uses the reference signal to compare the reference signal variation value with a threshold value associated with the body movement noise level to determine the body movement noise level (S3). Here, since the reference signal variation value (diff) is equal to or less than the first threshold value (TH1), the body movement noise level is determined to be C, i.e., a normal state. In the normal state, when the system microcomputer 2 receives an output bio-signal from the bio-sensor 4, it responds (ACK) to the bio-sensor 4 to confirm receipt. The system microcomputer 2 transmits the output biological signal and the reference signal to the terminal 12. In this way, the system microcomputer 2 determines the fluctuation of the reference signal, and if the reference signal fluctuation value is equal to or less than the first threshold, no instruction is given to change the offset control threshold value and the gain.

[0075] 8, the biosensor 4 acquires a detected biosignal (S4). The biosensor 4 processes and digitally converts the acquired detected biosignal into an output biosignal (biological data) and transmits it to the system microcomputer 2. The system microcomputer 2 acquires a reference signal (S5) and uses the reference signal to compare the reference signal variation value with a threshold value associated with the body motion noise level to determine the body motion noise level (S6). Here, since the reference signal variation value (diff) is greater than the first threshold value (TH1) or the second threshold value (TH2), it determines that the body motion noise level is A or B, i.e., the offset / gain control state. In the offset / gain control state, when the system microcomputer 2 receives an output bio-signal, it transmits an instruction to the bio-sensor 4 to change the offset control threshold value or change the gain. Based on this instruction, the biosensor 4 transitions to an offset / gain control state and changes the offset control threshold or the gain (S7). The system microcomputer 2 transmits the output biosignal and the reference signal to the terminal 12. When the offset / gain control state is entered, processing is performed according to the sequence diagram on the right side of FIG. In this way, the system microcomputer 2 determines the fluctuation of the reference signal, and if the reference signal fluctuation value is greater than the first threshold or the second threshold, an instruction to change the offset control threshold or the gain is issued.

[0076] As shown in the upper diagram of the sequence diagram in the offset / gain control state in Figure 8, the biosensor 4 and the system microcomputer 2 transition to the offset / gain control state and change the offset control threshold or change the gain (S8). The biosensor 4 acquires a detected biosignal (S9). The biosensor 4 processes and digitally converts the acquired detected biosignal into an output biosignal and transmits it to the system microcomputer 2. The system microcomputer 2 acquires the reference signal (S10). When the system microcomputer 2 receives the output biosignal, it sends a reception confirmation response (ACK) to the biosensor 4. The system microcomputer 2 transmits the output biosignal and the reference signal to the terminal 12. This series of processes is performed until 500 msec has elapsed since the transition to the offset / gain control state.

[0077] 8, when 500 msec has elapsed since the transition to the offset / gain control state, the biosensor 4 acquires a detected biosignal (S11). The biosensor 4 processes and digitally converts the acquired detected biosignal into an output biosignal, and transmits it to the system microcomputer 2. The system microcomputer 2 acquires the reference signal (S12). The system microcomputer 2 transmits to the biosensor 4 an instruction to restore the offset control threshold value or an instruction to restore the gain. The biosensor 4 receives the restoration instruction and returns the offset control threshold to the original value or the programmable gain to the original value (S13). As a result, the offset / gain control state is released in the biosensor 4 and the system microcomputer 2 (S14), and the state transitions to the normal state. In this way, when 500 msec has elapsed, an instruction to restore the offset control threshold or gain is issued. The offset / gain control state is released and the state transitions to the normal state.

[0078] (Information processing method using biosensors) FIG. 9 is a control flow diagram illustrating an information processing method in the biosensor 4. As shown in FIG. 9, after initialization (S20), the detected biosignal acquisition unit 42 acquires a detected biosignal (S21). The detected biosignal is sampled at a sampling frequency of, for example, 256 Hz. A sample counter counts how many times the detected biosignal has been read out (S22). The acquired detected biosignal is subjected to signal processing by the AFE circuit 48, and then digitally converted by the ADC 47. The sensor control unit 41 compares the digitally converted A / D value with the offset control threshold value and determines whether the A / D value exceeds the offset control threshold value (S23). If it is determined that it exceeds the offset control threshold value (YES), offset control is performed (S24) and the process proceeds to S25. If it is determined that it does not exceed the offset control threshold value (NO), the process proceeds to S25.

[0079] In S25, the sensor control unit 41 determines whether or not the biosensor 4 is in an offset / gain control state. If it is determined in S25 that the sensor is in the offset / gain control state (YES), it is determined whether an offset control threshold restoration instruction or a gain restoration instruction has been received (S26). If it is determined in S26 that an instruction has been received (YES), the sensor control unit 41 controls the AFE circuit 48 to return the offset control threshold or gain to the normal state (S27), and transitions to the normal state (S28).

[0080] If it is determined in S25 that the sensor is not in the offset / gain control state (NO), it is determined whether an offset control threshold change instruction or a gain change instruction has been received (S33). If it is determined that an offset control threshold change instruction or a gain change instruction has not been received (NO), the process proceeds to S29. If it is determined that an offset control threshold change instruction or a gain change instruction has been received (YES), the sensor control unit 41 controls the AFE circuit 48 to change the offset control threshold or the gain (S34), transitions to the offset / gain control state (S35), and the process proceeds to S29.

[0081] In S29, it is determined whether the sample counter value exceeds a predetermined value (S29). If it is determined that the sample counter value does not exceed the predetermined value (NO), the process returns to S21 and the series of processes are repeated. If it is determined that the sample counter value exceeds the predetermined value (YES), the sample counter value is set to 0 (S30). Next, the sensor control unit 41 transmits an output biosignal (biological data) to the system unit microcomputer 2 (S31). Next, the sensor control unit 41 receives an instruction to change the offset control threshold or gain, an instruction to restore the offset control threshold or gain, or an ACK (S32), and the process returns to S21 and is repeated.

[0082] (Information processing method in the system microcomputer) FIG. 10 is a control flow diagram illustrating an information processing method in the system microcomputer 2. As shown in FIG. 10, after initialization (S40), the reference signal acquirer 21 acquires a reference signal (S41). Next, the body movement noise prediction section 22 calculates a reference signal fluctuation value (reference signal fluctuation value) based on the reference signal using the formula of the square root of the sum of the squares of the differences between the above reference signals (S42). Next, the system control unit 20 determines whether the system unit microcomputer 2 is in an offset / gain control state (S43). If it is determined in S43 that the offset / gain control state is in progress (YES), it is determined whether or not the 500 ms timer has expired (S44). If the system control unit 20 determines that the 500 ms timer has expired (YES), an instruction to restore the offset control threshold or gain is confirmed (S45), and the process proceeds to S46. If it is determined in S44 that the 500 ms timer has not expired (NO), the process proceeds to S46. If it is determined in S43 that the offset / gain control state is not in progress (NO), the body movement noise prediction unit 22 determines whether the calculated reference signal fluctuation value is greater than a first threshold value (TH1) (S51). If it is determined in S51 that it is greater (YES), an instruction to change the offset control threshold value or gain is confirmed (S52). If it is determined in S51 that the reference signal fluctuation value is equal to or less than the first threshold value (NO), the process proceeds to S46.

[0083] In S46, the system control unit 20 determines whether or not the output biosignal has been received. If it is determined that the output biosignal has not been received, the process returns to S41 and is repeated. If it is determined that the output biosignal has been received, the output biosignal is acquired (S47). Next, it is determined whether the offset control threshold or gain restoration instruction has been confirmed (S48). If it is determined in S48 that the offset control threshold or gain restoration instruction has been confirmed, the offset control threshold or gain restoration instruction is transmitted to the biosensor 4 (S49), the biosensor transitions to a normal state (S50), and the process proceeds to S58. If it is determined in S48 that the change has not been confirmed, it is determined whether or not the change instruction for the offset control threshold or gain has been confirmed (S53). If it is determined in S53 that the change has not been confirmed (NO), an ACK is sent to the biosensor 4 (S57), and the process proceeds to S58. If it is determined in S53 that the change has been confirmed (YES), an instruction to change the offset control threshold or gain is sent to the biosensor 4 (S54). Next, a 500 ms timer is started (S55), and the system unit microcomputer 2 transitions to the offset / gain control state, and the process proceeds to S58. In S58, the system control unit 20 transmits the output biological signal (biological data) and the reference signal (reference signal data) to the terminal 12. Next, the process returns to S41 and is repeated.

[0084] [Additional Description of the Present Embodiment] The following provides a supplementary explanation of this embodiment. (Explanation of the appearance of body movement noise in the detected biosignal with a time lag from the detection of body movement by the reference signal sensor) The appearance of body movement noise in a detected biosignal with a time delay from the detection of body movement by the reference signal sensor will be described with reference to Figures 11 and 12. In Figures 11(A) to (D), the horizontal axis indicates the time axis, and Figures 11(A) to (D) correspond to each other and have the same time axis. FIG. 11A is a graph showing an example of a biosignal (electroencephalogram signal) detected by the biosensor 4, sampled at a sampling period of 256 Hz. FIG. 11(B) is a graph of the reference signal fluctuation value (acceleration fluctuation value) calculated using the reference signal (acceleration) detected from the reference signal sensor (3-axis acceleration sensor) 9, according to the square root of the sum of the squares of the differences between each of the above reference signals. Fig. 11(C) is an example of extracting points where the biosignal value fluctuation (brain wave value fluctuation) is abruptly fluctuating by 5.1 mV or more based on Fig. 11(A). In the example shown in Fig. 11(C), four peaks indicating abrupt fluctuations are extracted. Fig. 11(D) is a diagram based on Fig. 11(B) in which the reference signal fluctuation value (acceleration fluctuation value) is extracted at points where the reference signal fluctuation value (acceleration fluctuation value) is abruptly fluctuating by 0.07 G or more. In the example shown in Fig. 11(D), four peaks indicating abrupt fluctuations are extracted.

[0085] As shown in Figures 11(C) and (D), it can be seen that there is a correlation between the appearance of sudden acceleration fluctuations and the appearance of sudden EEG fluctuations in terms of time, and that the EEG fluctuations appear slightly after the appearance of the acceleration fluctuations. Figures 12(A) and (B) are partial enlargements of Figures 11(C) and (D), respectively. As shown in Figures 12(A) and (B), it can be seen that the brain waves suddenly fluctuate with a maximum delay of 400 msec after the sudden acceleration fluctuation appears. In this way, it can be seen that body movement noise caused by the body movement of the subject, which can be read from the detection result of the reference signal sensor, appears in the detected bio-signal with a delay from the time when the body movement occurs.

[0086] (Example of changing the offset control threshold) 13A to 13D are diagrams showing an example of a change in the number of times the dynamic range is exceeded due to a change in the offset control threshold. As described above, offset control is triggered by exceeding the offset control threshold. In each of Figs. 13A to 13D, the straight line extending vertically on the left side of the figure indicates dynamic range 37, dashed line 32 indicates the offset control threshold, and straight solid line 33 indicates the center of dynamic range 37.

[0087] Fig. 13(A) shows an example of an EEG signal, the number of samples exceeding the dynamic range, the signal availability rate, and the number of offset controls when the signal is processed with the offset control threshold set to 85%. The signal availability rate indicates the ratio of the number of samples obtained by subtracting the number of samples that lack accuracy from the total number of samples, with samples that exceed the dynamic range of 37 ±1 second being treated as samples that lack accuracy, divided by the total number of samples. The higher the signal availability rate, the fewer the number of times the dynamic range of 37 is exceeded. Figures 13(B) to (D) respectively show an example EEG signal, the number of samples that exceeded the dynamic range 37, the signal availability, and the number of offset controls when the offset control threshold was set to 50%, 20%, and 20% and the signal was processed. 13(A) to (C) show the results of electroencephalograms sampled at 256 Hz, and FIG. 13(D) shows the results of electroencephalograms sampled at 512 Hz.

[0088] 13(A) to (D), it can be seen that the closer the offset control threshold approaches the center of the dynamic range indicated by the solid line 33, that is, the narrower the range of the dashed lines 32, 32 indicating the offset control threshold, the fewer the number of times the dynamic range is exceeded and the higher the signal usability becomes. In other words, the accuracy of the acquired biological data can be improved. 13(C) and (D), it can be seen that doubling the sampling frequency reduces the number of times the dynamic range is exceeded and increases the signal usability. This is because the rapid fluctuations in the EEG signal due to body movement can be finely sampled, allowing the range of rapid fluctuations to be divided into smaller increments and offset control to be applied each time, further suppressing the exceeding of the dynamic range. In this way, by predicting in advance that body movement noise will be added and setting the offset control threshold closer to the center of the dynamic range to narrow the range of the offset control threshold, it is possible to prevent the dynamic range from being exceeded. In the above embodiment, the sampling frequency is set to 256 Hz, and the offset control threshold is set to 85% in the normal state and 20% in the offset / gain control state, but the present invention is not limited to this.

[0089] Here, the number of offset controls increases as the offset control threshold approaches the center of the dynamic range, and the power consumption increases as the number of offset controls increases. In contrast, in this embodiment, as described above, a timer is used to restore the offset / gain control state to the normal state after a predetermined time has elapsed. As a result, the offset control threshold is changed only when body movement noise is added to the detected biological signal, and the offset control threshold is not changed during periods when there is no body movement. Therefore, the number of offset controls during periods when there is no body movement is reduced, and an increase in power consumption is suppressed.

[0090] (Other configuration examples) The embodiments of the present technology are not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present technology.

[0091] For example, in the above-mentioned embodiment, an electroencephalogram sensor that detects an electroencephalogram signal is given as an example of a biosensor, but the present technology is not limited thereto. For example, the present technology can be applied to a pulse wave sensor, a blood flow sensor, and a sweat sensor as a biosensor. In these biosensors, as in the above-mentioned embodiment, body movement noise due to the body movement of the measurement subject observed by the reference signal sensor appears in the signal detected by the biosensor with a delay from the occurrence of the body movement of the measurement subject observed by the reference signal sensor. Therefore, based on the detection result of the reference signal sensor, it is possible to predict that body movement noise will be added to the detected biosignal, and it is possible to control the offset control threshold value and gain related to the signal processing of the detected biosignal in advance. This prevents the detected biosignal containing body movement noise from being outside the dynamic range of the ADC, and it is possible to improve the accuracy of the acquired biodata.

[0092] A pulse wave sensor detects the pulse wave of a living body to be detected by irradiating the living body with light from a light source such as an LED (Light-Emitting Diode) and obtaining a signal indicating the intensity of the light reflected from the living body with a light receiving element such as a photodiode. Since hemoglobin in the blood flowing through the blood vessels of the living body to be detected has the property of absorbing light, the pulse wave of the living body to be detected is detected by observing the reflected light with a photodiode.

[0093] A blood flow sensor is an optical sensor that measures blood flow. A blood flow sensor irradiates a body part of a subject with light (e.g., laser light or infrared light) and measures blood flow from the reflected light. For example, light can be irradiated onto the forehead and cerebral blood flow can be measured from the reflected light. A blood flow sensor has a light emitting element (e.g., a laser diode) and a light receiving element (e.g., a photodiode). A blood flow sensor may have multiple light receiving elements. A blood flow sensor may have multiple light emitting elements.

[0094] A sweat sensor is a sensor that detects sweat secreted from sweat glands in the skin (e.g., eccrine glands). Sweating puts the skin in a state where electricity can easily pass through it. Therefore, sweating can be detected by acquiring the electrodermal activity (EDA) of the skin. The sweat sensor can pass a weak current through the skin to measure the electrical resistance, and calculate the skin conductance (SCA) as the reciprocal of the electrical resistance. The SCA becomes sweat data. Note that the sweat sensor is not limited to one that calculates the SCA, and may be one that calculates the skin potential.

[0095] In addition, for example, in the bio-data measuring system of the above embodiment, an example was given in which one type of bio-sensor for detecting brain waves is used to obtain bio-data, but multiple different types of bio-sensors may be used. In this case, the threshold value used for determining the body movement noise level is appropriately set for each different type of bio-sensor.

[0096] Furthermore, for example, in the above-described embodiment, a three-axis acceleration sensor is used as the reference signal sensor, but a three-axis gyro sensor or a pressure sensor attached to the bioelectrode 5 (hereinafter referred to as the biocontact portion pressure sensor) may also be used. The three-axis gyro sensor detects angular velocity (rotation speed). Even when using a three-axis gyro sensor, the above formulas can be used to calculate the reference signal fluctuation value. In this case, in the formulas, N=3, r1 indicates the X-axis angular velocity, r2 indicates the Y-axis angular velocity, and r3 indicates the Z-axis angular velocity. The biological contact pressure sensor detects the stress applied to the skin of the subject. For example, a force sensor such as a piezoelectric sensor, a strain sensor such as a strain gauge, or a sensor that detects the deformation of a piezoelectric film can be used as the biological contact pressure sensor. Even when a biological contact pressure sensor is used, the above formulas can be used to calculate the reference signal variation value. In this case, in the formulas, N indicates the number of biological contact pressure sensors.

[0097] Also, a configuration may be made in which body movement information is obtained using a plurality of different types of reference signal sensors. For example, two or all three selected from a triaxial acceleration sensor, a triaxial gyro sensor, and a biological contact pressure sensor may be used as reference signal sensors. When a plurality of different types of reference signal sensors are used, reference signal fluctuations are obtained for each of the different types of sensors, and body movement information such as a body movement noise level can be obtained based on the results.

[0098] Also, different types of reference signal sensors may be used for different types of biosensors. For example, in one biodata measurement system, a pulse wave sensor and an electroencephalogram sensor may be used as biosensors, a three-axis acceleration sensor may be used as a reference signal sensor for the electroencephalogram sensor, and a biological contact pressure sensor may be used for the pulse wave sensor.

[0099] When a biological contact pressure sensor is used as a reference signal sensor, the biological contact pressure sensor can be provided in each of a plurality of detection units (corresponding to biological electrodes in the above embodiment) that contact different body parts of the measurement subject to acquire detected biological signals of each body part. This makes it possible to determine the predicted occurrence of body movement noise for each biological sensor, and to issue an instruction to change the offset control threshold value or gain for each biological sensor. In addition, the multiple detection units may correspond to the same type of biosensor, or may correspond to multiple biosensors of different types. For example, in one biodata measurement system, a pulse wave sensor and an electroencephalogram sensor are used as biosensors, the detection unit corresponding to the pulse wave sensor is provided so as to contact the wrist, the detection unit corresponding to the electroencephalogram sensor is provided so as to contact the head, and each detection unit is provided with a biocontact pressure sensor as a reference signal sensor.

[0100] Also, for example, in the above-described embodiment, in the offset / gain control state, an example was given in which either the offset control threshold change or the gain change is performed depending on the body movement noise level, but both the offset control threshold change and the gain change may also be performed. Also, for example, in the offset / gain control state, signal control may be performed in three stages according to the body movement noise level: changing only the offset control threshold, changing only the gain, or changing both the offset control threshold and the gain. Also, for example, in the control state, the gain may be changed to be lowered. In this case, a timer can be provided to adjust the period of the control state, so that the period during which the signal resolution becomes coarse can be adjusted to be shorter. Also, for example, in the control state, the offset control threshold may be narrowed. In this case, the period of the control state can be adjusted by providing a timer, so that the period of increase in power consumption due to an increase in the number of offset controls can be shortened.

[0101] In the above embodiment, the system microcomputer 2 having the system control unit 20 and the body motion noise prediction unit 22 is mounted on the head fixing support 14, but the present invention is not limited to this. For example, the system control unit 20 and the body motion noise prediction unit 22 may be provided in an information processing device separate from the head fixing support 14, such as a cloud server. Also, for example, the sensor control unit 41 and the AFE circuit 48 of the biosensor 4 may be provided in an information processing device or system microcomputer separate from the head fixing support 14, such as a cloud server. Also, the sensor control unit 41, the AFE circuit 48, the system control unit 20, and the body motion noise prediction unit 22 may be provided in an information processing device separate from the head fixing support 14, such as a cloud server.

[0102] The present technology can also be configured as follows. (1) a body movement noise prediction unit that predicts that body movement noise caused by the body movement of the measurement subject will be added to a detected biosignal detected from the measurement subject by a biosensor, based on a reference signal that is body movement information of the measurement subject detected by a reference signal sensor; A control unit that controls signal processing of the detected biological signal based on the prediction result in the body movement noise prediction unit An information processing device comprising: (2) The information processing device according to (1), The control unit changes at least one of an offset control threshold value and a gain used when controlling an offset of the detected biological signal based on the prediction result, and performs signal processing on the detected biological signal. Information processing device. (3) The information processing device according to (1) or (2), The body movement noise prediction unit compares a variation value of the reference signal with a previously prepared threshold value to predict that body movement noise will be added to the detected biological signal. Information processing device. (4) The information processing device according to (3) above, the body movement noise prediction unit determines a body movement noise level from a result of comparing a fluctuation value of the reference signal with a previously prepared threshold value; The control unit changes at least one of the offset control threshold and the gain based on the body movement level. Information processing device. (5) The information processing device according to (3) or (4), The control unit takes a normal state when the fluctuation value of the reference signal is equal to or smaller than the threshold value, and takes a control state in which at least one of the offset control threshold value and the gain is changed to a state different from the normal state when the fluctuation value of the reference signal is greater than the threshold value. Information processing device. (6) The information processing device according to (5) above, The control unit returns the changed offset control threshold value or the changed gain to the normal state after a predetermined time has elapsed since the normal state was changed to the control state. Information processing device. (7) The information processing device according to (5) or (6), The control unit narrows the range of the offset control threshold in the control state compared to the normal state. Information processing device. (8) The information processing device according to any one of (5) to (7), The control unit reduces the gain in the control state below that in the normal state. Information processing device. (9) The information processing device according to any one of (3) to (8), the thresholds include a first threshold and a second threshold greater than the first threshold, The control unit narrows the range of the offset control threshold from a normal state when the fluctuation value of the reference signal is equal to or greater than the first threshold and smaller than the second threshold, and reduces the gain when the fluctuation value of the reference signal is equal to or greater than the second threshold. Information processing device. (10) The information processing device according to any one of (3) to (9), The variation value of the reference signal is calculated using a two-point difference in the time domain of the reference signal. Information processing device. (11) The information processing device according to any one of (1) to (10) above, The reference signal sensor includes at least one of a three-axis acceleration sensor, a three-axis gyro sensor, and a pressure sensor. Information processing device. (12) The information processing device according to (11), the pressure sensor is provided for each of a plurality of detection units that contact a plurality of different body parts of the measurement subject to acquire the detected biological signal; the body movement noise prediction unit predicts that the body movement noise will be added to the detected biological signal for each of the body parts based on the reference signal detected for each of the pressure sensors; The control unit changes at least one of an offset control threshold value and a gain used when controlling an offset of the detected biological signal for each of the body parts based on the prediction result, and performs signal processing on the detected biological signal. Information processing device. (13) The information processing device according to any one of (1) to (12), The biosensor includes at least one of an electroencephalogram sensor, a pulse wave sensor, a blood flow sensor, and a sweat sensor. Information processing device. (14) a reference signal sensor for detecting a reference signal which is body movement information of a subject; A biosensor for detecting a biosignal of the subject; a body movement noise prediction unit that predicts that body movement noise will be added to the detected biological signal based on the reference signal; A control unit that controls signal processing of the detected biological signal based on the prediction result in the body movement noise prediction unit A biological data measuring system comprising: (15) predicting, based on a reference signal that is body movement information of the measurement subject detected by a reference signal sensor, that body movement noise will be added to the detected biosignal detected from the measurement subject by a biosensor; Based on the predicted result, signal processing of the detected biological signal is controlled. Information processing methods. (16) A step of predicting that body movement noise will be added to a detected biosignal detected from the measurement subject by a biosensor, based on a reference signal which is body movement information of the measurement subject detected by a reference signal sensor; Controlling signal processing of the detected biological signal based on the predicted result. A program for causing an information processing device to execute a process including the steps of: [Explanation of symbols]

[0103] 1. Biometric data measurement system 2...System microcomputer (information processing device) 3...3-axis acceleration sensor (reference signal sensor) 4...Sensor (biosensor) 5...Bioelectrode (detection part) 7... Brain wave sensor (biometric sensor) 20...System control unit (control unit) 22…Body movement noise prediction section

Claims

1. a body movement noise prediction unit that compares a fluctuation value of a reference signal, which is body movement information of the subject detected by a reference signal sensor, with a previously prepared threshold value, and predicts that body movement noise caused by the body movement of the subject will be added to a detected biosignal detected from the subject by a biosensor; A control unit that controls signal processing of the detected biological signal by taking a normal state when the fluctuation value of the reference signal is equal to or less than the threshold value, and taking a control state in which at least one of an offset control threshold value and a gain used in controlling the offset of the detected biological signal is changed to be different from the normal state when the fluctuation value of the reference signal is greater than the threshold value. Equipped with The control unit returns the offset control threshold value or the gain that has been changed to the normal state after a predetermined time has elapsed since the normal state was changed to the control state. Information processing device.

2. 2. The information processing device according to claim 1, the body motion noise prediction unit determines a body motion noise level from a comparison result between the fluctuation value of the reference signal and the threshold value; The control unit changes at least one of the offset control threshold and the gain based on the body movement noise level. Information processing device.

3. 2. The information processing device according to claim 1, The control unit narrows the range of the offset control threshold in the control state compared to the normal state. Information processing device.

4. 2. The information processing device according to claim 1, The control unit reduces the gain in the control state below that in the normal state. Information processing device.

5. 2. The information processing device according to claim 1, the thresholds include a first threshold and a second threshold greater than the first threshold, The control unit narrows the range of the offset control threshold from a normal state when the fluctuation value of the reference signal is equal to or greater than the first threshold and smaller than the second threshold, and reduces the gain when the fluctuation value of the reference signal is equal to or greater than the second threshold. Information processing device.

6. 2. The information processing device according to claim 1, The variation value of the reference signal is calculated using a two-point difference in the time domain of the reference signal. Information processing device.

7. 2. The information processing device according to claim 1, The reference signal sensor includes at least one of a three-axis acceleration sensor, a three-axis gyro sensor, and a pressure sensor. Information processing device.

8. The information processing device according to claim 7, the pressure sensor is provided for each of a plurality of detection units that contact a plurality of different body parts of the measurement subject to acquire the detected biological signal; the body movement noise prediction unit predicts that the body movement noise will be added to the detected biological signal for each of the body parts based on the reference signal detected for each of the pressure sensors; The control unit changes at least one of an offset control threshold value and a gain used when controlling an offset of the detected biological signal for each of the body parts based on the prediction result, and performs signal processing on the detected biological signal. Information processing device.

9. 2. The information processing device according to claim 1, The biosensor includes at least one of an electroencephalogram sensor, a pulse wave sensor, a blood flow sensor, and a sweat sensor. Information processing device.

10. a reference signal sensor for detecting a reference signal which is body movement information of a subject; A biosensor for detecting a biosignal of the subject; a body movement noise prediction unit that compares a variation value of the reference signal with a previously prepared threshold value to predict that body movement noise caused by the body movement of the measurement subject will be added to the detected biological signal; A control unit that controls signal processing of the detected biological signal by taking a normal state when the fluctuation value of the reference signal is equal to or less than the threshold value, and taking a control state in which at least one of an offset control threshold value and a gain used in controlling the offset of the detected biological signal is changed to be different from the normal state when the fluctuation value of the reference signal is greater than the threshold value. Equipped with The control unit returns the offset control threshold value or the gain that has been changed to the normal state after a predetermined time has elapsed since the normal state was changed to the control state. Biometric data measurement system.

11. An information processing method executed by an information processing device, comparing a fluctuation value of a reference signal, which is body movement information of the measurement subject detected by the reference signal sensor, with a previously prepared threshold value, to predict whether body movement noise will be added to the detected biosignal detected from the measurement subject by the biosensor; When the fluctuation value of the reference signal is equal to or less than the threshold value, a normal state is taken, and when the fluctuation value of the reference signal is greater than the threshold value, a control state is taken in which at least one of an offset control threshold value and a gain used in controlling an offset of the detected vital sign is changed to be different from the normal state, thereby controlling signal processing of the detected vital sign; After a predetermined time has elapsed since the normal state was changed to the control state, the offset control threshold value or the gain that had been changed is returned to the normal state. Information processing methods.

12. a step of comparing a fluctuation value of a reference signal, which is body movement information of the measurement subject detected by a reference signal sensor, with a previously prepared threshold value, and predicting that body movement noise will be added to a detected biosignal detected from the measurement subject by the biosensor; A step of controlling signal processing of the detected biological signal by taking a normal state when the fluctuation value of the reference signal is equal to or less than the threshold value, and taking a control state in which at least one of an offset control threshold value and a gain used in controlling an offset of the detected biological signal is changed to be different from the normal state when the fluctuation value of the reference signal is greater than the threshold value; returning the offset control threshold value or the gain that has been changed to the normal state after a predetermined time has elapsed since the normal state was changed to the control state. A program for causing an information processing device to execute a process including the steps of:

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