JP4155889B2 - Body motion detection device - Google Patents

Description

  The present invention relates to a body motion detection device provided with acceleration detection means for detecting accelerations in a plurality of axial directions directed in different directions.

  The body motion detection device is used for a pedometer or the like that detects the number of steps during a walking motion of a human body as a subject and calculates calorie consumption based on the number of steps detected. Conventionally, two or three acceleration sensors that detect acceleration in the directions of XY2 axis or XYZ3 axis orthogonal to each other in order to detect body movement with a simple configuration regardless of the posture of the apparatus when mounted on a subject And selecting one of the two or three acceleration sensors having a large vibration waveform amplitude and power, and calculating the output signal of the selected one acceleration sensor. A body motion detection device that detects walking motion (number of steps) and the like has been proposed (see Patent Document 1).

JP 2002-191580 A

In the body motion detection device of the above prior art, when the actual vibration direction is close to the detection direction of one acceleration sensor selected from the XY 2-axis or XYZ 3-axis acceleration sensor, the detection accuracy of the body motion does not decrease so much. When the vibration direction of the axis is close to the intermediate direction of the XY2 axis or the XYZ3 axis, the magnitude of the acceleration component in the unselected axial direction is ignored even though it is relatively large, resulting in a decrease in detection accuracy of body movement There is a disadvantage that becomes larger.
Further, in the above prior art, an acceleration sensor having a structure in which a deformation of a cantilever with a weight attached to the tip is detected by a piezoelectric element is used, so that the sensor size is increased. There is also a disadvantage that the body motion detection device equipped with three or three is increased in size.

  The present invention has been made in view of the above circumstances, and its purpose is body movement that can suppress a decrease in detection accuracy when detecting body movement of a subject while having a simple configuration. It is to provide a detection device.

  In order to achieve the above object, the first characteristic configuration of the body motion detecting device according to the present invention is such that the magnitude of the signal is large for each of the acceleration signal components in the plurality of axial directions detected by the acceleration detecting means. A signal synthesizer that synthesizes one signal by adding a weighting coefficient so as to give a greater weight to the acceleration signal component than a small acceleration signal component, and synthesizes by the signal synthesizer A body motion discriminating means for discriminating the body motion of the subject based on the one signal is provided.

That is, using all of the acceleration signal components in the multi-axis directions detected by the acceleration detection means while wearing the subject, the acceleration signal has a large signal magnitude and a high contribution rate to the actual acceleration signal. While components are added with a large weighting, acceleration signals with a small signal size and a low contribution to the actual acceleration signal are added with a small weighting. The signal component is also subject to addition processing, and the reproducibility of the synthesized single signal with respect to the actual acceleration signal is improved. As a result, a decrease in detection accuracy of body movement based on the synthesized single signal is suppressed.
In addition, the weighting addition process can be realized with a relatively simple arithmetic configuration.
Accordingly, there is provided a body motion detection device that can suppress a decrease in detection accuracy when detecting a body motion of a subject while having a simple configuration.

  In the second characteristic configuration, each of two or more acceleration signal components selected from the acceleration signal components in the plurality of axial directions detected by the acceleration detection means is converted into an acceleration signal component having a large signal magnitude. On the other hand, a signal synthesizing unit that synthesizes one signal by adding a weighting coefficient so that the weight of the signal is larger than that of a small acceleration signal component, and one signal synthesized by the signal synthesizing unit The body motion discriminating means for discriminating the body motion of the subject based on the signal is provided.

  In other words, in the state of being mounted on the subject, the actual acceleration signal is generated by using two or more acceleration signal components selected from the acceleration signal components in the plurality of axial directions detected by the acceleration detecting means and the magnitude of the signal is large. The acceleration signal component with a high contribution rate to the signal is added with a large weight, while the acceleration signal component with a small signal size and a low contribution rate to the actual acceleration signal is added with a small weight. As for the two or more selected acceleration signal components, even an acceleration signal component having a small signal size is subject to addition processing, and the reproducibility of the synthesized single signal with respect to the actual acceleration signal is improved. As a result, a decrease in detection accuracy of body movement based on one synthesized signal is suppressed.

In addition, the weighting addition process can be realized with a relatively simple calculation configuration, and a part of the acceleration signal components in the plurality of axial directions are not selected and are not subject to the addition process. This also simplifies the calculation configuration.
Accordingly, there is provided a body motion detection device that is capable of suppressing a decrease in detection accuracy when detecting a body motion of a subject while being a simpler configuration than the first characteristic configuration.

In the third feature configuration, in addition to the second feature configuration, the signal synthesizing unit excludes the acceleration signal components in the plurality of axial directions from the selection target in order of increasing signal magnitude. In the point.
That is, when two or more acceleration signal components are selected from the acceleration signal components in the plurality of axial directions, the remaining two signals are sequentially excluded from the acceleration signal components having the smallest signal magnitude among the acceleration signal components in the plurality of axial directions. Since the above acceleration signal components are selected, the acceleration signal component having the larger signal size is preferentially subjected to the addition process, and the reproducibility of the single signal synthesized by the addition process with respect to the actual acceleration signal is reduced. Can be suppressed.
Therefore, a preferred embodiment for implementing the body motion detection device having the second characteristic configuration is provided.

  The fourth characteristic configuration is that each of at least two acceleration signal components having a signal magnitude exceeding a predetermined threshold value among the acceleration signal components in the plurality of axial directions detected by the acceleration detecting means. A signal synthesizer that synthesizes one signal by adding a weighting coefficient so as to give a greater weight to an acceleration signal component having a larger signal magnitude than an acceleration signal component having a smaller signal magnitude; The body motion discriminating means for discriminating the body motion of the subject based on one signal synthesized by the signal synthesizing means is provided.

  That is, among the acceleration signal components detected by the acceleration detection means in the state of being mounted on the subject, the acceleration signal components whose signal magnitude does not exceed a predetermined threshold value are subject to addition processing. On the other hand, using at least two or more acceleration signal components whose signal magnitude exceeds a predetermined threshold, a large weight is given to an acceleration signal component having a large signal magnitude and a high contribution rate to the actual acceleration signal. Accelerating signal components with small signal magnitude and low contribution rate to the actual acceleration signal are added with a small weighting. As for the component, the acceleration signal component having a small signal size is also subject to addition processing, and the reproducibility of the synthesized single signal with respect to the actual acceleration signal is improved. As a result, reduction in the detection accuracy of the motion based on the synthesized one signal is suppressed.

As described above, since acceleration signal components whose signal magnitude exceeds a predetermined threshold value are always subject to addition processing, a decrease in accuracy in addition processing can be suppressed, while the signal magnitude is predetermined threshold value. Acceleration signal components that do not exceed 1 are not subject to addition processing, so that the calculation configuration may be simplified, and the weighted addition processing may be realized with a relatively simple calculation configuration. .
Therefore, there is provided a body motion detection device that has a possibility of being able to be made a simpler configuration than the first characteristic configuration and can suppress a decrease in detection accuracy when detecting a body motion of a subject. The

  In the fifth feature configuration, in addition to any of the first to fourth feature configurations, the signal synthesizing unit performs sampling for each sampling data obtained by sampling the detection information of the acceleration detection unit at a predetermined time interval. The point is to determine the magnitude of the signal for the acceleration signal component in each axial direction.

That is, in the first to fourth feature configurations, the weighting coefficient to be added to the acceleration signal component in each axis direction is determined based on the magnitude of the signal of the acceleration signal component in the plurality of axis directions determined for each sampling data. The addition process is performed for each sampling data.
At this time, as in the third feature configuration, the acceleration signal component to be excluded from the selection target may be determined based on the magnitude of the signal of the acceleration signal component in the plurality of axial directions determined for each sampling data. Then, as in the fourth feature configuration, based on the magnitude of the acceleration signal component in the multi-axis direction determined for each sampling data, whether or not the acceleration signal component in the multi-axis direction has exceeded a predetermined threshold value. Only the acceleration signal component that is determined and exceeds the threshold may be used.

  Therefore, since processing for storing sampling data is not performed and signal processing is performed by sequentially performing processing for each sampling data, processing performance such as storage and calculation is not so large as an arithmetic element constituting the signal combining means. A preferred embodiment of an inexpensive and practical body motion detection device that can use a microcomputer or the like is provided.

  In the sixth feature configuration, in addition to any one of the first to fourth feature configurations, the signal synthesis unit stores sampling data obtained by sampling detection information of the acceleration detection unit at a predetermined time interval. A vibration waveform is generated, and the magnitude of the signal of the acceleration signal component in each axial direction is determined based on the amplitude of the vibration waveform.

That is, in the first to fourth characteristic configurations, the acceleration signal in each axial direction is based on the magnitude of the acceleration signal component in each axial direction determined from the amplitude of the vibration waveform generated by accumulating the sampling data. The addition processing is performed by determining a weighting coefficient to be added to the component.
At this time, as in the third feature configuration, the acceleration signal component to be excluded from the selection target may be determined based on the magnitude of the signal of the acceleration signal component in each axis direction determined from the amplitude of the vibration waveform. In addition, as in the fourth feature configuration, whether or not the acceleration signal component in the plurality of axial directions has exceeded a predetermined threshold based on the magnitude of the acceleration signal component in each axial direction determined from the amplitude of the vibration waveform. It is also possible to use only the acceleration signal component exceeding the threshold.

  Therefore, when a microcomputer with sufficient processing performance such as storage and calculation can be used as the calculation element constituting the signal synthesis means, the signal of the acceleration signal component in each axis direction based on the amplitude of the vibration waveform over a predetermined period A preferred embodiment of a practical body motion detection device capable of determining the size of the body stably and accurately is provided.

  In the seventh feature configuration, in addition to any one of the first to sixth feature configurations, the signal synthesizing unit is configured such that the signal change direction and the magnitude of the signal in an acceleration signal component having a small signal magnitude are provided. When the direction of change of the signal in the acceleration signal component having a large value is the same direction, the sign of the weighting coefficient added to the acceleration signal component having a small signal magnitude is attached to the acceleration signal component having a large signal magnitude. When the sign of the weighting coefficient is the same sign, and the direction of signal change in the acceleration signal component with a small signal magnitude and the direction of signal change in the acceleration signal component with a large magnitude of the signal are opposite directions, The sign of the weighting coefficient attached to the acceleration signal component having a small signal magnitude is the sign of the weighting coefficient attached to the acceleration signal component having a large signal magnitude. It lies in the opposite sign.

That is, when the direction of change of the signal of the acceleration signal component with a small signal magnitude and the direction of change of the signal of the acceleration signal component with a large magnitude of the signal are the same direction, the weighting coefficients attached to both acceleration signal components are set. Even with the same sign, both acceleration signal components do not cancel each other by the addition process, and the reproducibility of the synthesized signal with respect to the original acceleration signal is ensured. On the other hand, when the direction of change of the signal of the acceleration signal component with a small signal magnitude is opposite to the direction of change of the signal of the acceleration signal component with a large magnitude of the signal, the same weighting coefficient is assigned to both acceleration signal components. If the code is used, both acceleration signal components cancel each other out due to the addition process, and the reproducibility of the synthesized signal with respect to the original acceleration signal is deteriorated. If the sign opposite to the weighting coefficient attached to the acceleration signal component having a large magnitude is used, both acceleration signal components are not canceled out by the addition process, and the reproducibility of the synthesized signal with respect to the original acceleration signal is improved.
Therefore, a preferred embodiment of a body motion detection device that can further suppress a decrease in detection accuracy is provided based on a synthesized signal that is highly reproducible with respect to the original acceleration signal.

In the eighth feature configuration, in addition to any of the first to sixth feature configurations, the signal synthesis unit adds the weighting coefficient to the absolute value of the acceleration signal component in each axial direction. The addition process is performed.
That is, regardless of the direction of change of the signal in the acceleration signal component in each axis direction, the above weighting coefficient is added to the absolute value of the acceleration signal component in each axis direction to add and synthesize one signal. In this case, since the actual acceleration signal is reproduced for at least the magnitude of the synthesized signal, the body movement can be determined based on the synthesized one signal. However, for example, when an acceleration signal is added as a simple vibration waveform, the signal synthesized by the above addition process has twice the number of waves as compared to the original acceleration signal waveform, so the body motion is determined based on the synthesized signal. For example, the determination of the number of steps requires processing such as setting the number of steps to ½ of the actual count value.
Therefore, a configuration for determining the direction of signal change in acceleration signal components in a plurality of axial directions is not necessary, and a preferred embodiment of a body motion detection device that simplifies the calculation configuration for signal synthesis is provided.

In the ninth feature configuration, in addition to any one of the first to sixth feature configurations, the signal synthesis unit adds the weighting coefficient to a value obtained by squaring the acceleration signal component in each axial direction. Thus, the addition process is performed.
That is, the above-mentioned weighting coefficient is added to a value obtained by squaring the acceleration signal component in each axis direction, and addition processing is performed to synthesize one signal. In this case, since the magnitude of the original acceleration signal is amplified by the square operation in the synthesized signal, the body movement can be determined more easily based on this synthesized signal. In this case as well, as in the eighth feature configuration, the composite signal has twice the number of waves as compared to the original acceleration signal. Etc. are required.
Accordingly, it is not necessary to determine the direction of change in the acceleration signal component in each axis direction by square calculation, simplifying the calculation configuration, and easily determining body movement based on the synthesized signal amplified by square calculation. A preferred embodiment of a body motion detection device that can be performed is provided.

In the tenth feature configuration, in addition to the ninth feature configuration, the signal synthesizing unit adds the signal magnitude of the acceleration signal component in each axial direction to the one signal obtained by the addition process. This is because a sign corresponding to the direction of change of the signal in the acceleration signal component having a large value is attached.
That is, the sign of the composite signal obtained by adding the square value of the acceleration signal component in each axis direction is the direction in which the signal changes in the acceleration signal component having a larger signal size among the acceleration signal components in each axis direction. Therefore, the combined signal reflects information on the direction of signal change in the original acceleration signal. For example, when a simple vibration acceleration signal is added, the simple vibration waveform of the original acceleration signal is reproduced in the composite signal.
Therefore, a suitable body motion detection device that can easily and appropriately perform body motion discrimination based on a synthesized signal that reproduces the direction of signal change in the original acceleration signal as much as possible and is amplified by a square operation. Embodiments are provided.

In the eleventh feature configuration, in addition to any one of the first to tenth feature configurations described above, the signal synthesizing means may include two signals for at least three acceleration signal components in each axial direction. The addition processing for adding the two is repeated stepwise to synthesize the one signal.
That is, when synthesizing at least three or more acceleration signal components in the respective axial directions, the addition processing using the two acceleration signal components in the two axial directions as two signals, or an intermediate synthesized signal obtained by this addition processing and One signal is synthesized by stepwise repeating the addition process using the other one acceleration signal component in the axial direction as two signals and the addition process using the two intermediate combined signals as two signals.
Accordingly, by repeating the same addition process for two signals, one signal can be synthesized from at least three acceleration signal components in the respective axial directions, so that the calculation configuration for signal synthesis is simplified. A preferred embodiment of a motion detection device is provided.

  In the twelfth feature configuration, in addition to any one of the first to eleventh feature configurations, the signal synthesizing unit adds the acceleration signal components in the biaxial directions orthogonal to each other. The ratio of the weighting coefficient attached to the acceleration signal component having a large signal magnitude and the weighting coefficient attached to the acceleration signal component having a small signal magnitude is set to a value of 1: 0.4 or the vicinity thereof. is there.

That is, when the actual acceleration direction coincides with one of the orthogonal biaxial directions by adding the weighting coefficients having the above values and adding the acceleration signal components in the biaxial directions orthogonal to each other. In addition, when the actual acceleration direction is located in the middle direction between the two orthogonal axes, that is, when the angles formed with respect to the two orthogonal axes are close to 45 degrees, the obtained synthesized signal is the original acceleration. Since the signal is reproduced well, the approximate accuracy of the synthesized signal with respect to the original acceleration signal is balanced and high in the entire angle (0 to 90 degrees) that the actual acceleration direction forms with respect to the two axes. Can be maintained.
Therefore, a preferred embodiment of the body motion detection device that specifically identifies the weighting coefficient for satisfactorily reproducing the original acceleration signal by the addition process from the acceleration signal components in the biaxial directions orthogonal to each other is provided.

  The thirteenth feature configuration is that, in addition to any one of the first to twelfth feature configurations, the acceleration detecting means is provided on any one of a reference side electrode and a vibration side electrode arranged to face each other. A plurality of electrostatic acceleration sensors, each of which includes an electret member that detects a change in electrostatic capacitance between the electrodes due to displacement of the vibration side electrode as an acceleration signal. , Respectively, to detect accelerations in the directions of the plurality of axes.

That is, when acceleration in the plurality of axial directions is applied, the vibration side electrode provided in each electrostatic acceleration sensor is displaced according to the acceleration in each axial direction, and the capacitance between the reference side electrode and the vibration side electrode is increased. The accelerations in the plurality of axial directions are detected by the change in capacitance between the electrodes of the plurality of electrostatic acceleration sensors.
Accordingly, since the acceleration detecting means is constituted by a simple structure of an electrostatic acceleration sensor in which a pair of electrodes are arranged to face each other, a preferred embodiment of a body motion detecting device capable of downsizing the device is provided. .

In the fourteenth feature configuration, in addition to any one of the first to thirteenth feature configurations described above, the body movement determination means may include a step count or exercise intensity associated with a walking motion of the human body as the subject, or The point is to determine the calorie consumption calculated from these.
That is, when a person walks while holding or wearing a body motion detection device or a device equipped with a body motion detection device, acceleration is applied to the body motion detection device due to vibrations in the front, back, left, and right, up and down of the human body accompanying walking, The number of steps or exercise intensity, or the calorie consumption calculated from the number of steps or exercise intensity is determined by the body movement determination means.
Therefore, in order to obtain body movement information associated with the walking motion of the human body, based on the detection of the number of steps or exercise intensity, the step count accumulation or exercise intensity accumulation, the product of the exercise intensity of a section and the number of steps of that section A preferred embodiment of a body motion detection device capable of performing integration and calculation of calorie consumption, that is, energy consumption calculated from these, is provided.

An embodiment of a body motion detection device according to the present invention will be described taking an example of application to a pedometer.
As shown in FIG. 1, the body motion detection device of the present invention includes an acceleration detection unit 100 that detects accelerations in a plurality of directions directed in different directions, and the plurality of axes detected by the acceleration detection unit 100. For each acceleration signal component in the direction, a weighting coefficient is added to an acceleration signal component having a large signal magnitude so as to be weighted more than an acceleration signal component having a small signal magnitude, and one acceleration signal component is added. A signal synthesizing unit 200 for synthesizing signals and a body movement determining unit 300 for determining the body movement of the subject based on one signal synthesized by the signal synthesizing unit 200 are provided.

  As shown in FIG. 2, the acceleration detecting means 100 detects the acceleration in the XYZ triaxial directions orthogonal to each other, the acceleration sensor 1A in the X axis direction, the acceleration sensor 1B in the Y axis direction, and the acceleration sensor in the Z axis direction. 1C is installed on the circuit board 9. Although a specific structural example is shown in FIG. 3, the acceleration detecting means 100 forms an electret member on either one of the reference side electrode 20 and the vibration side electrode 21 that are arranged to face each other, and the vibration side electrode 21. A plurality of (three) electrostatic acceleration sensors (also referred to as electret condenser acceleration sensors) 1A, 1B, and 1C for detecting changes in capacitance between the electrodes 20 and 21 due to the displacement as acceleration signals, A plurality of electrostatic acceleration sensors 1A, 1B, and 1C respectively detect accelerations in a plurality of axial directions (XYZ axial directions). The electrostatic acceleration sensors 1A, 1B, and 1C are arranged so that the XY-axis direction is set along the surface of the circuit board 9 and the direction orthogonal to the surface of the circuit board 9 is the Z-axis direction. Yes.

  The structure of the electrostatic acceleration sensors 1A, 1B, and 1C will be described. In one of the three electrostatic acceleration sensors 1A, 1B, and 1C, the reference-side electrode 20 is an acoustic vibration film, and vibrations are generated. The side electrode 21 is a vibrating membrane for oscillation. Then, electret members are respectively formed on the mutually facing surfaces of the acoustic vibration film 20 and the swing vibration film 21, and the acoustic vibration film 20 and the swing vibration film 21 function as electrodes. In the remaining two electrostatic acceleration sensors, the reference-side electrode 20 is a fixed electrode that does not vibrate, and an electret member is formed only on the surface of the oscillation film 21 for oscillation.

  The acoustic diaphragm 20 is mounted on the sound hole 22 side of a cylindrical housing 23 having a sound hole 22 while being sandwiched between an acoustic diaphragm ring 24 and a spacer 25. It is mounted in a state of being sandwiched between a swinging vibration film ring 27 supported by the swinging vibration film holder 26 and the spacer 25. Further, a weight 28 for adjusting the natural frequency is attached to the surface of the vibrating membrane 21 on the opposite side of the surface facing the acoustic vibrating membrane 20. Further, the oscillation film 21 for oscillation and the substrate 29 are connected via an oscillation film ring 27 for oscillation and a gate ring 30, and between the oscillation film 20 for oscillation and the oscillation film 21 for oscillation detected by the oscillation film 21 for oscillation. Is transferred as a voltage signal to the FET 31 provided on the substrate 29.

  Accordingly, in one electrostatic acceleration sensor 1A, 1B, 1C in which the reference-side electrode 20 is an acoustic vibration film, the capacitor portion is constituted by the acoustic vibration film 20 and the swing vibration film 21 in which electret members are formed. When the sound enters the housing 23 from the sound hole 22, the acoustic vibration membrane 20 vibrates in response to the acoustic signal, but the weight 28 responds to vibration having a frequency lower than the acoustic frequency. The vibrating membrane 21 for swinging adjusted as above functions as a fixed electrode without vibrating. As a result, the change in the electrostatic capacitance in the capacitor portion due to the vibration of only the acoustic vibration film 20 is output as a voltage signal. On the other hand, when acceleration of a frequency lower than the acoustic frequency is applied to the three electrostatic acceleration sensors 1A, 1B, and 1C, the oscillation diaphragm 21 is displaced in response to the acceleration. 20 acts as a fixed electrode without being displaced. As a result, the change in the electrostatic capacity in the capacitor portion accompanying the displacement of only the vibrating membrane 21 for oscillation is output as a voltage signal.

  The output signals of the electrostatic acceleration sensors 1A, 1B, and 1C are amplified by the amplifier 2 and then input to the microcomputer 10, converted into a digital signal by the AD conversion unit 3 in the microcomputer 10, and input to the arithmetic unit 4. . In addition, the calculating part 4 is specifically comprised by CPU, memory, etc. The signal synthesizing unit 200 and the body movement determining unit 300 are configured by the arithmetic unit 4. Here, the signal synthesizing means 200 samples the output signals of the acceleration detecting means 100 (respective electrostatic acceleration sensors 1A, 1B, 1C) at predetermined time intervals, and obtains detection data of each acceleration in the XYZ triaxial directions. It has gained. Furthermore, the microcomputer 10 is connected with an information input key 5, an information display 6, and a speaker 7 for sound output.

Next, with regard to the synthesizing process by the signal synthesizing means 200, first, a case of synthesizing acceleration signal components in the XY biaxial directions will be described.
As shown in FIG. 4, a state in which the surface of the substrate 9 is along the vertical direction and the acceleration detection direction (X-axis direction) of the acceleration sensor 1A is directed in the vertical direction is taken as a reference state. The acceleration signal component Vx in the X-axis direction and the acceleration signal component Vy in the Y-axis direction when the acceleration V of simple vibration (Sin waveform) is applied in the vertical direction in the state of each rotation angle α by rotating the angle α clockwise. Asked. In FIG. 4, since the acceleration signal component Vz in the Z-axis direction is not detected, the illustration of the acceleration sensor 1C in the Z-axis direction is omitted.

  5 to 8, the rotation angle α from the reference state of the substrate 9 is 0 degree, 30 degrees, 45 degrees, 60 degrees, 90 degrees, 120 degrees, 135 degrees, 150 degrees, 180 degrees, 210 degrees, 240 degrees. The acceleration signal component Vx in the X-axis direction and the acceleration signal in the Y-axis direction when acceleration for one cycle is applied at a low frequency of about 2 Hz with angles set to 270 degrees, 270 degrees, 300 degrees, and 330 degrees The concrete waveform of component Vy is shown.

  As can be seen from the acceleration waveform, when the rotation angle α is in the range of 0 ° to 90 ° and in the range of 180 ° to 270 °, the change direction of the signal is the same in the acceleration signal components Vx and Vy in both XY directions. However, when the rotation angle α is an angle range of 90 ° to 180 ° and an angle range of 270 ° to 360 °, the change direction of the signal is opposite in the acceleration signal components Vx and Vy in both XY directions. Here, the change direction of the signals of the acceleration signal components Vx and Vy is determined based on whether the detected acceleration value is a positive value (acceleration in the positive direction) or a negative value (acceleration in the negative direction) with reference to the zero point.

  Therefore, the signal synthesizing means 200 is used when the direction of signal change in the acceleration signal components Vx and Vy having a small signal magnitude is the same as the direction of signal change in the acceleration signal components Vx and Vy having a large signal magnitude. The sign of the weighting coefficient added to the acceleration signal components Vx and Vy having a small signal magnitude is the same as the sign of the weighting coefficient attached to the acceleration signal components Vx and Vy having a large signal magnitude. Specifically, both the weighting coefficients of both acceleration signal components Vx and Vy are given a positive sign. On the other hand, the signal synthesizing means 200 is used when the direction of signal change in the acceleration signal components Vx and Vy having a small signal magnitude and the direction of signal change in the acceleration signal components Vx and Vy having a large signal magnitude are opposite. The sign of the weighting coefficient attached to the acceleration signal components Vx and Vy having a small signal magnitude is opposite to the sign of the weighting coefficient attached to the acceleration signal components Vx and Vy having a large signal magnitude. Specifically, a positive sign is assigned to the weighting coefficients of the acceleration signal components Vx and Vy having a large signal magnitude, and a negative sign is assigned to the weighting coefficients of the acceleration signal components Vx and Vy having a small signal magnitude.

  The signal synthesizing unit 200 determines the magnitude of the signal for the acceleration signal components Vx and Vy in the respective axial directions for each sampling data obtained by sampling the detection information of the acceleration detecting unit 100 at a predetermined time interval. That is, the magnitude of each acceleration signal component Vx, Vy is determined by the magnitude of the absolute value of the sampling data of the acceleration detection signal of each electrostatic acceleration sensor 1A, 1B, 1C.

  Further, when the signal synthesis means 200 adds the acceleration signal components in the biaxial directions orthogonal to each other (in this case, the acceleration signal component Vx in the X axis direction and the acceleration signal component Vy in the Y axis direction), The ratio of the weighting coefficient attached to the acceleration signal component having a large magnitude and the weighting coefficient attached to the acceleration signal component having the small signal magnitude is set to a value of 1: 0.4 or the vicinity thereof. That is, as a result of various examinations on specific numerical values of the weighting coefficient, by setting the coefficient ratio (a value of 1: 0.4 or a value close thereto), the synthesized acceleration signal Vxy is converted into the original acceleration signal (single vibration). ) Was reproducible with good approximation accuracy.

  FIG. 9 summarizes the numerical values of the weighting coefficients and the result of the encoding, and adds the acceleration signal component Vx in the X-axis direction and the acceleration signal component Vy in the Y-axis direction to correspond to the acceleration in the XY plane. An addition formula in the case of synthesizing one signal Vxy is shown. In FIG. 9, the weighting coefficient of the acceleration signal component having a large signal magnitude is set to 1, and the weighting coefficient of the acceleration signal component having a small signal magnitude is set to 0.41.

  FIG. 10 shows an example of two cases where the rotation angle α is 30 degrees and 150 degrees, and when an acceleration V of simple vibration having an amplitude of 1 is applied in the vertical direction, acceleration signal components Vx and Y in the X-axis direction are applied. It shows that one signal Vxy corresponding to the original acceleration V can be synthesized from the acceleration signal component Vy in the axial direction by the above addition formula. Note that the acceleration application conditions are the same in the acceleration synthesized signal described below.

  Next, a simple synthesis of the one signal Vxy will be described. That is, for example, in an application where it is desired to simply reproduce only the absolute value of the acceleration signal, the signal synthesizing means 200 is configured so that the acceleration signal components Vx, It is also possible to perform the addition process by attaching the weighting coefficient to the absolute value of Vy. FIG. 11 shows a combined signal Vxy when the above addition equation (Equation 1) is used for two cases where the rotation angle α is 30 degrees and 150 degrees. In this addition formula, the change direction (sign) of the signal in the acceleration signal components Vx and Vy is ignored, and a weighting coefficient with a positive sign is added to the absolute value of the acceleration signal components Vx and Vy in each axis direction and added. Therefore, the acceleration signal, which is originally a negative value, is a positive value. That is, it is a composite waveform in which a negative acceleration signal is folded back to the positive side with zero as a reference.

(Equation 1)
Vxy = | Vx | + 0.41 × | Vy | (when | Vx | ≧ | Vy |)
Vxy = 0.41 × | Vx | + | Vy | (when | Vx | ≦ | Vy |)

  Next, as for the synthesizing process by the signal synthesizing means 200, the case of synthesizing acceleration signal components Vx, Vy, Vz in the XYZ triaxial directions will be described. In this case, the signal synthesizing unit 200 repeats the addition process of adding two signals to at least three acceleration signal components Vx, Vy, and Vz in each axial direction in a stepwise manner to generate one signal Vxyz. Synthesize.

  Specifically, the intermediate signal Vxy is synthesized by performing the addition processing (see FIG. 9) on the acceleration signal components Vx and Vy in the XY2 axis direction of the XYZ3 axis directions, and then the intermediate synthesized signal Vxy. The above addition processing (see FIG. 9) is performed on the acceleration signal component Vz in the Z-axis direction among the three-axis directions of XYZ and one signal Vxyz is synthesized. That is, in this specific example, regardless of the magnitudes of the acceleration signal components Vx, Vy, and Vz in the directions of the respective axes, the two axes to be initially added are determined in advance as the X axis and the Y axis, so that the remaining Z axes The second addition process is always executed.

  In addition, when performing the addition process stepwise as described above, the biaxial acceleration signal component to be added first is not the X axis and the Y axis, but the Y axis and the Z axis, or the X axis and the Z axis. You may decide. Further, in order to avoid a decrease in signal synthesis accuracy, the first and second biaxial acceleration signal components are selected in order of magnitude from the acceleration signal components Vx, Vy, and Vz in the directions of the respective axes, and the biaxial acceleration signals are selected. It is also possible to perform addition processing first for the components.

A specific example of the synthesis of the XYZ triaxial acceleration signal components Vx, Vy, and Vz will be described below.
First, as shown in FIG. 12A, the composite signal Vxyz in the reference state in which the surface of the substrate 9 is along the vertical direction and the acceleration detection direction (X-axis direction) of the acceleration sensor 1A is vertical is obtained. . FIG. 12B shows that the intermediate signal Vxy is synthesized by the addition processing of the acceleration signal component Vx in the X-axis direction and the acceleration signal component Vy in the Y-axis direction. FIG. 12C shows that the final signal Vxyz is synthesized by the addition process of the intermediate signal Vxy and the acceleration signal component Vz in the Z-axis direction. In this example, the acceleration signal component Vy in the Y-axis direction and the acceleration signal component Vz in the Z-axis direction are both 0, and only the acceleration signal component Vx in the X-axis direction is not 0. Although not shown in the figure, in the state rotated by 90 degrees around the Z axis from the reference state (α = 90 degrees), only the acceleration signal component Vy in the Y axis direction is not 0, but the intermediate signal Vxy is different. And the final signal Vxyz are synthesized with the same signal.

  Next, as shown in FIG. 13A, the substrate 9 is rotated 30 degrees around the Z axis (α = 30 degrees) from the above-mentioned reference state, and subsequently, parallel to the XY plane, as shown in (B). The synthesized signal Vxyz in a state rotated by 30 degrees (β = 30 degrees) when viewed from a different direction was obtained. In FIG. 14 (a), the acceleration signal component Vx in the X-axis direction and the acceleration signal component Vy in the Y-axis direction are subjected to addition processing by the addition formula of the following formula (the first formula of Formula 2) to synthesize an intermediate signal Vxy. FIG. 14 (b) shows that the intermediate signal Vxy and the acceleration signal component Vz in the Z-axis direction are added by the addition formula of the following formula (the second formula of Formula 2), and the final signal Vxyz is synthesized. Indicates that

(Equation 2)
Vxy = Vx + 0.41 × Vy (since Vx and Vy have the same sign and | Vx |> | Vy |)
Vxyz = Vxy−0.41 × Vz (since Vxy and Vz are different signs and | Vxy |> | Vz |)

  Incidentally, with respect to the single-vibration acceleration signal V of amplitude 1 acting in the vertical direction in the state of FIG. 13B, the calculated value of the amplitude of the acceleration signal component in each axis direction is the acceleration signal component Vx in the X-axis direction. 1 × cos (30 degrees) × cos (30 degrees) = 3/4 = 0.75, and the acceleration signal component Vy in the Y-axis direction is 1 × cos (30 degrees) × cos (60 degrees). ) = (Square root of 3) /4=0.43, and the acceleration signal component Vz in the Z-axis direction is 1 × cos (60 degrees) = 1/2 = 0.5.

  Next, although the values of the rotation angles α and β are different from those in FIG. 13, the substrate 9 is rotated 45 degrees around the Z-axis from the reference state by the same operation (α = 45 degrees), and then XY A composite signal Vxyz was obtained in a state rotated by 45 degrees (β = 45 degrees) when viewed from a direction parallel to the plane. In FIG. 15 (a), the acceleration signal component Vx in the X-axis direction and the acceleration signal component Vy in the Y-axis direction are subjected to addition processing by the addition formula of the following formula (the first formula of Formula 3) to synthesize an intermediate signal Vxy. FIG. 15 (b) shows that the intermediate signal Vxy and the acceleration signal component Vz in the Z-axis direction are added by the addition formula of the following formula (the second formula of Formula 3), and the final signal Vxyz is synthesized. Indicates that

(Equation 3)
Vxy = Vx + 0.41 × Vy (since Vx and Vy have the same sign and | Vx | = | Vy |)
Vxyz = Vxy−0.41 × Vz (since Vxy and Vz are different signs and | Vxy | = | Vz |)

  Incidentally, in this case, with respect to the acceleration signal V of a single vibration having an amplitude of 1 acting in the vertical direction, the calculated value of the amplitude signal component in each axis direction is the acceleration signal component Vx in the X axis direction and the Y axis direction acceleration signal component Vx. For the acceleration signal component Vy, 1 × cos (45 degrees) × cos (45 degrees) = 1/2 = 0.5, and for the acceleration signal component Vz in the Z-axis direction, 1 × cos (45 degrees) = 1 / (square root of 2) = 0.70.

  Next, the determination of the body movement of the subject by the body movement determination unit 300 will be described. The body movement determination unit 300 determines the number of steps associated with the walking motion of the human body as the subject. Specifically, when the step counting mode is set by the information input key 5, it is determined whether one signal Vxy or Vxyz synthesized by the signal synthesizing means 200 exceeds a predetermined threshold value, and the synthesized signals Vxy, Vxyz are determined. Each time exceeds a predetermined threshold, it is counted as one step. In the case of the simple synthesis shown in Equation 1, since the change in waveform is twice that of the original waveform, for example, every time the synthesized signals Vxy and Vxyz exceed a predetermined threshold twice, one step is counted. .

  In the determination of the number of steps, if the combined signals Vxy and Vxyz exceed the predetermined threshold for too long, it is determined that the vehicle is on a vehicle such as an elevator, and conversely, the combined signals Vxy and Vxyz are If the time exceeding the predetermined threshold is too short, it is determined that the player is exercising vigorously, for example, running, so that it is possible to determine that both are not walking.

  Further, the calorie consumption is calculated by multiplying the number of steps by a predetermined walking motion coefficient. The walking motion coefficient differs depending on the physique of the person. It is also possible to set an arbitrary value. Alternatively, it is also possible to obtain the exercise intensity directly from the maximum value in a certain section of the combined one signal Vxy, Vxyz, and calculate the calorie consumption by multiplying this by the number of steps in that section. Then, these step count value, calorie consumption, etc. are displayed on the screen of the display 6 to inform the user.

  In the pedometer, when the sound recording mode is set by the information input key 5, the electrostatic sensors 1A, 1B, 1C having an acoustic detection function among the electrostatic sensors 1A, 1B, 1C are externally connected. Sound is detected, and the sound signal can be recorded in a storage unit such as a memory of the microcomputer 10. And the sound recorded with the speaker 7 can also be reproduced | regenerated as needed.

[Another embodiment]
In the above embodiment, the acceleration detection unit 100 is configured to detect accelerations in a plurality of axial directions orthogonal to each other. However, the acceleration detection unit 100 is not configured to detect the accelerations in a plurality of axial directions directed in different directions. I just need it. If necessary, the multi-axis direction for detecting the acceleration may be a biaxial direction (for example, an XY axis direction) or a direction of four or more axes instead of the triaxial direction (XYZ axis direction).

  In the above embodiment, the acceleration detecting means 100 is constituted by the electrostatic acceleration sensors 1A, 1B, and 1C which are electret condenser type acceleration sensors. However, the acceleration detecting means 100 may be constituted by other types of acceleration detection sensors.

  In the above embodiment, when the signal synthesizing unit 200 determines the magnitudes of the acceleration signal components Vx, Vy, and Vz in the respective axial directions, the detection information of the acceleration detecting unit 100 is sampled at predetermined time intervals. In addition to this, the sampling data obtained by sampling the detection information of the acceleration detecting means 100 at a predetermined time interval is accumulated to generate a vibration waveform, and the direction of each axis is determined by the amplitude of the vibration waveform. It is also possible to determine the magnitude of the signal for the acceleration signal components Vx, Vy, and Vz. For example, when the rotation angle α is 30 degrees in the acceleration signal components Vx and Vy in the biaxial direction (see FIG. 5), the amplitude of the vibration waveform of the acceleration signal component Vx in the X axis direction is the acceleration in the Y axis direction. Since the amplitude of the vibration waveform of the signal component Vy is larger, the acceleration signal component Vx in the X-axis direction corresponds to an acceleration signal component having a larger signal magnitude, and the acceleration signal component Vy in the Y-axis direction has a smaller signal magnitude. Corresponds to the acceleration signal component.

  It should be noted that the signal synthesizing unit 200 has a configuration other than the above, for example, the acceleration signal component Vx in each axis direction by the power of the acceleration signal components Vx, Vy, Vz in each axis direction (average value of the square of the signal). , Vy, and Vz, it is also possible to determine the signal magnitude.

  Further, when the signal synthesis means 200 adds the acceleration signal components Vx, Vy, and Vz in the XYZ triaxial directions, for example, in order of the magnitude of each of the triaxial acceleration signal components Vx, Vy, and Vz. It is also possible to obtain a single signal Vxyz by adding weighting coefficients that are sequentially reduced and combining the three-axis acceleration signal components Vx, Vy, and Vz by one addition process.

  In the above-described embodiment, the signal synthesis unit 200 adds all the acceleration signal components Vx, Vy, and Vz in the multi-axis directions (XYZ 3-axis directions) as an object of addition processing. An acceleration signal component may be selected for addition processing. That is, in the body motion detection device of this another embodiment, two or more accelerations selected from the acceleration signal components in the plurality of axial directions detected by the acceleration detection means 100 instead of the signal synthesis means 200 are used. For each of the signal components, a weighting coefficient is added to an acceleration signal component having a large signal magnitude so as to give a greater weight than an acceleration signal component having a small signal magnitude, and a single signal is synthesized. A signal synthesis means 200A is provided.

  Specifically, the signal synthesizing unit 200A excludes the acceleration signal components in the directions of the plurality of axes from the selection targets in order of increasing signal magnitude. Therefore, for example, from the acceleration signal components Vx, Vy, and Vz in the XYZ three-axis directions, the acceleration signal component having the smallest signal magnitude is excluded, and addition processing is performed on the remaining two acceleration signal components. The arithmetic processing is simplified by synthesizing the signals.

  Furthermore, as another embodiment of the signal synthesizing means 200, only the acceleration signal component whose signal magnitude exceeds a predetermined threshold in the acceleration signal components in a plurality of axial directions may be added. That is, in the body motion detection device according to this another embodiment, the magnitude of the signal among the acceleration signal components in the plurality of axial directions detected by the acceleration detection means 100 instead of the signal synthesis means 200 is large. For each of at least two or more acceleration signal components exceeding a predetermined threshold, a weighting coefficient is assigned so that the acceleration signal component having a large signal magnitude has a greater weight than the acceleration signal component having a small signal magnitude. Thus, signal combining means 200B for combining the signals by addition processing is provided.

  Specifically, the signal synthesizing unit 200B, for example, determines the acceleration signal component Vx in the XYZ triaxial direction if the magnitudes of the acceleration signal components Vx, Vy, Vz in the XYZ triaxial direction all exceed a predetermined threshold. , Vy, and Vz are all subject to addition processing, but the magnitudes of some of the acceleration signal components in the XYZ triaxial directions of the acceleration signal components Vx, Vy, and Vz must exceed a predetermined threshold. For example, only the remaining acceleration signal components excluding some of the acceleration signal components are subjected to addition processing. In this case, since the number of objects to be added is reduced, the calculation process is simplified.

  Each of the signal synthesizing units 200A and 200B is configured by using the arithmetic unit 4 (see FIG. 1) in the microcomputer 10 in the same manner as the signal synthesizing unit 200.

  In the above embodiment, the body motion detection device according to the present invention is applied to a pedometer. However, in addition to the pedometer, it can also be applied to a limb motion detector, a bat swing detector, and the like. Further, the body motion detection device according to the present invention may be mounted on a mobile phone so as to have the function of a pedometer.

Circuit block diagram of body motion detection device of the present invention Front view and side view showing configuration of acceleration detecting means Sectional view and schematic circuit diagram showing specific structure of electrostatic acceleration sensor Diagram for explaining synthesis of acceleration signal Waveform diagram showing an example of acceleration signal components in the X-axis direction and the Y-axis direction Waveform diagram showing an example of acceleration signal components in the X-axis direction and the Y-axis direction Waveform diagram showing an example of acceleration signal components in the X-axis direction and the Y-axis direction Waveform diagram showing an example of acceleration signal components in the X-axis direction and the Y-axis direction The figure which shows an example of the addition type | formula of the acceleration signal component of a X-axis direction and a Y-axis direction The figure which shows an example of the synthetic | combination waveform of the acceleration signal component of a X-axis direction and a Y-axis direction The figure which shows the synthetic | combination waveform of the acceleration signal component of the X-axis direction and Y-axis direction by another addition type | formula The figure for demonstrating the synthesis | combination of the acceleration signal component of 3 axial directions The figure for demonstrating the synthetic | combination process of the acceleration signal component of a XYZ 3-axis direction Waveform diagram showing synthesis processing of acceleration signal components in XYZ 3-axis direction Waveform diagram showing synthesis processing of acceleration signal components in XYZ 3-axis direction

Explanation of symbols

1A, 1B, 1C Electrostatic acceleration sensor 20 Reference side electrode 21 Vibration side electrode 100 Acceleration detecting means 200 Signal synthesizing means 200A Signal synthesizing means 200B Signal synthesizing means 300 Body motion discrimination means

Claims (14)

A body motion detection device provided with acceleration detection means for detecting accelerations in a plurality of axial directions directed in different directions,
For each of the acceleration signal components detected in the acceleration detecting means in the directions of the plurality of axes, the acceleration signal component having a large signal magnitude is weighted more than the acceleration signal component having a small signal magnitude. Signal combining means for adding a weighting coefficient and adding and synthesizing one signal and body movement determining means for determining the body movement of the subject based on one signal synthesized by the signal synthesizing means are provided. Body motion detection device. A body motion detection device provided with acceleration detection means for detecting accelerations in a plurality of axial directions directed in different directions,
For each of the two or more acceleration signal components selected from the acceleration signal components in the plurality of axial directions detected by the acceleration detecting means, the signal size is small with respect to the acceleration signal component having a large signal size. A signal synthesis means for adding a weighting coefficient so as to give a weight greater than that of the acceleration signal component, and synthesizing one signal, and a body of the subject based on the one signal synthesized by the signal synthesis means A body movement detection device provided with body movement determination means for determining movement.   The body motion detection device according to claim 2, wherein the signal synthesizing unit excludes the acceleration signal components in the plurality of axial directions from the selection target in order of increasing signal magnitude. A body motion detection device provided with acceleration detection means for detecting accelerations in a plurality of axial directions directed in different directions,
Among the acceleration signal components detected by the acceleration detecting means in the directions of the plurality of axes, the acceleration having a large signal size for each of at least two acceleration signal components having a signal size exceeding a predetermined threshold. A signal synthesizer that synthesizes one signal by adding a weighting coefficient so that the signal component has a greater weight than a small acceleration signal component, and is synthesized by the signal synthesizer. A body motion detection device provided with body motion discrimination means for discriminating body motion of a subject based on a single signal.   5. The signal synthesizing means determines the magnitude of the signal for the acceleration signal component in each axial direction for each sampling data obtained by sampling the detection information of the acceleration detecting means at a predetermined time interval. The body movement detection apparatus as described.   The signal synthesis unit accumulates sampling data obtained by sampling the detection information of the acceleration detection unit at a predetermined time interval to generate a vibration waveform, and the magnitude of the signal for the acceleration signal component in each axis direction according to the amplitude of the vibration waveform. The body motion detection device according to claim 1, wherein the body motion is determined.   When the signal synthesizing means has the same direction of change of the signal in the acceleration signal component having a small signal magnitude and the direction of change of the signal in the acceleration signal component having a large signal magnitude, the magnitude of the signal The sign of the weighting coefficient attached to the acceleration signal component with a small signal is the same as the sign of the weighting coefficient attached to the acceleration signal component with a large signal magnitude, and the signal of the acceleration signal component with a small signal magnitude When the direction of change and the direction of change of the signal in the acceleration signal component having a large signal magnitude are opposite, the sign of the weighting coefficient attached to the acceleration signal component having a small signal magnitude is the magnitude of the signal. The body motion detection device according to any one of claims 1 to 6, wherein a sign opposite to a sign of the weighting coefficient attached to a large acceleration signal component is used.   The body motion detection device according to claim 1, wherein the signal synthesizing unit adds the weighting coefficient to the absolute value of the signal of the acceleration signal component in each axial direction to perform the addition process.   The body motion detection device according to claim 1, wherein the signal synthesis unit performs the addition process by adding the weighting coefficient to a value obtained by squaring the acceleration signal component in each axis direction.   10. The signal synthesizing unit attaches a code corresponding to a signal change direction in an acceleration signal component having a large signal size among acceleration signal components in the respective axis directions to one signal obtained by the addition processing. The body movement detection apparatus as described.   11. The signal synthesizing unit synthesizes the one signal by stepwise repeating the addition process of adding two signals to at least three acceleration signal components in each axial direction. The body motion detection device according to any one of the above.   When the signal synthesizing unit adds the acceleration signal components in the biaxial directions orthogonal to each other, the weighting coefficient attached to the acceleration signal component having a large signal magnitude and the acceleration signal component having a small signal magnitude The body motion detection device according to any one of claims 1 to 11, wherein a ratio of the weighting coefficient to be attached to is set to 1 to 0.4 or a value in the vicinity thereof.   The acceleration detecting means forms an electret member on either one of the reference side electrode and the vibration side electrode arranged to face each other, and changes the capacitance between the electrodes due to the displacement of the vibration side electrode. The body motion according to claim 1, comprising a plurality of electrostatic acceleration sensors that detect acceleration signals, and the accelerations in the plurality of axial directions are detected by the plurality of electrostatic acceleration sensors, respectively. Detection device.   The body motion detection device according to any one of claims 1 to 13, wherein the body motion discrimination means discriminates the number of steps or exercise intensity associated with a walking motion of a human body as the subject, or calorie consumption calculated from these.

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