JP6376799B2 - Tactile sensory perception threshold measurement device, measurement method, and measurement program - Google Patents

Description

  The present invention relates to a measurement apparatus, a measurement method, and a measurement program that can measure a perceptual threshold value of a tactile stimulus with higher accuracy and ease than before.

  The present day is said to be a stress society, and there is a strong demand for objective measurement and evaluation methods for fatigue that can be used in daily life. Conventionally, a phenomenon in which the perception of “flicker” (flicker) when a person sees a blinking light source changes depending on the fatigue level, in particular, the blinking frequency (Critical Flicker Frequency: CFF) at which the “flicker” can be perceived is fatigued. Quantitative evaluation of fatigue (flicker inspection) is performed using a phenomenon that decreases with increasing degree of fatigue. In the flicker test, the flashing frequency of the flashing light is changed (monotonically increased or decreased) over time and presented to the subject, and when the flashing changes from the invisible state to the visible state, or the flashing is visible. The frequency is measured by causing the subject to react, such as pressing a button, when there is no change. The quantitative evaluation of the degree of fatigue using the flicker test is widely used particularly in the industrial hygiene field.

  There is also known a technique that makes it possible to perform a mental fatigue test based on the same flicker perception principle as the flicker test using an image presentation device having a fixed refresh rate such as a liquid crystal display and a CRT (described below). Patent Document 1). In this technique, instead of changing the blinking frequency of the blinking light used in the conventional flicker inspection, the flicker perception is generated by changing the contrast of the blinking light. This makes it possible to easily measure mental fatigue on a daily basis using a mobile terminal device such as a mobile phone, a personal computer, or the like.

  As another fatigue measurement method, a method of measuring the fatigue level of the body or the cranial nerve system based on hearing is also known. For example, Patent Literature 2 below discloses an auditory fatigue testing machine that measures an index representing the degree of fatigue of the body or cranial nerve system. This auditory fatigue testing machine presents two auditory stimuli in succession, and changes the time interval between the two stimuli, whereby the time interval when the presented stimuli are recognized as two stimuli, and 1 A boundary value (threshold value) with a time interval perceived as one stimulus is measured as an index of fatigue level.

  In addition, a two-point identification method using tactile sensation is known. In this identification method, two points on the skin are pressed with a metal stick, a stimulus is applied, the distance between the two points is changed, and a boundary value between the distance perceived as two points and the distance perceived as one point ( Threshold) is used as an index. The two-point identification method is an index representing the spatial resolution of the haptic system.

  For example, in the following Patent Document 3, a plurality of stimuli by light, sound, and vibration are individually or simultaneously presented to a subject of sensory fatigue test, and fusion discrimination of visual, auditory, and skin tactile sensations is performed based on the response of the subject to the stimulus. A technique is disclosed in which a threshold value is obtained, a test value of a fusion discrimination threshold value of a subject, and a reference value of the fusion discrimination threshold value are quantitatively displayed on a list chart, and the state of sensory fatigue of the subject is examined. . Specifically, tactile stimulation and auditory stimulation are presented simultaneously or separately, and fatigue measurement is performed using a sensory threshold value of the stimulation. Two stimuli having a very long duration of 1 second are presented with a slight time difference, and a threshold value is determined as to whether the stimuli are continuous or separated into two.

JP 2010-088862 A Japanese Utility Model Publication No. 6-9609 JP 2006-263248 A

  It is preferable if the fatigue level of a person during work, in particular, the fatigue level of a driver while driving an automobile can be easily evaluated.

  However, visual flicker (perception threshold of blinking) is affected by disturbance of the external light environment, and auditory flicker (perception threshold of two sound stimuli) is affected by noise of the external environment. Change. Therefore, in the fatigue measurement method using visual flicker or auditory flicker, it is necessary to prepare a good ambient environment for measurement in order to obtain an accurate measurement value, which is troublesome.

  In addition, the fatigue measurement method using visual flicker or auditory flicker occupies visual or auditory sense for measurement, although temporarily, when it is carried out during work in daily life, especially while driving a car. So there is a safety problem.

  In contrast, somatosensory flicker (perception threshold of two tactile stimuli) depends on the somatosensory environment between the object and the living body. It is not affected by noise. In addition, somatosensory sensation is independent of vision and hearing, and if measurement is performed during work, attention may be directed to the measurement, which may reduce the attention required for the original work. The degree is slight, and it is possible to measure fatigue while performing operations such as driving a car.

  Therefore, it is desired to measure somatic sensation flicker of a person who is working, particularly a driver who is driving a car. However, according to Patent Documents 2 and 3, somatosensory flicker cannot be measured efficiently.

  Therefore, an object of the present invention is to provide a measuring device, a measuring method, and a measuring program capable of measuring the perceptual threshold value of a tactile stimulus with higher accuracy and ease than before.

  The method for measuring a perceptual threshold value of a tactile stimulus according to the first aspect of the present invention is a method of measuring a perceptual threshold value of a tactile stimulus by giving the subject a tactile stimulus. The tactile stimulus is a stimulus having a constant carrier frequency and the intensity changing with time, and the envelope of the tactile stimulus includes the first pulse and the second pulse adjacent to each other, and the time width of the first pulse. Is 20 milliseconds or more and 500 milliseconds or less, and the second pulse has the same intensity as the first pulse following the first pulse, and the second pulse, the first pulse next to the second pulse, The signal level in the period between is greater than 0 and less than or equal to the intensity of the second pulse. This measurement method includes a measurement step in which a parameter which is a time interval between a first pulse and a second pulse is monotonously changed over time to give a tactile stimulus to the subject, and a state in which the tactile stimulus is given to the subject And determining a parameter value as a perceptual threshold value for the tactile stimulus when the operating device is operated while the subject perceives that the vibration state perceived by the tactile stimulus has undergone a predetermined change.

  Preferably, the carrier frequency is 100 Hz or more and 300 Hz or less, the time width of the first pulse is 100 milliseconds, and the parameter change period is 1 second.

  More preferably, the signal level in the period between the second pulse and the first pulse next to the second pulse is 0 instead of being greater than 0 and less than or equal to the intensity of the second pulse, The time width of the second pulse is the same as the time width of the first pulse, and the time interval between the first pulse and the second pulse is between the second pulse and the first pulse next to the second pulse. Is the same as the time interval.

  The method for measuring a perceptual threshold value of a tactile stimulus according to the second aspect of the present invention is a method of measuring a perceptual threshold value of the tactile stimulus by giving the subject a tactile stimulus. The tactile stimulus is a stimulus having a constant carrier frequency and the intensity changing with time, and the envelope of the tactile stimulus includes the first pulse and the second pulse adjacent to each other, and the time width of the first pulse. Is from 20 milliseconds to 500 milliseconds, and the second pulse follows the first pulse and has the same intensity as the first pulse. In this measurement method, a first parameter, which is a time interval between the first pulse and the second pulse, and a second parameter, which is a signal level in a period between the first pulse and the second pulse, are expressed as time passes. A measurement step in which a tactile stimulus is given to the subject by simultaneously monotonously changing or fixing the first parameter to a predetermined value greater than 0 and monotonously changing the second parameter over time; The subject changes the first parameter and the second parameter when the subject feels that the vibration state perceived by the tactile stimulus has caused a predetermined change and operates the operating device. Determining a parameter value as a perceptual threshold for tactile stimulation.

  Preferably, the second pulse is continuous with the first pulse next to the second pulse.

  More preferably, the signal level in the period between the second pulse and the first pulse next to the second pulse is greater than 0 and smaller than the intensity of the second pulse.

  More preferably, the measuring step is a step of fixing the first parameter to a predetermined value larger than 0 and increasing or decreasing the second parameter monotonously.

  Preferably, the measurement step is a step of increasing the first parameter and the second parameter simultaneously monotonously or decreasing monotonously.

  More preferably, the carrier frequency is 100 Hz to 300 Hz, the time width of the first pulse is 100 milliseconds, the parameter change period is 1 second, and the predetermined value when the first parameter is fixed is: 30 milliseconds.

  More preferably, the time width of the second pulse is the same as the time width of the first pulse, and the time interval between the first pulse and the second pulse is the second pulse after the second pulse and the second pulse. It is the same as the time interval between one pulse.

  A tactile stimulus perception threshold measurement apparatus according to a third aspect of the present invention vibrates in accordance with an input signal and applies a tactile stimulus to a subject, a signal generation unit that generates an input signal, and a subject's instruction. And an operation unit to be received. The input signal has a constant carrier frequency and is a stimulus whose intensity varies with time. The envelope of the input signal includes a first pulse and a second pulse adjacent to each other, and the time width of the first pulse. Is 20 milliseconds or more and 500 milliseconds or less, and the second pulse has the same intensity as the first pulse following the first pulse, and the second pulse, the first pulse next to the second pulse, The signal level in the period between is greater than 0 and less than or equal to the intensity of the second pulse. The signal generation unit generates an input signal by monotonically changing a parameter, which is a time interval between the first pulse and the second pulse, with the passage of time. This measuring device is a parameter value when the subject perceives that the vibration state perceived by the tactile stimulus has undergone a predetermined change and operates the operation unit in a state where the subject is given a tactile stimulus by the vibrator. Further includes a determination unit that determines as a perceptual threshold for tactile stimulation.

  A tactile stimulus perception threshold measurement device according to a fourth aspect of the present invention vibrates in accordance with an input signal and applies a tactile stimulus to a subject, a signal generation unit that generates an input signal, and an instruction from the subject. And an operation unit to be received. The input signal has a constant carrier frequency and is a stimulus whose intensity varies with time. The envelope of the input signal includes a first pulse and a second pulse adjacent to each other, and the time width of the first pulse. Is from 20 milliseconds to 500 milliseconds, and the second pulse follows the first pulse and has the same intensity as the first pulse. The signal generation unit sets a first parameter, which is a time interval between the first pulse and the second pulse, and a second parameter, which is a signal level in a period between the first pulse and the second pulse, over time. The input signal is generated by changing monotonously at the same time, or fixing the first parameter to a predetermined value larger than 0, and monotonously changing the second parameter over time. This measuring apparatus is the first when the subject is operating the operation unit while perceiving that the vibration state perceived by the tactile stimulus has undergone a predetermined change in a state in which the subject has given the tactile stimulus to the subject. It further includes a determining unit that determines the value of the parameter that has been changed among the one parameter and the second parameter as the perceptual threshold value of the tactile stimulus.

  Preferably, the vibration unit and the operation unit are disposed on a steering wheel of the automobile.

  A tactile stimulus perception threshold measurement program according to a fifth aspect of the present invention provides a tactile stimulus to a subject to a computer or a portable terminal device including an operation unit and a vibration unit, and measures the perception threshold of the tactile stimulus. It is a program to let you. The tactile stimulus is a stimulus having a constant carrier frequency and the intensity changing with time, and the envelope of the tactile stimulus includes the first pulse and the second pulse adjacent to each other, and the time width of the first pulse. Is 20 milliseconds or more and 500 milliseconds or less, and the second pulse has the same intensity as the first pulse following the first pulse, and the second pulse, the first pulse next to the second pulse, The signal level in the period between is greater than 0 and less than or equal to the intensity of the second pulse. This measurement program has a function of giving a tactile stimulus to a subject by changing a parameter, which is a time interval between the first pulse and the second pulse, monotonously with the passage of time on a computer or a portable terminal device. A function of determining a parameter value as a perceptual threshold value of the tactile stimulus when the subject perceives that the vibration state perceived by the tactile stimulus has caused a predetermined change and operates the operation device in a state where the stimulus is applied; Is realized.

  A tactile stimulus perception threshold measurement program according to a sixth aspect of the present invention provides a tactile stimulus to a subject to a computer or portable terminal device including an operation unit and a vibration unit, and measures the perception threshold of the tactile stimulus. It is a program to let you. The tactile stimulus is a stimulus having a constant carrier frequency and the intensity changing with time, and the envelope of the tactile stimulus includes the first pulse and the second pulse adjacent to each other, and the time width of the first pulse. Is from 20 milliseconds to 500 milliseconds, and the second pulse follows the first pulse and has the same intensity as the first pulse. The measurement program stores a first parameter that is a time interval between the first pulse and the second pulse and a second parameter that is a signal level in a period between the first pulse and the second pulse. Are simultaneously changed monotonically with the passage of time, or the first parameter is fixed to a predetermined value larger than 0, and the second parameter is changed monotonically with the passage of time to give a tactile stimulus to the subject. The first parameter and the second parameter when the operation device is operated by perceiving that the vibration state perceived by the tactile stimulus has caused a predetermined change in a state where the tactile stimulus is given to the function and the subject. Among the parameters, the function of determining the changed parameter value as the perceptual threshold value of the tactile stimulus is realized.

  According to the present invention, it is possible to measure the perceptual threshold value for tactile stimulation more accurately and simply than before.

  If a vibration device for applying a tactile stimulus is disposed on the steering wheel of an automobile, the perception threshold value of the tactile stimulus of the driving driver can be measured safely as well as when the vehicle is stopped.

  Further, by comparing the measured value with the perceptual threshold (reference value) of the tactile stimulus measured in advance without fatigue, the driver's fatigue state can be determined and promptly presented to the driver. . Therefore, the driver can objectively know his / her fatigue level and can take a break spontaneously when the fatigue level is large. Further, when the driver's fatigue level is large, a warning prompting to take a break can be issued.

It is a block diagram which shows the structure of the measuring apparatus of the perception threshold value of a tactile stimulus which concerns on the 1st Embodiment of this invention. It is a figure which shows the state with which the measuring apparatus of FIG. 1 was mounted | worn with the steering wheel of the motor vehicle. It is a flowchart which shows the control structure of the program which measures the perception threshold value of the tactile stimulus performed in the measuring apparatus of FIG. It is a graph which shows the 1st pulse sequence used for the measurement of the perception threshold of a tactile stimulus. It is a graph which shows the 1st pulse sequence which fixed a specific parameter. 6 is an enlarged graph showing a part of the pulse sequence of FIG. It is a graph which shows the 2nd pulse sequence used for the measurement of the perception threshold of a tactile stimulus. It is a graph which shows the 2nd pulse sequence which fixed a specific parameter. It is a graph which shows the 3rd pulse sequence used for the measurement of the perception threshold of a tactile stimulus. It is a graph which shows the 3rd pulse sequence which fixed the specific parameter. It is a graph which shows the 4th pulse sequence used for the measurement of the perception threshold of a tactile stimulus. It is a graph which shows the 4th pulse sequence which fixed a specific parameter. It is a figure which shows the state with which the measuring device of the perceptual threshold value of the tactile stimulus which concerns on the 2nd Embodiment of this invention was mounted | worn with the steering wheel of the motor vehicle. It is a flowchart which shows the control structure of the program which measures the perception threshold value of the tactile stimulus performed in the measuring apparatus of FIG. It is a figure which shows the example of application to a portable terminal device. It is a figure which shows the example of application to a portable terminal device different from FIG. It is sectional drawing which shows the vibration apparatus used in experiment. It is a graph which shows the measurement result of the perception threshold of tactile stimulation in the process of continuous fatigue loading. It is a graph which shows the measurement result of the perception threshold of tactile stimulation in the process of continuous fatigue loading. It is a graph which shows the measurement result of the conventional fatigue index in the process of continuous fatigue loading. It is a graph which shows the regression analysis result of an experimental result. It is a graph which shows the regression analysis result of an experimental result. It is the graph which plotted the relative change rate of the external field intensity | strength change of a stimulus with respect to a flicker value, and a stimulus presentation frequency change. It is a table | surface which shows the coefficient (alpha) and (beta) of the mutual conversion type | formula calculated | required regarding each external stimulus environment and a flicker value.

  In the following embodiments, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

(First embodiment)
Referring to FIG. 1, the tactile stimulus perception threshold measurement device according to the first embodiment of the present invention includes a control device 100, a signal processing unit 116, a vibration unit 118, and an operation unit 120. The control device 100 includes a CPU 102, ROM 104, RAM 106, recording unit 108, timer 110, bus 112, and signal generation unit 114.

  The CPU 102 controls the entire control device 100. The ROM 104 is a non-volatile storage device, and stores a program and data for controlling the operation of the control device 100. The RAM 106 is a volatile storage device. The recording unit 108 is a non-volatile storage device that retains data even when power is cut off, and is, for example, a hard disk drive, a flash memory, or the like.

  A CPU 102, ROM 104, RAM 106, recording unit 108, timer 110, and signal generation unit 114 are connected to the bus 112. The operation unit 120 is connected to the bus 112 via a predetermined interface (not shown). Data (including control information) is exchanged between the units via the bus 112. The CPU 102 reads a program from the ROM 104 onto the RAM 106 via the bus 112, and executes the program using a part of the RAM 106 as a work area. CPU102 controls each part which comprises the control apparatus 100 according to a program.

  The timer 110 outputs current time information using an internal clock. Under the control of the CPU 102, the signal generation unit 114 generates a predetermined analog signal (hereinafter also referred to as a measurement signal) used for measurement of the perceptual threshold value of the tactile stimulus. The pulse sequence of the measurement signal is generated based on the time information of the timer 110.

  The signal processing unit 116 adjusts the intensity (amplitude) of the measurement signal output from the signal generation unit 114, amplifies and outputs the signal. The vibration unit 118 vibrates according to the input analog signal. The operation unit 120 receives input from the user to the control device 100.

  Referring to FIG. 2, the measurement apparatus according to the present embodiment is attached to the handle of an automobile. FIG. 2 is a view of the handle 200 of the automobile as viewed from the back side (front glass side). The control device 100 is disposed at the center of the steering wheel 200, and on one side of the steering wheel 200 (for example, the right side when viewed from the driver in the steering wheel 200 in a state in which the automobile goes straight), the signal processing unit 116, the vibration unit 118, and An operation unit 120 is arranged.

  The vibration unit 118 vibrates at a frequency that can be perceived by a human. Various devices using a coil or a piezoelectric element (piezo element) can be used for the vibration unit 118. The amplification factor of the signal processing unit 116 is preferably changed appropriately according to the characteristics of the vibration unit 118. The operation unit 120 is, for example, a momentary switch.

  This makes it possible to measure the perceptual threshold value of the driver's tactile stimulus while driving the automobile. The measurement is started with the driver touching the vibration unit 118 with a finger, and the driver maintains the state of touching the vibration unit 118 with the finger during the measurement. The control device 100 generates a measurement signal having a predetermined pulse sequence, and thereby vibrates the vibration unit 118. The control device 100 changes the pulse sequence of the measurement signal as time passes, and changes the vibration state of the vibration unit 118. When the driver perceives that the vibration state perceived by the tactile sense has undergone a predetermined change, the driver operates the operation unit 120 to input the perception to the control device 100. When receiving an input from the operation unit 120, the control device 100 determines the measurement signal generation condition output from the signal generation unit 114 as a perceptual threshold for tactile stimulation.

  Hereinafter, the measurement of the perceptual threshold for tactile stimulation will be described in detail. Referring to FIG. 3, in step 300 of the perceptual threshold measurement program for tactile stimulation, CPU 102 reads a plurality of conditions for determining a pulse sequence of a measurement signal from the storage unit to RAM 106 as an initial setting.

  As the measurement signal, for example, a pulse sequence signal (hereinafter referred to as a first pulse sequence) as shown in FIG. 4 is used. In the first pulse sequence, the constant intensity A0 is maintained for the time T1, and then the intensity (A0-A1) smaller than the constant intensity A0 is maintained for the time T2, and then the original intensity A0 is returned to the time T1. During this period, the waveform that maintains the value is repeated N times at the repetition period T0. The first pulse sequence is a waveform in which two adjacent pulse peaks are periodically repeated. The total time Tm is Tm = T0 × N.

  Here, the waveform of FIG. 4 shows an envelope of a carrier waveform (for example, a sine wave) having a constant frequency f0. That is, the period of the vibration waveform is sufficiently smaller than the pulse width (time) of the pulse sequence. For example, the frequency f0 of the vibration waveform is 250 Hz (period 4 msec), and the time T1 is 100 msec.

When the intensity A0 is fixed to, for example, 20 dBSL (Sensation Level) which is 10 times the sensory threshold, the parameters for determining the first pulse sequence are T0, T1, T2, and A1. Here, the pulse sequence is changed by the parameters T2 and A1 under the conditions of T0 = 1 (sec) and T1 = 100 (msec). Specifically, the following three types of conditions are used. The signal intensity decrease amount A1 is expressed as a ratio (%) to the intensity A0.
Time change condition: A1 is fixed to 100%, and T2 is changed in a range of 1 msec to 30 msec in 1 msec increments.
Strength change condition: T2 is fixed at 30 msec, and A1 is changed in 1% increments within a range of 1% to 30%.
-Time and intensity change conditions: A1 (%) and T2 (msec) are simultaneously changed to the same value. That is, (A1, T2) is changed in the range of (1, 1) to (30, 30).

  The first pulse sequence of the time change condition is referred to as a “time change bistimulus sequence”. The first pulse sequence of the intensity change condition is referred to as “intensity change bistimulus sequence”. The first pulse sequence of the time and intensity change condition is referred to as “time and intensity change bistimulus sequence”.

  FIG. 5 shows a time-varying bistimulus sequence. That is, if A1 = 100 (%) is fixed, the pulse sequence in FIG. 4 becomes the pulse sequence in FIG. A predetermined time is required for the rise and fall of the pulse. Here, as shown in FIG. 6, in the time-varying bi-stimulus sequence, the rising edge of the first pulse in the repetition period T0 and the falling edge of the next pulse are, for example, 4 msec, the falling edge of the first pulse, The rise of the next pulse is, for example, 2 msec.

  The rise and fall of the pulse are not limited to the values exemplified here. What is necessary is just to set to an appropriate value with the characteristic of a pulse width and a signal generator.

  When using the time-varying bi-stimulus sequence, in step 300, T1 is set to 100 (msec), A1 is set to 100 (%), and the upper limit of the parameter (T2) is set to 30 (msec). When the intensity change bi-stimulus sequence is used, in step 300, T1 is set to 100 (msec), T2 is set to 30 (msec), and the upper limit of the parameter (A1) is set to 30 (%). When the time and intensity change bi-stimulus sequence is used, in step 300, T1 is set to 100 (msec), and the upper limit of parameters (A1, T2) is set to (30 (%), 30 (msec)).

  In step 302, the CPU 102 sets initial values for parameters according to the sequence used for measurement. When the time-varying bistimulus sequence is used, the initial value of the parameter (T2) is 1 (msec). When the intensity change bi-stimulus sequence is used, the initial value of the parameter (A1) is 1 (%). When using the time and intensity change bistimulation sequence, the initial values of the parameters (A1, T2) are A1 = 1 (%) and T2 = 1 (msec).

  In step 304, the CPU 102 controls the signal generation unit 114 to generate a measurement signal based on the settings in steps 300 and 302.

  In step 306, the CPU 102 determines whether or not the operation unit 120 has been operated. Specifically, the CPU 102 determines whether or not a signal indicating that a switch as the operation unit 120 has been pressed is received. When the signal is received, it is determined that the signal has been operated, and the control proceeds to Step 314. Otherwise, control passes to step 308.

  Here, as will be described later, it is changed so that the degree of separation between adjacent pulses is increased in the repetition period T0. For example, when a time-varying bistimulus sequence is used, the interval T2 is gradually increased from 1 msec. If the driver is touching the vibration unit 118 with the middle finger of the right hand during driving of the automobile, for example, the driver first perceives the vibration as one stimulus. Thereafter, when the degree of separation between the two pulses increases to some extent, the driver perceives vibration as two stimuli. When the driver perceives vibration as two stimuli, the driver presses the switch that is the operation unit 120 with, for example, the index finger of the right hand.

  In step 308, the CPU 102 obtains the current time from the timer and determines whether or not the repetition period T0 has been repeated a predetermined number of times (N times), that is, whether or not the time Tm = T0 × N has elapsed. . If it is determined that the time has elapsed, control proceeds to step 310. Otherwise, control returns to step 304 and a measurement signal is generated under the current conditions.

  In step 310, the CPU 102 determines whether or not the parameter currently used for generating the measurement waveform is a limit value (here, an upper limit value). If it is a limit value, the CPU 102 ends the program. Otherwise control passes to step 312.

  In step 312, the CPU 102 changes the current parameter. For example, the current parameter value is increased by a predetermined increment to obtain a new parameter value. When using a time-varying bistimulus sequence, the value of parameter T2 is increased by 1 msec. When the intensity change bistimulus sequence is used, the value of the parameter A1 is increased by 1%. When using the time and intensity change bistimulus sequence, the value of parameter A1 is increased by 1% and the value of parameter T2 is increased by 1 msec.

  Thereafter, control returns to step 304. Thus, a measurement signal is generated using the new parameter value.

  If it is determined in step 306 that an operation has been received, in step 314, the CPU 102 stores the current parameter value in, for example, the RAM 106.

  As described above, the parameter value when the driver perceives vibration as one stimulus with his / her finger as two stimuli can be determined as the perceptual threshold value for the tactile stimulus. The perceptual threshold value of the measured tactile stimulus changes in accordance with the degree of fatigue, as will be described later. Therefore, if the perception threshold of the tactile stimulus is measured and stored as a reference value in a state where the user is not fatigued in advance, the perception threshold of the tactile stimulus is measured in any fatigue state and compared with the reference value. The degree of fatigue at that time can be evaluated.

  In the above description, the case where the driver touches the vibration unit 118 with the middle finger of the right hand and operates the operation unit 120 with the index finger of the right hand is described, but the present invention is not limited to this. For example, the vibration unit 118 and the operation unit 120 may be arranged so that the driver can touch the vibration unit 118 with the index finger of the right hand and operate the operation unit 120 with the thumb of the right hand. Further, the vibration unit 118, the operation unit 120, and the signal processing unit 116 may be arranged so that the driver can perform measurement using the left hand.

  Although the case where the first pulse sequence shown in FIG. 4 is used as the measurement signal has been described above, the present invention is not limited to this. For example, a pulse sequence signal (hereinafter referred to as a second pulse sequence) as shown in FIG. 7 may be used as the measurement signal.

  In the second pulse sequence, after maintaining the constant intensity A0 for the time T1, the intensity (A0-A1) smaller than the constant intensity A0 is maintained for the time T2, and then the original intensity A0 is returned to the value. Is maintained for the remaining period of the repetition period T0. When repeating N times, the total time Tm is Tm = T0 × N. The second pulse sequence is a waveform (a missing waveform) obtained by reducing a carrier waveform of a constant intensity at a predetermined timing for a predetermined period (T2).

  Specifically, when the carrier frequency f0 is 250 Hz and the intensity A0 is fixed to 20 dBSL, the parameters for determining the second pulse sequence are T0, T1, T2, and A1 as in the first pulse sequence. . Similarly to the first pulse sequence, the pulse sequence is changed by the parameters T2 and A1 under the conditions of T0 = 1 (sec) and T1 = 100 (msec). Specifically, similarly to the first pulse sequence, the decrease amount A1 of the signal intensity is expressed as a ratio (%) to the intensity A0, and the above three types of conditions (time change condition, intensity change condition, time and Intensity change condition) is used.

  The second pulse sequence with the time change condition is referred to as a “time change missing sequence”. The second pulse sequence of the intensity change condition is referred to as “intensity change missing sequence”. The second pulse sequence of the time and intensity change condition is referred to as “time and intensity change missing sequence”.

  FIG. 8 shows a time change missing sequence. That is, when A1 = 100 (%) is fixed, the pulse sequence of FIG. 7 becomes the pulse sequence of FIG. The rise and fall times of the pulse are the same as in FIG. 6, and the rise of the first pulse in the repetition period T0 and the fall of the next pulse are, for example, 4 msec, and the fall of the first pulse and The rise of the next pulse is, for example, 2 msec.

  When the second pulse sequence is used, for example, when the time change missing sequence (FIG. 8) is used, the interval T2 is gradually increased from 1 msec. Therefore, first, the subject perceives the vibration as a uniform stimulus, and when the missing degree (interval of T2) increases to some extent, the subject perceives the lack in the stimulus. The test subject operates the operation unit 120 when the subject perceives the lack in the stimulus. Therefore, even when the second pulse sequence is used, when the state of vibration perceived by the subject changes with a finger or the like (when a defect starts to be perceived in a stimulus from a uniform stimulus) ) Parameter value can be determined as the perceptual threshold for tactile stimulation.

  Further, a pulse sequence signal as shown in FIG. 9 (hereinafter referred to as a third pulse sequence) may be used as the measurement signal.

  In the third pulse sequence, the constant intensity A0 is maintained for the time T1, and then the intensity (A0-A1) smaller than the constant intensity A0 is maintained for the time T2, and then the original intensity A0 is returned. Is repeated. The third pulse sequence is a continuous waveform of pulses.

  Specifically, when the carrier frequency f0 is 250 Hz and the intensity A0 is fixed to 20 dBSL, the parameters for determining the third pulse sequence are T1, T2, and A1. Further, the pulse sequence is changed by changing the parameters T2 and A1 under the conditions of T1 = 100 (msec) or T1 = T2 and the time Tm = 1 (sec) for maintaining the parameter value. Specifically, similarly to the first pulse sequence, the decrease amount A1 of the signal intensity is expressed as a ratio (%) to the intensity A0, and the above three types of conditions (time change condition, intensity change condition, time and Intensity change condition) is used.

  The third pulse sequence with the time change condition when T1 is fixed at 100 (msec) is referred to as “time change continuous sequence A”, and the third pulse sequence with the time change condition when T1 = T2 is set to “time This is referred to as “change continuous sequence B”. The third pulse sequence of the intensity change condition when T1 is fixed at 100 (msec) is referred to as “intensity change continuous sequence A”, and the third pulse sequence of the intensity change condition when T1 = T2 is expressed as “intensity change condition”. This is referred to as “change continuous sequence B”. The third pulse sequence of the time and intensity change condition when T1 is fixed to 100 (msec) is referred to as “time and intensity change continuous sequence A”, and the third of the time and intensity change condition when T1 = T2 is set. The pulse sequence is referred to as “time and intensity change continuous sequence B”.

  FIG. 10 shows time-varying continuous sequences A and B. That is, when A1 = 100 (%) is fixed, the pulse sequence of FIG. 9 becomes the pulse sequence of FIG. Here, the rise and fall times of the pulse are the same for all pulses, unlike FIG. 6, for example, 2 msec.

  When using the third pulse sequence, for example, when using a time-varying continuous sequence (FIG. 10), the pulse time T1 and the interval T2 are gradually increased from the lower limit value. Therefore, at first, the subject perceives the vibration as one uniform stimulus, and when the pulse time T1 and the interval T2 increase to some extent, the subject perceives as a plurality of stimuli. When the subject perceives vibration as a plurality of stimuli, he / she operates the operation unit 120. Therefore, when the third pulse sequence is used, the parameter value when the subject perceives vibration as a single stimulus from a state where the subject perceives vibration as a single stimulus is perceived as a tactile stimulus perception. It can be determined as a threshold.

  Further, a pulse sequence signal as shown in FIG. 11 (hereinafter referred to as a fourth pulse sequence) may be used as the measurement signal. In the first pulse sequence shown in FIG. 4, the signal has a predetermined intensity (A0-A2) during the period in which the signal intensity is zero. When A2 = 0 (%) and the predetermined intensity (A0-A2) is made equal to A0, the second pulse sequence shown in FIG. 7 is obtained. Therefore, the fourth pulse sequence is an intermediate sequence between the first pulse sequence and the second pulse sequence. The fourth pulse sequence is also a sequence including a first pulse sequence (fourth pulse sequence with A2 = 100 (%)) and a second pulse sequence (fourth pulse sequence with A2 = 0 (%)).

  In FIG. 11, if the repetition period T0 is changed to T0 = 2 × (T1 + T2), the intensity (A0−A2) time T3 = T2. Further, if A2 = A1, the fourth pulse sequence shown in FIG. 11 becomes the third pulse sequence shown in FIG. Therefore, the fourth pulse sequence is also a sequence including the third pulse sequence. That is, the fourth pulse sequence is a sequence including the first to third pulse sequences.

  Specifically, when the carrier frequency f0 is 250 Hz and the intensity A0 is fixed to 20 dBSL, the parameters for determining the fourth pulse sequence are T0, T1, T2, A1, and A2. The parameter A2 is fixed to a predetermined value, and the pulse sequence is changed by the parameters T2 and A1 under the conditions of T0 = 1 (sec) and T1 = 100 (msec).

  Regarding the fourth pulse sequence, similarly to the first pulse sequence, the decrease amount A1 of the signal intensity is expressed as a ratio (%) to the intensity A0, the parameter A2 is fixed to a predetermined value, and the above three types of conditions ( Time change conditions, intensity change conditions, and time and intensity change conditions) can be used.

  For example, FIG. 12 shows a pulse sequence when A1 = 100 (%) in FIG. Furthermore, A2 can be set to a specific value, for example, 10%, 50%, or 100%.

  In FIG. 12, a pulse sequence with A2 = 10 (%) is referred to as a “first intermediate stimulation sequence”. In FIG. 12, a pulse sequence with A2 = 50 (%) is referred to as a “second intermediate stimulation sequence”. In the first and second intermediate stimulation sequences, T0 = 1 (sec) and T1 = 100 (msec). When the perceptual threshold value of the tactile stimulus is measured using the first or second intermediate stimulus sequence, the other parameters are the above three types of conditions (time change condition, intensity change condition, and time and intensity change condition). ) According to any of the conditions.

  In FIG. 12, the pulse sequence when A2 = 100 (%) and the repetition period T0 = 0.5 (sec) is referred to as a “third intermediate stimulation sequence”. In the third intermediate stimulation sequence, T1 = 100 (msec). When the perception threshold of tactile stimulation is measured using the third intermediate stimulus sequence, the other parameters are the above three conditions (time change condition, intensity change condition, and time and intensity change condition). Change according to any condition.

(Second Embodiment)
In the first embodiment, the case where the measurement device includes one vibration unit has been described. However, in the second embodiment, the arbitraryness of the subject in the measurement of the perceptual threshold value of the tactile stimulus is eliminated, and the objective is objectively performed. In order to perform the measurement, the measurement apparatus includes a plurality of vibration units.

  The tactile stimulus perception threshold measurement device according to the present embodiment is configured in the same manner as the measurement device (FIG. 1) according to the first embodiment. However, unlike the first embodiment, the measurement apparatus according to the present embodiment is arranged on both sides of the handle 200 as shown in FIG. 13 and includes a signal processing unit, a vibration unit, and an operation unit. 1 unit 222 and 2nd unit 224 are provided.

  A different measurement signal is input to each signal generation unit of the first unit 222 and the second unit 224, amplified, and input to the corresponding vibration unit. Accordingly, the vibration units of the first unit 222 and the second unit 224 realize different vibration states.

  The measurement process executed in the present embodiment will be described with reference to FIG. The flowchart of FIG. 14 differs from the flowchart of FIG. 3 only in that step 330 and step 332 are added. In FIG. 13, in the step having the same reference number as in FIG. 3, basically the same processing as in FIG. 3 is executed. However, the processing of some steps is slightly different because two sets of the signal processing unit, the vibration unit, and the operation unit are included. In the following, differences will be mainly described.

  After initial settings and initial values are set for parameters, a measurement signal is generated based on the parameter values in step 304. At this time, the signal generation unit 114 generates two measurement signals. One measurement signal (hereinafter also referred to as a true measurement signal) is generated based on the parameter changed in step 312 as in the first embodiment. The other measurement signal (hereinafter also referred to as a dummy signal) is not changed from the measurement signal generated first. For example, the dummy signal maintains the same pulse sequence as the measurement signal generated by first executing step 304.

  Of the two signal processing units, one signal processing unit receives a true measurement signal and the other signal processing unit receives a dummy signal. That is, the vibration part corresponding to each signal processing part vibrates by a true measurement signal or a dummy signal.

  At the start of measurement (for example, in step 302), the CPU 102 determines a signal processing unit (vibration unit) to which a true measurement signal and a dummy signal are input. During one measurement, the signal processing unit to which the true measurement signal and the dummy signal are respectively input is not replaced. For example, when a true measurement signal is first input to the signal processing unit of the first unit 222 (a dummy signal is input to the signal processing unit of the second unit 224), the parameter value is changed during the measurement. The newly generated true measurement signal is input to the signal processing unit of the first unit 222.

  In the determination process of step 306, the CPU 102 determines whether or not at least one of the operation unit of the first unit 222 and the operation unit of the second unit has been operated. If it is determined that it has been operated, control proceeds to step 330. Otherwise, control proceeds to step 308 as in the first embodiment.

  In step 330, the CPU 102 determines whether or not the operation unit determined to have been operated in step 306 is a correct operation unit (correct answer), that is, an operation corresponding to the vibration unit to which a true measurement signal is input. It is determined whether it is a part. When it is determined that the answer is correct, the control proceeds to step 314, and the CPU 102 stores the current parameter value. Otherwise, that is, when the operation unit determined to be operated corresponds to the vibration unit to which the dummy signal is input, or when two operation units are operated simultaneously, the control proceeds to step 332. .

  In step 332, the CPU 102 presents a predetermined warning message (eg, auditory or visual information) and control returns to step 302. As a result, when the wrong operation unit is operated, the measurement is started again.

  As described above, it is possible to detect that the driver has arbitrarily operated the operation unit even though the driver cannot perceive it as two stimuli, and to exclude measurement values (parameter values) in that case. it can.

  In the above description, the case where the measurement device includes two sets of units including the signal generation unit, the vibration unit, and the operation unit has been described, but the measurement device is not limited thereto. The measurement device may include three or more sets of units. Even in such a case, a true measurement signal and a dummy signal are generated, and among the plurality of vibration parts, one vibration part vibrates with the true measurement signal, and the other vibration parts vibrate with the dummy signal. To do. Increasing the number of units can more accurately eliminate the subject's arbitraryness and more objectively measure the perceptual threshold of tactile stimulation.

  For example, four units are attached to the steering wheel, the two units correspond to the driver's right hand, and the remaining two units correspond to the left hand. For example, when the driver grips the steering wheel, the middle finger and ring finger of the right hand touch two vibration parts, and the operation part corresponding to the vibration part touched by the middle finger is arranged near the index finger of the right hand, and the vibration part touched by the ring finger The two units are attached to the handle so that the corresponding operation unit is arranged near the little finger. The remaining two units are attached to the handle so that they have the same positional relationship with the finger of the left hand. The driver operates the operation unit near the vibration unit that perceives the change in the vibration state.

  The present invention has been described above by describing the embodiment. However, the above-described embodiment is an exemplification, and the present invention is not limited to the above-described embodiment, and is implemented with various modifications. be able to.

  In the above, T1 = 100 (msec) is fixed in the first and second pulse sequences, but the present invention is not limited to this. T1 may be 20 msec or more and 500 msec or less.

  In the above description, T2 = 30 (msec) is fixed in the intensity change bi-stimulation sequence of the first pulse sequence and the intensity change missing sequence of the second pulse sequence. However, the present invention is not limited to this. T2 may be 5 msec or more and 90 msec or less.

  Although the case where the parameter T2 is monotonously increased has been described above, the present invention is not limited to this. The parameter T2 may be monotonously decreased from the upper limit value. In this case, the subject perceives one stimulus from the state in which the two stimuli are first perceived. Therefore, if the subject operates the operation unit when one stimulus is perceived from a state where two stimuli are perceived, the value of the parameter T2 at that time is determined as the perception threshold. Can do.

  Similarly, although the case where the parameter A2 between the two stimuli is monotonously increased has been described, it may be monotonously decreased. In this case, similarly to the above, if the subject operates the operation unit when perceiving one stimulus from the state of perceiving two stimuli, the parameter A1 at that time The value can be determined as a perceptual threshold.

  Further, the parameters T2 and A1 are not limited to increasing simultaneously, but may be decreased simultaneously. In this case, similarly to the above, if the subject operates the operation unit when one stimulus is perceived from the state in which two stimuli are perceived, the parameter T2 at that time and The value of A1 can be determined as the perception threshold.

  In the above, the parameters T2 and A1 are changed in 1% increments within the range of 1 to 30% of the respective reference values (the reference value of the parameter T2 is a pulse width of 100 msec and the reference value of the parameter A1 is a pulse height A0). However, the present invention is not limited to this. For example, the upper limit values of the parameters T2 and A1 may be 60% (if the reference value of the parameter T2 is a pulse width of 100 msec, the upper limit value of the parameter T2 is 60 msec).

  Further, when the parameters T2 and A1 are changed simultaneously, if the change directions of the parameters T2 and A1 are the same (that is, if both increase monotonously or decrease monotonously), the change of the parameter T2 The degree and the degree of change of the parameter A1 may be different. For example, the parameter T2 may be changed in 0.5% increments in the range of 1-30%, and the parameter A1 may be changed in 1% increments in the range of 1-30%. In that case, the same value is set for the parameter A1 twice.

  The carrier frequency f0 (Hz) is not limited to 250 Hz. The carrier frequency f0 may be a frequency that can be perceived as vibration by a human sense of touch, and is preferably a value of 100 Hz to 300 Hz (100 ≦ f0 ≦ 300).

  In the above description, the case where the measurement device is attached to the steering wheel is described so that the measurement can be performed during the driving of the automobile. However, the present invention is not limited to this. The measuring device may be mounted at a position other than the steering wheel inside the automobile as long as it is a position where the driver can safely drive without driving the driver during driving.

  Further, the vibration unit may be configured to be attachable to the fingertip. For example, you may arrange | position the vibration part 118 to the front-end | tip part of the finger | toe of a glove or a finger sack.

  Transmission of signals (measurement signals, operation unit output signals) between the units is not limited to wired communication, and may be via wireless communication such as Bluetooth (registered trademark).

  A car navigation system may be used as the control device 100. For example, if the car navigation system includes an acoustic output terminal, a measurement signal may be output from the output terminal and input to a signal processing unit (amplifier). A predetermined message may be displayed on the display unit of the car navigation system according to the degree of fatigue determined from the measurement result.

  Moreover, it is not limited to the case of measuring during work. As the control device 100, for example, a known computer or a mobile terminal device (a mobile phone, a smartphone, a PHS, a PDA, or the like) can be used. When a computer is used as the control device 100, for example, a computer keyboard or mouse can be used as the operation unit 120.

  When a portable terminal device is used as the control device 100, it can be configured as shown in FIG. In FIG. 15, the mobile terminal device 230 has the same configuration as the control device 100 of FIG. The signal processing unit is arbitrary and may be included in the mobile terminal device 230. A part of the touch panel display constituting the upper surface of the mobile terminal device 230 is used as the operation areas 232 and 234. The vibration parts 236 and 238 are configured integrally with the touch panel display.

  The program shown in FIG. 13 is executed by the CPU inside the mobile terminal device 230 while the user touches the vibration units 236 and 238 with a finger or the like, as in the second embodiment, and the vibration units 236 and 238 are executed. The true measurement signal and dummy signal generated by the signal generation unit are input to. As described above, when the user perceives a change in one vibration state of the vibration units 236 and 238, the user touches the corresponding region of the operation regions 232 and 234. As a result, as in the second embodiment, it is possible to measure the perceptual threshold value of the tactile stimulus without the user's arbitraryness.

  Moreover, when using a portable terminal device as the control apparatus 100, it can also comprise as shown in FIG. In FIG. 16, the mobile terminal device 250 has the same configuration as the control device 100 of FIG. The signal processing unit is arbitrary and may be included in the mobile terminal device 250. A large number of vibrators 260 are arranged on the entire surface of the touch panel display constituting the upper surface of the mobile terminal device 250. As in FIG. 15, a part of the touch panel display is used as the operation areas 252 and 254.

  When the user touches the vibration areas 256 and 258 with a finger or the like, the program shown in FIG. 13 is executed by the CPU inside the mobile terminal device 230 as in the second embodiment, and the vibration areas 256 and 258 are executed. The true measurement signal and the dummy signal generated by the signal generation unit are input to the transducer 260 arranged in FIG. As described above, when the user perceives a change in one vibration state of the vibration areas 256 and 258, the user touches the corresponding area of the operation areas 252 and 254. As a result, as in the second embodiment, it is possible to measure the perceptual threshold value of the tactile stimulus without the user's arbitraryness.

  Experimental results are shown below, and it is shown that the perceptual threshold value of the tactile stimulus of the present invention is effective as a fatigue index.

  A fatigue load experiment was performed in which subjects were subjected to desk work all night continuously from 2:00 pm on the first day to 8:00 am on the second day (next day). During the fatigue load, the subject measured the fatigue state every 3 hours. The subject took a nap for about 4 hours from 9:00 am to 1:00 pm after measurement at 8:00 am the next morning, and then performed fatigue measurement again.

  The fatigue measurement was performed by the four types of methods for the same subject. That is, fatigue measurement was performed using the measurement of the perceptual threshold of the tactile stimulus according to the present invention, the flicker value measurement as described above, the Visual Analog Scale (hereinafter referred to as VAS) using the questionnaire, and the “subjective symptom search”.

  VAS is a known fatigue evaluation method proposed by the Japan Fatigue Society. The left end of the 10cm line printed on paper is defined as "the best sense that does not feel tired at all", and the right end is defined as "the worst interval that is exhausted so that nothing can be done". This is a subjective evaluation method in which it is determined subjectively whether or not it is located in a place where it is filled with a cross mark.

  Subjective symptoms are also one of the known subjective indicators. Focusing on the 25 subjective symptoms of the body that occur during the fatigue process, which was announced about 20 years ago by the Occupational Health Research Institute under the jurisdiction of the Ministry of Health, Labor and Welfare, The total score of all items is used as an index of fatigue. For example, items such as “blind eyes”, “shoulder shoulders”, “dull feet” are rated on a five-point scale from “very good: 5 points” to “not at all: 1 point”. It is a subjective evaluation method to evaluate.

  The apparatus used for the measurement of the perceptual threshold for tactile stimulation according to the present invention was configured in the same manner as in FIG. A small speaker (4Ω, 0.5 W) was used for the vibration unit 118. As shown in FIG. 17, the cone (shown by a broken line) was removed from the speaker 130 to inhibit the generation of sound. A vibrating bar 136 is attached to a voice coil unit 134 that is disposed above the magnet unit 132 and constitutes the vibrator. As the vibrating bar 136, a square acrylic bar having a length of 5 cm and a cross-sectional shape of 3 mm on a side was used.

  A block 140 is arranged around the speaker 130 so as to be in contact with the speaker 130 so that the subject can support the hand during measurement and to prevent sound. The height of the block 140 is substantially the same as the tip of the vibrating bar 136.

  A computer was used as the control device. For the signal processing unit, an attenuator (attenuator) and an amplifier (amplifier) were used. A sound band signal was generated by a computer and input to an external attenuator to adjust the signal strength. The adjusted signal was input to the amplifier and amplified, and then input to the speaker 130 to vibrate the vibrating bar 134.

  The test was performed with the finger lightly touching the tip of the vibrating rod 136 so as not to apply force to the vibrating rod 136, and a weight of 24 g applied in a cantilevered manner on the finger. During measurement, in order to prevent information other than vibration from being brought about by hearing, the subject was asked to wear headphones, and white noise of 60 dBSL was supplied from the headphones to eliminate the influence of hearing.

  Since the first to fourth pulse sequences described above include a plurality of parameters, various pulse sequences can be realized by fixing some parameters. The vibration intensity A0 was 20 dBSL. The measurement was performed five times under each condition, and the average value of the three measured values excluding the maximum value and the minimum value was used as the perception threshold.

  The graph which plotted the measured value of the perception threshold of a tactile stimulus is shown in FIG.18 and FIG.19. The relationship between the plot figure and the pulse sequence used for the measurement is as follows.

The plot figure ◆ in FIG. 18 is the same as that in FIG. 4 (first sequence), T0 = 1 (sec), T1 = 100 (msec), measurement time Tm = 1 (sec) at each parameter value (repetition count N = 1). ) Represents the measured value in the sequence. This fixed condition is referred to as a first fixed condition.
・ ◆ in Fig. 18 (a)
In addition to the first fixed condition, A1 = 100 (%), and T2 was changed in a range of 1 msec to 30 msec in 1 msec increments (time-varying bistimulation sequence in FIG. 5).
・ ◆ in Fig. 18 (b)
In addition to the first fixed condition, T2 = 30 (msec), and A1 was changed in a range of 1% to 30% in increments of 1% (intensity change bistimulus sequence).
-◆ in (c) of FIG.
Under the first fixed condition, A1 (%) and T2 (msec) were changed in the range of (1, 1) to (30, 30) (time and intensity change bi-stimulation sequence).

The plot figure 1 in FIG. 18 is the same as that in FIG. 11 (fourth sequence), T0 = 1 (sec), T1 = 100 (msec), and measurement time Tm = 1 (sec) at each parameter value (repetition count N = 1). ), The measured value in the second intermediate stimulation sequence with A2 = 50 (%). This fixed condition is referred to as a second fixed condition.
・ ■ in Figure 18 (a)
In addition to the second fixed condition, A1 = 100 (%), and T2 was changed in a range of 1 msec to 30 msec in 1 msec increments.
・ ■ in Figure 18 (b)
In addition to the second fixed condition, T2 = 30 (msec), and A1 was changed in a range of 1% to 30% in 1% increments.
・ ■ in (c) of FIG.
Under the second fixed condition, A1 (%) and T2 (msec) were changed in the range of (1, 1) to (30, 30).

The plot figure Δ in FIG. 18 is shown in FIG. 11 (fourth sequence) as T0 = 1 (sec), T1 = 100 (msec), and measurement time Tm = 1 (sec) at each parameter value (repetition count N = 1). ), The measured value in the first intermediate stimulation sequence with A2 = 10 (%). This fixed condition is referred to as a third fixed condition.
・ △ in Fig. 18 (a)
In addition to the third fixed condition, A1 = 100 (%), and T2 was changed in a range of 1 msec to 30 msec in 1 msec increments.
・ △ in Fig. 18 (b)
In addition to the third fixed condition, T2 was set to 30 (msec), and A1 was changed in a range of 1% to 30% in 1% increments.
・ △ in Fig. 18 (c)
Under the third fixed condition, A1 (%) and T2 (msec) were changed in the range of (1, 1) to (30, 30).

The plot figure x in FIG. 18 is the same as that in FIG. 7 (second sequence), T0 = 1 (sec), T1 = 100 (msec), measurement time Tm = 1 (sec) at each parameter value (repetition count N = 1). ) Represents the measured value in the sequence. This fixed condition is referred to as a fourth fixed condition.
・ X in Fig. 18 (a)
In addition to the fourth fixed condition, A1 = 100 (%), and T2 was changed in a range of 1 msec to 30 msec in 1 msec increments (time change missing sequence in FIG. 8).
-X in FIG. 18 (b)
In addition to the fourth fixed condition, T2 = 30 (msec), and A1 was changed in a range of 1% to 30% in steps of 1% (intensity change missing sequence).
-X in (c) of FIG.
Under the fourth fixed condition, A1 (%) and T2 (msec) were changed in the range of (1, 1) to (30, 30) (time and intensity change missing sequence).

  The plot figure ◆ in FIG. 19 has the same conditions as those in FIG.

The plot figure (3) in FIG. 19 is the same as that in FIG. 11 (fourth sequence). = 1), A2 = 100 (%) represents a measurement value in the third intermediate stimulation sequence. This fixed condition is referred to as a fifth fixed condition.
・ ■ in Fig. 19 (a)
In addition to the fifth fixed condition, A1 = 100 (%), and T2 was changed in a range of 1 msec to 30 msec in 1 msec increments.
・ ■ in Figure 19 (b)
In addition to the fifth fixed condition, T2 = 30 (msec), and A1 was changed in a range of 1% to 30% in 1% increments.
・ ■ in (c) of FIG.
Under the fifth fixed condition, A1 (%) and T2 (msec) were changed in the range of (1, 1) to (30, 30).

Plot figure Δ in FIG. 19 represents a measurement value in a sequence in FIG. 9 (third sequence) where T1 = 100 (msec) and measurement time Tm = 1 (sec) at each parameter value. This fixed condition is referred to as a sixth fixed condition.
・ △ in Fig. 19 (a)
In addition to the sixth fixed condition, A1 = 100 (%), and T2 was changed in a range of 1 msec to 30 msec in 1 msec increments (time change continuous sequence A).
・ △ in Fig. 19 (b)
In addition to the sixth fixed condition, T2 = 30 (msec), and A1 was changed in a range of 1% to 30% in steps of 1% (intensity change continuous sequence A).
・ △ in Fig. 19 (c)
Under the sixth fixed condition, A1 (%) and T2 (msec) were changed in the range of (1, 1) to (30, 30) (time and intensity change continuous sequence A).

Plot figure x in FIG. 19 represents a measurement value in a sequence in FIG. 9 (third sequence) where T1 = T2 and measurement time Tm = 1 (sec) at each parameter value. This fixed condition is referred to as a seventh fixed condition.
-X in FIG.
In addition to the seventh fixed condition, A1 = 100 (%), and T2 (= T1) was changed in a range of 1 msec to 30 msec in 1 msec increments (time change continuous sequence B).
-X in FIG. 19 (b)
In addition to the seventh fixed condition, T2 (= T1) = 30 (msec) was set, and A1 was changed in a range of 1% to 30% in steps of 1% (intensity change continuous sequence B).
-X in (c) of FIG.
Under the seventh fixed condition, A1 (%) and T2 (= T1) (msec) were changed in the range of (1, 1) to (30, 30) (time and intensity change continuous sequence B).

  From FIG. 18 and FIG. 19, in all 12 conditions (12 pal sequences), it is possible to confirm a tendency that the threshold value increases with fatigue load and a tendency that it decreases due to rest due to a nap. This means that the threshold value increases with fatigue load, and the threshold value decreases with rest. It was confirmed that fatigue measurement is possible under these conditions in the presentation of tactile stimuli under 12 conditions.

  Moreover, it is confirmed from FIG. 18 that there is a difference in how the perception threshold changes depending on the external stimulus condition. Here, “external” means a part other than a stimulus that is a target of determination as to whether or not it is perceived as two stimuli in the pulse sequence, and specifically, a time T3 in the pulse sequence of FIG. Is the period. The “external stimulus condition” means the signal level (A0-A2) in the period of time T3 in the pulse sequence of FIG. In most cases, the perceptual threshold measured by changing time, intensity, or time and intensity is a plot figure ◆ (A0-A2 = 0% in FIG. 11) and a plot figure ■ (A0-A2 = 50 in FIG. 11). %) Of the plot figure Δ (A0−A2 = 90% in FIG. 11) and the plot figure × (A0−A2 = 100% in FIG. 11) show larger values. Therefore, by adjusting the external stimulus condition, the dynamic range of the threshold change can be controlled as necessary.

  Further, from FIG. 19, it is confirmed that there is a difference in the way of changing the perceptual threshold depending on the stimulus frequency condition, and the dynamic range of the change of the threshold is adjusted as necessary by adjusting the external stimulus condition. Can be controlled.

  FIG. 20 shows the results of flicker value measurement, VAS, and subjective symptoms. These are established fatigue indices, and it was confirmed that the fatigue of the test subjects increased and updated due to the fact that these values changed. In other words, flicker value measurement, VAS, and subjective symptom check values monotonously decrease or increase monotonously with continuous overnight work, and values change in the opposite direction to the previous change with nap. Was confirmed.

  The perceptual threshold graphs for tactile stimuli shown in FIGS. 18 and 19 also change similarly to the graph of FIG. Thus, since it has the property to change similarly to the conventional fatigue index, it was confirmed that the method for measuring a perceptual threshold for tactile stimulation according to the present invention is effective as a fatigue measurement method.

  In order to investigate the relationship between the change in the perception threshold and the change in the flicker value, the VAS, and the subjective symptom, which are fatigue indices, regression analysis was performed for all combinations.

  As a result of the regression analysis, the combination of the subjective symptom check and the intermediate condition (50% change condition) of the intensity change condition of the external region of the stimulus (plot figure in FIG. 18), the subjective symptom check, and the change of the stimulus presentation frequency The P value is 0.05 or less in all combinations except for two examples of combinations when the interval and intensity are changed by presenting two stimuli per second under the intermediate conditions (plotted figure in FIG. 19). became. From this, it was found that the change in the perception threshold of tactile stimulation showed a significant correlation with any of the three fatigue indices (flicker value, VAS, and subjective symptoms).

  As an example, in FIG. 21 and FIG. 22, the perception threshold value and flicker value of the tactile stimulus measured at the same measurement time in the first to eighth measurements during the fatigue load experiment described above are plotted, and the regression line is plotted. The drawn graph is shown. (A) to (c) of FIG. 21 show the correlation between the perception threshold values shown in (a) to (c) of FIG. 18 and the flicker values shown in FIG. In FIG. 21A and FIG. 18A, the same plot figure represents the same measurement value. The same applies to the plot figures of FIG. 21B and FIG. 18B and the plot figures of FIG. 21C and FIG. 22A to 22C show the correlation between the perception threshold shown in FIGS. 19A to 19C and the flicker value shown in FIG. In FIG. 22 (a) and FIG. 19 (a), the same plot figure represents the same measurement value. The same applies to the plot figures of FIGS. 22B and 19B and the plot figures of FIGS. 22C and 19C.

  21 and 22 also show that the change in the perceptual threshold value of the tactile stimulus has a significant correlation with the flicker value.

  The effect of the stimulus presentation environment (corresponding to the above “external stimulus condition”) on the measured value of the tactile threshold (fatigue sensitivity) was examined. Specifically, the relationship between the tactile sensation threshold value, the flicker value of the fatigue index, the VAS value, and the subjective symptom search value (score) was analyzed by regression analysis. As a result, 2 cases (in the condition of 2 stimulus presentation per second in the intermediate condition (50% change condition) of the subjective symptom check value and the intensity change condition of the external area of the stimulus, and the intermediate condition of the change of the stimulus presentation frequency, It was confirmed that there was a significant correlation (p <0.05) in all tactile threshold measurement conditions except for the regression analysis when both the interval and intensity were changed. In the intermediate condition (50% change condition) of the intensity change condition of the stimulus external region, the case where both the interval and intensity are changed is the condition when the plot figure (2) in FIG. 18C is acquired. . Further, the case where both the interval and the intensity are changed in the bi-stimulus presentation condition per second under the intermediate condition of the change of the stimulus presentation frequency is a condition when the plot figure (2) in FIG. 19C is acquired. .

  It was also observed that the angle of change of the tactile threshold with respect to the fatigue index (flicker value, VAS value, and subjective symptom check value) changes depending on the stimulus presentation environment (external stimulus condition). In order to examine the influence of the external stimulus condition (hereinafter also referred to as an external stimulus environment) on the tactile threshold, the influence of the external stimulus environment on the angle of change of the tactile threshold with respect to the fatigue index was examined. The tactile thresholds of the respective measurement results are different in units of stimulation interval time (msec), stimulation interval intensity (%), stimulation interval time (msec) + stimulus interval intensity (%), and thus are compared with each other. Therefore, a relative comparison was performed with the bi-stimulus condition as a control condition (reference condition), and an examination was made as to how the change rate of the tactile threshold changes with a change in the external stimulus environment. Specifically, as the external stimulus environment, the stimulus external region intensity change (0% (2 stimulus presentation) (corresponding to the plot figure ◆ in FIG. 18), 50% (corresponding to the plot figure ■ in FIG. 18), 90% ( 18 (corresponding to the plot figure Δ in FIG. 18)), 100% (corresponding to the plot figure x in FIG. 18)), and stimulus presentation frequency change (one time / second (two stimulus presentation) (corresponding to the plot figure ◆ in FIG. 19)) 2 times / second (corresponding to the plot figure ■ in FIG. 19), continuous stimulus A (stimulus 100 msec) (corresponding to the plot figure Δ in FIG. 19), continuous stimulus B (stimulus and interval are uniformly changed) (FIG. 18) Corresponding to the plot figure x))). Then, a relative comparison is made with respect to how the rate of change (angle) with respect to the flicker value, the VAS value, and the subjective symptom check value of the fatigue index changes with the bi-stimulus condition as the control condition (reference condition). It was.

  The F value (with degrees of freedom 3 and 11) corresponds to F (3/11) = 24.04 (p = 0.001) when the external stimulus environment is a stimulus external region intensity change with respect to the flicker value. Value), when the external stimulus environment is a stimulus presentation frequency change, F (3/11) = 6.54 (value corresponding to p = 0.025). Therefore, it has been clarified that the change of the tactile threshold with respect to the flicker value, that is, the sensitivity of the tactile threshold with respect to fatigue significantly changes with the change of the external stimulus environment. Similarly, when the external stimulus environment is a stimulus external region intensity change with respect to the VAS value, F (3/11) = 24.08 (p = 0.001), and the external stimulus environment is a stimulus presentation frequency change. In this case, F (3/11) = 6.54 (p = 0.022), and F (3/11) = when the external stimulus environment is a stimulus external region intensity change with respect to the subjective symptom check value. 16.05 (p = 0.003), and F (3/11) = 6.76 (p = 0.024) when the external stimulus environment was a stimulus presentation frequency change. Therefore, it has been clarified that the sensitivity of the tactile threshold to the VAS value and the subjective symptom check value, that is, the sensitivity of the tactile threshold to fatigue significantly changes as the external stimulus environment changes.

  As described above, it has been clarified that the sensitivity to tactile threshold fatigue changes significantly with changes in the external stimulus environment. Therefore, it was clarified that fatigue measurement using a tactile threshold in an appropriate sensitivity region can be performed by controlling the external stimulus environment.

  (A) and (b) of FIG. 23 are diagrams plotting the relative change rates of the stimulus external region intensity change and the stimulus presentation frequency change with respect to the flicker value, respectively. In FIG. 23, “*” indicates that the p value between them is p <0.05. Similarly, “**” indicates that the p value between them is p <0.01, and “***” indicates that the p value between them is p <0.001.

  As described above, a significant correlation (p <0.05) was confirmed between the tactile threshold and the flicker value as a result of the regression analysis for all the tactile threshold measurement conditions. Based on these correlations, a relational expression between the measured flicker value and the tactile threshold was obtained. That is, as an external stimulus environment, stimulus external region intensity change (0% (2 stimulus presentation), 50%, 90%, and 100%), and stimulus presentation frequency change (1 time / second (2 stimulus presentation), 2 times / Sec, continuous stimulus A (stimulus 100 msec), continuous stimulus B (stimulus and interval are uniformly changed)), the respective regression lines are obtained, and an interconversion formula between the tactile threshold value and the flicker value is obtained using the regression line. It was.

When the external stimulus environment is a stimulus external region intensity change, the flicker value (cycle in msec unit) is X, the stimulus interval time (msec) which is a tactile threshold is Y, and the following formula is obtained for each measurement condition. It was.
0% condition: Y = −1.42X + 61.13
50% condition: Y = −1.34X + 59.32
90% condition: Y = -1.77X + 81.78
100% condition: Y = -2.74X + 119.20

  FIG. 24 shows the coefficients α and β of the mutual conversion formula between the haptic threshold value and the flicker value obtained for each external stimulus environment. The conversion formula is Y = αX + β.

  As a method of evaluating the degree of fatigue based on the flicker value, the fatigue state is evaluated according to the percentage of the flicker value measured in the fatigued state with respect to the reference value, with the flicker value measured in a non-fatigue state as the reference value. Evaluation methods to perform are known. It has been reported that when the flicker value is reduced by 5% with respect to the reference value, the response rate of the reflex response to a healthy stimulus is reduced by 15%. Further, it has been reported that when the flicker value is reduced by 10% with respect to the reference value, the results of the Krippelin test in which the addition of one's place starts to decrease extremely. By using the above relational expression, it is possible to infer the state of change of the living body corresponding to the flicker value even by the change in the tactile threshold. For example, if the increase rate of the tactile threshold corresponding to a 5% decrease from the reference value of the flicker value is calculated, the response rate of the reflex response to the stimulus in the normal state is 15 using the value and the measured value of the tactile threshold. It is possible to determine a state of decreasing by%. Similarly, if the increase rate of the haptic threshold corresponding to a 10% decrease from the reference value of the flicker value is calculated, it is possible to determine a state in which the result of the Krippelin test for performing the addition of the ones starts to decrease extremely. it can.

100 control device 102 CPU
104 ROM
106 RAM
108 Recording unit 110 Timer 112 Bus 114 Signal generation unit 116 Signal processing unit 118 Vibration unit 120 Operation unit 200 Handle 220 Control device 222 First unit 224 Second unit 230, 250 Mobile terminal device 232, 234 Operation area 236, 238 Vibration unit 252 and 254 Operation area 256 and 258 Vibration area

Claims (14)

A method for applying a tactile stimulus to a subject and measuring a perception threshold of the tactile stimulus,
The tactile stimulus is a stimulus having a constant carrier frequency and intensity varying with time,
The tactile stimulus envelope includes a first pulse and a second pulse adjacent to each other;
The time width of the first pulse is 20 milliseconds or more and 500 milliseconds or less,
The second pulse has the same intensity as the first pulse following the first pulse,
A signal level in a period between the second pulse and the first pulse next to the second pulse is greater than 0 and less than or equal to the intensity of the second pulse;
A step of measuring a parameter that is a time interval between the first pulse and the second pulse in a monotonous manner with the passage of time to give the subject the haptic stimulus;
In the state where the subject is given the tactile stimulus, the value of the parameter when the subject perceives that the vibration state perceived by the tactile stimulus has caused a predetermined change and operates the operating device is tactile. A method for measuring a perceptual threshold value of a tactile stimulus, comprising: determining a perceptual threshold value of the stimulus. The carrier frequency is 100 Hz or more and 300 Hz or less,
The time width of the first pulse is 100 milliseconds,
The method for measuring a perceptual threshold value of a tactile stimulus according to claim 1, wherein a change period of the parameter is 1 second. A method for applying a tactile stimulus to a subject and measuring a perception threshold of the tactile stimulus,
The tactile stimulus is a stimulus having a constant carrier frequency and intensity varying with time,
The tactile stimulus envelope includes a first pulse and a second pulse adjacent to each other;
The time width of the first pulse is 20 milliseconds or more and 500 milliseconds or less,
The second pulse has the same intensity as the first pulse following the first pulse,
A first parameter, which is a time interval between the first pulse and the second pulse, and a second parameter, which is a signal level in a period between the first pulse and the second pulse, are simultaneously set as time passes. A measurement step of monotonously changing or fixing the first parameter to a predetermined value greater than 0 and monotonously changing the second parameter over time to give the subject the tactile stimulus;
The first parameter when the subject feels that the vibration state perceived by the tactile stimulus has caused a predetermined change and operates the operating device in a state where the subject is given the tactile stimulus, and the first parameter and the A determination step of determining a value of a parameter that has been changed among the second parameters as a perceptual threshold value of the tactile stimulus. The method according to claim 3 , wherein the second pulse is continuous with the first pulse next to the second pulse. The tactile stimulus perception according to claim 3 , wherein a signal level in a period between the second pulse and the first pulse next to the second pulse is larger than 0 and smaller than the intensity of the second pulse. Threshold measurement method. Said measuring step, said fixed to the first parameter is greater than a predetermined 0 value, the a second step of parameter monotonously increase or monotonously decrease, according to any one of claims 3 to 5 A method for measuring the perception threshold of tactile stimulation. The method for measuring a perceptual threshold value of a tactile stimulus according to any one of claims 3 to 5 , wherein the measuring step is a step of simultaneously monotonously increasing or monotonically decreasing the first parameter and the second parameter. . The carrier frequency is 100 Hz or more and 300 Hz or less,
The time width of the first pulse is 100 milliseconds,
The parameter change period is 1 second,
The method for measuring a perceptual threshold value of a tactile stimulus according to any one of claims 3 to 6 , wherein the predetermined value when the first parameter is fixed is 30 milliseconds. The time width of the second pulse is the same as the time width of the first pulse,
The tactile stimulus according to claim 3 , wherein a time interval between the first pulse and the second pulse is the same as a time interval between the second pulse and the first pulse next to the second pulse. Perception threshold measurement method. A vibration means that vibrates according to an input signal and gives a tactile stimulus to the subject;
Signal generating means for generating the input signal;
An operation means for receiving a test subject's instruction,
The input signal is a stimulus having a constant carrier frequency and intensity varying with time,
The envelope of the input signal includes a first pulse and a second pulse adjacent to each other,
The time width of the first pulse is 20 milliseconds or more and 500 milliseconds or less,
The second pulse has the same intensity as the first pulse following the first pulse,
A signal level in a period between the second pulse and the first pulse next to the second pulse is greater than 0 and less than or equal to the intensity of the second pulse;
The signal generation means generates the input signal by monotonically changing a parameter that is a time interval between the first pulse and the second pulse as time passes,
The parameter when the test means perceives that the vibration state perceived by the tactile stimulus has undergone a predetermined change and the operation means is operated in a state where the subject is given the tactile stimulus by the vibration means. An apparatus for measuring a perceptual threshold value of a tactile stimulus, further comprising: a determination unit that determines a value of the tactile stimulus as a perceptual threshold value of the tactile stimulus. A vibration means that vibrates according to an input signal and gives a tactile stimulus to the subject;
Signal generating means for generating the input signal;
An operation means for receiving a test subject's instruction,
The input signal is a stimulus having a constant carrier frequency and intensity varying with time,
The envelope of the input signal includes a first pulse and a second pulse adjacent to each other,
The time width of the first pulse is 20 milliseconds or more and 500 milliseconds or less,
The second pulse has the same intensity as the first pulse following the first pulse,
The signal generating means includes a first parameter that is a time interval between the first pulse and the second pulse, and a second parameter that is a signal level in a period between the first pulse and the second pulse. The input signal is generated by simultaneously changing monotonically with the passage of time, or fixing the first parameter to a predetermined value greater than 0, and changing the second parameter monotonically with the passage of time,
In a state where the subject is given the tactile stimulus by the vibration means, the subject feels that the vibration state perceived by the tactile stimulus has caused a predetermined change, and operates the operation means. An apparatus for measuring a perceptual threshold value of a tactile stimulus, further comprising: a determining unit that determines a value of a parameter that has been changed among the first parameter and the second parameter as a perceptual threshold value of the tactile stimulus. Said vibrating means and said operating means is located a steering wheel, the measuring device of the perceptual threshold of tactile stimulation according to claim 1 0 or 1 1. A program for giving a subject a tactile stimulus to a computer or portable terminal device including an operation unit and a vibration unit and measuring a perception threshold of the tactile stimulus,
The tactile stimulus is a stimulus having a constant carrier frequency and intensity varying with time,
The tactile stimulus envelope includes a first pulse and a second pulse adjacent to each other;
The time width of the first pulse is 20 milliseconds or more and 500 milliseconds or less,
The second pulse has the same intensity as the first pulse following the first pulse,
A signal level in a period between the second pulse and the first pulse next to the second pulse is greater than 0 and less than or equal to the intensity of the second pulse;
A function of monotonously changing a parameter, which is a time interval between the first pulse and the second pulse, with time, and giving the tactile stimulus to the subject;
In the state where the subject is given the tactile stimulus, the value of the parameter when the subject perceives that the vibration state perceived by the tactile stimulus has undergone a predetermined change and operates the operating device is the tactile stimulus. Program for measuring the perception threshold of a tactile stimulus that realizes the function of determining the perception threshold of a tactile stimulus. A program for giving a subject a tactile stimulus to a computer or portable terminal device including an operation unit and a vibration unit and measuring a perception threshold of the tactile stimulus,
The tactile stimulus is a stimulus having a constant carrier frequency and intensity varying with time,
The tactile stimulus envelope includes a first pulse and a second pulse adjacent to each other;
The time width of the first pulse is 20 milliseconds or more and 500 milliseconds or less,
The second pulse has the same intensity as the first pulse following the first pulse,
A first parameter, which is a time interval between the first pulse and the second pulse, and a second parameter, which is a signal level in a period between the first pulse and the second pulse, are monotonously simultaneously with the passage of time. Or a function of fixing the first parameter to a predetermined value greater than 0 and changing the second parameter monotonously with time to give the subject the haptic stimulus,
The first parameter when the subject feels that the vibration state perceived by the tactile stimulus has caused a predetermined change and operates the operating device in a state where the subject is given the tactile stimulus, and the first parameter and the A program for measuring a perceptual threshold value of a tactile stimulus that realizes a function of determining a value of a parameter that has been changed among the second parameters as a perceptual threshold value of the tactile stimulus.

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