WO2002094091A1

WO2002094091A1 - Fatigue inspection device and fatigue evaluation method

Info

Publication number: WO2002094091A1
Application number: PCT/JP2001/010197
Authority: WO
Inventors: Kazuyoshi Sakamoto
Original assignee: Kazuyoshi Sakamoto
Priority date: 2001-05-22
Filing date: 2001-11-22
Publication date: 2002-11-28
Also published as: JPWO2002094091A1

Abstract

A fatigue inspection device and a fatigue evaluation method capable of measuring the fatigue of a person by a rather simple means; the method, comprising the steps of installing an accelerator sensor on the arm of the measured person, and analyzing the acceleration data obtained from the acceleration sensor by an analyzing part (20) to provide vibration spectra and spectra percentage content for each zone in total power wherein, for superior limb shivering, when the components in high frequency zone are large in the vibration spectra, the fatigue can be evaluated to be large in the cerebrum system and, when the components in low frequency zone are large, the fatigue can be evaluated to be large in the spinal chord system, whereby the state of fatigue can be judged properly.

Description

Description Fatigue inspection device and fatigue evaluation method Technical field

The present invention relates to a fatigue inspection device and a fatigue evaluation method. Background art

There are tremors in human body parts. Tremors are unconscious mechanical vibrations with small amplitudes that are invisible to the eye. For example, a document by the present inventors (“On the Mechanism of Tremor Occurrence”, Proceedings of the Conference on Biomechanisms, pp. 31-34, Kazuyoshi Sakamoto, et al., July 12, 1989--12 As described in (3), studies are being conducted to measure the location and degree of injury using the frequency characteristics of tremor caused by pathological causes.

However, no attempt has been made to measure the tremor of a healthy person (this is called physiological tremor) and to measure the degree of human fatigue.

The inventor has found that the degree of human fatigue can be measured using the vibration characteristics of tremor.

The present invention has been made based on the above findings, and has as its object to provide a fatigue inspection apparatus and a fatigue evaluation method capable of measuring the degree of human fatigue by relatively simple means. Disclosure of the invention

The fatigue inspection device according to claim 1 includes a detection unit that detects vibration of tremor in a body part of the subject, and an analysis unit that analyzes a spectrum of the vibration.

The fatigue inspection device according to claim 2 is the device according to claim 1, wherein the vibration is , Acceleration.

The fatigue detection device according to claim 3, according to claim 1, wherein the analysis unit outputs data including a high-frequency band component and a Z or low-frequency band component in the vibration spectrum. The configuration was adopted.

The fatigue inspection apparatus according to claim 4, wherein the analysis unit is configured to determine a high frequency band component and a low frequency band component in a total power of a spectrum of the vibration. It is configured to output the ratio.

The fatigue inspection apparatus according to claim 5, wherein the detection unit is an acceleration sensor according to any one of claims 1 to 4.

The fatigue inspection apparatus according to claim 6, wherein the threshold for separating the high frequency band component and the low frequency band component is set to a high frequency side in the vibration spectrum. And the average value of the peak frequencies on the low frequency side or near it.

The fatigue evaluation method according to claim 7, further comprising: acquiring a vibration spectrum of a tremor in a body part of the subject, and evaluating the fatigue state of the subject based on the vibration spectrum. Has become.

The fatigue evaluation method according to claim 8, further comprising: obtaining a vibration spectrum of a tremor in a body part of the subject, and converting the vibration spectrum into a value of a high frequency band component Z or a value of a low frequency band component. The fatigue evaluation method according to claim 9, wherein the fatigue state of the subject is evaluated based on the threshold value that separates the high-frequency band component from the low-frequency band component. The average value of the peak frequencies on the high frequency side and the low frequency side in the vibration spectrum or a value close to the average value.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a view for explaining the knowledge that is the premise of the fatigue evaluation method according to the present invention. FIG.

FIG. 2 is a graph for explaining the findings obtained by the inventor, and shows a change in the upper limb tremor vector when a load is applied. In this graph, the horizontal axis represents frequency, and the vertical axis represents power spectrum.

FIG. 3 is a graph for explaining the findings obtained by the present inventors. The tremor power spectrum is shown when the upper limb is unloaded in air and when immersed in water. In the figure, the horizontal axis represents frequency, and the vertical axis represents power spectrum.

FIG. 4 is a graph for explaining the findings obtained by the present inventors. The horizontal axis represents the magnitude of the load, and the vertical axis represents the relative total power when the value at no load is set to 1. It is.

FIG. 5 is a graph for explaining the findings obtained by the present inventors, and shows the change in the spectrum content of the upper limb tremor spectrum by band during load application. . In this graph, the horizontal axis indicates the magnitude of the load, and the vertical axis indicates the ratio of the high frequency band component to the low frequency band component in the total power. FIG. 6 is a schematic block diagram of the fatigue evaluation device according to one embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a fatigue inspection device and a fatigue evaluation method according to an embodiment of the present invention will be described.

First, experimental results (that is, findings) showing the relationship between tremor and fatigue, which are the premise of the embodiment of the present invention, will be described. Here, the parts that can be measured for tremor include the fingers, hands, forearms, upper limbs, feet, lower legs, lower limbs, head, and trunk. In the following, upper limb tremor is measured using the upper limb part of the body part as an example.

First, as shown in Fig. 1, a load (weight) 2 is attached from the elbow joint of the right arm 1 of the subject sitting on the chair to the forearm. Load 2 between subjects In order to keep the load intensity constant, the maximum voluntary contraction strength (hereinafter referred to as “MVC” for Maximum Voluntary Contraction) was measured for each subject in advance, and 5%, 10%, 15% %, 20% MVC and zero external load (sometimes referred to as “no load” or “postural” in this specification). Load 2 is mounted midway between the wrist and the elbow. It is desirable to attach load 2 so that it does not move with respect to arm 1.

Further, an acceleration sensor 3 is attached near the wrist of the arm 1. As the acceleration sensor, for example, MT-3T manufactured by Nihon Kohden can be used. The subject puts his arm vertically and forward with respect to the trunk, and stretches out with the pronation turned (the entire upper limb is twisted inward and the hand is horizontal to the ground). Keep your wrists and fingers relaxed to avoid the effects of the tremor (Figure 1).

Under these conditions, the subject keeps the same posture for a certain period of time (usually 1 minute) while visually observing the subject so that the arm 1 does not deviate from the marker 4 (visual feedback). Then, the vibration of the tremor is acquired by the acceleration sensor 3 while maintaining the visual feedback. This data was subjected to Fourier transform to obtain a power spectrum. The subjects in this experiment were 10 males (average age 23.4 years). As data, the average value among all subjects was adopted. Figure 2 shows the results of the experiment. The vibration here is based on acceleration only. It can be seen that the spectrum has a high-frequency peak and a low-frequency peak. The peak of upper limb tremor increased as the load increased. In particular, the tendency was strong at the high frequency peak.

From the results shown in Fig. 2 (and Fig. 3 described later), in upper limb tremor, the magnitude of the high frequency peak corresponds to the magnitude of the cerebral fatigue, and the magnitude of the low frequency peak corresponds to the magnitude of the spinal cord fatigue. It turns out that it corresponds. In finger tremor, where the mass of the body part is small, the high-frequency component works as the spinal system and the low-frequency component works as the cerebrum, and the function of the frequency component is opposite to that of upper limb tremor.

The reason for this determination is as follows. For upper limb tremor, see Figure 2. As shown, increasing the load weight from zero external load weight (ie, no load or ostural) to 20% MVC increases the high frequency component (frequency component around 10 Hz for the upper limb) by a factor of 15. On the other hand, the low frequency component (frequency component near 3 Hz in the upper limb) is quadrupled. In general, maintaining the posture of the upper limb by applying a load cannot be performed using only the automated functions of the spinal cord. Consciousness level activity by the cerebral system is required, and the upper limb vibrates to adjust the posture. To maintain the posture of the upper limb, a component corresponding to the force (acceleration component) is applied to the upper limb. As a result, the acceleration component increases. Therefore, the increase in the power spectrum of the 10 Hz component in Fig. 2 means that the origin of the 1 OH z component of upper limb tremor is caused by the function of the cerebrum. Is shown experimentally. Here, it is considered that the reason why the 3 Hz component also increased was that the function of the cerebrum affected the spinal cord, which is a subordinate mechanism.

On the other hand, in order to investigate the origin of the low-frequency components, the power spectrum of the tremor vibration was measured with the upper limb immersed in water. The result is shown by the thick line in FIG. The thin line in the figure is the measurement result at zero external load in air. When the upper limb is immersed in water, the buoyancy added to it reduces the strain on the muscles involved in holding the upper limb. To maintain posture in the water, there are two types of muscles and nerve functions, mainly the spinal cord, which keeps the upper limbs reflexively, and conscious muscles and nerve functions, which keep the upper limbs in contact with the target. Two types of functions are involved. Underwater buoyancy reduces the upper limb holding power, the need for a reflexive upper limb holding function is not required, the vibration component based on it is reduced. In Fig. 3, the low-frequency component (3 Hz) is sharply reduced in the underwater curve of the two peaks generated in the curve in the air (no-load in the figure). A vector has been detected. From this result, it can be seen that the oscillation of the 3 _Hz component is generated by the action of the spinal cord system. In addition, the relationship between the total power of the vibration spectrum of tremor and the load was obtained. Fig. 4 shows the results. Figure 4 shows the negative load at every 5% MVC from the state where no external load weight is applied (no load) to the state where the load is applied to 20% MVC. It expresses the relationship between the loading state and the total power (TP), which is the sum of the power spectrum of acceleration related to upper limb tremor. At that time, the value of each subject under no load was used as a reference value, and the value at each load was expressed as a relative value. further

The average (solid circle in Fig. 4) and standard deviation (vertical bar in Fig. 4) of the relative values of all subjects were calculated and displayed in Fig. 4. As the load weight increases, the relative total power value increases. In particular, at a load weight of 15% MVC or more, the relative total power value sharply increases. The “*” and “**” marks in the figure indicate the difference between the no-load and the relative total power under other load weights statistically tested (t-test for paired data). This indicates that there is a statistical difference (significant difference) between 1% and 1%. Here, generally speaking, the load on skeletal muscle can be maintained for a long time at a load of 15% MVC or less, and muscle fatigue after a certain period of time at a load of 15% MVC or more. Always happens. The results in Fig. 4 show that the total power value increases sharply above 15% MVC, explaining this phenomenon.

Furthermore, in upper limb tremor, the total power of all frequency components at 0.5 to 5 OHz is set to 100%, and the high frequency band component (5 to 50 Hz) and the low frequency band component (0.5 to 5 Hz) The spectral content for each band was determined. Figure 5 shows the results. This result supports the results in Figure 2. However, as can be seen from the change from no load to 5% load, it was found that in the case of mild fatigue, the ratio of the high-frequency component could be rather lowered. However, the overall trend is that the higher the load, the higher the high-frequency component ratio.

The present invention is based on the above findings.

Next, a fatigue inspection device according to one embodiment of the present invention will be described with reference to FIG. This fatigue testing apparatus includes a detecting unit 10 for detecting vibration of tremor, an analyzing unit 20 for analyzing a vibration spectrum, and a display unit 30 for displaying data output from the analyzing unit 20. Have.

The detection unit 10 is an acceleration sensor in this embodiment. An acceleration sensor similar to the acceleration sensor 1 shown in FIG. 1 can be used. You. Therefore, an output (for example, a voltage) based on the acceleration is sent from the detection unit 10 to the analysis unit 20.

The analysis unit 20 can be configured by a normal computer having an interface for taking in the output from the detection unit 10. Examples of functions in the analysis unit 20 include an AD converter that performs AD conversion on an input, a function that performs a Fourier transform on the obtained digital data to obtain a vibration spectrum, and a vibration spectrum. It is a function to acquire the status of the statue content for each band in the total part. These functions can be easily implemented as software or hardware. Also, these functions may be realized by a plurality of distributed elements. In the present embodiment, the sampling time of the AD conversion is set to 10 ms.

The display unit 30 displays the data on the vibration spectrum obtained by the analysis unit 20 via a display or a printer.

Next, the fatigue evaluation method ′ in the present embodiment will be described with reference to FIG. Load 2 is also used for fatigue evaluation. Here, as an example of the load to be worn in the fatigue evaluation of the upper limb, as shown in FIG. 4, the load can be 5% MVC. However, since the magnitude of the load is inversely proportional to the time indicating the increase in the total power of the tremor vibration, it is advisable to apply a load of 15% MVC or more in order to perform a quick fatigue evaluation.

First, as shown in FIG. 1, the acceleration sensor 3 as the detection unit 10 is attached to the arm 1 of the subject. The analysis unit 20 analyzes the acceleration data obtained from the acceleration sensor 3. As a result, as shown in FIGS. 2 and 5, the spectrum content of each band in the vibration spectrum and the total power is obtained. Such a graph is displayed on the display unit 30 in an appropriate medium. Here, in deriving the spectrum content rate by band, in the case of upper limb tremor, the frequency band of the high frequency component is set to 5 Hz to 50 Hz, and the frequency band of the low frequency component is set to 0.5 Hz to 0.5 Hz. A specific evaluation of 5 Hz is performed as follows. First, the upper extremity tremor as shown in Fig. 2 If there are many components in the high-frequency band in the tuttle, it can be evaluated that the cerebral system fatigue is large. On the other hand, if there are many components in the low frequency band, it can be evaluated that the spinal cord fatigue is large. Then, it is possible to appropriately make a determination according to the characteristics of the fatigued part, for example, a type of a fatigue recovery measure. This determination can also be made based on the stall content as shown in FIG. Here, the threshold for separating the high frequency band component and the low frequency band component should be the average value of the peak frequencies (that is, two peak frequencies) on the high frequency side and the low frequency side in the vibration spectrum or in the vicinity thereof. Can be. As described above, when the average value or a value in the vicinity thereof is set as the threshold value, the frequency component of the tremor vibration is rationally divided into two bands, high and low, in response to frequency fluctuations due to individual differences and differences in body parts. It can be divided into components.

Further, according to the present embodiment, there is an advantage that the degree of fatigue can be quantitatively indicated by using the spectrum content. This makes it possible to accurately perform fatigue evaluation.

Further, in the present embodiment, since the vibration is obtained as acceleration data (data indicating force) from the acceleration sensor, there is an advantage that the change of the spectrum, particularly, the increase and decrease of the high-frequency spectrum is clear.

In the above embodiment, the acceleration sensor is attached near the wrist of the subject to measure upper limb tremor, but may be attached to another part (for example, upper arm). Also, the tremor of various body parts may be measured by being attached to many body parts such as fingers, hands, forearms, lower legs, lower limbs, and trunk, not limited to the upper limbs. In short, any part that generates tremor may be used. In that case, the frequency separating the high frequency and the low frequency fluctuates. In order to obtain this frequency, as described in this specification, an experiment is performed on a subject in advance to obtain high and low peak values. Also, in the tremor of other body parts, if the mass of the body part is small (for example, finger tremor), the function of the frequency band component is opposite to that of the upper limb tremor. , 'The function of the frequency band may be reversed from that of upper limb tremor.

Note that the description of the above embodiment is merely an example, and shows an essential configuration of the present invention. It was not done. The configuration of each unit is not limited to the above as long as the purpose of the present invention can be achieved. Industrial applicability

According to the present invention, it is possible to provide a fatigue inspection apparatus and a fatigue evaluation method capable of measuring the degree of fatigue of a subject with a simple configuration.

Claims

The scope of the claims

1. A fatigue inspection device comprising: a detection unit that detects vibration of tremor in a body part of a subject; and an analysis unit that analyzes a spectrum of the vibration.

2. The fatigue inspection device according to claim 1, wherein the vibration is caused by acceleration.

3. The fatigue according to claim 1, wherein the analysis unit is configured to output data including a high frequency band component Z or a low frequency band component in the spectrum of the vibration. Inspection equipment.

4. The analysis unit according to claim 1, wherein the analysis unit is configured to output a ratio of a high frequency band component and a low frequency band component in a total power of the spectrum of the vibration. The fatigue inspection device as described.

5. The fatigue detection device according to any one of claims 1 to 4, wherein the detection unit is an acceleration sensor.

6. The threshold value for separating the high-frequency band component and the low-frequency band component is an average value of peak frequencies on the high frequency side and the low frequency side in the vibration tale or in the vicinity thereof. The fatigue inspection device according to any one of claims 1 to 5.

7. A fatigue evaluation method comprising: obtaining a vibration spectrum of a tremor in a body part of a subject; and evaluating the fatigue state of the subject based on the vibration spectrum.

8. Obtain the vibration spectrum of tremor in the body part of the subject, and evaluate the fatigue state of the subject based on the values of the high frequency band component and the Z or low frequency band component of the vibration spectrum. A fatigue evaluation method characterized in that:

9. The threshold value for separating the high frequency band component and the low frequency band component is an average value of peak frequencies on the high frequency side and the low frequency side in the vibration spectrum or in the vicinity thereof. Fatigue evaluation method.