JPH102817A - Joint moment measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cost of a force plate for detecting component forces in triaxial directions in a joint moment measuring device and reduce system cost. SOLUTION: A computer 6 obtains respective luminous intensity I of reflected light from a marker by extracting an image of the marker bonded to a person to be tested from an image signal entered from a video camera 3 and also obtains respective two dimensional coordinates X, Z (distance data in cross direction and upper direction) from an X axial component force detect signal and a Z axial component detect signal provided from a force plate 4 through an amplifier 5. The computer 6 corrects the obtained luminous intensity I by luminous intensity set in a correcting table 6a previously stored and obtains coordinate Y of the third dimension (distance data in width direction) set in a correction table 6a corresponding to the corrected respective luminous intensity, and joint moment of measuring portion is analyzed from the previously obtained two dimensional coordinate (X, Y) at the obtained Y coordinate position and the analyzed result is provided to a CRT 7 to display or provided to a color printer 8 to print.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint moment measuring device for measuring a joint moment (muscle force torque) as one means for analyzing the motion of a subject in the medical field.

[0002]

2. Description of the Related Art Conventionally, rehabilitation medicine and physical education /
In the medical field such as sports medicine, joint moment (muscle torque) is used as a means for analyzing the motion of a subject during exercise.
Is used for measuring joint moment.
In this joint moment measuring device, for example, in order to detect a joint moment below a knee during exercise of a subject by three-dimensional coordinates, a force plate including a plurality of three-component load cells, which are sensors capable of detecting the three-dimensional coordinates, is used. I use.

[0003] This three-component force load cell is composed of two orthogonal axes (hereinafter referred to as an X axis and a Y axis) of a reaction force acting on a force plate at the time of movement of a subject along the surface direction of the upper surface of the force plate. X-axis component force sensor, Y-axis component force sensor, and component force in an axis perpendicular to the upper surface of the force plate (hereinafter, referred to as Z-axis). And a Z-axis direction component force sensor.

A force plate having such a three-component load cell measures a joint moment about each axis from a detection result from each component sensor of each three-component load cell to distribute weight during exercise. In addition, it is possible to analyze a driving force, a braking force, a weight transferability, a torsional force, a stride when walking, a walking speed, and the like.

[0005]

However, in such a conventional joint moment measuring apparatus, each of the three-component load cells provided on the force plate has X, X- and Y-components for detecting triaxial component forces, respectively. Since the component force sensors in the Y and Z axis directions are provided, there is a problem that the cost of the force plate increases and the system cost increases.

An object of the present invention is to reduce the cost of a force plate for detecting a component force in three axial directions in a joint moment measuring device, thereby reducing the system cost.

[0007]

According to the first aspect of the present invention,
A plate corresponding to the floor on which the subject rides, component force detecting means for detecting a biaxial component force on the plate due to the movement of the subject, and photographing means for photographing the operation of the subject and outputting a video signal, A reflected light amount detecting means for detecting the reflected light amount from the subject from the video signal, and a calibration light amount for calibrating the reflected light amount detected by the reflected light amount detecting means, are set from the photographing position corresponding to the calibrated light amount. Calibrating means for setting coordinates indicating the distance to the subject, extracting two-dimensional horizontal and upward coordinates of the subject from the biaxial component force detection signal, and detecting the reflected light detected by the reflected light amount detecting means. The light quantity is calibrated by the calibrating means, and coordinates in the depth direction corresponding to the calibrated light quantity are obtained, and the joint moment of the subject on the position coordinates is calculated based on the two-dimensional coordinates. It analyzes Te, and characterized in that and a joint moment measuring means for outputting a joint moment during exercise of the subject.

According to the joint moment measuring apparatus of the present invention, a plate corresponding to a floor on which a subject rides,
The component force in the biaxial direction with respect to the plate body due to the movement of the subject is detected by the component force detecting means, the movement of the subject is photographed by the photographing means, and a video signal is output. From the video signal, the amount of reflected light from the subject is calculated. When detected by the reflected light amount detecting means, the joint moment measuring means extracts the two-dimensional coordinates in the lateral direction and the upward direction of the subject from the biaxial component force detection signal, and detects the reflected light amount by the reflected light amount detecting means. The reflected light amount is calibrated by calibration means in which coordinates indicating the distance from the imaging position to the subject corresponding to the calibration light amount are calibrated, and the calibrated light amount is calibrated to the calibrated light amount. The corresponding coordinates in the depth direction are obtained, and the joint moment of the subject on the position coordinates is analyzed based on the two-dimensional coordinates,
The joint moment during exercise of the subject is output.

Therefore, by preparing a calibration table in which the relationship between the reflected light intensity I and the distance coordinate Y in the depth direction is set in advance and acquiring the Y coordinate, the component force detecting means provided on the plate detects the two-component force. That is, it can be a two-component force detection sensor that detects a component force in the X-axis direction and a component force in the Z-axis direction. it can. As a result, the cost of the force plate for detecting the component force can be reduced, and the cost of the joint moment measuring device can be reduced.

Further, the joint moment can be accurately measured while detecting the position of the subject in the depth direction, and the reliability of the joint moment measuring device can be improved.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 4 are views showing an embodiment of a joint moment measuring device to which the present invention is applied.

First, the configuration will be described. FIG. 1 is a diagram showing a schematic configuration of a joint moment measuring system according to the present embodiment. In FIG. 1, a joint moment measuring device 1
Is detected by the illumination device 2 that irradiates the subject with light, the video camera 3 that photographs the subject, the force plate 4 that detects the reaction force of the subject during exercise as a biaxial component, and the force plate 4. An amplifier 5 for amplifying a detection signal, a computer 6 for processing a video signal input from the CCD camera 3 and a detection signal input from the amplifier 5, and outputting a joint moment, and displaying a result processed by the computer 6. CRT 7 and computer 6
A color printer 8 for printing the result processed by
It is composed of

An illuminating device (illuminating means) 2 is arranged near the video camera 3 and irradiates a subject with light.

The video camera (photographing means) 3 is, for example,
CCD (Charge Coupled D)
evice), which is provided with an external terminal for recording a photographed image on a video cassette and outputting a video signal during photographing, and is disposed at a predetermined position on the force plate 4 for photographing a subject. For example, NTSC (National Television System)
The image is output to the computer 6 as an analog video signal of the stem committee).

The force plate 4 is provided with a plurality of two-component load cells for detecting a reaction force during exercise of the subject by a biaxial component force. The two-component load cell is composed of two orthogonal force axes on the upper surface of the force plate 4. An X-axis direction component force sensor that detects a component force in the X-axis direction of the X-axis and Y-axis) and a Z-axis direction component force sensor perpendicular to the upper surface of the force plate 4 are provided. Therefore, force plate 4
Outputs an X-axis direction component force detection signal and a Z-axis direction component force detection signal to the amplifier 5.

The amplifier 5 amplifies the X-axis direction component force detection signal and the Z-axis direction component force detection signal output from the force plate 4 at a predetermined amplification factor and outputs the amplified signal to the computer 6.

The computer 6 extracts an image of a marker attached to a measurement site (for example, a joint of a foot) of a subject from an image signal input from the video camera 3 and outputs each luminous intensity of reflected light from the marker. I, and two-dimensional coordinates X, Z (lateral and upward distance information) from the X-axis direction component force detection signal and the Z-axis direction component force detection signal output from the force plate 4 via the amplifier 5. ) To get. Then, the computer 6 calibrates the acquired luminosity I with the luminosity set in the calibration table 6a stored in advance, and coordinates the third dimension set in the calibration table 2a corresponding to each calibrated luminosity. Y (distance information in the depth direction) is acquired, and the joint moment on the XZ plane of the measurement site is analyzed from the previously acquired two-dimensional coordinates (X, Z) at the acquired coordinates Y, and the analysis result is expressed by CRT7. And output to the color printer 8 for printing.

The calibration table (calibration means) 2a
A predetermined y-coordinate measurement area is set, and the y-coordinate measurement area is divided by cells (for example, in units of 1 cm × 1 cm), and the relationship between the luminosity I of the reflected light and the coordinate y (distance in the depth direction). Is a table set by the inverse square law of distance and the cos law described later.

A CRT (Cathode Ray Tube) 7 displays the joint moment analyzed by the computer 6 in a predetermined data format. The color printer 8 prints the joint moment analyzed by the computer 6 in a predetermined data format.

Next, the operation of this embodiment will be described. First, Y of the joint moment measurement system 1 of the present embodiment
The principle of coordinate measurement will be described with reference to FIG.

FIG. 2A is a diagram schematically showing a point light source s for irradiating a marker (not shown) attached to a subject with light, and the luminous intensity of the light emitted from this point light source s I (c
d: candela) is uniform in all directions. And FIG.
(B) is a diagram for obtaining the relationship of the illuminance at each point separated by a distance sufficiently larger than the size of the point light source s. That is, in FIG.
With reference to the illuminance of a point O that is a distance x (m) away from
The illuminances at the points P and P 'are obtained below.

First, the illuminance Eo at the point O can be obtained by the following equation (1) according to the inverse square law of the distance and the cos law. Eo = I / x2 ‥‥ (1) The illuminance Ep at the point P can be obtained by the following equation (2). Ep = (I / x2) cos3 φ ‥‥ (2) The illuminance Eo of the point O ′ is based on the concept of obtaining this illuminance.
'Can be obtained by the following equation (3). Eo'=I/(x+.DELTA.x)@2 (3) The point Ep 'illuminance Ep' can be obtained by the following equation (4). Ep ′ = {I / (x + Δx) 2} cos3 φ} (4) The reflection marker used in the present embodiment reflects light only in the same direction as the optical axis from the light source to the marker. Therefore, it can be considered that illuminance at each point 点 reflected light amount.

For example, as a reflection marker, FIG.
The bead sheet 20 in which the glass beads 21 are embedded as shown in FIG. 5 is cut and attached to a marker ball as shown in FIG. As shown in the enlarged view of the cross section of the bead sheet 20 in FIG. 4C, an aluminum deposition surface 20 a is formed in the embedded portion of the glass beads 21, and the light incident on the glass beads 21 is substantially in the same direction. To reflect light. A spherical marker on which the bead sheet 20 in which the glass beads 21 are embedded is attached to a measurement site (joint or the like) of a measurement subject, the amount of reflected light from the marker is detected, and the Y coordinate is measured.

Next, a joint moment measurement process executed by the joint moment measurement system 1 of the present embodiment will be described with reference to a flowchart shown in FIG.

First, the bead sheet 2 is placed on the subject's knee or the like.
A marker of a sphere to which 0 is attached is attached, light is irradiated by an illuminating device, a motion of the subject on a force plate 4 is photographed by a video camera 3, and an XZ coordinate plane of a measurement site of the subject is taken. The case where the joint moment at is measured will be described.

The computer 6 receives the video signal from the video camera 3 and the X-axis direction component detection signal and the Z-axis direction component detection signal from the amplifier 5 (step S).
1) Extracting the image of the marker attached to the measurement site of the subject from the image signal to obtain the luminous intensity I of the reflected light from the marker, and from the X-axis direction component detection signal and the Z-axis direction component detection signal The X coordinate and the Z coordinate of the measurement site are acquired (Step S2).

Next, the acquired luminous intensity I is calibrated by the luminous intensity set in the calibration table 6a stored in advance (step S3), that is, the true value of each acquired luminous intensity I is obtained from the calibration table 6a. Then, the third-dimensional coordinates Y (distance information in the depth direction) set in the calibration table 6a corresponding to each calibrated luminous intensity I are obtained (step S4), and the first coordinate Y at the obtained coordinates y is obtained. The joint moment at the measurement site is analyzed from the two-dimensional coordinates (X, Z) (step S5). Then, the result of the analysis is
7 for display, and output to the color printer 8 for printing (step S6).

As described above, in the joint moment measuring system 1 of the present embodiment, the relationship between the reflected luminous intensity I and the distance coordinate Y in the depth direction is calculated based on the above-mentioned formula based on the inverse square law and the cos law. By preparing the calibration table 2a set in advance and obtaining the Y coordinate, the load cell provided on the force plate 4 detects the two-component force, that is, detects the X-axis component force and the Z-axis component force. A two-component load cell including a sensor can be provided, and the number of sensors can be reduced as compared with the case where a conventional three-component load cell is used.

Therefore, the cost of the force plate 4 can be reduced, and the cost of the joint moment measuring system 1 can be reduced.

In the joint moment measuring system 1 according to the present embodiment, when measuring the joint moment on the XZ plane of the measurement site, a marker is attached to the measurement site of the subject and the Y coordinate in the depth direction is set. Since the joint moment is acquired, the joint moment can be accurately measured while detecting the position of the measurement site in the depth direction, and the reliability of the joint moment measuring system can be improved.

[0031]

According to the joint moment measuring apparatus of the present invention, a calibration table in which the relationship between the reflected light intensity I and the distance coordinate Y in the depth direction is prepared in advance and the Y coordinate is obtained. By this, the component force detecting means provided on the plate can detect a component force, that is, a component force detection sensor that detects a component force in the X-axis direction and a component force in the Z-axis direction,
The number of sensors can be reduced as compared with the case where a conventional three-component detection sensor is used. As a result, the cost of the force plate can be reduced, and the cost of the joint moment measuring device can be reduced.

Furthermore, the joint moment can be accurately measured while detecting the position of the subject in the depth direction, and the reliability of the joint moment measuring device can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system configuration of a joint moment measurement system to which the present invention is applied.

FIG. 2 is a diagram schematically showing a relationship between a point light source and an illuminance measurement point in order to explain a principle of measuring ay coordinate in the joint moment measuring system of the present embodiment.

FIG. 3 is a diagram showing a specific example of a reflection marker used in the joint moment measurement system of the present embodiment.

FIG. 4 is a flowchart of a joint moment measurement process executed by the computer of FIG. 1;

[Explanation of symbols]

 Reference Signs List 1 joint moment measuring system 2 lighting device 3 CCD camera 4 force plate 5 amplifier 6 computer 6a calibration table 7 CRT 8 color printer

Claims (1)

[Claims] 1. A plate corresponding to a floor on which a subject rides, component force detecting means for detecting a biaxial component force on the plate due to the movement of the subject, and outputting a video signal by photographing the operation of the subject. Imaging means for detecting, a reflected light amount detecting means for detecting a reflected light amount from the subject from the video signal, and a calibration light amount for calibrating the reflected light amount detected by the reflected light amount detecting means, and corresponding to the calibrated light amount. A calibration means for setting coordinates indicating a distance from the imaging position to the subject; and extracting two-dimensional horizontal and upward coordinates of the subject from the two-axis direction component force detection signal, and the reflected light amount detection means. Is calibrated by the calibrating means to obtain position coordinates in the depth direction corresponding to the calibrated light amount. Analyzes based on bets on the two-dimensional coordinates, joint moment measuring device characterized by comprising a, a joint moment measuring means for outputting a joint moment during exercise of the subject.