JP4946447B2 - Fatigue evaluation method and fatigue evaluation apparatus. - Google Patents

Description

  The present invention relates to a method and an apparatus for evaluating the degree of physical fatigue of an operator that occurs in accordance with an operation performed by the operator.

  For example, fatigue caused by a driving operation that occurs in a driver who is driving a vehicle impairs the comfort that the driver feels while driving, and thus the safety of driving. As a matter of course, for a driver of a vehicle, particularly a professional driver who operates for a long time, the fatigue during driving should be as small as possible. As a characteristic that a tire should have, a characteristic that reduces fatigue felt by a driver during driving, that is, a characteristic that does not easily fatigue is important. In order to develop tires having such fatigue-resistant characteristics, it is important to know the degree of fatigue of the driver of the vehicle, in order to quantitatively evaluate the fatigue generated by the driver who is driving the vehicle. A method is needed.

The degree of fatigue generated in the driver who is driving the vehicle can be obtained by expressing the degree of fatigue felt by the driver based on his / her own sense. However, such information based on the driver's own sense is not objective and is not quantitative. For this reason, conventionally, for example, the following Non-Patent Documents 1 and 2 have proposed a technique aimed at objectively evaluating the degree of driver fatigue using measured biological information. Non-Patent Document 3 below shows that an EMD (electromechanical delay) value, which is a time delay of a muscle strength rise timing with respect to a myoelectric potential rise timing, represents the degree of muscle fatigue. Yes. As an example of a method for quantitatively evaluating human fatigue, a method using this EMD value is also conceivable.
Nagata, et al., Changes in Urinary Coleamine and ECG RR Interval during Long Distance Driving, Automotive Technology, vol. 7, 1996 Yoshihiro Noguchi et al., Examination of heart rate variability index analysis method for actual driving, automotive technology, vol. 29, no. 1, 1998 Gleeson, N .; P. , Et. al. , Influencing of a fatigue task on electromechanical delay in the knee flexors of soccer players. Med. sci. Sports Exerc. 29: S281, 1997.

  In the said nonpatent literature 1, although the fatigue degree is evaluated from the biochemical aspect by the component analysis in urine, in addition to lack of immediacy, the burden concerning a measurement and a test subject are also large. In addition, the evaluation using the fluctuation of the heart rate represented by Non-Patent Document 2 is essentially an evaluation of arousal level, and there are many unknown disturbance factors as an evaluation of the fatigue level, and the actual operation is difficult. there were. In addition, as described in Non-Patent Document 3, the evaluation of muscle fatigue by measuring EMD is, for example, fatigue evaluation in work performed by the resultant force of two antagonized forces such as driving work. It was unsuitable for.

  For example, in the driving work, the muscle strength exerted by the driver is measured for each muscle in the steering work in which the driver rotates the steering shaft of the steering means provided in the vehicle to control the steering angle of the vehicle. For example, the magnitude and direction of the torque around the steering shaft axis are measured as information on the magnitude and direction of the force generated by the activity of each muscle. In general, such a steering operation is performed by, for example, the right rotation direction force generated by the left muscle of the driver's left and right deltoid muscles and the reverse direction (left) generated by the other (right) muscle activity. The steering shaft is rotationally driven by the resultant force with the force in the rotational direction) (note that the correspondence between the active muscle and the rotational direction differs for each driver). For example, the magnitude of the torque of the steering shaft when the steering shaft is rotated in the right direction is, for example, the force in the right rotation direction caused by the activity of the left muscle and the reverse direction caused by the activity of the other (right) muscle. This represents the magnitude of the resultant force with the force in the (left rotation direction). Even if the magnitude of the torque of the steering shaft when the steering shaft is rotated to the right is treated as the force in the right rotation direction caused by the activity of the left muscle, the actual strength of the muscle against the rise timing of the myoelectric potential The EMD that is the time width of the time delay of the rising timing cannot be obtained accurately. For this reason, in the work carried out by the resultant force of the two antagonized muscles, there is a problem that the fatigue of the worker cannot be evaluated with high accuracy.

  Therefore, the present invention has been made in view of the above, and an evaluation method and an evaluation apparatus for quantitatively evaluating with high accuracy the degree of physical fatigue of the worker accompanying the work performed by the worker. provide.

  In order to solve the above-mentioned problem, the present invention is a method for evaluating the degree of physical fatigue of an operator that occurs in accordance with the operation performed by the operator, and the operation includes the two muscles of the operator. Among them, the work is performed by the resultant force of the forward force generated by the activity of one muscle and the reverse force generated by the activity of the other muscle, and the magnitude of the activity of the two muscles of the worker The action myoelectric potential information of each of the two muscles, and the sign of the acquired myoelectric potential information of the one muscle is positive, the action myoelectric potential information of the other muscle The action potential information of each of the two muscles is synthesized, and a combined myoelectric waveform representing a time-series change of the synthesized action myoelectric potential information is output; Obtaining synthetic muscle strength information representing the direction and magnitude of the resultant force generated by an activity in time series, outputting a composite muscle strength waveform expressed as positive in the forward direction and negative in the reverse direction, and the synthetic muscle The degree of time delay of the change of the resultant force caused by the activity of each of the two muscles with respect to the change of the component of the activity contributing to the work of the two muscles by comparing the radio wave form and the synthetic muscle strength waveform And a step of evaluating a degree of physical fatigue accompanying the work of the worker based on the evaluation reference value. . In the present invention, the muscle activity refers to all the biological activities of the muscle for exerting muscle strength, and in a narrow sense, discharge (myoelectric potential) associated with electrical excitation of muscle fibers constituting the muscle. As measured).

  Furthermore, it is preferable to further include a step of evaluating the degree of physical fatigue accompanying the work of the worker based on the evaluation reference value.

  In addition, the operator is a driver who drives the vehicle, and the operation is performed by using the resultant force generated by the activity of two muscles of the driver to change the vehicle operation means included in the vehicle to the forward direction and the reverse direction. It may be a driving operation for controlling the operation of the vehicle by driving in any one direction.

  The driving operation is a steering operation of the vehicle, and the driver controls a steering angle of the vehicle by rotating a steering shaft of a steering means provided in the vehicle by the resultant force. There may be.

  The two muscles of the worker are preferably the left half muscle of the worker and the right half muscle of the worker corresponding to the left half muscle, The right-sided deltoid muscle of the operator may be used.

  In the step of deriving the evaluation reference value, a cross-correlation function having a phase shift time between the synthetic myoelectric waveform and the synthetic myoelectric strength waveform as a variable is obtained, and the phase at which the value of the cross-correlation function is maximized is obtained. The deviation time is preferably derived as the evaluation reference value.

  Further, in the step of evaluating, the acquired myoelectric waveform and the time series waveform of the synthetic myoelectric strength information are compared, and for the myoelectric rise timing when the synthetic myoelectric waveform exceeds a predetermined value, It is also preferable to derive, as the evaluation reference value, the time delay width of the muscle strength rising timing at which the time series waveform of the combined muscle strength exceeds a predetermined value.

  The present invention is also an apparatus for evaluating the degree of physical fatigue of the worker, which occurs in accordance with the work performed by the worker, and the work includes one of the two muscles of the worker. The work performed by the resultant force of the forward force generated by the activity and the reverse force generated by the activity of the other muscle, each representing the magnitude of the activity of the two muscles of the worker, 2 Means for acquiring the action myoelectric potential information of each of the two muscles in time series, the sign of the action myoelectric potential information of the acquired one muscle is positive, the sign of the action myoelectric potential information of the other muscle is negative, Means for synthesizing the action potential information of each of the two muscles, and outputting a combined myoelectric waveform representing a time-series change of the synthesized action myoelectric potential information; and the resultant force generated by the activity of the two muscles. , Means for acquiring synthetic muscle strength information representing a direction and a magnitude in time series, outputting a synthetic muscle strength waveform expressed with the forward direction being positive and the reverse direction being negative, the synthetic myoelectric waveform and the synthetic muscle strength An evaluation reference value representing the degree of time delay of the change of the resultant force caused by the activity of each of the two muscles with respect to the change of the component of the activity contributing to the work of the two muscles by comparing with waveforms There is also provided a fatigue evaluation apparatus characterized by comprising means for deriving and means for evaluating the degree of physical fatigue accompanying the work of the worker based on the evaluation reference value.

  According to the present invention, it is possible to quantitatively evaluate fatigue generated in a worker who is working, such as fatigue generated in a driver who is driving a vehicle. For example, it is possible to objectively and quantitatively evaluate the fatigue of a specific driver when the specific driver performs long-time continuous driving in each case where a plurality of different tires are mounted on a specific vehicle. it can. As a result, it is possible to objectively and quantitatively know which tire is difficult to get tired for the driver. By using such information, it is possible to efficiently develop tires that are less tiring for the driver. By using the present invention, it is possible to grasp in detail the relationship with the driver's fatigue for various conditions such as the vehicle, the vehicle control system, and the environment (road design, road surface, weather) as well as the tire.

  Hereinafter, the fatigue evaluation method and apparatus of the present invention will be described in detail on the basis of preferred embodiments shown in the accompanying drawings. FIG. 1 is a schematic configuration diagram illustrating a driver fatigue evaluation device 10 (hereinafter, evaluation device 10), which is an example of the fatigue evaluation device of the present invention. The evaluation apparatus 10 performs a driving operation of a driver 12 driving a vehicle having an operation system 14, particularly a steering operation for driving a steering wheel 16 and steering a vehicle (not shown) by rotating a steering shaft 18 around an axis. It is an apparatus for evaluating the magnitude of physical fatigue associated with. The evaluation apparatus 10 includes a measuring unit 20, a data processing unit 40, and an output unit 58 that is a display unit.

  The measuring means 20 includes a known torque sensor 24 for detecting the torque around the axis of the steering shaft 18 generated by the driving operation of the driver 12 (rotation operation of the steering wheel), and the activity of the left and right deltoid muscles of the driver 12. And a myoelectric detection sensor unit 30 for detecting myoelectric potential (hereinafter simply referred to as myoelectric potential).

  The myoelectric detection sensor unit 30 includes detection sensors 32 and 34 that detect myoelectric potentials of the left and right deltoid muscles of the driver 12, an electrode 36, and an amplifier 38 that amplifies myoelectric potentials from the detection sensors 32 and 34. It is configured. The left and right deltoid muscles of the driver 12 are operation-related muscles related to the steering operation of the vehicle 10 that work when the driver 12 rotates the steering wheel 16.

The detection sensor 32 is a sensor for detecting myoelectric potential of the deltoid muscle of the left shoulder of the driver, and is configured by a pair of Ag / AgCL dish-shaped electrodes, and the pair of dish-shaped electrodes are arranged at a predetermined interval, several mm, For example, it is affixed to the surface of the left shoulder where the deltoid muscle is located 5 mm apart.
The detection sensor 34 is a sensor that detects the myoelectric potential of the deltoid muscle of the right shoulder of the driver. Like the detection sensor 32, the detection sensor 34 is configured by a pair of Ag / AgCL dish-shaped electrodes. Is affixed to the surface of the left shoulder where the deltoid muscle is located at a predetermined interval of several mm, for example, 5 mm.
The electrodes of the detection sensors 32 and 34 are not limited to Ag / AgCL, and may be made of other materials such as Ag and stainless steel.
Here, the attachment of the driver to the skin surface is carried out using an electrode paste by rubbing with a scrub, removing dirt with alcohol. At that time, the dirt is removed until the electric resistance is 30 kΩ or less (preferably 5 kΩ). The two electrodes are attached to the muscle belly of the muscle to be measured, parallel to the muscle fibers. As shown in FIG. 2, the affixing position is affixed at a predetermined interval to a position Y that is three fingers away from the outer end X of the clavicle, in the arm longitudinal direction.

On the other hand, the electrode 36 is a ground electrode that is affixed to the driver's earlobe, which is in an electrically inactive position in order to keep the driver's potential constant, and is provided to accurately perform the measurement by the detection sensors 32 and 34. It is done. The electrode 36 connected to the amplifier 38 is grounded via the amplifier 38.
The amplifier 38 is a known operational amplifier that is connected to the detection sensors 32 and 34 by lead wires and amplifies the myoelectric potential detected by the detection sensors 32 and 34. The left and right myoelectric potential information (activity myoelectric potential information) detected and amplified by the detection sensors 32 and 34 is sent to the myoelectric information acquisition unit 42 of the data processing unit 40.

  The torque sensor 24 is a known torque sensor that acquires magnitude information and rotational direction information of the rotational torque around the steering shaft 18. As the torque sensor 24, for example, a sensor constituting a part of a vehicle power steering system can be used. In the evaluation apparatus 10 of the present embodiment, the evaluation apparatus is configured at a low cost by using a general automobile vehicle having a power steering system (using a sensor or the like that constitutes a part of the power steering system). Can evaluate fatigue. In the evaluation apparatus 10 of the present embodiment, it is possible to evaluate the fatigue generated in the driver who drives the actual vehicle using the automobile vehicle actually used. The steering operation performed by the driver 12 includes, for example, a rightward rotation force generated by the left muscle activity of the left and right deltoid muscles of the driver and a reverse direction (left rotation direction) generated by the other (right) muscle activity. ), The steering shaft 18 is rotationally driven by the resultant force. Information about the magnitude of the rotational torque and the rotational direction (right direction or left direction) measured by the torque sensor 24 is the direction and magnitude of the resultant force (muscle strength) generated by the activities of the left and right deltoid muscles of the driver 12. It can be said that it represents. Information about the magnitude and direction of rotation torque (combined muscle strength information) measured by the torque sensor 24 is sent to the combined muscle strength information acquisition unit 44 of the data processing unit 40.

  The data processing means 40 includes a myoelectric information acquisition unit 42, a synthetic muscle strength information acquisition unit 44, a synthetic myoelectric waveform derivation unit 46, a synthetic muscle strength waveform derivation unit 48, an evaluation reference value derivation unit 50, an evaluation unit 52, a memory 54, and A CPU 56 is provided. The data processing unit 40 is a computer in which each unit functions when the CPU 56 executes a program stored in the memory 54. The data processing unit 40 may be a dedicated device in which each unit is configured by a dedicated circuit.

Here, before describing the function of each part of the data processing means 40, the principle of fatigue evaluation of the driver 12 performed in the data processing means 40 will be described. FIG. 3 is an example of a graph showing a time-series variation of myoelectric potential generated in a muscle related to this motion and a time-series variation of muscle strength exerted by this muscle when a human in a stationary state causes a predetermined motion. is there. As shown in FIG. 3, when a person in a stationary state takes a predetermined action, the muscles related to this action are activated. At this time, the myoelectric potential first rises rapidly (rise timing T _E ), and the muscle strength rises after a delay (rise timing T _F ). Such, when a person is operating, the time delay from the rise timing _{T E} myoelectric potential to rise timing _{T F} of muscle strength, called EMD (electromechanical delay). It is known that the size of such an EMD changes depending on the degree of fatigue of the muscle, and the EMD increases as the muscle fatigue increases. The degree of time delay of the muscle force change with respect to the change of the myoelectric potential of the operation-related muscle of the driver 12 (the deltoid muscle in this embodiment) indicates the degree of fatigue of the operation-related muscle, and thus the degree of fatigue of the driver 12. It can be said that it represents.

  In the present embodiment, as described above, the magnitude of the rotational torque applied to the steering shaft 18 and the rotational direction (right direction or left direction) are the resultant force (muscle strength) generated by the activities of the left and right deltoid muscles of the driver 12. Is measured by the torque sensor 24 as information representing the direction and size. In the present embodiment, the left and right deltoid muscles cause the change in the activity component (representing myoelectric potential information component) that contributes to the driving work among the activities (representing myoelectric potential information) of the left and right deltoid muscles. The degree of time delay of the change in resultant force is treated as an index representing the overall degree of fatigue of the left and right deltoid muscles, that is, the degree of fatigue of the driver 12. In the data processing means, the activity of the left and right deltoid muscles with respect to the change of the activity component (representing myoelectric potential information component) contributing to the driving work out of the activities of the left and right deltoid muscles (representing myoelectric potential information). An evaluation reference value representing the degree of time delay of the resultant resultant force change is obtained, and the degree of fatigue of the driver 12 is evaluated based on the evaluation reference value.

  The combined muscle strength information acquired by the combined muscle strength information acquiring unit 44 of the data processing means 40 is sequentially output to the combined muscle strength waveform deriving unit 48. In the present embodiment, the combined muscle strength waveform deriving unit 48 outputs a combined muscle strength waveform expressed with the right direction torque being positive and the left direction torque being negative. The output combined muscle strength waveform is sent to the evaluation value calculation unit 48.

  The myoelectric information acquisition unit 42 acquires the action myoelectric potential information of each of the left and right deltoid muscles acquired by the myoelectric detection sensor unit 30 in time series, and sends it to the combined myoelectric waveform deriving unit 46. At this time, the myoelectric information acquisition unit 42 samples the action myoelectric potential information detected by the detection sensors 32 and 34, performs full-wave rectification, and then smoothes the muscle using a smoothing filter (low-pass filter). A potential signal waveform (smoothed myoelectric waveform) is generated for each of the left and right deltoid muscles. Then, the smoothed electromyogram waveforms of the left and right deltoid muscles are sent to the combined myoelectric waveform deriving unit 46 as the action myoelectric potential information of the left and right deltoid muscles. In the present embodiment, the synthetic electromyogram derivation unit 46 sets the sign of the action myoelectric potential information of the left deltoid muscle to be positive and the sign of the action myoelectric potential information of the right deltoid muscle to be negative, and the active muscle of each of the two muscles. The potential information is synthesized, and a synthesized myoelectric waveform representing a time-series change in the synthesized activity myoelectric potential information is derived. For example, the combined myoelectric waveform deriving unit 46 sets the sign of the activity myoelectric potential information of the left deltoid muscle at the same timing as positive and sets the sign of the action myoelectric potential information of the right deltoid muscle at the same timing as negative, for each timing. A composite electromyogram waveform is derived by obtaining the total value of the left and right action myoelectric potential information.

  As described above, in the steering operation performed by the driver 12, among the left and right deltoids of the driver, for example, a rightward rotation force generated by the activity of the left deltoid and the other (right) deltoid are generated. The steering shaft 18 is rotationally driven by the resultant force with the force in the reverse direction (left rotation direction). The above-mentioned composite myoelectric waveform represents the magnitude and direction of the activity component that contributes to the steering operation performed by rotating the steering shaft out of the total activity magnitude of the left and right deltoid muscles. . Even if changes in myoelectric potentials of each deltoid muscle are measured as information representing the activities of the left and right deltoid muscles, only time series changes in the magnitude (absolute value) of each myoelectric potential of each deltoid muscle can be measured. In the present embodiment, positive and negative signs are assigned to the myoelectric information of the left and right deltoid muscles to express the direction of muscle strength generated by the muscle activity represented by each myoelectric information (muscle strength direction information). ). Then, by combining the myoelectric information of the left and right deltoid muscles to which the information on the direction of the muscular strength has been given, the steering shaft is rotationally driven out of the total activity of the left and right deltoid muscles. A synthetic electromyogram representing the time-series change in the magnitude and direction of the active component contributing to the steering operation is derived.

  Depending on the driver, for example, when the steering hole is rotated clockwise, it is conceivable that the muscle strength of the right deltoid muscle mainly works. Which muscle is to be operated during steering, that is, whether each of the torques in the left and right rotational directions represents the strength of the left and right deltoid muscles may be set in accordance with the driver.

  The evaluation reference value deriving unit 50 compares the obtained synthetic myoelectric waveform and the synthetic muscle strength waveform, and each of the left and right deltoid muscles with respect to the change of the activity component contributing to the driving work among the activities of the left and right deltoid muscles. An evaluation reference value representing the degree of time delay of the resultant force change caused by the activity is derived. For example, the evaluation reference value deriving unit 50 obtains a cross-correlation function having the phase shift time τ between the synthetic myoelectric waveform and the synthetic muscle force waveform as a variable, and the phase shift time τ when the value of the cross-correlation function is maximized. Is derived as an evaluation reference value representing the degree of the time delay. The evaluation reference value deriving unit 50 compares the acquired synthetic myoelectric waveform with the synthetic myoelectric strength waveform, and the synthetic myoelectric waveform with respect to the myoelectric rise timing at which the synthetic myoelectric waveform exceeds a predetermined reference value is used as a reference. The time delay width of the muscle strength rising timing exceeding the value may be derived as the evaluation reference value. The evaluation reference value may be information indicating the degree of time delay, and the specific derivation method is not particularly limited.

  The evaluation unit 52 evaluates the degree of physical fatigue accompanying the driving operation of the driver 12 based on the derived evaluation reference value. At this time, the evaluation unit 52 classifies the degree of fatigue of the driver 12 by comparing the derived evaluation reference value with a predetermined numerical range. For example, according to the degree of fatigue of the evaluation reference value, the degree of fatigue of the driver 12 is classified into levels such as a small fatigue state, a medium fatigue state, and a large fatigue state. Then, the result of the level division is output to the output means 52.

At this time, the evaluation unit 52 uses the normalized evaluation reference value obtained by normalizing the obtained evaluation reference value by using the maximum fatigue time delay information and the no fatigue time delay information for the driver 12. Evaluation may be performed. The maximum fatigue delay width information is information representing the degree of time delay when the left and right deltoid muscles of the driver 12 are sufficiently fatigued. The no-fatigue delay information is information indicating the degree of the time delay when the operation-related muscle (triangular muscle) of the driver 12 is in a no-fatigue state. For example, as the maximum fatigue delay information and the no fatigue delay information, the EMD value E _max of the deltoid when the deltoid is in the maximum fatigue state and the deltoid when the deltoid is in the no fatigue state, respectively. The evaluation reference value may be normalized using the EMD value E ₀ of the.

The maximum fatigue delay width information E _max and the no fatigue delay width information E ₀ are stored in the memory 54 in advance. For example, both torques are successively applied to the steering wheel, and the driver 12 is forced to apply a force against the torque to keep the steering wheel from rotating. When the driver's 12 fatigue reaches the limit, the steering wheel cannot continue to be prevented from rotating in either of the two directions. In this way, in a state in which the rotation of the steering wheel cannot be prevented, the maximum fatigue delay width information E _max may be obtained in the same manner as the evaluation reference value and stored in the memory 54. In addition, for example, the EMD value of the deltoid muscle when the operation-related muscle of the driver 12 has not performed any work for a predetermined time or more is measured, and this value is used for the deltoid muscle when the deltoid muscle is in a fatigue-free state. The EMD value E ₀ may be stored. In the evaluation unit 50, the evaluation reference value E _i in the time domain to be evaluated is referred to, for example, normalized evaluation shown in the following formula (1) using the maximum fatigue EMD value E _max and the no fatigue EMD value E ₀ . A value Es _i may be derived and the driver's 12 fatigue may be evaluated based on the normalized evaluation reference value Es _i .
Es _i = (E _i −E ₀ ) / (E _max −E ₀ ) (1)

  FIG. 4 is a flowchart of an example of the fatigue evaluation method of the present invention performed using the evaluation apparatus 10. Hereinafter, a case where the fatigue of the left and right deltoid muscles of the driver 12 who steers the vehicle is evaluated will be described.

  Fatigue evaluation is started when the driver 12 operates the vehicle and the vehicle is running. FIG. 5 is time-series data of the rotation angle of the steering shaft 18 (that is, the steering angle of the vehicle) in the driving operation performed by the driver 12 in the present embodiment. In FIG. 5, the case where the steering shaft rotates in the right direction is positive. As shown in FIG. 5, in this embodiment, the driver 12 performs a steering operation in which the vehicle rotates a certain amount in the left direction immediately after the steering shaft 18 is rotated in the right direction by a certain amount so as to perform a so-called lane change. Is doing.

  When the operation of the vehicle is started, the myoelectric detection sensor unit 30 detects the myoelectric potentials of the left and right deltoid muscles of the driver 12 and transmits them to the myoelectric information acquisition unit 42 in time series, and the myoelectric information. The acquisition unit 42 acquires action myoelectric potential information of each of the left and right deltoid muscles in time series (step S102).

  The myoelectric information acquisition unit 42 samples the action myoelectric potential information detected by the detection sensors 32 and 34, performs full-wave rectification, and then smooths the myoelectric potential signal using a smoothing filter (low-pass filter). A waveform (smoothed potential waveform) is generated for each of the left and right deltoid muscles, and these smoothed myoelectric waveforms are sent to the synthetic myoelectric waveform deriving unit 46 as active myoelectric potential information for each of the left and right deltoid muscles. Then, the synthetic myoelectric waveform deriving unit 46 sets the sign of the activity myoelectric potential information of the left deltoid muscle to be positive and the sign of the action myoelectric potential information of the right deltoid muscle to be negative, and obtains the action myoelectric potential information of each of the two muscles. The synthesized myoelectric waveform representing the time-series change of the synthesized action myoelectric potential information is derived (step S104). The derived synthetic myoelectric waveform is sent to the evaluation reference value deriving unit 50.

  Further, when the operation of the vehicle is started, the myoelectric potentials of the left and right deltoid muscles are detected, and at the same time, the torque sensor 24 obtains the magnitude information and the direction information of the rotational torque around the steering shaft 18. It detects and transmits to the synthetic muscle strength acquisition part 44, and the synthetic muscle strength information acquisition part 44 acquires synthetic muscle strength information (step S108). The combined muscle strength information acquired by the combined muscle strength information acquisition unit 44 is sequentially output to the combined muscle strength waveform deriving unit 48. In the present embodiment, the combined muscle strength waveform deriving unit 48 derives a combined muscle strength waveform expressed with the right direction torque being positive and the left direction torque being negative (step S110). The derived combined muscle strength waveform is sent to the evaluation reference value deriving unit 50.

  FIGS. 6A to 6D are graphs each showing an example of information acquired or derived in the present embodiment. FIG. 6A is a graph of active myoelectric potential information of the left deltoid muscle of the driver 12 that is detected by the detection sensor 32 and acquired by the myoelectric information acquisition unit 42. FIG. It is a graph of the action myoelectric potential information of the right deltoid muscle of the driver 12 detected by the sensor 34 and acquired by the myoelectric information acquisition unit 42. As is obvious from comparison with the time-series change in the steering angle shown in FIG. 5, in the driver 12, when the steering shaft 18 is rotated in the right direction, the left deltoid is mainly active, and the steering shaft 18 is moved in the left direction. The right deltoid muscle is mainly active when rotating to the right. FIG. 6C shows a state in which the myoelectric information acquisition unit 42 performs full-wave rectification and smoothing processing on the active myoelectric potential information of the left and right deltoid muscles shown in FIGS. 6A and 6B. The smoothed waveforms of the left and right deltoid muscles are also shown. The smoothed waveform after full-wave rectification and smoothing processing represents the magnitude of the activity of the left and right deltoid muscles, but does not include information on the direction of the force exerted by each deltoid muscle. The combined myoelectric waveform deriving unit 46 combines the action myoelectric potential information of the two muscles with the sign of the action myoelectric potential information of the left deltoid muscle being positive and the sign of the action myoelectric potential information of the right deltoid muscle being negative. . FIG. 6D shows a combined myoelectric waveform obtained by synthesizing the smoothed waveforms of the left and right deltoid muscles shown in FIG. As shown in FIG. 6 (d), the changes in the synthetic myoelectric waveform and the synthetic myocardial waveform are in good agreement, and after the synthetic myoelectric waveform changes, the synthetic myoelectric waveform shows the same change. I understand that.

  Then, the evaluation reference value deriving unit 50 compares the acquired synthetic myoelectric waveform and the synthetic muscle strength waveform, and the left and right deltoid muscles with respect to the change in the activity component that contributes to the driving work among the activities of the left and right deltoid muscles. An evaluation reference value representing the degree of time delay of the resultant force change caused by each activity is derived (step S112). In the present embodiment, the evaluation reference value deriving unit 50 obtains a cross-correlation function using the phase shift time τ between the synthetic electromyogram waveform and the synthetic muscle force waveform as a variable, and the phase at which the value of the cross-correlation function is maximized. The deviation time τ is derived as an evaluation reference value representing the degree of the time delay.

  Then, the evaluation unit 52 evaluates the degree of physical fatigue accompanying the driving work of the driver 12 based on the derived evaluation reference value (step S114), and outputs the result of this level division to the output means 52 (step S114). S116).

  In the above, the fatigue evaluation method and system of the present invention have been described by taking the fatigue evaluation in the driving work performed by the worker as an example. In the present invention, the work performed by the worker is not particularly limited. In the present invention, it is possible to quantitatively evaluate a worker's fatigue quantitatively with high accuracy in a work performed by the resultant force of two antagonized forces such as a driving work. In the above embodiment, the muscle fatigue of this test muscle was evaluated using the left and right deltoid muscles of the driver 12 that work when the driver 12 rotates the steering wheel 16 as test muscles. In the present invention, the test muscle for evaluating muscle fatigue is not limited to the deltoid muscle. In the present invention, the test muscles for evaluating the driver's fatigue may be those two muscles that perform the driving work by the resultant force of the two antagonized forces. In particular, it is preferable to employ a muscle of a part where the driver's fatigue is likely to appear when driving the vehicle. The test muscle is preferably, for example, the triceps, biceps, humeral, triangular or trapezius around the shoulder, forearm flexor or extensor. In the above embodiment, the time series data of the torque around the steering shaft is used as the time series data representing the fluctuation of the muscular strength. In the present invention, the time series data of the force related to the measuring means corresponding to the subject muscle may be measured as the time series data representing the fluctuation of the muscle strength. When muscles around the shoulders and arms are the test muscles, the time series data of the steering operation force and the lever operation force may be acquired as time series data representing the fluctuation of the muscle strength. Further, when the muscles around the waist and legs are used as the test muscles, time-series data on the accelerator pedal, the brake pedal, and the footrest force of the footrest may be acquired as time-series data representing the fluctuation of the muscle strength.

  As described above, the fatigue evaluation method and the fatigue evaluation apparatus of the present invention have been described in detail. However, the present invention is not limited to the above-described embodiments, and various improvements and modifications may be made without departing from the gist of the present invention. Of course it is good.

It is a schematic block diagram explaining an example of the fatigue evaluation apparatus of this invention. It is a figure explaining the sticking position to the driver | operator of the myoelectric detection sensor unit of the fatigue evaluation apparatus shown in FIG. It is a figure explaining the evaluation reference value calculated | required with the fatigue evaluation apparatus shown in FIG. 1, and when a human in a still state raise | generates a predetermined | prescribed operation | movement, the fluctuation | variation of the time series of the myoelectric potential which generate | occur | produces in the muscle regarding this operation | movement, and this muscle It is a graph showing the fluctuation | variation of the time series of the muscular strength which is exhibited. It is a flowchart figure of an example of the fatigue evaluation method of this invention performed using the fatigue evaluation apparatus shown in FIG. 5 is time-series data of the rotation angle of the steering shaft in the driving work performed by the driver in the fatigue evaluation method shown in FIG. (A)-(d) is a graph which respectively shows an example of the information acquired or derived | led-out by the fatigue evaluation apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Driver fatigue evaluation apparatus 12 Driver 14 Operation system 16 Steering wheel 18 Steering shaft 20 Measuring means 24 Torque sensor 30 Myoelectric detection sensor unit 32, 34 Detection sensor 36 Electrode 38 Amplifier 42 Myoelectric information acquisition part 44 Synthetic muscle force information acquisition Unit 46 Synthetic myoelectric waveform deriving unit 48 Synthetic muscle force waveform deriving unit 50 Evaluation reference value deriving unit 52 Evaluation unit 54 Memory 56 CPU

Claims (9)

A method for evaluating the degree of physical fatigue of the worker, which occurs with the work performed by the worker,
The work is a work performed by a resultant force of a forward force generated by the activity of one of the two muscles of the worker and a reverse force generated by the activity of the other muscle,
Obtaining, in time series, action myoelectric potential information of each of the two muscles, each representing the magnitude of the activity of the two muscles of the operator;
The action potential information of the two muscles is synthesized with the sign of the action muscle potential information of the acquired one muscle being positive and the sign of the action muscle potential information of the other muscle being negative. Outputting a synthetic myoelectric waveform representing a time series change of myoelectric potential information;
Synthetic muscle strength information indicating the direction and magnitude of the resultant force generated by the activities of the two muscles is acquired in time series, and a composite muscle strength waveform expressed as the forward direction being positive and the reverse direction being negative is output. Steps,
Time of change of the resultant force caused by the activity of each of the two muscles with respect to a change of the component of the activity contributing to the work of the two muscles by comparing the synthetic electromyogram waveform and the synthetic muscle force waveform And a step of deriving an evaluation reference value representing a degree of delay.   The fatigue evaluation method according to claim 1, further comprising a step of evaluating a degree of physical fatigue accompanying the work of the worker based on the evaluation reference value. The worker is a driver driving a vehicle,
The work is performed by driving the vehicle operation means provided in the vehicle in one of the forward direction and the reverse direction by the resultant force generated by the activity of the two muscles of the driver. The fatigue evaluation method according to claim 1, wherein the operation is a controlled operation.   The driving operation is a steering operation of the vehicle, and the driver controls the steering angle of the vehicle by rotationally driving a steering shaft of a steering means provided in the vehicle with the resultant force. The fatigue evaluation method according to claim 3, wherein:   The two muscles of the worker are a muscle of the left half of the worker and a muscle of the right half of the worker corresponding to the muscle of the left half. The method for evaluating fatigue according to crab.   The fatigue evaluation method according to any one of claims 1 to 5, wherein the two muscles of the worker are the left triangular muscle of the worker and the right triangular muscle of the worker.   In the step of deriving the evaluation reference value, a cross-correlation function having a phase shift time between the synthetic myoelectric waveform and the synthetic muscle force waveform as a variable is obtained, and the phase shift time when the value of the cross-correlation function is maximized Is derived as the evaluation reference value, the fatigue evaluation method according to any one of claims 1 to 6.   In the step of evaluating, the synthesized myoelectric waveform is compared with the time series waveform of the synthetic myoelectric strength information, and the synthetic myoelectric waveform with respect to a myoelectric rise timing exceeding a predetermined value is determined. The fatigue evaluation method according to any one of claims 1 to 6, wherein a time delay width of a muscle strength rising timing at which a time series waveform of muscle strength exceeds a predetermined value is derived as the evaluation reference value. An apparatus for evaluating the degree of physical fatigue of the worker, which occurs with the work performed by the worker,
The work is a work performed by a resultant force of a forward force generated by the activity of one of the two muscles of the worker and a reverse force generated by the activity of the other muscle,
Means for acquiring, in time series, action myoelectric potential information of each of the two muscles, each representing the magnitude of the activity of the two muscles of the operator;
The action potential information of the two muscles is synthesized with the sign of the action muscle potential information of the acquired one muscle being positive and the sign of the action muscle potential information of the other muscle being negative. Means for outputting a synthetic myoelectric waveform representing a time-series change in myoelectric potential information;
Synthetic muscle strength information indicating the direction and magnitude of the resultant force generated by the activities of the two muscles is acquired in time series, and a composite muscle strength waveform expressed as the forward direction being positive and the reverse direction being negative is output. Means,
Time of change of the resultant force caused by the activity of each of the two muscles with respect to a change of the component of the activity contributing to the work of the two muscles by comparing the synthetic electromyogram waveform and the synthetic muscle force waveform Means for deriving an evaluation reference value representing the degree of delay;
And a means for evaluating the degree of physical fatigue accompanying the work of the worker based on the evaluation reference value.

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