Head position change analysis system

Abstract

To provide a head position change analysis system for analyzing whether or not the head position of a subject is appropriately operated.SOLUTION: According to an aspect of the invention, there is provided a measurement device including a measurement unit that measures a head posture of a subject at predetermined time intervals, and an analysis unit that analyzes measurement data and generates waveform data indicating a change in an angular velocity of the head posture, in which the analysis unit determines whether or not waveform data generated based on the measurement data generated within a target period including a first timing at which the angular velocity of the head posture of the subject exceeds a first threshold value is valid.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a head position change analysis system. [Background technology]

[0002] One of the tests for dizziness is known as the Video Head Impulse Test (vHIT). The video head impulse test is a test in which the subject wears examination goggles (goggles equipped with equipment to measure the position of the gaze and head position), and the doctor or other medical professional measures and analyzes the movement of the eyeballs when the subject rapidly moves their head, thereby determining whether or not there is a disease in the left and right semicircular canals, which is one of the causes of dizziness.

[0003] Patent Document 1 discloses an invention relating to a device for assisting balance training using a head-mounted display capable of displaying virtual reality images. This invention plays virtual reality images that induce visually induced dizziness on the head-mounted display, and controls the playback speed to induce dizziness in the user. Furthermore, Patent Document 1 discloses the above-mentioned video head impulse test. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-39250 Summary of the Invention [Problem to be solved by the invention]

[0005] When conducting a video head impulse test, medical professionals must rapidly move the subject's head position multiple times, but not all movements are appropriate, and if the subject's head position cannot be moved appropriately, the measurement data required for the test cannot be obtained.

[0006] In view of the above-mentioned problems, the present invention can provide a head position change analysis system that analyzes whether the head position of a subject is moving appropriately. [Means for solving the problem]

[0007] According to the present invention, there is provided a head position change analysis system comprising: a measurement means for measuring the head position of a subject at predetermined time intervals; and an analysis means for analyzing the measurement data generated by the measurement means to generate waveform data representing changes in the angular velocity of the head position, wherein the analysis means determines whether the generated waveform data is valid based on the measurement data generated within a target period including a first timing at which the angular velocity of the head position of the subject exceeds a first threshold. [Effects of the Invention]

[0008] According to the above invention, it is possible to determine whether a change in head position is valid or not based on measurement data generated within the period to be analyzed (the period to be analyzed including the first timing at which the angular velocity of the subject's head position exceeds the first threshold).

[0009] According to the present invention, there is provided a head position change analysis system for analyzing whether or not the head position of a subject is moving appropriately. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a configuration diagram of an analysis system according to the present invention. [Figure 2] 1 is a flowchart showing a processing procedure for head position analysis according to the present invention. [Figure 3] FIG. 10 is a diagram showing the display screen of the display means at the timing when it is determined that the waveform is a success in the lateral mode. [Figure 4] FIG. 10 is a diagram showing the display screen of the display means at the timing when it is determined that the waveform is not a successful waveform in the lateral mode. [Figure 5]FIG. 10 is a diagram showing the display screen of the display means at the time when a successful waveform is determined in LARP mode. [Figure 6] FIG. 10 is a diagram showing the display screen of the display means at the time when it is determined that the waveform is not a successful waveform in LARP mode. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and the description thereof will be omitted where appropriate.

[0012] <Configuration of the analysis system 100 according to the present invention> First, the configuration of an analysis system 100 according to the present invention will be described. The analysis system 100 is a system that analyzes changes in head position of a subject. Note that, in this embodiment, the present invention will be described on the premise that changes in head position of a subject are analyzed for a video head impulse test, but the present invention is not necessarily limited to cases where a video head impulse test is performed, and may be used when performing other tests.

[0013] FIG. 1 is a configuration diagram of an analysis system 100 according to the present invention. As shown in FIG. 1, the analysis system 100 comprises a head-mounted device 110 and a computer terminal 120, which are communicatively connected to each other, and is capable of transmitting measurement data measured by the head-mounted device 110 (data showing changes in the subject's line of sight and head position over time) to the computer terminal 120. In implementing the present invention, communication between the head-mounted device 110 and the computer terminal 120 may be wireless or wired, and they may be directly connected to each other or indirectly connected via another device not shown. In addition, both the head-mounted device 110 and the computer terminal 120 have an information processing device such as a CPU (not shown) and a storage device such as a ROM or RAM (not shown), and can execute the various processes described below through cooperation between this hardware and the installed software.

[0014] The head-mounted device 110 is a pair of examination goggles that is worn on the head of the subject, and includes a gaze measuring means 111, a head position measuring means 112, and an eyeball photographing means 113. The gaze measurement means 111 measures the gaze of the subject at predetermined time intervals during the video head impulse test. The gaze measurement means 111 can be realized by an eye tracker (a sensor that detects the gaze of the subject), etc. The gaze of the subject measured by the gaze measurement means 111 includes the rotation axis and rotation angle of the subject's eyeball, as well as the position of the subject's gaze (the position at which the subject is gazing). The head position measurement means 112 measures the head position of the subject at predetermined time intervals during the video head impulse test, and corresponds to the measurement means of the present invention. The head position measurement means 112 can be realized by a gyro sensor (a sensor that detects angular velocity) or the like. Because head position changes rapidly during the video head impulse test, it is preferable that the time interval for measurement by the head position measurement means 112 be very short, and in this embodiment it is 120 fps (120 measurements per second). The eyeball photographing means 113 photographs the eyeballs of the subject during the video head impulse test. The eyeball photographing means 113 can be realized by a camera or the like.

[0015] In carrying out the present invention, the component corresponding to the measuring means (head position measuring means 112 in this embodiment) does not necessarily have to be attached to the head of the subject, but may be attached to another part of the body, or may measure the subject from the outside.

[0016] The computer terminal 120 is a device that processes the measurement data measured by the head-mounted device 110 , and includes an analysis means 121 and a display means 122 . The analysis means 121 can analyze the measurement data measured by the head-mounted device 110, and corresponds to the analysis means of the present invention. The analysis results by the analysis means 121 include eye movement waveforms (waveform data representing changes in the position of the subject's gaze), head position angular velocity (peak value of the head position angular velocity of the subject), head position sway amplitude (angle by which the subject's front direction sways left and right or forward and backward), and head position waveforms (waveform data representing changes in the head position angular velocity of the subject). The analysis means 121 can be realized by executing application software installed on the computer terminal 120. Display means 122 displays the results of the analysis by analysis means 121. The display mode of display means 122 will be described later. In carrying out the present invention, the output of the analysis results by analysis means 121 does not necessarily have to be a display output, and may be replaced with another mode of output such as a printed output.

[0017] <Head position analysis flow according to the present invention> Next, the flow of head position analysis according to the present invention will be described. FIG. 2 is a flowchart showing the processing procedure for head position analysis according to the present invention.

[0018] First, the computer terminal 120 acquires the measurement data measured by the head-mounted device 110 (step S101). In the process of step S101, the computer terminal 120 may acquire the measurement data directly from the head-mounted device 110, or may acquire the measurement data by reading it out from a storage device (not shown).

[0019] The head position waveform included in the measurement data acquired in step S101 contains a large amount of noise, so the influence of noise needs to be reduced in order to analyze nystagmus with high accuracy. Therefore, in order to reduce the influence of noise, the computer terminal 120 smoothes the head position waveform acquired in step S101 (step S102). The smoothing method performed in step S102 is not particularly limited, and may be appropriately selected from known methods.

[0020] Next, the computer terminal 120 analyzes the head position waveform (waveform data representing changes in the angular velocity of the subject's head position) to determine the start point (step S103). Here, the "start point" refers to the point in time when the angular velocity of the subject's head position exceeds A degrees / second (the first threshold value according to the present invention), and corresponds to the first timing according to the present invention. When the computer terminal 120 does not detect the start point in the process of step S103 (NO in step S104), the computer terminal 120 returns to the process of step S103. When the computer terminal 120 detects the start point in the processing of step S103 (YES in step S104), it refers to the measurement data after the start point and determines whether the measurement data is worth analyzing (step S105). Specifically, the computer terminal 120 determines that the measurement data is worth analyzing when the state in which the angular velocity of the subject's head position is A degrees / second or more is maintained for B seconds or more from the start point. The angular velocity corresponding to A degrees / second and the time corresponding to B seconds can be changed as appropriate within the scope of achieving the object of the present invention.

[0021] If the measurement data is not worthy of analysis (NO in step S105), the process returns to step S103. If the measurement data is deemed worthy of analysis (YES in step S105), the computer terminal 120 determines whether the waveform data generated based on the measurement data generated within the target period including the start point is valid (step S106). Here, the "target period" is a finite period determined based on the start point, and in this embodiment, it is 0.7 seconds including C seconds before the start point (corresponding to the first period according to the present invention) and D seconds after the start point (corresponding to the second period according to the present invention). The time corresponding to C seconds and the time corresponding to D seconds can be changed as appropriate within the scope of achieving the object of the present invention. In the following description, waveform data that is determined to be valid in step S106 will be referred to as a successful waveform.

[0022] The conditions under which the computer terminal 120 determines a waveform as successful in step S106 are as follows: In carrying out the present invention, it is not necessary to use all of the conditions, and some of them may be omitted or replaced with other conditions. Furthermore, the numerical values ​​of the conditions mentioned below can be changed as appropriate within the scope of achieving the object of the present invention.

[0023] In step S106, the computer terminal 120 determines that the waveform is successful if the number of measurement data points generated during the period (corresponding to the third period according to the present invention) starting from the starting point and ending when the angular velocity of the subject's head position falls below E degrees / second (the second threshold according to the present invention) is F frames / second or more (corresponding to the third threshold according to the present invention), and determines that the waveform is not successful if the number of measurement data points generated during the period is below F frames / second. Also, in step S106, the computer terminal 120 determines that the waveform is a successful waveform if the length of the period is G seconds or less (corresponding to the fourth threshold value according to the present invention), and determines that the waveform is not a successful waveform if the length of the period is more than G seconds. The time corresponding to E seconds, the number of points corresponding to F frames / second, and the time corresponding to G seconds can be changed as appropriate within the scope of achieving the object of the present invention.

[0024] In step S106, the computer terminal 120 determines that the waveform is successful when all of the angular velocities of the subject's head position analyzed from the measurement data generated during a period (corresponding to the fourth period according to the present invention) starting from the beginning of the initial part of the target period (the first period according to the present invention) and ending before the starting point are below A degrees / second (the first threshold according to the present invention), and determines that the waveform is not successful when any of the angular velocities of the subject's head position analyzed from the measurement data generated during that period exceeds A degrees / second. Furthermore, in step S106, the computer terminal 120 determines that the waveform is a success when all of the angular velocities of the subject's head position analyzed from the measurement data generated during the period (corresponding to the fifth period according to the present invention) ending at the end of the final part of the target period (the second period according to the present invention) are below A degrees / second (the first threshold according to the present invention), and determines that the waveform is not a success when any of the angular velocities of the subject's head position analyzed from the measurement data generated during that period exceeds A degrees / second.

[0025] In step S106, the computer terminal 120 determines that the waveform is a success when all of the angles of the subject's head position analyzed from the measurement data generated during the target period are equal to or greater than the angles of the subject's head position analyzed from the measurement data generated at the starting point (i.e., when the head position angle has not returned from the starting position of the head swing). Furthermore, in step S106, if the angle of the subject's head position analyzed from the measurement data generated during the target period includes an angle that is lower than the angle of the subject's head position analyzed from the measurement data generated at the starting point (i.e., if the head position angle is returned from the starting position of the head swing), the computer terminal 120 determines that the waveform is not a successful waveform.

[0026] In step S106, the computer terminal 120 determines that the waveform is a success when all of the angles of the subject's head position analyzed from the measurement data generated during the target period are within the designated range. In step S106, the computer terminal 120 determines that the waveform is not a success if the angles of the subject's head position analyzed from the measurement data generated during the target period include angles outside a specified range. Here, the "specified range" refers to the range of head swing angles that a user (e.g., a medical professional) specifies beforehand before conducting a video head impulse test.

[0027] In step S106, the computer terminal 120 detects from the target period the peak point (corresponding to the third timing according to the present invention) at which the angular velocity of the subject's head position is at its maximum, the start point of the crest (corresponding to the fourth timing according to the present invention) at which the angular velocity of the subject's head position first falls below 20 degrees / second (the fourth threshold according to the present invention) by sequentially referring to the measurement data on the front side using the peak point as a reference, and the end point of the crest (corresponding to the fifth timing according to the present invention) at which the angular velocity of the subject's head position first falls below 0 degrees / second (the fifth threshold according to the present invention) by sequentially referring to the measurement data on the back side using the peak point as a reference, and detects extreme value data where the product of the front and back slopes is negative for each of the measurement data generated from the start point of the crest to the end point of the crest. The computer terminal 120 determines that the waveform is successful if the angular velocity at the peak point is within a specified range, and determines that the waveform is not successful if the angular velocity at the peak point is outside the specified range. Here, the "specified range" refers to the range of angular velocities that the user specifies in advance of the video head impulse test. Furthermore, the computer terminal 120 determines that the waveform is successful when the difference in head position angle from the start point to the peak point is within a specified range, and determines that the waveform is not successful when the difference in head position angle from the start point to the peak point is outside the specified range. Here, the "specified range" refers to the range of angle difference from the start point to the peak point that the user specifies arbitrarily before conducting the video head impulse test. In addition, the computer terminal 120 determines that the waveform is successful when the extreme value data with a positive leading slope and a negative trailing slope is the only measurement data at the peak point, and determines that the waveform is not successful when extreme value data with a positive leading slope and a negative trailing slope is present in any data other than the measurement data at the third timing. Furthermore, the computer terminal 120 determines that a waveform is not a successful waveform when there are multiple extreme value data with a negative leading slope and a positive trailing slope. Furthermore, when there is one extreme value data with a negative leading slope and a positive trailing slope, the computer terminal 120 determines that the waveform is successful if the value obtained by multiplying the larger of the slopes before and after the extreme value data by a predetermined value is greater than the smaller one, and determines that the waveform is not successful if the value obtained by multiplying the larger of the slopes before and after the extreme value data by a predetermined value (0.3 in this embodiment) is less than or equal to the smaller one. Alternatively, the waveform is successful if the value obtained by dividing the larger of the slopes before and after the extreme value data by the smaller one is greater than a predetermined value, and determines that the waveform is not successful if the value obtained by dividing the larger of the slopes before and after the extreme value data by the smaller one is less than or equal to the predetermined value. Here, the predetermined value is a value that is greater than 0 and less than 1, and is determined in advance.

[0028] When the computer terminal 120 determines in the process of step S106 that the waveform is a successful waveform (YES in step S107), the computer terminal 120 displays the successful waveform on the display means 122 (step S108). Furthermore, when the computer terminal 120 determines in the process of step S106 that the waveform is not a successful waveform (NO in step S107), it displays the reason why the waveform was not determined to be a successful waveform (cause of an error) on the display means 122 (step S109).

[0029] When the analysis of the measurement data acquired in step S101 has not been completed (NO in step S110), the computer terminal 120 returns to the processing in step S103. Furthermore, when the analysis of all the measurement data acquired in step S101 is completed (YES in step S110), the computer terminal 120 ends the head position analysis process.

[0030] <Display of head position analysis results> Next, a display mode of the analysis results of the head position analysis will be described. 3 to 6 are diagrams showing screens of the display means 122 that display the results of head position analysis. As shown in each of these drawings, the screen displaying the analysis results of head position analysis is divided into display area A1, which mainly displays waveform data, display area A2, which displays successful waveforms, display area A3, which displays eyeball images, and display area A4, which displays the control panel.

[0031] Display area A1 can display eye movement waveforms measured by gaze measurement means 111 and head position waveforms measured by head position measurement means 112, and waveform data that changes over time scrolls from the right to the left of display area A1 (from the top to the bottom in Figures 3 to 6). Note that, because eye movement waveforms are not necessary for explaining the present invention, only head position waveforms are shown and eye movement waveforms are not shown. Display area A2 displays the successful waveform when it is determined to be a successful waveform by analysis means 121. This display corresponds to the processing of step S108 in FIG. Display area A3 can display an image of an eyeball captured by eyeball imaging means 113, but the specific image content is not shown in the figure because it is not necessary for explaining the present invention. When the analysis means 121 determines that the waveform is not a successful waveform, the display area A4 displays the cause of the error that led to this determination. This display corresponds to the processing of step S109 in Fig. 2. In addition, the display area A4 can also display the direction in which the subject's head is currently facing, the type of test mode currently being performed, the number of times a successful waveform has been determined in that test mode, and so on.

[0032] 3 is a diagram showing the display screen of the display means 122 at the timing when it is determined that the waveform is a successful waveform in the lateral mode. Specifically, in FIG. 3, the mountain-shaped waveform displayed in the center of the display area A1 is determined to be a successful waveform. 4 is a diagram showing the display screen of the display means 122 at the timing when it is determined that the waveform is not a successful waveform in the lateral mode. In FIG. 4, the mountain-shaped waveform displayed in the center of the display area A1 is determined not to be a successful waveform. Lateral mode is a test that tests the lateral semicircular canal function in a video head impulse test. In the lateral mode, the practitioner moves the subject's head rapidly from side to side.

[0033] As shown in FIG. 3, at the timing when it is determined that the waveform is a success, the display means 122 displays the success waveform in the display area A2. 4, at the timing when it is determined that the waveform is not a success, the display means 122 displays the cause of the error in the determination in the display area A4. In the same figure, it is displayed that the causes of the error are that the angular velocity at the peak point was faster than the specified range, that the difference in the head position angle from the start point to the peak point was larger than the specified range, and that the duration of the target period was too long.

[0034] 5 is a diagram showing the display screen of display means 122 at the timing when a successful waveform is determined in LARP mode. Specifically, in FIG. 5, the mountain-shaped waveform displayed in the center of display area A1 is determined to be a successful waveform. 6 is a diagram showing the display screen of display means 122 at the timing when it is determined that the waveform is not a successful waveform in LARP mode. In FIG. 6, the mountain-shaped waveform displayed in the center of display area A1 is determined to be not a successful waveform. Here, LARB stands for Left Anterior-Right Posterior, and is a test to evaluate the function of the left anterior and right posterior semicircular canals. In LARB mode, the subject's head is rotated 45 degrees horizontally to the right from the position in which it is facing forward in a video head impulse test, i.e., the subject's left cheek is facing forward, and the practitioner rapidly moves the subject's head back and forth.

[0035] As shown in FIG. 5, at the timing when it is determined that the waveform is a success, the display means 122 displays the success waveform in the display area A2. 6, when it is determined that the waveform is not a success, the display means 122 displays the cause of the error in the determination in the display area A4. Note that the figure displays that the cause of the error is that the difference in head position angle from the start point to the peak point was larger than the specified range, and that the subject's head position angle during the target period contained an invalid value.

[0036] As described above, by using the analysis system 100 according to this embodiment, the practitioner of the video head impulse test can perform the test while visually checking the analysis results of the head position analysis, making the test easier to carry out.

[0037] <Modification> The above-described embodiment of the present invention can be modified in various ways within the scope of achieving the object of the present invention.

[0038] The system configuration shown in FIG. 1 is merely one specific example of the configuration of the present invention, and some components may be omitted or other components may be added within the scope of achieving the object of the present invention.

[0039] The processing procedure shown in FIG. 2 is merely one specific example of the processing procedure according to the present invention, and some processing may be omitted, other processing may be added, the order of the processing procedure may be changed, or one processing may be executed in parallel with another processing, within the scope of achieving the object of the present invention.

[0040] The display modes shown in Figures 3 to 6 are merely specific examples of output modes of analysis results according to the present invention, and the layout of each display area and the content of each display can be changed as appropriate within the scope of achieving the object of the present invention.

[0041] The present embodiment encompasses the following technical ideas. (1) A head position change analysis system comprising: a measurement means for measuring the head position of a subject at predetermined time intervals; and an analysis means for analyzing the measurement data generated by the measurement means to generate waveform data representing changes in the angular velocity of the head position, wherein the analysis means determines whether the waveform data generated based on the measurement data generated within a target period including a first timing at which the angular velocity of the head position of the subject exceeds a first threshold is valid. (2) The head position change analysis system according to (1), wherein the target period includes a first period before the first timing and a second period after the first timing. (3) The head position change analysis system described in (2), wherein the analysis means determines that the waveform data is valid when the number of points of the measurement data generated during a third period, which starts at the first timing and ends at the second timing at which the angular velocity of the subject's head position falls below a second threshold, is equal to or greater than a third threshold, and determines that the waveform data is invalid when the number of points of the measurement data generated during the third period is below the third threshold. (4) The head position change analysis system described in (2), wherein the analysis means validates the waveform data when the length of a third period, which starts at the first timing and ends at the second timing at which the angular velocity of the subject's head position falls below the second threshold, is equal to or less than a fourth threshold, and invalidates the waveform data when the length of the third period exceeds the fourth threshold. (5) The head position change analysis system described in (2), wherein the analysis means validates the waveform data when all of the angular velocities of the head position of the subject analyzed from the measurement data generated during a fourth period, which starts at the beginning of the first period and ends before the first timing, are equal to or less than the first threshold, and invalidates the waveform data when any of the angular velocities of the head position of the subject analyzed from the measurement data generated during the fourth period exceeds the first threshold. (6) The head position change analysis system described in (2), wherein the analysis means validates the waveform data when all of the angular velocities of the head position of the subject analyzed from the measurement data generated during a fifth period that starts after the first timing and ends at the end of the second period are equal to or less than the first threshold, and invalidates the waveform data when any of the angular velocities of the head position of the subject analyzed from the measurement data generated during the fifth period exceeds the first threshold. (7) The head position change analysis system described in (2), wherein the analysis means validates the waveform data when all of the angles of the subject's head position analyzed from the measurement data generated during the target period are equal to or greater than the angles of the subject's head position analyzed from the measurement data generated at the first timing, and invalidates the waveform data when any of the angles of the subject's head position analyzed from the measurement data generated during the target period is lower than the angles of the subject's head position analyzed from the measurement data generated at the first timing. (8) The head position change analysis system described in (2), wherein the analysis means validates the waveform data when all of the angles of the subject's head position analyzed from the measurement data generated during the target period are within a specified range, and invalidates the waveform data when any of the angles of the subject's head position analyzed from the measurement data generated during the target period are outside the specified range. (9) The analysis means detects from the target period a third timing at which the angular velocity of the head position of the subject is at its maximum, a fourth timing at which the angular velocity of the head position of the subject first falls below a fourth threshold value by sequentially referring to the measurement data on the front side with respect to the third timing as a reference, and a fifth timing at which the angular velocity of the head position of the subject first falls below a fifth threshold value by sequentially referring to the measurement data on the back side with respect to the third timing as a reference, and detects extreme value data where the product of the front and back slopes is negative for each of the measurement data generated from the fourth timing to the fifth timing, and validates the waveform data when the extreme value data where the front slope is positive and the back slope is negative is only present in the measurement data at the third timing, and invalidates the waveform data when the extreme value data where the front slope is positive and the back slope is negative is present in measurement data other than the measurement data at the third timing. (10) The head position change analysis system according to (9), wherein the analysis means determines that the waveform data is invalid when there are multiple pieces of extreme value data in which the previous slope is negative and the subsequent slope is positive. (11) The head position change analysis system according to (9), wherein the analysis means, when there is one extreme value data in which the preceding slope is negative and the following slope is positive, determines the waveform data to be valid when the value obtained by multiplying the larger of the slopes before and after the extreme value data by a predetermined value is greater than the smaller one, and determines the waveform data to be invalid when the value obtained by multiplying the larger of the slopes before and after the extreme value data by the predetermined value is equal to or less than the smaller one, or determines the waveform data to be valid when the value obtained by dividing the larger of the slopes before and after the extreme value data by the smaller one is greater than the predetermined value, and determines the waveform data to be invalid when the value obtained by dividing the larger of the slopes before and after the extreme value data by the smaller one is equal to or less than the predetermined value. [Explanation of symbols]

[0042] 100 Analysis System 110 Head-mounted device 111 Eye Tracking Methods 112 Head position measurement means 113 Eyeball Photography Method 120 computer terminals 121 Analysis means 122 Display means

Claims

1. a measuring means for measuring the head position of the subject at predetermined time intervals; an analysis means for analyzing the measurement data generated by the measurement means and generating waveform data representing changes in the angular velocity of the head position; Equipped with The analysis means determining whether the waveform data generated based on the measurement data generated within a target period including a first timing at which the angular velocity of the head position of the subject exceeds a first threshold is valid; A head position change analysis system characterized by:

2. The target period includes a first period before the first timing and a second period after the first timing. The head position change analysis system according to claim 1 .

3. The analysis means When the number of points of the measurement data generated during a third period, which starts at the first timing and ends at a second timing at which the angular velocity of the head position of the subject falls below a second threshold, is equal to or greater than a third threshold, the waveform data is validated; When the number of measurement data points generated during the third period is less than the third threshold, the waveform data is determined to be invalid. The head position change analysis system according to claim 2 .

4. The analysis means the waveform data is validated when a time length of a third period, which starts at the first timing and ends at a second timing at which the angular velocity of the head position of the subject falls below a second threshold, is equal to or less than a fourth threshold; When the length of the third period exceeds the fourth threshold, the waveform data is deemed invalid. The head position change analysis system according to claim 2 .

5. The analysis means when all of the angular velocities of the head position of the subject analyzed from the measurement data generated during a fourth period, which starts at the beginning of the first period and ends before the first timing, are equal to or less than the first threshold value, the waveform data is validated; When the angular velocity of the head position of the subject analyzed from the measurement data generated during the fourth period exceeds the first threshold, the waveform data is determined to be invalid. The head position change analysis system according to claim 2 .

6. The analysis means when all of the angular velocities of the head position of the subject analyzed from the measurement data generated during a fifth period whose starting point is after the first timing and whose ending point is the end of the second period is equal to or less than the first threshold value, the waveform data is validated; When the angular velocity of the head position of the subject analyzed from the measurement data generated during the fifth period exceeds the first threshold, the waveform data is determined to be invalid. The head position change analysis system according to claim 2 .

7. The analysis means when all of the angles of the head position of the subject analyzed from the measurement data generated during the target period are equal to or greater than the angle of the head position of the subject analyzed from the measurement data generated at the first timing, the waveform data is validated; When an angle of the head position of the subject analyzed from the measurement data generated during the target period is lower than an angle of the head position of the subject analyzed from the measurement data generated at the first timing, the waveform data is determined to be invalid. The head position change analysis system according to claim 2 .

8. The analysis means When all of the angles of the head position of the subject analyzed from the measurement data generated during the target period are within a specified range, the waveform data is validated; When the head position angle of the subject analyzed from the measurement data generated during the target period includes an angle outside a specified range, the waveform data is deemed invalid. The head position change analysis system according to claim 2 .

9. The analysis means a third timing at which the angular velocity of the head position of the subject becomes maximum; a fourth timing at which the angular velocity of the head position of the subject becomes smaller than a fourth threshold value for the first time by sequentially referring to the measurement data on the front side of the third timing as a reference; and a fifth timing at which the angular velocity of the head position of the subject becomes smaller than a fifth threshold value for the first time by sequentially referring to the measurement data on the back side of the third timing as a reference; detecting extreme value data in which the product of the slopes before and after the measurement data is negative for each of the measurement data generated from the fourth timing to the fifth timing; when the extreme value data having a positive leading slope and a negative trailing slope is the only measurement data at the third timing, the waveform data is validated; When the extreme value data having a positive leading slope and a negative trailing slope is present in data other than the measurement data at the third timing, the waveform data is determined to be invalid. The head position change analysis system according to claim 2 .

10. The analysis means When there are a plurality of extreme value data pieces each having a negative leading slope and a positive trailing slope, the waveform data pieces are deemed invalid. The head position change analysis system according to claim 9.

11. The analysis means When there is one extreme value data whose previous slope is negative and whose subsequent slope is positive, The waveform data is determined to be valid when the value obtained by multiplying the larger of the slopes before and after the extreme value data by a predetermined value is greater than the smaller of the slopes, and the waveform data is determined to be invalid when the value obtained by multiplying the larger of the slopes before and after the extreme value data by a predetermined value is equal to or less than the smaller of the slopes, or When the value obtained by dividing the larger of the slopes before and after the extreme value data by the smaller of the slopes before and after the extreme value data is greater than a predetermined value, the waveform data is determined to be valid, and when the value obtained by dividing the larger of the slopes before and after the extreme value data by the smaller of the slopes before and after the extreme value data is equal to or less than the predetermined value, the waveform data is determined to be invalid. The head position change analysis system according to claim 9.

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