JP2012223452A - Leg strength evaluation method, and leg strength evaluation device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leg strength evaluation method in which the convenience is excellent and the leg strength can be evaluated accurately, and to provide a leg strength evaluation device using the same.SOLUTION: The leg strength evaluation method includes: a step in which an acceleration and an angular velocity that show the movements of an upper-body section and femoral region in a subject H during a posture change from a maximum squat down posture which is a posture in which the subject H squats down as much as possible to a standing posture are acquired by an upper-body section sensor and a femoral region sensor; and a step in which the maximum value max(T(t)) of the sum of the joint moment of a hip joint and a knee joint of the subject H is acquired from the acceleration and the angular velocity of the upper-body section and the femoral region, and the margin degree of the leg strength is calculated based on the maximum value and the reference value Tthat shows a minimum muscular strength necessary for the subject H to stand up from the squatting down posture.

Description

  The present invention relates to a method for evaluating a lower limb muscle strength of a subject and a muscle strength evaluation apparatus used therefor.

Lower limb muscle strength is very important in daily life such as walking movement, standing motion, sitting motion, etc. As aging progresses, the need to measure and evaluate this lower limb strength on a daily basis is increasing. .
Methods for measuring lower extremity muscle strength include methods for directly measuring muscle strength during knee joint and hip joint extension and flexion using a dynamometer, etc. (Method 1), and evaluation values based on daily living activities. There is a method of measuring (Method 2).

  Method 2 includes, for example, a method in which standing and sitting is repeated a predetermined number of times using a normal chair, and the time required for this is evaluated (chair sitting standing test), or the subject stands in a squatting position. There is a method of measuring a change in the foot load of the subject at the time of transition to the posture and evaluating the lower limb muscle strength based on the load change (for example, see Patent Document 1).

JP 2008-92979 A

  In the above-described method 1, an objective measurement value can be obtained with high accuracy because a measurement apparatus that includes a dynamometer and can directly measure the muscular strength of each part of the subject is used. However, since the measuring apparatus is large and expensive, it is usually installed in a research institution or a specialized institution. For this reason, it cannot be said that the convenience is so good that measurement can be performed on a daily basis.

The method 2 is superior in terms of convenience without requiring a large-scale device. However, in the above-described chair-sitting test, when the person cannot stand using a normal chair because of his / her old age, the test itself cannot be performed.
In addition, in the method for evaluating lower limb muscle strength based on the change in the foot load of the subject when moving from the crouching posture to the standing posture, the change in the foot load includes the factor of the posture, so the muscle strength is sufficiently low. When the squatting posture cannot be taken or when the squatting posture varies depending on the person, there is a possibility that the measurement cannot be performed with high accuracy. Further, the method 2 has a problem that it is difficult to make a clear evaluation as to whether or not the obtained measurement result has sufficient muscular strength to perform the standing and sitting motion.

  The present invention has been made in view of such circumstances, and provides a lower limb strength evaluation method capable of accurately evaluating the lower limb strength with good convenience, and a lower limb strength evaluation apparatus used therefor. Objective.

(1) The present invention is a lower limb strength evaluation method for evaluating a lower limb strength of a subject, a sensor installation step of installing a sensor for acquiring a parameter value indicating the movement of the subject; The thigh parameter value indicating the movement of the subject's thigh during the period from the maximum squatting posture, where the subject is crouching as much as possible, to the standing posture is changed by the sensor. Based on the acquired parameter value acquisition step and the acquired parameter value of the thigh, a maximum value of the sum of joint moments of the hip joint and knee joint of the subject is obtained, and the maximum value and the subject A calculation step of calculating a margin of lower limb muscle strength based on a reference value indicating a necessary minimum muscle strength required to stand up from a squatting posture.

According to the lower limb muscle strength evaluation method configured as described above, the hip and knee joint values are determined from the thigh parameter values until the subject changes from the maximum squatting posture to the standing posture as much as possible. Since the maximum value of the sum of the joint moments is obtained and the margin is calculated using this maximum value and the reference value indicating the necessary minimum muscle force required for standing, evaluation can be performed with high accuracy.
Further, since the margin of lower limb muscle strength is calculated based on the maximum value, the margin can be obtained as a value including the influence of the maximum squatting posture of the subject. For this reason, even if there is a difference in the maximum squatting posture due to a difference in muscle strength for each subject, it can be evaluated as a margin of lower limb muscle strength including a difference in the maximum squatting posture.
In addition, according to the present invention, if a sensor that can acquire a parameter value indicating the movement of the subject, such as an inertial sensor, is installed, the margin of lower limb muscle strength can be obtained, so that the evaluation of lower limb muscle strength can be performed. Can be performed conveniently.

(2) In the parameter value acquisition step, the subject in the standing posture changes the posture to the maximum squatting posture and further changes the posture of the thigh from the maximum squatting posture to the standing posture again. It is preferable to acquire a parameter value.
In this case, it is possible to grasp the relative change in the sum of the joint moments of the subject's hip joint and knee joint when the posture changes from the standing posture to the maximum crouching posture, and the maximum based on the subject's standing posture. The state of the crouching posture can be grasped.

(3) Moreover, in the said calculation step, it is preferable to obtain | require the margin of the said leg muscular strength based on a following formula.

In the above formula, Muscle_margin is the margin of lower limb muscle strength, T _{hip + knee} (t) is the sum of the joint moments of the hip and knee joints, and max (T _{hip + knee} (t)) is the squatting posture of the subject. The maximum value of hip joint and knee joint T _{hip + knee} (t), T ^ref _{hip + knee} during the posture change from standing to standing posture, is necessary for the subject to stand up from the squatting posture. This is a reference value indicating the required minimum muscle strength.

(4) Further, in the calculation step, it is preferable to obtain the reference value T ^ref _{hip + knee} based on the following equation.

In the above formula, L _Thigh is the length of the thigh in the longitudinal direction, k _Thigh is a parameter indicating the center of mass position in the longitudinal direction of the thigh, Bal _RL is a parameter indicating the left-right balance in the floor reaction force, m _Body is the total mass of the subject, m _HAT is the mass of the upper body, m _Thigh is the mass of the thigh segment, and g is the acceleration of gravity.

In the above equation, the value obtained from the right side is the sum T _{hip + knee} of the _hip joint and knee joint when the thigh is kept horizontal and the crouching posture is maintained (static state). This coincides with a reference value T ^ref _{hip + knee} that is a value indicating a necessary minimum muscle strength necessary for the person to stand up from a squatting posture.
The reference value T ^ref _{hip + knee} can be obtained as a constant that does not vary with time by being obtained from the above formula.

(5) In the lower limb muscle strength evaluation method, the sensor includes a thigh sensor for acquiring a parameter value of the thigh, and the thigh sensor is attached to the subject in the sensor installation step. It is preferable to fix.
In this case, the parameter value of the thigh can be acquired by a simple operation of fixing the thigh sensor to the subject, and convenience can be further improved.

(6) (7) The longitudinal position of the center of mass of the thigh is located in the vicinity of the thickest part. For this reason, in the sensor installation step, the thigh sensor is preferably fixed to the thickest part of the thigh.
Furthermore, it is preferable that the thigh sensor is fixed to an outer surface of the thigh. This is because the outer surface of the thigh is generally thin in fat and can be fixed at a stable position for each subject.

Further, for example, when the thigh is regarded as one segment and the movement at the center of mass of this segment is obtained as the thigh movement, the thigh parameter value detected by the thigh sensor at the sensor position is It is necessary to correct the value at the center of mass.
On the other hand, in the above case, the thigh sensor can be fixed in the vicinity of the center of mass of the thigh and can be fixed at a stable position for each subject. It becomes easy to standardize or simplify. As a result, convenience can be further improved.

(8) (9) The sensor includes an upper body sensor for acquiring a parameter value of the upper body part indicating the movement of the upper body part of the subject, and in the sensor installation step, the sensor for the upper body part is included in the sensor installation step. In the calculation step, the maximum value of the sum of the joint moments of the subject's hip joint and knee joint is obtained based on the thigh parameter value and the upper body parameter value. Further, it is preferable that the upper body part sensor is fixed to the most prone portion of the waist on the back side in the upper body part.

In this case, the maximum value of the sum of the joint moments of the hip joint and the knee joint is obtained based on the thigh parameter value and the upper body parameter value, so that the evaluation can be performed with higher accuracy.
In general, the back side is thin in fat and the like, and the upper body sensor can be fixed to a stable position for each subject by fixing the upper body sensor to the back side of the subject.
Furthermore, the center of mass when the upper body part is regarded as a segment exists in the vicinity of the most prone portion of the waist. Therefore, if the upper body sensor is fixed at a position close to the center of mass of the upper body, even when the upper body parameter value by the upper body sensor is corrected to the value at the center of mass of the upper body, the calculation required for the correction is normalized. Simplification or the like. As a result, convenience can be further improved.

(10) The method further includes a step of inputting the height of the subject, and in the calculation step, based on the height, a parameter indicating a length in the longitudinal direction of the thigh, a center of mass position, the subject The total mass of the examiner, the mass of the upper body, and the mass of the thigh may be estimated.
In this case, even if not all the constants necessary for obtaining the margin of lower limb muscle strength are prepared, if the data such as literatures or other statistical data is used, the constants are estimated according to the height of the subject. Therefore, convenience can be improved without reducing the evaluation accuracy.

(11) Further, the present invention is a lower limb strength evaluation apparatus for evaluating a lower limb strength of a subject, a sensor for acquiring a parameter value indicating the movement of the subject, and the sensor Based on the thigh parameter value indicating the movement of the subject's thigh during the period from the maximum squatting posture, where the subject is crouched as much as possible, to the standing posture. The maximum value of the sum of the joint moments of the subject's hip joint and knee joint is obtained, and the maximum value and a reference value indicating the minimum muscle strength necessary for the subject to stand up from the squatting posture. And a calculation unit that calculates a margin of lower limb muscle strength.

  According to the lower limb muscle strength evaluation apparatus configured as described above, as described above, convenience is good and the lower limb muscle strength can be accurately evaluated.

(12) (13) The sensor may include a thigh sensor that is fixed to a brace attached to the thigh and acquires a parameter value of the thigh.
Further, the sensor includes an upper body sensor that is fixed to a brace attached to the upper body part of the subject and acquires a parameter value of the upper body part indicating movement of the upper body part of the subject, and the arithmetic unit However, the maximum value of the sum of the joint moments of the subject's hip joint and knee joint may be obtained based on the thigh parameter value and the upper body parameter value.

  According to the lower limb muscle strength evaluation method of the present invention and the lower limb muscle strength evaluation apparatus used therefor, convenience is good and the lower limb muscle strength can be accurately evaluated.

It is a block diagram which shows the structure of the leg strength evaluation apparatus which concerns on 1st embodiment of this invention. It is a figure which shows the state which fixed and installed the upper body part sensor and the thigh sensor to the subject. It is an external view which shows an example of a main-body part. It is a flowchart which shows the procedure of the calculation of the margin of a leg muscular strength, and the evaluation method using a leg muscular strength evaluation apparatus. It is a figure which shows an example of the attitude | position change operation | movement which makes a subject perform. It is the figure which showed each part of the subject as a segment. It is an example of the calculation result of a lower limb muscle strength margin, and an example of the output of an evaluation result, (a) shows the display of the display of a main-body part, (b) is a graph of the calculation result of a lower limb muscle strength margin. FIG. In other examples of a first embodiment, it is a figure showing the state where a thigh sensor was fixed and installed in a subject. It is a figure which shows the state which installed the sensor of the leg muscular strength evaluation apparatus which concerns on 2nd embodiment of this invention in the subject H. It is the figure which showed typically the reaction force which acts on the subject H which a floor reaction force sensor detects. It is a figure which shows the variation of inertial sensor installation in 2nd embodiment. It is a figure which shows an example of the stand which the said subject mounts when a subject performs posture change operation | movement.

[First embodiment]
[About overall configuration]
Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of the lower limb muscle strength evaluation apparatus according to the first embodiment of the present invention.
In FIG. 1, a lower limb muscle strength evaluation apparatus 1 includes an upper body sensor 2 fixed to an upper body part of a subject, a thigh sensor 3 fixed to a thigh part of the subject, and a main body part 4. I have.

  FIG. 2 is a diagram showing a state in which the upper body sensor 2 and the thigh sensor 3 are fixed and installed on the subject. Both sensors 2 and 3 have built-in inertial sensors, and have a function of acquiring parameter values indicating movements of the upper body and thigh of the subject H.

  The upper body part sensor 2 is fixed to a waist belt 5 which is a brace attached to the waist of the subject H. When the subject H wears the waist belt 5 on his / her waist, the upper body sensor 2 is fixed and installed on the upper body part of the subject H, the most prone portion on the back side of the waist. The waist belt 5 is formed in a shape that makes it easy to be worn so that the upper body sensor 2 is located on the back side of the subject H and in the most prone portion of the waist. Since the center of mass of the upper body exists in the vicinity of the most prone portion of the waist, by wearing the waist belt 5 as described above, a certain positional relationship is established with respect to the center of mass of the upper body. The upper body sensor 2 can be fixed at a position having a certain relation to a predetermined direction of the upper body (for example, the direction of the spine).

  Furthermore, since the fat or the like is generally thin on the back side, the upper body part sensor 2 can be fixed near the center of mass of the upper body part by being fixed to the back side, and fixed to a stable position for each subject H. can do.

  The thigh sensor 3 is fixed to a thigh belt 6 which is a brace attached to the thigh of the subject H. When the subject H wears the thigh belt 6 on one thigh of the subject H, the thigh sensor 3 is provided on the outer side surface of the thickest part of the one side thigh of the subject H. Fixed in the center of the width direction. The thigh belt 6 is formed using an elastic rubber material, and is attached in a state where the thigh is appropriately tightened. The thigh is usually tapered from the crotch side toward the toes, so that the thigh belt 6 can be attached to the thigh while being moderately tightened. It is possible to prevent the position belt 6 from being displaced.

In addition, since the center of mass of the thigh exists near the thickest part of the thigh, by attaching the thigh belt 6 as described above, the center of mass of the thigh is greatly increased. The thigh sensor 3 can be fixed. Further, the thigh sensor 3 can be fixed at a position that has a constant positional relationship with the center of mass of the thigh and also has a fixed relationship with respect to the longitudinal direction of the thigh.
Further, since the outer surface of the thigh is generally thin in fat or the like, the thigh sensor 3 can be fixed at a stable position for each subject H by being fixed to the outer surface of the thigh. it can.

Further, the upper body part and the thigh part of the subject H are each regarded as a segment as described later, and a parameter indicating the movement at the center of mass is obtained. At this time, the detection result detected by the sensors 2 and 3 at the position of the sensor needs to be corrected to the value at the center of mass of each segment.
In this respect, in the present embodiment, both sensors 2 and 3 are fixed in a fixed positional relationship with respect to the center of mass of each part and in the vicinity of the center of mass, and are fixed at a stable position for each subject H. Therefore, it is easy to standardize or simplify the calculation required for the correction. As a result, convenience can be further improved.

  Returning to FIG. 1, the upper body sensor 2 and the thigh sensor 3 include acceleration sensor units 21 and 31 and angular velocity sensor units 22 and 32 as inertial sensors, respectively. The upper body sensor 2 and the thigh sensor 3 are transmission control units 23 and 33 that wirelessly transmit output signals indicating detection results output from the sensor units 21, 22, 31, and 32 to the main body unit 4. It has.

The acceleration sensor units 21 and 31 are configured by, for example, biaxial acceleration sensors, and detect and transmit control the movement (and posture) of the upper body and thigh of the subject H as biaxial acceleration. It has a function of outputting to the units 23 and 33.
Further, the angular velocity sensor units 22 and 32 are constituted by angular velocity sensors, and a function of detecting movements (and postures) of the upper body and thighs of the subject as angular velocities and outputting them to the transmission control units 23 and 33. have.

  Each sensor unit 21, 22, 31, 32 is provided so as to detect acceleration and angular velocity in a necessary direction with respect to the fixed positions of the upper body sensor 2 and the thigh sensor 3 with respect to the subject H. Yes.

  As described above, the upper body sensor 2 detects the biaxial acceleration and angular velocity in the back waist of the subject H as the parameter values of the upper body indicating the movement of the upper body of the subject H, and detects the detection. The result is output to the main unit 4 by wireless transmission. Similarly, the thigh sensor 3 has a biaxial acceleration on the outer surface of the thickest portion of the thigh of the subject H as a thigh parameter value indicating movement of the thigh of the subject H. The angular velocity is detected, and the detection result is output to the main unit 4 by wireless transmission.

  Both sensors 2 and 3 start detection when a power switch (not shown) is turned on, and start transmission of signals indicating acceleration and angular velocity as detection results.

  The main unit 4 includes a receiving unit 41 that receives radio signals transmitted from the sensors 2 and 3, an input unit 42 including an input switch, a keyboard, a mouse, and the like, an output unit 43 including a display, and a system program. And a memory 44 for storing various information, and a data processor 45 for performing data processing based on various data obtained from the receiver 41 and the input unit 42.

The receiving unit 41 receives a radio signal transmitted as a signal indicating a detection result from both the sensors 2 and 3, and outputs the received signal to the data processing unit 45.
The storage unit 44 is installed with a program for calculating a margin for lower limb muscle strength, which will be described later, and a functional unit for calculating and evaluating the margin for lower limb muscle strength is realized by this program.

  FIG. 3 is an external view showing an example of the main body 4. The main unit 4 has a power button 52 for turning on / off the power of the apparatus, an input button 53 for inputting the height of the subject H, and a measurement start on the outer surface of a casing 51 housing each part. Is provided with a measurement start button 54 and a display 55 for displaying calculation results.

The input button 53 and the measurement start button 54 constitute an input unit 42 (FIG. 1), and the display 55 constitutes an output unit 43 (FIG. 1).
That is, when the subject H inputs his / her height using the input button 53, the data processing unit 45 can acquire information on the height of the subject H. In addition, the data processing unit 45 can recognize the measurement start timing when the subject H inputs the start of measurement using the measurement start button 54.
When the measurement is completed, the data processing unit 45 displays the calculation and evaluation results on the display 55. Thereby, the data processing unit 45 can make the subject H recognize the calculation and the evaluation result.

  The main body 4 is provided with an interface (not shown) for connection to an external computer or the like, and can be controlled via the external computer. Therefore, in this case, the keyboard and mouse of the external computer constitute the input unit 42, and the display and printer of the external computer constitute the output unit 43.

  Returning to FIG. 1, the data processing unit 45 includes a control unit 45 a that comprehensively controls the operation of each unit included in the main body unit 4, and a calculation unit 45 b that has a function of calculating a margin of lower limb muscle strength. . The function of the data processing unit 45 will be described in detail later.

[Calculation and evaluation method for lower limb muscle strength]
FIG. 4 is a flowchart showing a procedure for calculating and evaluating a lower limb muscle strength margin using the lower limb strength evaluation apparatus 1.
In order to calculate and evaluate the margin of the lower limb muscle strength, first, a waist belt 5 to which the upper body sensor 2 of the lower limb muscle strength evaluation apparatus 1 is fixed, and a thigh belt 6 to which the thigh sensor 3 is fixed; Is attached to the subject H, so that both sensors 2 and 3 are fixed and installed on the subject H (step S1).

At this time, the waist belt 5 is attached to the subject H so that the upper body sensor 2 is located on the back side of the subject H and the most prone portion of the waist.
In addition, the thigh belt 6 is attached to the subject H so that the thigh sensor 3 is positioned at approximately the center in the width direction of the outer side surface of the thickest part of the one side thigh of the subject H.
Thereby, both sensors 2 and 3 are fixed so as to be in a fixed positional relationship with respect to the mass center of the upper body and the mass center of the thigh.

  Further, after the sensors 2 and 3 are installed on the subject H, the power switches (not shown) of the sensors 2 and 3 are turned on. Thereby, both sensors 2 and 3 start transmission of signals indicating acceleration and angular velocity as parameter values indicating the movement of each part, which are detection results.

Next, the power switch of the lower limb muscle strength evaluation apparatus 1 is turned on, and the input button 53 provided on the main body 4 is operated to input a set value such as the height of the subject H (step S2).
When the height of the subject H is input by operating the input button 53, the control unit 45a (FIG. 1) of the main body unit 4 stores the input value in the storage unit 44 (FIG. 1).
Even if the height of the subject H is not input, the control unit 45a continues the process. In this case, the control unit 45a reads the standard height of the subject H, which is stored in advance in the storage unit 44, to calculate the margin of lower limb muscle strength, and performs processing using this.

  After inputting the height of the subject H, by operating the measurement start button 54, the control unit 45a can obtain the acceleration, which is the detection result of both the sensors 2 and 3, obtained from the received signal received by the receiving unit 41. Acquisition of the angular velocity (parameter value indicating the movement of the subject H) is started (step S3).

Next, the posture change operation is performed on the subject H who has fixed and installed both the sensors 2 and 3 (step S4). FIG. 5 is a diagram illustrating an example of a posture change operation to be performed by the subject H.
As shown in FIG. 5, first, as an initial posture, the subject H takes a standing posture. Next, from this standing posture, the subject is crouched at the maximum depth for the subject H, and is temporarily stopped in that posture (maximum crouching posture).
Thereafter, the subject H gets up from the maximum squatting posture with full power and takes the standing posture again.

  While the subject H is performing the posture changing operation, the control unit 45a continuously acquires the acceleration and the angular velocity that are the detection results of both the sensors 2 and 3. The control unit 45a acquires the acceleration and angular velocity, which are detection results of the sensors 2 and 3, as discrete values associated with a predetermined sampling time, and stores them in the storage unit 44 as needed.

  When the measurement start button 54 is operated again because the subject H has finished the posture changing operation, the control unit 45a ends the acquisition of the detection results of both the sensors 2 and 3 (step S5).

  When the control unit 45a finishes obtaining the detection results of both the sensors 2 and 3, the control unit 45a causes the calculation unit 45b to perform a calculation for calculating the margin of the lower limb muscle strength (step S6).

  First, the calculation unit 45b includes the upper body part, the thigh part, the crus part, and the foot part of the subject H as segments (upper body part segment, thigh segment, crus segment, and foot segment), respectively. The sum of the joint moment (hip joint moment) of the hip joint that connects the upper body and the thigh and the joint moment (knee joint moment) of the knee joint that connects the thigh and the lower leg is obtained.

FIG. 6 is a diagram showing each part of the subject H as a segment. The calculation unit 45b is configured to coordinate the movement of each segment of the subject H with the subject's front-rear direction as the X coordinate, the vertical direction as the Y coordinate, and the left and right direction as the Z coordinate, as shown in the page of FIG. It is grasped in the system, and the sum T _{hip + knee} (t) of the joint moment of the hip joint and the knee joint is obtained based on the following formula (1).

However, in formula (1), A is represented by the following formula (2). Also, P _H is translational acceleration, P _T of the center of mass of the upper body portion segments in the inertial coordinate system is a translational acceleration of the center of mass of the thigh segment in the inertial coordinate system, the following equation (3), (4) Represented by

In Formula (1), L _Thigh is the length in the longitudinal direction of the thigh segment, k _Thigh is a parameter indicating the center of mass position in the longitudinal direction of the thigh segment, and θ _Thigh (t) is large. This is the angle of the thigh segment, and each of these parameters is represented as shown in FIG.
Furthermore, in the formula (1), Bal _RL is a parameter indicating the left-right balance in the floor reaction force (in this embodiment, set to 0.5), m _Body is the total mass of the subject H, m _HAT is The mass of the upper body segment, m _Thigh is the mass of the thigh segment, g is the gravitational acceleration, t is the subject H transitions from the standing posture to the maximum squatting posture, and then stands again from the maximum squatting posture. The time until the transition to.
In equation (2), rad _Thigh is a value obtained by standardizing the radius of rotation for obtaining the moment of inertia of the thigh segment by the length of the segment.

The angular acceleration of the thigh segment may be expressed as (d ² / dt ² ) θ _Thigh (t).

In the above formula (1), the translation acceleration P _H , translation acceleration P _T , thigh segment angle θ _Thigh (t), thigh segment angular acceleration (d ² / dt ² ) θ _Thigh (t) are: It is a variable that changes in accordance with time t (operation of the subject H) obtained from the detection results of both the sensors 2 and 3. The processing for the calculation unit 45b to obtain these variables from the detection results of both the sensors 2 and 3 will be described later.
On the other hand, the other parameters (L _Thigh , k _Thigh , Bal _RL , m _Body , m _HAT , m _Thigh , rad _Thigh , g) are constants that do not change with respect to time t. The calculation unit 45b is preset to use “0.5” for the parameter Bal _RL indicating the left-right balance in the floor reaction force and “9.8665” for the gravitational acceleration g among these constants.

For the remaining parameters (L _Thigh , k _Thigh , m _Body , m _HAT , m _Thigh ) that change according to the physique etc. of the subject H, the calculation unit 45 b receives the subject H input in step S 2. Use an estimate based on the height of the.
For example, if a database in which the height of the subject H and the estimated values of the parameters corresponding to the height are associated and registered is stored in the storage unit 44, the calculation unit 45b can input the subject to be input. The estimated value of each parameter according to the height of H can be obtained by referring to the database. In addition, as the estimated value of each parameter registered in the database, the value of each parameter corresponding to the height is based on data based on literatures reported as research results or other statistical data. The estimated one can be used.

  Further, even if the height of the subject H is not input, as described above, the calculation unit 45b is a standard subject in calculating the lower limb muscle strength margin stored in the storage unit 44 in advance. The height of the examiner H is read, and the estimated value of each parameter is acquired using this.

The calculation unit 45b calculates the translation acceleration P _H , translation acceleration P _T , thigh segment angle θ _Thigh (t), and thigh segment angular acceleration (d ² / dt ² ) in the above formula (1). θ _Thigh (t) is obtained from the detection results of both sensors 2 and 3.

  The acceleration sensor units 21 and 31 of the sensors 2 and 3 detect biaxial acceleration on the XY plane in FIG. 6 when the sensors 2 and 3 are fixed to the subject H. It is provided so that you can.

  As for the angle θ (t) of the thigh segment, the calculation unit 45b uses the segment angle at the start of the operation as an initial value, and sets the angular velocity of the thigh segment included in the detection result of the thigh sensor 3 at time t. Find by integration. Further, the initial value at the start of the operation can be grasped from the acceleration direction of the thigh segment included in the detection result. That is, if the segment is in a stationary state, the acceleration sensor unit detects only gravity, and therefore the relative angle of the segment can be grasped from the direction of gravity with respect to the sensor unit.

Regarding the angular acceleration (d ² / dt ² ) θ _Thigh (t) of the thigh segment, the calculation unit 45b determines the angular velocity ((d / dt) of the thigh segment included in the detection result of the thigh sensor 3. θ _Thigh (t)) is obtained by differentiating with respect to time t.

The translational acceleration P _H of the center of mass of the upper body portion segments, and the acceleration of the upper body portion segments included in the detection results upper body section sensor 2 is determined using the angular velocity.
The acceleration that is the detection result of the upper body sensor 2 indicates the acceleration at the position of the acceleration sensor unit 21 in its own coordinate system (sensor coordinate system). Therefore, in order to obtain the acceleration at the center of mass of the upper body segment, the calculation unit 45b corrects the acceleration as a detection result to the acceleration at the center of mass of the upper body segment, and further, the corrected acceleration is represented by an inertial coordinate system (see FIG. The coordinate is converted to the coordinate system shown in FIG. This makes it possible to determine the translational acceleration P _H of the center of mass of the upper body portion segments.

  In order to correct the acceleration as a detection result to the acceleration at the center of mass of the upper body segment, the calculation unit 45b includes a relative positional relationship between the position of the acceleration sensor unit 21 and the center of mass of the upper body segment, The deviation of acceleration is calculated and corrected using the angular velocity included in the detection result.

  As the relative positional relationship between the position of the acceleration sensor unit 21 and the center of mass of the upper body segment, an actually measured value can be used, but in the present embodiment, as described above, Since the upper body sensor 2 is fixed at a position having a certain positional relationship with respect to the center of mass, data indicating the positional relationship approximately can be stored in advance, and the stored data can be used. Moreover, since the data indicating the positional relationship may change slightly depending on the height of the subject H, for example, the height of the subject H and the positional relationship corrected according to the height are indicated. If the database associated with the data is stored in the storage unit 44, the calculation unit 45b refers to the database for data indicating the positional relationship according to the height of the subject H, so that the accuracy is higher. Data can be acquired.

  Even if the height of the subject H is not input, the calculation unit 45b uses the data indicating the standard positional relationship stored in the storage unit 44 in advance for calculating the margin of lower limb muscle strength. It can also be read and acquired.

  Thus, in this embodiment, since the upper body part sensor 2 was fixed appropriately, it becomes easy to standardize or simplify the calculation required for correction. As a result, convenience can be further improved.

Furthermore, since the acceleration sensor unit 21 is fixed in a fixed positional relationship with respect to the upper body segment, an approximate conversion matrix for coordinate conversion from the sensor coordinate system to the inertial coordinate system is obtained in advance. It can be stored in the storage unit 44.
The calculation unit 45 b converts the corrected acceleration, which is the sensor coordinate system, into the inertial coordinate system using the conversion matrix stored in the storage unit 44.
Accordingly, the arithmetic unit 45b can calculate the translational acceleration _{P H.}

Calculation unit 45b, similarly to the translational acceleration P _H, and the acceleration of the thigh segments included in the detection result of the thigh sensor 3, angular velocity, corrected, performs coordinate transformation, translation of the center of mass of the thigh The acceleration _PT is obtained.

As described above, the calculation unit 45b obtains the above values based on the height of the subject H and the detection results of the sensors 2 and 3, and the sum T _{hip + knee} (t )

Next, the calculation unit 45b acquires the maximum value of the sum T _{hip + knee} (t) of the _hip joint and knee joint during the posture change operation shown in FIG. Based on this, the margin of lower limb muscle strength is obtained.

In the above equation (5), Muscle_margin is the margin of lower limb muscle strength, max (T _{hip + knee} (t)) is the maximum value of the joint moment T _{hip + knee} (t) of the _hip joint and knee joint, T ^ref _{hip + knee} is a reference value indicating the minimum muscular strength necessary for the subject to stand up from the squatting posture. The reference value T ^ref _{hip + knee} is expressed by the following formula (6).

In the above formula (6), the value obtained from the right side is the sum T _{hip + knee} of the joint moment of the hip joint and the knee joint when the thigh is kept horizontal and the crouching posture is maintained (static state). This coincides with a reference value T ^ref _{hip + knee} which is a value indicating the necessary minimum muscle strength necessary for the subject to stand up from the squatting posture.

That is, the muscle strength that can exert a value greater than the sum T _{hip + knee} (reference value T ^ref _{hip + knee} ) of the joint moment of the hip joint and the knee joint when maintaining a crouching posture in which the thigh is horizontal in the posture changing operation. When the subject is in the subject H, the subject H can be evaluated as having muscle strength that allows standing up even from a squatting posture in which the thigh is crouched deeper than horizontal.
In other words, the hip and knee joints obtained by measurement are more than the sum T _{hip + knee} (reference value T ^ref _{hip + knee} ) of the joint moments of the hip and knee joints when maintaining a crouching posture in which the thigh is horizontal. if the maximum value _{max (T hip + knee (t} )) is greater of the sum of the joint moment T _{hip + knee} (t), that the subject H, it can be evaluated that there is a strength that can stand up from the squatting posture .
The reference value T ^ref _{hip + knee} can be obtained as a constant that does not vary with time by being obtained from the above equation (6).

The calculation unit 45b of the present embodiment sets the sum T _{hip + knee} of the _hip joint and the knee joint when maintaining the crouching posture in which the thigh is horizontal as the reference value T ^ref _{hip + knee} , Maximum value max (T _{hip + knee} (t) of the sum T _{hip + knee} (t) of _hip joint and knee joint of subject H obtained by measurement (detection result) during posture change by examiner H )) Calculates the percentage of the reference value T ^ref _{hip + knee} as a percentage, and outputs this as a margin of lower limb muscle strength. Therefore, the reference value T ^ref _{hip + knee,} the maximum value max of the sum of the joint moment _{T hip + knee (t) (} T hip + knee (t)) is large and the strength for rising is large, The margin is a value exceeding 100%. Conversely, if the maximum value max (T _{hip + knee} (t)) of the sum of joint moments T _{hip + knee} (t) is smaller than the reference value T ^ref _{hip + knee and} the muscle strength to stand up is small, there is a margin. The degree is less than 100.

  When the calculation unit 45b calculates the margin of the lower limb muscle strength, the control unit 45a performs the level evaluation of the margin of the lower limb muscle strength from the value of the margin of the lower limb muscle strength. For example, the control unit 45a evaluates the level of the lower limb muscle strength margin according to the value in three stages of “high”, “medium”, and “low”.

  Returning to FIG. 4, next, the control unit 45a displays the numerical value of the margin of the lower limb muscle strength and the evaluation level on the display 55, thereby outputting the calculation result and the evaluation result (step S7). Finish.

FIG. 7 is an example of a calculation result of the lower limb muscle strength margin and an evaluation result output. FIG. 7A shows a display on the display 55 of the main body 4.
FIG. 7A shows a case where the numerical value of the margin of the lower limb muscle strength is “186%” and the evaluation level is “medium”. As described above, the lower limb muscle strength evaluation apparatus 1 outputs the calculation and evaluation results to the subject H.

Moreover, FIG.7 (b) is the figure which represented the calculation result of the margin of the leg muscular strength with the graph.
In the graph in FIG. 7B, the horizontal axis represents time t, and the vertical axis represents moment. The diagram in the figure shows a calculation result during a series of operations in which the subject H shifts from the standing posture to the maximum squatting posture and further rises from the maximum squatting posture to the standing posture.

In the figure, a diagram I indicated by a solid line indicates a sum T _{hip + knee} (t) of the _hip joint and the knee joint (hereinafter also simply referred to as a sum of joint moments T _{hip + knee} (t)). Yes. In the figure, the subject H is in a standing posture within a range where the sum of joint moments T _{hip + knee} (t) on the left side of the drawing is relatively low. When the subject H starts to move from the standing posture to the squatting posture, the sum of joint moments T _{hip + knee} (t) _gradually increases and is maintained at a substantially constant value at the maximum squatting posture. The
Thereafter, when the subject H stands up with full power, the sum of joint moments T _{hip + knee} (t) rapidly increases and takes the maximum value, and rapidly decreases when reaching the standing posture. Then, by maintaining the standing posture, it is stabilized again at a low value.

Here, the reference value T ^ref _{hip + knee} is indicated by a broken line R in the graph of FIG. Therefore, when the maximum value max (T _{hip + knee} (t)) of the joint moment is larger than the broken line R, the margin of the lower limb muscle strength becomes 100% or more.

In the figure, a diagram II indicated by a broken line is a value indicating a total value of acceleration-related values such as the translational accelerations P _H and P _{T in} the above formula (1), and the agility of movement of the subject H Is shown. Moreover, the diagram III shown with a dashed-dotted line is a value which shows the total value of the term containing "g" in the said Formula (1), and is how deep the subject H is squatting. It shows the degree of crouching. A diagram IV indicated by a two-dot chain line is a value indicating a term including “rad” in the above formula (1), and indicates a component in the Z-axis direction in FIG. 6. Therefore, the diagram IV has almost no change in the posture change of the subject H from the standing posture to the standing posture.
That is, the diagram I is a diagram obtained by summing up the diagrams II, III, and IV, and the maximum sum max of joint moments (T _{hip + knee} (t)) is the degree of squatting of the subject H. And a value based on the agility of the standing motion of the subject H, and can be obtained as a value including the influence of the maximum squatting posture of the subject.

The graph shown in FIG. 7B shows the calculation result of the subject H who has a relatively young leg muscle strength margin. Here, the leg muscle strength is low and the maximum squatting posture is large. When the thigh is shallow enough not to reach the horizontal state, the value of the diagram III is low, and the sum of joint moments T _{hip + knee} (t) is also a relatively low value that does not reach the reference value T ^ref _{hip + knee.} It becomes.
Even in this case, the maximum value max (T _{hip + knee} (t)) of the joint moment can be acquired by changing the posture from the state to the standing posture.
At this time, the sum T _{hip + knee} (t) of the joint moment starts to rise by taking a standing posture from the value in the maximum squatting posture that appears as a relatively low value, and the maximum value max (T _{hip +} since reaches _knee (t)), the maximum value _{max (T hip + knee (t} )) also include the effect of the sum of the joint moment in the maximum squatting posture T _{hip + knee} (t), the subject H Can be obtained as a value including the influence of the maximum crouching posture.

[About the effect of this method]
In the method for evaluating the lower limb muscle strength configured as described above, a sensor installation step for installing the upper body sensor 2 and the thigh sensor 3 for acquiring a parameter value indicating the movement of the subject H (step S1). And the acceleration and angular velocity (upper body) indicating the movement of the upper body and thigh of the subject H during the period from the maximum squatting posture, which is the posture where the subject H is crouched as much as possible, to the standing posture. Parameter value acquisition step (steps S3 to S5) in which the upper body sensor 2 and the thigh sensor 3) are acquired by the upper body sensor 2 and the thigh sensor 3, and the acceleration and angular velocity of the acquired upper body and thigh From this, the maximum value max (T _{hip + knee} (t)) of the joint moment of the hip joint and knee joint of the subject H is obtained, and the subject H stands up from the squatting posture. A calculation step (step S6) for calculating a margin of lower limb muscular strength based on a reference value T ^ref _{hip + knee} indicating a necessary minimum muscular strength necessary for performing.

According to the above-described method for evaluating the lower limb muscle strength, the hip joint and knee are determined from the acceleration and angular velocity of the subject's H thigh and upper body while the subject H changes from the maximum squatting posture to the standing posture. The maximum value max (T _{hip + knee} (t)) of the sum of the joint moments of the joint is obtained, and the maximum value and the reference value reference value T ^ref _{hip + knee} indicating the minimum muscle force necessary for standing are used. Since the margin is calculated, the evaluation can be performed with high accuracy.
Further, since the margin of lower limb muscle strength is calculated based on the maximum sum max of joint moments (T _{hip + knee} (t)), the margin includes the influence of the maximum squatting posture of the subject H. Can be obtained as For this reason, even if there is a difference in the maximum squatting posture due to a difference in muscle strength for each subject H, it can be evaluated as a margin of lower limb muscle strength including a difference in the maximum squatting posture.

In addition, the calculation unit 45b of the present embodiment calculates the sum T _{hip + knee} of the joint moment of the hip joint and the knee joint when the thigh is kept horizontal and the crouching posture is maintained (static state). H is adopted as a reference value (reference value T ^ref _{hip + knee} ) indicating a necessary minimum muscle force necessary for standing up from a squatting posture, and a margin of lower limb muscle strength is obtained. As a result, the reference value T ^ref _{hip + knee} can be obtained as a constant that does not change with time (see Expression (6)), so that the margin of lower limb muscle strength can be calculated with more stable accuracy.

  In the present embodiment, sensors that can acquire parameter values indicating the movement of the subject H, such as inertial sensors such as the acceleration sensor units 21 and 31 and the angular velocity sensor units 22 and 32, are installed, and Since the margin of lower limb muscle strength is obtained, it is possible to evaluate with good convenience.

  Further, in step S1 of the present embodiment, the upper body sensor 2 and the thigh sensor 3 are fixed to the subject H as described above, so that the thigh sensor 3 is fixed and the thigh sensor 3 is fixed by a simple operation. The parameter value indicating the movement of the part can be acquired, and the convenience can be enhanced.

In addition, the calculation unit 45b of the present embodiment sets the maximum sum max of joint moments of the hip joint and the knee joint (T _{hip + knee} (t)), the acceleration and angular velocity of the thigh, and the acceleration and angular velocity of the upper body. Therefore, the evaluation can be performed with higher accuracy.
In this respect, the margin of lower limb muscle strength can also be obtained from only the thigh acceleration and angular velocity, which are detection results of the thigh sensor 3.

In the present embodiment, the height of the subject H is input in step S2, and the length L _Thigh in the longitudinal direction of the thigh of the subject H and the parameter k indicating the center of mass position based on the height. _Thigh , total mass m _Body of subject H, upper body mass m _HAT , and thigh mass m _Thigh are estimated, so it is not necessary to prepare all the constants necessary for obtaining the margin of lower limb muscle strength The constants can be estimated according to the height of the subject H using data such as documents and other statistical data, and convenience can be improved without degrading the evaluation accuracy.

Further, in the present embodiment, in steps S3 to S5 that are parameter value acquisition steps, the subject H in the standing posture changes the posture to the maximum squatting posture and further changes the posture from the maximum squatting posture to the standing posture again. The acceleration and angular velocity, which are the detection results of both sensors 2 and 3, are acquired. Therefore, the sum T _{hip +} of the joint moments of the hip joint and knee joint of the subject H when the posture changes from the standing posture to the maximum squatting posture The relative change in _knee (t) can be grasped, and the state of the maximum squatting posture based on the standing posture of the subject H can be grasped.
[Regarding Modification of First Embodiment]
In the formula (1), the translational acceleration P _H of the upper body portion segments, as shown in the following formula (7) can be expressed using a translational acceleration P _T of the thigh segment.

In the above formula (7), L _HAT is the length of the upper body segment in the longitudinal direction, k _HAT is a parameter indicating the center of mass position in the longitudinal direction of the upper body segment, and θ _HAT (t) is the upper body segment. It is an angle, and each of these parameters is represented as shown in FIG.

Here, the calculation unit 45b substitutes the equation (7) into the equation (1), and also calculates the angle θ _HAT (t) of the upper body segment, the angular velocity (d / dt) θ _HAT (t) of the upper body segment, Angular acceleration (d ² / dt ² ) θ _HAT (t), thigh segment angle θ _Thigh (t), upper body segment angular velocity (d / dt) θ _Thigh (t), angular acceleration (d ² / By using the estimated value estimated based on dt ² ) θ _Thigh (t), the sum T _{hip + knee} (t) of the _hip joint and the knee joint can be obtained.

When estimating the angular velocity (d / dt) θ _HAT (t) and angular acceleration (d ² / dt ² ) θ _HAT (t) of the upper body segment, the computing unit 45b uses statistical information based on past data, Estimate using physical constraints.

As described above, by using the expression (1) substituted with the expression (7), the calculation unit 45b can obtain the angle θ _Thigh (t) of the thigh segment obtained only from the detection result of the thigh sensor 3. Based on the angular velocity (d / dt) θ _Thigh (t) and angular acceleration (d ² / dt ² ) θ _Thigh (t) of the upper body segment, the sum of hip and knee joint moments T _{hip + knee} (t ).

In this case, since the calculation unit 45b can obtain the sum T _{hip + knee} (t) of the _hip joint and the knee joint from only the detection result of the thigh sensor 3, the upper body sensor 2 is detected by the subject. It is not necessary to install in H.
Therefore, when the calculation unit 45b uses the equation (1) obtained by substituting the equation (7), if only the thigh sensor 3 is installed in the thigh of the subject H, the margin of the lower limb muscle strength can be reduced. Evaluation can be made.
In this case, since only one thigh sensor 3 needs to be installed on the subject H, the convenience can be further improved.

  Further, in the above case, as shown in FIG. 8, if the subject H holds and fixes the thigh sensor 3 to the front side of the thigh by hand, the thigh belt as shown in FIG. 2. Thus, the thigh sensor 3 can be fixed and installed on the thigh of the subject H without using a fixing device. For this reason, the thigh sensor 3 can be easily attached to and detached from the thigh.

  In this case, as shown in FIGS. 8 (a) and 8 (b), the subject H has the thigh sensor 3 in the center of the front side of the thigh in the width direction and in the vicinity of the base of the leg. Press to fix. This is because if the arm is fixed near the center of the thigh in the longitudinal direction, the arm cannot reach when the subject H stands up, and the thigh sensor 3 cannot be fixed. At this time, the calculation unit 45b determines the positional relationship between the center of mass of the thigh and the thigh sensor 3 when the thigh sensor 3 is installed at a position (near the base of the leg) as shown in FIG. It is set to perform the correction according to the above.

In addition, the arithmetic unit 45b calculates the angle θ _HAT (t) of the upper body segment, the angular velocity (d / dt) θ _HAT (t), and the angular acceleration (d ² / dt ² ) of the upper body segment in the above equation (7). theta _HAT (t) may be calculated translational acceleration P _H of the upper body portion segments approximately using the following equation (8), which was considered "0" to the section containing the.

Further, the calculation unit 45b uses the following equation (9) in which the angular acceleration (d ² / dt ² ) θ _Thigh (t) of the thigh in the above equation (8) is regarded as “0”, and the upper body segment it may be obtained of the translational acceleration P _H to approximate.

Furthermore, the calculation unit 45b can obtain the sum T _{hip + knee} (t) of the joint moments of the hip joint and the knee joint by approximating the term A to “0” in the above formula (1).

  By using the approximate expression, the amount of calculation performed by the calculation unit 45b can be suppressed, and the lower limb muscle strength margin can be calculated and evaluated more quickly.

[Second Embodiment]
FIG. 9 is a diagram illustrating a state in which the sensor of the lower limb muscle strength evaluation apparatus according to the second embodiment of the present invention is installed on the subject H.
The lower limb muscle strength evaluation apparatus 1 according to the present embodiment is configured to detect the floor reaction force that acts on the upper surface 60 and allows the subject H to stand on the upper surface 60 of the housing 51 of the main body 4. It differs from the first embodiment in that a floor reaction force sensor 61 is provided.

In the present embodiment, the lower limb muscle strength evaluation apparatus 1 acquires a parameter value indicating the movement of the subject H by the thigh sensor 3 and the floor reaction force sensor 61 provided in the main body 4.
The main body 4 is provided with a display 55 on the upper surface 60 for displaying calculation and evaluation results in addition to the floor reaction force sensor 61.
In the present embodiment, the thigh sensor 3 is wired to the main body 4 and outputs a detection result via the communication line 62.

FIG. 10 is a diagram schematically showing the reaction force acting on the subject H detected by the floor reaction force sensor 61.
As shown in the figure, the floor reaction force sensor 61 provided on the upper surface 60 of the main body 4 detects a vertical component and a front-rear component of the reaction force acting on the subject H. The floor reaction force sensor 61 outputs the detection result to the data processing unit 45 (FIG. 1).

The calculation unit 45b of the present embodiment calculates the sum T _{hip + knee} (t) of the joint moment between the hip joint and the knee joint, which is used in the calculation for calculating the margin of lower limb muscle strength performed in step S6 in FIG. It calculates | requires based on Formula (10).

In the above formula (10), A is represented by the above formula (2).
P _S is the translational acceleration, P _F of the center of mass of the crus segment in the inertial coordinate system is a translational acceleration of the center of mass of the foot segment in the inertial coordinate system, the following equation (11) is represented by (12) The

In Expression (10), m _Shank represents the mass of the lower leg segment, and m _Foot represents the mass of the foot segment.
Furthermore, R _{cop1_G} (t) indicates the front and rear components of the floor reaction force acting on the subject H. Further, R _{cop2_G} (t) indicates the vertical component of the floor reaction force acting on the subject H.

In the above equation (10), the calculation unit 45b calculates the longitudinal component floor reaction force R _{cop1_G} (t), the vertical component floor reaction force R _{cop2_G} (t), the translational acceleration P _T , and the thigh segment angle θ _Thigh (t). And, the angular acceleration (d ² / dt ² ) θ _Thigh (t) of the thigh segment is obtained from the detection results of both sensors 3 and 61.

The front / rear component floor reaction force R _{cop1_G} (t) and the upper / lower component floor reaction force R _{cop2_G} (t) use the output of the floor reaction force sensor 61. As described above, the other values are obtained based on the thigh acceleration, which is the detection result of the thigh sensor 3, and the angular velocity.
In the formula (10), the translational acceleration P _S of the center of mass of the lower leg _segment, and the translational acceleration P _F of the center of mass of the foot segment, the inertial sensor to the crus and feet of the subject H It can also be detected by installing, in the present embodiment, the arithmetic unit 45b, the translational acceleration P _S of the center of mass of the lower leg _segment, and a translational acceleration P _F of the center of mass of the foot segment, " Approximate to “0”, and obtain the sum T _{hip + knee} (t) of the joint moment of the hip joint and the knee joint.

The calculation unit 45b calculates the margin of lower limb muscle strength using the sum T _{hip + knee} (t) of the joint moments of the hip joint and the knee joint.

As described above, in this embodiment, the sum T _{hip + knee} (t) of the _hip joint and the knee joint can be obtained using the detection results of the floor reaction force sensor 61 and the thigh sensor 3. The subject H stands on the floor reaction force sensor 61 of the main body 4, the thigh sensor 3 is fixed to the thigh, and then the squatting posture is changed to the maximum squatting posture. If it shifts to a standing posture by standing up from a crouching posture with full power, it is possible to calculate and evaluate a margin of lower limb muscle strength.

In the present embodiment, the equation (10) used by the calculation unit 45b includes the front / rear component floor reaction force R _{cop1_G} (t), the upper / lower component floor reaction force R _{cop2_G} (t), and the time t (operation of the subject H). as a variable which varies according to, the translational acceleration _{P T,} translational acceleration _{P S,} translational acceleration _{P F,} the angle theta _thigh thigh segment (t), and the angular acceleration of the thigh segment ^{(d 2} / dt 2 ) Θ _Thigh (t) is included.
Therefore, if an inertial sensor for obtaining the above variable is installed in the subject H, the motion of the subject H can be grasped with higher accuracy, and as a result, the calculation and evaluation of the margin of lower limb muscle strength are also accurate. It can be carried out. In other words, in addition to the thigh segment, an inertial sensor is fixed to the crus segment and the foot segment, and the acceleration and angular velocity obtained as a result of detection by each sensor can be used for more accurate calculation and evaluation. Can do.

FIG. 11 is a diagram showing variations of the inertial sensor installation in the second embodiment.
FIG. 11A shows a configuration similar to that shown in FIG. 9 and using the thigh sensor 3 and the floor reaction force sensor 61.
FIG. 11 (b) shows a case where the inertial sensor 70 is fixed to the crus segment in addition to the configuration of (a). In this example, the detection result of the inertial sensor 70 fixed to the lower leg segment, it is possible to obtain the translational acceleration P _S.

FIG. 11C shows a case where the inertial sensor 71 is fixed to the foot segment in addition to the configuration of FIG. In this example, the detection result of the inertial sensor 71 fixed to the foot segment, it is possible to obtain the translational acceleration P _F.

FIG. 11 (d) shows an inertial sensor 70 on the lower leg segment in addition to the configuration of (a).
The case where the inertial sensor 71 is fixed to the foot segment is shown. In this example, the detection results of both the inertial sensors 70 and 71, the translational acceleration _{P S,} can be determined translational acceleration _{P F.}

As described above, translational acceleration P _S, the translational acceleration P _F can be approximated to "0". Further, the front / rear component floor reaction force R _{cop1_G} (t) detected by the floor reaction force sensor 61 can be approximated to “0” in the squatting operation. That is, even if the floor reaction force sensor 61 that can detect only the floor reaction force of the vertical component is used, the margin of the lower limb muscle force can be calculated.
Furthermore, in the equation (10), the term A can also be approximated to “0”.
Therefore, in the present embodiment, it is possible to select which variable value is approximated to “0” according to the installation status of the inertial sensor and the required accuracy, and to calculate and evaluate the margin of lower limb muscle strength. it can.

[Other variations]
The embodiments disclosed herein are illustrative and non-restrictive in every respect.
For example, in the first embodiment, the upper body sensor 2 and the thigh sensor 3 include biaxial acceleration sensor units 21 and 31 and angular velocity sensor units 22 and 32, respectively, as inertial sensors. Although the case has been shown, it is not necessary for one sensor to include both the acceleration sensor unit and the angular velocity sensor unit. That is, based on the acceleration detected by the acceleration sensor, the tilt angle of the sensor with respect to the vertical direction can be obtained. This is because the angle with respect to the vertical direction of the coordinate system of the sensor can be obtained from the direction and magnitude of gravity detected by the sensor.
For the above reasons, both the sensors 2 and 3 may be configured to include only a biaxial acceleration sensor unit.

  Moreover, both sensors 2 and 3 may be provided with a geomagnetic sensor in addition to the acceleration sensor units 21 and 31 and the angular velocity sensor units 22 and 32. In this case, the angular velocity is obtained by using the geomagnetic data from the geomagnetic sensor. Can be corrected with higher accuracy.

Further, in each of the above embodiments, the case where a biaxial acceleration sensor is used as the acceleration sensor is exemplified. However, a triaxial acceleration sensor can also be used, and in this case, the movement of the subject H is measured three-dimensionally. Can be detected.
The inertial sensor described above is appropriately selected according to required accuracy and cost.

  Further, in each of the above-described embodiments, the upper body sensor 2 is fixed to the most prone portion of the waist back side, and the thigh sensor 3 is fixed to substantially the center in the width direction of the outer side surface of the thickest portion of the thigh. Although the case is illustrated, if the detection results of the sensors 2 and 3 are corrected to the value at the position of the center of mass of each part, the upper body sensor 2 is fixed to, for example, the chest front of the subject H or the front of the abdomen The thigh sensor 3 can be fixed near the base of the thigh or the knee joint.

In the lower limb muscle strength evaluation method of the present invention, evaluation can be performed if a squatting posture of a certain depth can be taken, but it is difficult to squat in the case of the subject H whose ankle joint (ankle) has low flexibility. In some cases, the maximum crouching posture may not reach a crouching depth that can be evaluated.
In such a case, as shown in FIG. 12 (a), a pedestal 75 having a toe-down slope formed on the surface on which the subject H is placed, and a heel platform for placing the heel of the subject H 76 may be used to cause the subject H to perform a posture change operation.
In this case, even if the flexibility of the ankle joint is low, the subject H can easily take a crouching posture, and can reliably calculate and evaluate the degree of lower limb muscle strength.

In the first embodiment described above, in step S2 (FIG. 4), the height of the subject H is obtained as the set value, and the margin of the lower limb muscle strength is calculated using the height. Further, not only the height but also the weight of the subject H may be obtained, and the margin of the lower limb muscle strength may be calculated using the weight in addition to the height. In this case, it is possible to further increase the estimation accuracy of the upper body mass m _HAT and the thigh mass m _Thigh .

  The floor reaction force sensor 61 used in the second embodiment can also measure the weight of the subject H if the subject H is stationary. Therefore, in this case, the body weight of the subject H may be acquired by the floor reaction force sensor 61.

Here, the lower limb muscle strength evaluation apparatus of the present invention can also show a change in the margin of the lower limb muscle strength according to the change in the body weight of the subject H by combining with a body coarse meter or a weight scale. For example, a subject with a weight of 100 kg and a margin of 120% can calculate the margin when the weight is reduced to 80 kg and output it to the subject. In this case, when the weight of the subject decreases to 80 kg, the margin can be calculated as 150% as shown in the following formula (13).
(100/80) × 120 = 150 (13)

  By providing the subject H with the above information, direction of rehabilitation, training, and the like, confirmation of effects, and the like can be performed.

DESCRIPTION OF SYMBOLS 1 Lower limb strength evaluation apparatus 2 Upper body sensor 3 Thigh sensor 45 Data processing part (calculation part)

Claims (13)

A lower limb strength evaluation method for evaluating a lower limb strength of a subject,
A sensor installation step of installing a sensor for obtaining a parameter value indicating the movement of the subject;
The thigh parameter value indicating the movement of the subject's thigh during the period from the maximum squatting posture, where the subject is crouching as much as possible, to the standing posture is changed by the sensor. A parameter value acquisition step to be acquired;
Based on the acquired thigh parameter value, the maximum value of the sum of the joint moments of the subject's hip joint and knee joint is obtained, and the maximum value and the subject to stand up from the squatting posture A calculation step for calculating a margin of lower limb muscle strength based on a reference value indicating a necessary minimum muscle strength;
A method for evaluating lower limb muscle strength, comprising:   In the parameter value acquisition step, the parameter value of the thigh during the period from when the subject in the standing posture changes the posture to the maximum squatting posture and further changes the posture from the maximum squatting posture to the standing posture again. The lower limb muscle strength evaluation method according to claim 1 to be acquired. The lower limb strength evaluation method according to claim 1 or 2, wherein in the calculation step, a margin of the lower limb strength is obtained based on the following formula.

In the above formula, Muscle_margin is the margin of lower limb muscle strength, T _{hip + knee} (t) is the sum of the joint moments of the hip and knee joints, and max (T _{hip + knee} (t)) is the squatting posture of the subject. The maximum value of hip joint and knee joint T _{hip + knee} (t), T ^ref _{hip + knee} during the posture change from standing to standing posture, is necessary for the subject to stand up from the squatting posture. This is a reference value indicating the required minimum muscle strength. The lower limb strength evaluation method according to claim 3, wherein, in the calculating step, the reference value T ^ref _{hip + knee} is obtained based on the following formula.

In the above formula, L _Thigh is the length of the thigh in the longitudinal direction, k _Thigh is a parameter indicating the center of mass position in the longitudinal direction of the thigh, Bal _RL is a parameter indicating the left-right balance in the floor reaction force, m _Body is the total mass of the subject, m _HAT is the mass of the upper body, m _Thigh is the mass of the thigh segment, and g is the acceleration of gravity. The sensor includes a thigh sensor for obtaining a parameter value of the thigh,
The lower limb muscle strength evaluation method according to any one of claims 1 to 4, wherein the thigh sensor is fixed to the subject in the sensor installation step.   The lower limb strength evaluation method according to any one of claims 1 to 5, wherein in the sensor installation step, the thigh sensor is fixed to a thickest part of the thigh.   The lower limb strength evaluation method according to any one of claims 1 to 6, wherein in the sensor installation step, the thigh sensor is fixed to an outer surface of the thigh. The sensor includes an upper body sensor for acquiring a parameter value of the upper body part indicating movement of the upper body part of the subject,
In the sensor installation step, the upper body sensor is fixed to the subject,
The calculation step according to claim 1, wherein a maximum value of a sum of joint moments of the hip joint and knee joint of the subject is obtained based on a parameter value of the thigh and a parameter value of the upper body. The lower limb muscle strength evaluation method according to any one of the above.   The lower limb muscle strength evaluation method according to claim 8, wherein, in the sensor installation step, the upper body part sensor is fixed to a most prone portion of the waist on the back side in the upper body part. Further comprising the step of inputting the height of the subject;
In the calculation step, based on the height, the length of the thigh in the longitudinal direction, a parameter indicating the center of mass position, the total mass of the subject, the mass of the upper body, and the mass of the thigh are estimated. The method for evaluating lower limb muscle strength according to claim 4. A lower limb strength evaluation apparatus for evaluating a lower limb strength of a subject,
A sensor for obtaining a parameter value indicating the movement of the subject;
The thigh that indicates the movement of the thigh of the subject during the period from the maximum squatting posture acquired by the sensor to the standing posture, where the subject is crouched as much as possible. Based on the parameter value, the maximum value of the sum of the joints of the subject's hip joint and knee joint is obtained, and the maximum value and the minimum muscle force necessary for the subject to stand up from the squatting posture are indicated. Based on the reference value, a calculation unit that calculates a margin of lower limb muscle strength,
A lower limb muscle strength evaluation apparatus comprising:   The lower limb strength evaluation apparatus according to claim 11, wherein the sensor includes a thigh sensor that is fixed to a brace attached to the thigh and acquires a parameter value of the thigh. The sensor includes an upper body sensor that is fixed to a brace that is attached to the upper body part of the subject and acquires a parameter value of the upper body part that indicates the movement of the upper body part of the subject,
The calculation unit according to claim 11 or 12, wherein the calculation unit obtains a maximum value of a sum of joint moments of the subject's hip joint and knee joint based on a parameter value of the thigh and a parameter value of the upper body. The lower limb muscle strength evaluation apparatus according to any one of the above.