JP5594689B2 - Ankle impedance measuring device - Google Patents

Description

  The present invention relates to a measuring apparatus for measuring an ankle impedance (ankle viscoelastic coefficient).

  The measuring device according to the present invention is intended to measure impedances such as the elastic modulus and viscosity coefficient of the ankle, but the device itself for measuring the elastic modulus of the ankle is disclosed in Non-Patent Documents 1 and 2, etc. It is publicly known.

  In the measuring device described in Non-Patent Document 1, the subject is placed on a foot plate connected to an inverted pendulum and configured to be swingable about a horizontal axis, and then the subject is asked to generate a predetermined torque. Further, the inverted pendulum is requested to be tilted at a predetermined angle. Then, the elastic modulus of the ankle is calculated from the measured torque and angle.

  In the measuring apparatus described in Non-Patent Document 2, the subject is placed on a foot plate that is connected to a servo motor and configured to be swingable about a horizontal axis, and then a predetermined angle range (−0.5 ° to At + 0.5 °, the foot plate is driven and swung so that the subject's foot moves up and down. That is, in the apparatus described in Non-Patent Document 2, a pulse with a short period (1 second) corresponding to the above angle range is given to the servomotor to give a pulse stimulus to the subject's foot, and the floor reaction after the measurement is performed. The distance between the center position (COP) of the pressure to which force (reaction force against the foot plate) is applied and the ankle is measured, the torque is calculated from the position of the COP, and the elastic coefficient of the ankle is calculated.

Loram.D and LakieM, "Direct measurement of human ankle stiffness during quiet standing: The intrinsic mechanical stiffness is insufficient for stability.", Journal of Physiology, 545.3, pp.1041-1053 (2002) Casadio M, Morasso P and Sanguineti V, "Direct measurement of ankle stiffness during quiet standing: implications for control modering and clinical application", Gait & posture, 21pp.410-424 (2004)

  In the measurement devices disclosed in these Non-Patent Documents 1 and 2, measurement is performed on a subject standing on the foot plate based on the view that body swinging in a stationary posture is equivalent to the motion of an inverted pendulum. The elastic modulus of the ankle is obtained from the measurement result. However, in the method of measuring with the subject placed in a standing posture in this way, the measurement is performed with the whole body weight received by the ankle, so the obtained elastic modulus is the influence of the force of the joints etc. In response, it was impossible to obtain an elastic modulus centered on a truly pure ankle. That is, in the measuring devices disclosed in Non-Patent Documents 1 and 2, the obtained elastic modulus values are various such as the body weight of the subject or weight shift using joints and muscle strength of the whole body of the subject to maintain equilibrium. It was difficult to obtain the value of the elastic modulus of the ankle accurately.

  In addition, human skeletal muscles, including the ankles, can be thought of as actuators that can generate very large forces, and not only generate forces but also viscoelasticity like springs and dampers. ing. This is clear from the fact that muscles become stiff when skeletal muscles are activated, and conversely, they become soft when relaxed with relaxation. Therefore, for example, in order to elucidate the mechanism of maintaining the body balance in the standing posture, it is necessary to consider not only the elastic coefficient of the ankle but also the viscosity coefficient of the ankle. The viscosity coefficient was not measured, and there was room for improvement. In Non-Patent Document 2, although attention is paid to viscosity, the measurement is performed in a standing position and the influence of the upper body is not taken into consideration, and there is room for improvement in that respect.

  The present invention has been made in order to solve the problems of the conventional measuring apparatus as described above, and more accurately obtaining an elastic coefficient and a viscosity coefficient (hereinafter, these viscoelastic coefficients are referred to as impedance). An object of the present invention is to obtain a novel ankle impedance measuring device that can be used.

  The present inventors can measure the ankle torque more accurately if the measurement is performed with the subject in the sitting position, and in addition, based on the measured ankle torque, the ankle torque can be measured more accurately. It has been found that not only the elastic coefficient but also the viscosity coefficient can be measured, and the present invention has been completed.

That is, the present invention is directed to an ankle impedance measurement device. This measuring device is configured to swing and rotate around a rotating shaft 18 horizontally disposed on a seating plate 11 that receives the buttocks 2a of the subject 2 when the subject 2 is seated. 2b on which the foot plate 12 is mounted, a drive source 31 for applying a driving rotational force to the foot plate 12 via the rotating shaft 18, and a torque for detecting the torque applied to the foot plate 12 at the time of swinging rotation. A detecting means 33; an angle detecting means 23 for detecting an inclination angle of the foot plate 12 at the time of swinging rotation; a crus fixing tool 25 for fixing the crus 2c of the subject 2 in the sitting position; And a foot tip fixing tool 20 for fixing the foot tip 2b of the subject 2 placed on the foot plate 12. Then, using the crus fixing device 25 and the toe fixing device 20, the leg portion of the subject 2 is fixed so that the heel 2d of the subject 2 is positioned on the axis of the rotation shaft 18, and the leg portion In the fixed state, the driving source 31 is driven to swing and rotate the foot plate 12 around the rotary shaft 18 to forcibly displace the foot 2b in the vertical direction around the heel 2d. The detection value by the torque detection means 33 when the tip 2b is displaced in the vertical direction, the detection value by the angle detection means 23 , the mass M of the foot plate 12, the crus 2c and the toes 2b The mass m of the subject's foot defined by the mass, the distance L1 from the axis of the rotating shaft 18 to the center of gravity G1 of the foot plate 12, and the distance L2 from the axis of the rotating shaft 18 to the foot pressure center G2 The weight of the foot plate 12 The moment of inertia I ₁ derived from the weight of the foot plate 12 at the G1 position, the moment of inertia I ₂ derived from the weight of the subject's foot at the foot pressure center G2 position obtained from the value detected by said angle detecting means 23 A viscoelastic coefficient of the ankle is calculated based on the angular velocity and the angular acceleration .

  The foot plate 12 may have a configuration in which a cushioning material 28 is provided for receiving the heel of the subject 2 when the foot tip 2b is placed on the foot plate 12.

  It is possible to adopt a configuration including a regulation mechanism 40 for regulating the swing rotation limit of the foot plate 12 around the rotary shaft 18.

  The measuring device may be provided with a vertical position adjustment mechanism for the seating plate 11 and / or a vertical position adjustment mechanism and / or a longitudinal position adjustment mechanism for the foot plate 12.

  According to the present invention, since the impedance of the ankle can be measured in a sitting position where the lower limb muscles do not exert a force, the ankle is more accurately compared to the conventional measuring devices described in Non-Patent Documents 1 and 2. The viscoelastic coefficient of the ankle can be obtained from the torque. That is, when trying to maintain a posture in a standing position, a person tries to balance using not only the legs but the entire body. Therefore, as in the measurement devices described in Non-Patent Documents 1 and 2, when the ankle torque is measured in a standing posture, the obtained value is influenced by other joints, particularly the upper body joint. It is inevitable that it becomes a value. On the other hand, if the measurement is performed after the subject is in the sitting position as in the present invention, the factor for maintaining the posture by the upper body can be completely eliminated, and thus the ankle can be more accurately detected. The viscoelastic coefficient can be measured.

  If the heel 2d of the subject 2 deviates from the axis of the rotation shaft 18 of the foot plate 12 on which the foot tip 2b is placed, the position of the heel of the foot shifts back and forth as the foot plate 12 rotates. For this reason, it is inevitable that the lower leg 2c of the subject 2 moves back and forth, and the muscular strength of the lower leg 2c is applied to the foot plate 12 via the toes 2b (the lower limb muscle exerts the force), and accurately. It becomes difficult to measure the viscoelastic coefficient of the ankle. On the other hand, when the heel 2d of the subject 2 is positioned on the axis of the rotary shaft 18 of the foot plate 12 on which the foot 2b is placed as in the present invention, the foot plate 12 is rotated. The lower leg 2c of the subject 2 does not move, and the influence of the muscle strength of the lower leg 2c (muscle strength of the lower limb muscle) can be eliminated, and the viscoelastic coefficient of the ankle can be measured more accurately.

The ankle viscoelasticity coefficient measured by the measurement apparatus according to the present invention as described above is considered to be extremely useful information that can contribute to, for example, prevention of a fall accident of the elderly. That is, if each part of the body is moved at a different speed, the position of the center of gravity changes every moment, but it is nevertheless due to the balance function that it can stand without breaking the balance. This balance function does not work normally when aged, and is a major cause of falls in elderly people (showing those 65 years and older as defined by the Ministry of Internal Affairs and Communications). The balance function is managed by the movement of the center of pressure (COP), which is a fulcrum that supports the body, and is greatly influenced by the impedance (viscoelasticity) characteristics of the ankle. Accordingly, if the viscoelastic coefficient of the ankle can be accurately measured, it is possible to estimate the degree of decrease in the equilibrium function of the subject, and it is possible to prevent the occurrence of a fall accident or the like. In addition, if the ankle viscoelasticity coefficient can be accurately measured, it is possible to quantitatively evaluate the recovery of the equilibrium function in the field of medical rehabilitation.
In addition, for an elderly person or a patient being treated, measuring the impedance of the ankle in a standing posture places a heavy burden on the subject, and the measurement itself may be difficult in the first place, but the apparatus according to the present invention is used. For example, since the measurement can be performed in the sitting position, the burden on the subject is small and the practical convenience is excellent.

  When the cushioning material 28 for catching the subject's 2 eyelid is disposed on the foot plate 12, the position of the foot tip 2b in the foot plate 12 can be easily adjusted. That is, while adjusting the position of the foot tip 2 b in the foot plate 12, it is possible to securely fix the foot tip 2 b using the foot tip fixing tool 20. This means that the foot tip 2b can be placed in a predetermined position (position where the heel 2d is on the axis of the rotation shaft 18) in the foot plate 12 irrespective of the size of the foot of the subject 2. In addition, it can contribute to the improvement of the measurement accuracy and practical convenience of the device.

  Providing a regulation mechanism 40 for regulating the swing rotation limit of the foot plate 12 around the rotation shaft 18 reliably prevents measurement accidents caused by excessive swing rotation of the foot plate 12. be able to.

  When a vertical position adjustment mechanism for the seating plate 11 and / or a vertical position adjustment mechanism for the foot plate 12 and / or a front-rear position adjustment mechanism are provided, Accurate position adjustment and accurate posture adjustment of the lower leg 2c are possible. That is, for elucidating the mechanism of the body balance maintaining function in the standing posture, the present inventors are in the sitting posture but in the state close to the standing posture, that is, the lower leg 2c is in the vertical posture. We believe it is important to measure the ankle impedance in the state. Accordingly, when the position adjusting mechanism for the seating plate 11 and the foot plate 12 is provided, the lower leg 2c is set in the vertical posture regardless of the length of the body part of the subject 2 (particularly the lower leg 2c). Therefore, it is possible to improve the measurement accuracy of the ankle impedance using this measuring apparatus. Moreover, since accurate position adjustment of the lower leg 2c and the heel 2d can be easily performed, it is also excellent in that the practical convenience of the measuring device is greatly improved. Specific examples of the position adjustment mechanism include a mechanical jack, a hydraulic jack, a pneumatic jack, and the like.

It is a schematic block diagram of the measuring apparatus of the ankle impedance of this invention. It is an external appearance perspective view of a measuring device. It is a top view of a measuring device. FIG. 4 is a sectional view taken along line AA in FIG. 3. It is a figure for demonstrating the measuring method using the measuring apparatus of this invention. It is a figure for demonstrating a control mechanism. It is a block diagram for demonstrating the circuit structure of the measuring apparatus of this invention. It is a figure which shows the calculation method of an ankle impedance typically. It is a figure for demonstrating the time-dependent change of the setting value of torque, an actual measurement angle value, and the actual value of a torque meter. It is a figure which shows an impedance measurement model. It is a figure which shows typically the calculation method of another ankle impedance. It is a figure which shows the other Example of the measuring apparatus of the ankle impedance of this invention.

(Example) The ankle impedance measuring apparatus according to the present invention will be described in detail with reference to FIGS. In the description of this embodiment, front and rear, left and right, and up and down directions are in accordance with the arrows shown in FIGS. 1 to 4 and the directions attached to the arrows.

  As shown in FIG. 1, the measuring apparatus 1 according to the present embodiment measures the ankle impedance (viscoelastic coefficient) of the subject 2 such as the elastic coefficient (k) and the viscosity coefficient (d) while the subject 2 is sitting. To do. As shown in FIG. 2, the measuring device 1 includes a measuring unit 3 that is disposed on the left and on which the subject 2 sits, a mechanical unit 4 that is disposed on the right and that includes a motor 31 and the like, and a control unit 5 (see FIG. 2). 7).

  As shown in FIGS. 1 to 4, the measuring unit 3 is based on a frame body 10 composed of a plurality of frames extending in the vertical (vertical) direction, the front-rear horizontal direction, and the left-right horizontal direction, A sitting plate 11 that receives the buttocks 2a of the subject 2 when the sitting posture is taken, and a foot plate 12 on which the toes 2b of the subject 2 are placed.

  As shown in FIG. 2, the frame body 10 constituting the measuring unit 3 includes a plurality of vertical columns 13 that run in the vertical direction and a plurality of horizontal columns that run in the horizontal direction so as to connect the vertical columns. It is comprised by the support | pillar 14 and the front-back horizontal support | pillar 15 which runs in the front-back horizontal direction. Each support | pillar 13,14,15 is a square tube made from aluminum.

  Specifically, the vertical strut 13 has four vertical struts 13a, 13a, 13b, and 13b that are arranged at the left and right ends of the measuring unit 3 and have a larger vertical length than the vertical struts 13a and 13b. It is composed of small vertical columns 13c and 13c. The front and rear horizontal struts 15 include a horizontal strut 15a that connects the upper ends of the vertical struts 13a and 13b, a horizontal strut 15b that connects the middle of the vertical struts 13a and 13b and the upper end of the vertical strut 13c, The horizontal support 15c is arranged below the horizontal support 15b and connects the middle portions of the vertical supports 13a and 13b, and the horizontal support 15d connects the lower ends of the vertical supports 13a, 13b, and 13c. The left and right horizontal struts 14 are a horizontal strut 14a that connects the lower ends of the vertical struts 13a and 13a, a horizontal strut 14b that connects the lower ends of the vertical struts 13c and 13c, and a horizontal link that connects the upper ends of the vertical struts 13c and 13c. It is comprised by the support | pillar 14c and the horizontal support | pillar 14d which connects the middle parts of the front-back direction of the horizontal support | pillar 15b * 15b. The horizontal struts 14c and 14d constitute a plate receiving frame that receives the seating plate 11. As shown in FIG. 1, the height position of the upper end of the horizontal strut 15a is approximately at the shoulder height position of the subject 2 when the subject 2 takes the sitting posture.

  As shown in FIGS. 1 and 2, a measurement space that allows insertion of the lower leg 2 c and the toe 2 b of the subject 2 when the subject 2 sits down on the seating plate 11, in front of the seating plate 11. S is formed, and a foot plate 12 is disposed below the measurement space S. The foot plate 12 is swingably supported by a pair of left and right rotating shafts 18 and 18 (see FIG. 4). 3 and 4, reference numerals 19 and 19 denote bearing blocks fixed to the frame body 10 (15c), and the rotary shafts 18 and 18 are supported by the bearing blocks 19 and 19, respectively.

  As shown in FIGS. 2 to 5, the foot plate 12 has a bottom wall 12 a that contacts the sole of the subject 2, a rear wall 12 b erected at the rear end of the bottom wall 12 a, and left and right ends of the bottom wall 12 a. It is formed in the shape of a bottomed container that has standing side walls 12c and 12c and that has openings upward and forward. The bottom wall 12a is provided with a pair of left and right foot tip fixing tools 20 for fixing the foot tip 2b of the subject 2 placed on the bottom wall 12a. Each foot fixing tool 20 includes a pair of left and right bands 21 and 21 attached to the bottom wall 12 a and a urethane resin cushioning material 22 disposed on the lower surface of the one band 21. Both bands 21, 21 are provided with hook-and-loop fasteners, and the entire soles are placed in contact with the bottom wall 12 a, and both bands 21, 21 are pressed against the back of the foot while the cushioning material 22 is pressed. By engaging the hook-and-loop fasteners, the toe 2b of the subject 2 can be fixed so as not to move freely. An angle sensor (angle detection means) 23 for detecting the inclination angle of the foot plate 12 is provided between the both foot tip fixtures 20.

  As shown in FIG. 4, a pair of left and right leg fixing tools 25 for fixing the lower leg part 2 c of the subject 2 in the sitting posture are provided in front of the seating plate 11. Each crus fixing device 25 includes a pair of left and right bands 26 and 26 attached to the left and right lateral struts 14d. Both bands 26 and 26 are provided with hook-and-loop fasteners. Corresponding to each crus fixing device 25, a cushioning material 27 is arranged on the left and right horizontal struts 14d. The buffer material 27 is a rectangular block body made of urethane resin. By fixing the lower leg 2c of the subject 2 with the lower leg fixing device 25 while pressing the upper part of the calf against the cushioning material 27, the lower leg 2c is fixed without immobility and without giving excessive pressure. be able to.

  As shown in FIGS. 3 and 5, a pair of left and right cushioning members 28 that receive the heel of the subject 2 are arranged on the rear wall 12 b of the foot plate 12 corresponding to each foottip fixture 20. Each cushioning material 28 is a rectangular block body made of urethane resin, and when the heel is pressed against this cushioning material 28, the cushioning material 28 is deformed, so that the size of the foot, etc. Regardless, the toe 2b of the subject 2 can be positioned at a desired position on the bottom wall 12a. However, as will be described later, in this measuring apparatus 1, it is important to place the heel 2d of the subject 2 on the axis of the rotation shafts 18 and 18, and the subject 2 so that the heel 2d is arranged at the position. It is important to position the second toe 2b on the bottom wall 12a. Reference numeral 28a denotes a vertically long concave groove provided on the front surface of the cushioning material 28. By fitting the ridge to the concave groove 28a, an excessive repulsive force of the cushioning material 28 is applied to the ridge. Can be prevented. In FIG. 2, the description of the foot tip fixing tool 20, the crus fixing tool 25, and the cushioning materials 22, 27, and 28 is omitted.

  As shown in FIGS. 2, 3, and 4, the mechanical unit 4 has a frame body 30 assembled in a rectangular shape as a base, and a drive source of the foot plate 12 is provided inside the frame body 30. A motor (drive source) 31, a reduction mechanism 32, a torque meter (torque detection means) 33, a transmission mechanism 34 that connects the output shaft 32 a of the reduction mechanism 32 and the rotary shaft 18, and the like are assembled. The transmission mechanism 34 includes a transmission shaft 35, a first coupling 36 that connects one end (right end) of the transmission shaft 35 and the output shaft 32 a of the speed reduction mechanism 32, and protrudes from the measurement unit 3 into the mechanical unit 4. And a second coupling 37 that connects the other end (left end) of the transmission shaft 35 to the right rotation shaft 18. A torque meter (torque detection means) 33 for measuring torque acting on the transmission shaft 35 is provided in the middle of the transmission shaft 35.

  As shown in FIGS. 3 and 4, a regulating mechanism 40 for regulating the rotation limit of the transmission shaft 35, that is, the swing rotation limit around the rotation shaft 18 of the foot plate 12, is provided in the middle of the transmission shaft 35. Is provided. As shown in FIG. 6, the regulation mechanism 40 includes a regulated member 41 mounted in the middle portion of the transmission shaft 35 and a regulating member 42 that contacts the regulated member 41 and regulates its movement limit. . The regulated member 41 includes a pair of upper and lower rectangular plate-like plates 41a and 41a and a pair of bolts 41b and 41b for connecting both the plates 41a and 41a. The restricting member 42 is a pair of front and rear plates fixed to the support plate 43, and both plates are fixed to the support plate 43 in a C-shaped posture that extends downward. As indicated by the phantom line in FIG. 6, when the attitude angle of the regulated member 41 reaches a predetermined angle (± 30 ° in this embodiment) with respect to the horizontal plane as the transmission shaft 35 rotates, the regulating member 42 The regulated member 41 comes into surface contact so that the rotational limits of the regulated member 41, the transmission shaft 35, the rotating shaft 18, and the foot plate 12 are regulated. Thus, the subject 2 can be prevented from hurting the ankle due to the foot plate 12 being excessively swung and rotated.

  FIG. 7 is a block diagram illustrating a circuit configuration of the measuring apparatus 1 according to the present embodiment. As shown in the figure, the measuring apparatus 1 drives the motor 31 by a signal from the control unit 5 that controls the entire apparatus to swing the foot plate 12. In addition, the control unit 5 includes a detection result regarding the inclination angle of the foot plate 12 detected by the angle sensor 23 during the swing operation and a detection result regarding the torque acting on the foot plate 12 detected by the torque meter 33. It is sent. The control unit 5 pulses an oscilloscope on which the tilt angle and torque detection results are displayed, a personal computer that calculates the viscoelastic coefficient of the ankle based on the tilt angle and torque detection results, and a control signal from the personal computer. And a motor controller or the like that sends it to the motor 31.

  In addition to the restriction mechanism 40 described above, various safety measures are taken for the measuring device 1. First, the motor controller manages the value of the current flowing through the motor 31, and immediately stops the rotation of the motor 31 when an overcurrent flows for a specified time or longer. Further, when torque that may cause danger to the subject 2 due to disturbance or system is applied to the transmission shaft 35, the first coupling 36 is mechanically broken before the motor 31 so that the torque becomes free. Designed to. Further, when an emergency stop button 45 is provided on the upper portion of the frame body 10 and the subject 2 feels danger, when the button 45 is pressed, the rotation of the motor 31 is immediately stopped and the foot plate 12 is rotated. It will stop immediately.

  Next, an ankle impedance measuring method using the measuring apparatus 1 having the above configuration will be described with reference to FIGS. The ankle impedance is obtained by measuring the torque (τ) and the angle (θ) (measurement process) and using the least square method from the sample data of the torque (τ) and the angle (θ) (elastic coefficient: k, Viscosity coefficient: can be roughly divided into calculation (d) of d).

  In the measurement process, the subject 2 is seated on the seating plate 11, and then the lower leg part 2 c and the foot tip 2 b of the subject 2 are fixed using the lower leg fixing tool 25 and the foot tip fixing tool 20. At this time, after adjusting the toe position of the subject 2 on the foot plate 12 so that the heel 2d of the subject 2 is on the axis of the rotation shaft 18, the lower leg 2c and the toe 2b of the subject 2 are adjusted. To fix. Further, after adjusting the sitting position and the toe position of the subject 2 so that the lower leg 2c of the subject 2 is in a vertical posture, the lower leg 2c and the toe 2b of the subject 2 are fixed.

  Next, the foot plate 12 is set to a predetermined initial angle posture (for example, a horizontal posture (tilt angle = 0 °)). Specifically, while taking the detection signal from the angle sensor 23 into consideration, an instruction is given from a personal computer via a motor controller to drive the motor 31, and the foot plate 12 is swung until it reaches the initial angle posture. When the motor 31 is driven, the output shaft 32a of the speed reduction mechanism 32 is driven to rotate, and the driving rotational force of the output shaft 32a is transmitted to the foot plate 12 via the transmission mechanism 34 and the rotating shaft 18, and to this. Thus, the foot plate 12 can be set to a predetermined initial angle posture.

Next, from the initial angle posture, the foot plate 12 is slowly swung while applying a predetermined torque (τ ₁ ) within a predetermined angle range (for example, ± 15 °), and acts on the transmission shaft 35 at this time. The torque change is measured by the torque meter 33. Specifically, for example, the foot plate 12 is swung by applying a predetermined torque (τ ₁ ) so that one cycle is a long cycle of 1 second or longer. FIG. 9 shows an example of the time change of the torque set value (τ ₁ ), the actual side angle value (θ), and the actual torque value (τ) measured by the torque meter 33.

  Here, the torque (τ) at each angle (θ) until the footplate 12 returns to the initial angle posture after being swung from the initial angle posture within a predetermined angle range (± 15 °) (one cycle). ). In this measuring apparatus 1, it is possible to perform several to thousands of measurements in one cycle. Further, the measurement is performed over several cycles to several tens of cycles.

In the next calculation step, the elastic coefficient (k) and the viscosity coefficient (d) are estimated from the obtained measured angle (θ) and measured torque value (τ) using the least square method (see FIG. 8). ). FIG. 10 is an impedance measurement model of the device of the present invention. As can be seen from the figure, the transmission shaft 35 includes an inertia moment (I ₁ ) derived from the weight (Mg) of the foot plate 12 and an inertia moment derived from the weight (mg) of the foot of the subject 2 at the time of measurement. (I ₂ ) acts. Therefore, the dynamic equation in this measurement model is expressed as the following equation (1).

In the above formula (1), τ is an actual measurement value of the torque meter 33, and θ is an actual measurement value of the angle sensor 23. The mass (M) of the foot plate 12 and the distance (L ₁ ) from the center of gravity (G ₁ ) of the foot plate 12 to the center of rotation of the foot plate 12 are known values that do not always change. The measuring apparatus 1 of the present embodiment does not use a force plate for measuring the mass of the subject 2 (m) and the position of COP (G ₂ ). This is for the purpose of preventing an increase in the moment of inertia (I ₂ ) due to the weight of the force plate, and further reducing the load on the subject's 2 foot due to the increase in (I ₂ ) to improve safety. However, since the mass (m) of the foot of the subject 2 is substantially the mass of the lower leg 2c and the toe 2b, the mass (m) is the subject of the foot (the lower leg 2c and the toe 2b). It can be calculated from the ratio of 2 to the body weight. That is, since the ratio of the weight of the foot to the human body weight is roughly determined, the foot mass (m) is a value that can be estimated from the height and weight data of the subject 2. Further, the position of (G ₂ ) that is COP can be estimated from the size of the foot. Therefore, the distance (L ₂₎ that can also be estimated value of to the rotational center of the foot plate 12 from (G _2).
As described above, the expression (1) includes two unknown values of the elastic coefficient (k) and the viscosity coefficient (d).

  Next, the above equation (1) is discretized by differential approximation and converted into an equation of only (θ), and the measured value (θ) (τ) obtained at every predetermined sampling interval is applied to the equation. , N pieces of angle data and torque data are acquired. Here, when the above equation (1) is discretized by differential difference approximation, the following equation (2) is obtained. Expression (3) summarizes Expression (2).

  Finally, the elastic coefficient (k) and the viscosity coefficient (d) can be calculated by minimizing the error component included in Equation (3) by the least square method using a pseudo-retrograde example.

In the above measurement method, the weight (m) of the foot and the distance (L ₂ ) from (G ₂ ) to the center of rotation of the foot plate 12 were estimated from the height and weight data of the subject 2, but in the formula (1) , The elastic modulus (k), the viscosity coefficient (d), and the numerical value (L ₂ m) obtained by multiplying the foot mass (m) and the distance (L ₂ ). Good (see FIG. 11). Here, (L ₂ m) is set as one value because there is no calculation using only the individual values of (L ₂ ) or (m) in the formula. By minimizing the error component included in Equation (3) from the obtained angle data and torque data by the least square method using a pseudo-reverse example, the elastic coefficient (k), the viscosity coefficient (d), and the foot A numerical value (L ₂ m) obtained by multiplying the mass and the distance to the rotation center of the foot plate 12 can be calculated. As described above, even with the measurement method shown in FIG. 11, the elastic coefficient (k) and the viscosity coefficient (d) can be calculated.

  FIG. 12 shows another embodiment of the present invention. In FIG. 12, a mechanical jack (position adjustment mechanism) 50 is provided below the seating plate 11 so that the position of the seating plate 11 can be adjusted in the vertical direction according to the body size of the subject 2 by the jack 50. ing. Further, a jack (position adjusting mechanism) 51 is provided below the foot plate 12 so that the position of the foot plate 12 can be adjusted in the vertical direction according to the body size of the subject 2 by the jack 51. Further, the jack 51 may be configured to be movable in the front-rear direction so that the position of the foot plate 12 can be adjusted in the front-rear direction. In this case, a U-shaped support body 52 that supports the foot plate 12 and the jack 51 is provided, and a pair of left and right rotating shafts 18 and 18 are provided on the support body 52 so as to be swingably supported. .

  As described above, the jacks 50 and 51 are arranged so that the seating plate 11 can be moved in the vertical direction, and the foot plate 12 is configured to be movable in the vertical direction and the front-rear direction. It is possible to align the crus 2c and the heel 2d.

DESCRIPTION OF SYMBOLS 1 Ankle impedance measuring apparatus 2 Test subject 2a Test subject's buttocks 2b Test subject's toe 2d Test subject's heel 12 Foot plate 18 Rotating shaft 23 Angle detection means (angle sensor)
28 Buffer material 31 Drive source (motor)
33 Torque detection means (torque meter)
40 Restriction mechanism 50 Position adjustment mechanism (jack)
51 Position adjustment mechanism (jack)

Claims (4)

A sitting plate (11) for receiving the buttocks (2a) of the subject (2) when the subject (2) is seated;
A foot plate (12) configured to be swingable and rotatable about a rotation shaft (18) disposed horizontally, and on which a foot tip (2b) of the subject (2) is placed;
A driving source (31) for applying a driving rotational force to the foot plate (12) via the rotating shaft (18);
Torque detecting means (33) for detecting torque applied to the foot plate (12) during swinging rotation;
An angle detecting means (23) for detecting an inclination angle of the foot plate (12) at the time of swinging rotation;
A lower leg fixing device (25) for fixing the lower leg (2c) of the subject (2) in the sitting position;
A toe fixture (20) for fixing the toe (2b) of the subject (2) placed on the foot plate (12);
With
Using the crus fixing device (25) and the toe fixing device (20), the subject (2) is placed on the axis of the rotation shaft (18) so that the heel (2d) of the subject (2) is positioned on the axis of the rotation shaft (18). Fix the legs,
With the legs fixed, the drive source (31) is driven to drive the foot plate (12) to oscillate and rotate about the rotation shaft (18), so that the foot tip (2b) is heeled (2d). Forcibly displace the posture up and down around
The detected value by the torque detecting means (33) when the posture of the foot (2b) is displaced in the vertical direction, the detected value by the angle detecting means (23), and the mass (M of the foot plate (12)) ), The mass (m) of the subject's foot defined by the mass of the lower leg (2c) and the tip of the foot (2b), and the center of gravity (G1) of the foot plate (12) from the axis of the rotating shaft (18) ), The distance (L2) from the axis of the rotation shaft (18) to the foot pressure center (G2), and the foot plate (G1) at the center of gravity (G1) position of the foot plate (12). 12) the moment of inertia (I ₁ ) derived from the weight of the subject, the moment of inertia (I ₂ ) derived from the weight of the subject's foot at the position of the foot pressure center (G2 ), and the detected value by the angle detection means (23). and the angular velocity and angular acceleration obtained from the Zui, the measuring device of the ankle impedance and calculates the viscoelastic coefficients of the ankle.   The foot plate (12) is provided with a cushioning material (28) for receiving a heel of the subject (2) when the foot tip (2b) is placed on the foot plate (12). The ankle impedance measuring apparatus as described.   The ankle impedance measuring device according to claim 1 or 2, further comprising a regulating mechanism (40) for regulating a swing rotation limit of the foot plate (12) around the rotation axis (18).   The position adjustment mechanism (50) of the up-down direction of the said seating board (11) and / or the position adjustment mechanism (51) of the up-down direction and / or the front-back direction of the said footplate (12) are provided. The ankle impedance measuring apparatus according to any one of the above.

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