KR20210092647A - Method and apparatus for biomechanical based balance analysis - Google Patents

Abstract

A biomechanical-based balance analysis method and an apparatus thereof are disclosed. According to an embodiment of the present invention, the biomechanical-based balance analysis method comprises the following steps of: measuring three-dimensional joint center position data by a depth camera; measuring ground reaction force data about the user from a ground reaction force device; and analyzing the three-dimensional joint center position data and the ground reaction force data to calculate a joint reaction force and torque acting on a lower extremity joint of the user.

Description

Biomechanical-based balance analysis method and apparatus {METHOD AND APPARATUS FOR BIOMECHANICAL BASED BALANCE ANALYSIS}

The present invention relates to a practical system using a depth camera and a ground reaction forcer, and a biomechanical-based balance analysis method and apparatus, which provide efficient calibration for matching the coordinate system of the depth camera and the coordinate system of the ground reaction force.

In particular, in the present invention, a device for biomechanical analysis is configured with a depth camera and a ground reaction force, so that the subject's standing posture or gait analysis can be performed and the subject's balance ability can be evaluated through relatively simple devices. do.

In general posture analysis, a three-dimensional coordinate value of the center of a human body joint is measured with a camera, and the balance or quality of the posture is determined based on the measured three-dimensional coordinate value.

However, with only the three-dimensional coordinates of the joints of the human body, it is not possible to take into account the kinematic factors such as the force or torque applied to each joint in the corresponding posture, and thus a detailed diagnosis cannot be made.

In addition, products that are currently mainly used for professional 3D motion analysis are marker-type motion capture systems, which use multiple cameras, so they require a large space, are expensive, and have disadvantages in that they are not easy to install and calibrate.

Due to the cost and spatial limitations of the conventional three-dimensional motion analysis, research on posture measurement using a markerless-type entry-level measurement device represented by a low-cost depth camera such as the kinect has been actively conducted in recent years.

However, kinematic studies using only low-cost depth cameras such as Kinect do not consider forces, so kinetic analysis cannot be performed.

Therefore, there is an urgent need for a new technique for constructing a practical system using a depth camera and a ground reaction force.

An object of the present invention is to provide a biomechanical-based balance analysis method and apparatus, which enables biomechanical analysis to be performed using a depth camera that is inexpensive and practical compared to the conventional optical motion capture system.

In addition, the embodiment of the present invention can be utilized in more professional clinical trials because it is possible to evaluate the kinetics inside the body considering not only the kinematic shape of the outside of the body, but also the forces acting inside the human body. to make it possible, for the purpose

In addition, an embodiment of the present invention aims to propose an automated algorithm for converting a depth camera and a ground reaction force coordinate system into a global coordinate system.

In addition, an embodiment of the present invention aims to enable global coordinate system transformation robust to scan noise of a depth camera by performing estimation of the marker center point and fusing the planar characteristics of the ground reaction force.

In addition, an embodiment of the present invention can perform a biomechanical analysis to compare the force and torque of the left/right joints, and through this, it is an object of the present invention to propose quantification and training of balance ability in walking and standing postures .

According to an embodiment of the present invention, a biomechanical-based balance analysis method includes: measuring, from a depth camera, data on a user's three-dimensional joint center position; measuring, from the ground reaction force device, ground reaction force data about the user; and analyzing the three-dimensional joint center position data and the ground reaction force data, and calculating the joint reaction force and torque acting on the lower extremity joint of the user.

In addition, the biomechanical-based balance analysis apparatus according to an embodiment of the present invention measures the user's three-dimensional joint center position data from the depth camera, and measures the ground reaction force data about the user from the ground reaction forcer wealth; and an analysis unit that analyzes the three-dimensional joint center position data and the ground reaction force data to calculate the joint reaction force and torque acting on the lower extremity joint of the user.

According to an embodiment of the present invention, it is possible to provide a biomechanical-based balance analysis method and apparatus, which enables biomechanical analysis to be performed using a depth camera that is inexpensive and practical compared to a conventional optical motion capture system.

In addition, according to an embodiment of the present invention, it is possible to evaluate not only the kinematic shape of the outside of the body, but also the kinetic evaluation of the inside of the body considering the forces acting inside the human body, so that more professional clinical trials are possible. can be used for

In addition, according to an embodiment of the present invention, it is possible to propose an automation algorithm for converting the coordinate system of the depth camera and the ground reaction force to the global coordinate system.

In addition, according to an embodiment of the present invention, it is possible to perform global coordinate system transformation robust to scan noise of the depth camera by performing estimation of the marker center point and fusing the planar characteristics of the ground reaction force.

In addition, according to an embodiment of the present invention, by performing biomechanical analysis, it is possible to compare the force and torque of the left/right joints, and through this, it is possible to quantify and train balance ability in walking and standing postures. .

1 is a block diagram showing the configuration of a biomechanical-based balance analysis apparatus according to an embodiment of the present invention.
2 is a schematic diagram of a biomechanical analysis system according to an embodiment of the present invention.
3 is a diagram illustrating an example of a marker for constructing an FSR pressure mat and a global coordinate system.
4 is a view for explaining a lower extremity free body diagram according to an embodiment of the present invention.
5 is a view for explaining an example of converting the coordinate system of the ground reaction force and the depth camera into the global coordinate system.
6 is a flowchart illustrating a biomechanical-based balance analysis method according to an embodiment of the present invention.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, since various changes may be made to the embodiments, the scope of the patent application is not limited or limited by these embodiments. It should be understood that all modifications, equivalents and substitutes for the embodiments are included in the scope of the rights.

The terms used in the examples are used for description purposes only and should not be construed as limiting. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present specification, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiment belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

In addition, in the description with reference to the accompanying drawings, the same components are given the same reference numerals regardless of the reference numerals, and the overlapping description thereof will be omitted. In the description of the embodiment, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the embodiment, the detailed description thereof will be omitted.

1 is a block diagram showing the configuration of a biomechanical-based balance analysis apparatus according to an embodiment of the present invention.

Referring to FIG. 1 , a biomechanical-based balance analysis apparatus 100 according to an embodiment of the present invention includes a measuring unit 110 , a coordinate system aligning unit 120 , an analysis unit 130 , and an output unit 140 . can be configured including

First, the measurement unit 110 measures the user's three-dimensional joint center position data from a depth camera. That is, the measurement unit 110 may serve to scan the user's skeleton with a depth camera, and obtain the three-dimensional joint center position data from the depth information of the skeleton according to the scan. The three-dimensional joint center position data may be motion data related to a movement of a skeleton by recognizing a gesture taken by a user.

In addition, the measurement unit 110 measures the ground reaction force data about the user from the ground reaction force machine. That is, the measurement unit 110 may serve to obtain information on the gait of the user walking on the ground reaction force or the balance posture of the user standing on the ground reaction force.

The ground reaction force device is a device for measuring the reaction force when a force is applied to the ground, and may be a means to determine the degree of absorption of an impact or foot received by the human body through ground reaction force analysis, for example, running, walking, jumping, etc.

Specifically, a ground reaction force device is a sensor capable of measuring ground reaction force data, and herein may refer to a force plate and a force sensing register (FSR) pressure mat. The force plate measures the force and the moment of each of the x-axis, y-axis, and z-axis according to the marker according to the marker, and the moment of each of the x-axis, y-axis, and z-axis, and the FSR pressure mat is the z-axis force can only be measured.

The three-dimensional joint center position data measured from the depth camera and the ground reaction force data measured from the ground reaction force device display values according to the coordinate system individually set in the device, so calibration is required to show it as an integrated single coordinate system. may be needed

To this end, the biomechanical-based balance analysis apparatus 100 of the present invention may be configured to include the coordinate system alignment unit 120 .

That is, the coordinate system aligning unit 120 may serve to calibrate the depth camera and the ground reaction force by converting the coordinate system of the ground reaction forcer and the coordinate system of the depth camera into a global coordinate system.

The coordinate system alignment unit 120 converts points in an input 3D point cloud registered in association with the depth camera into a marker area and a ground reaction forcer area using K-Means or a color-based classification method. classify That is, the coordinate system aligning unit 120 may serve to classify the points scanned as the input 3D point cloud into points related to the marker area and points related to the ground reaction forcer area through clustering.

Also, the coordinate system aligning unit 120 estimates a marker center point for the points classified as the marker regions. That is, the coordinate system aligner 120 may assume a center point between points of the marker area.

_{In addition, the coordinate system aligning unit 120 uses the first rigid body transformation R 1} and t ₁ calculated according to the correspondence between the marker center point and the true value defined in the global coordinate system, the point classified into the marker area and , each of the points classified as the ground reaction force region is first transformed into a global coordinate system.

Rigid body transformation may be a model representing transformation using translation and Euclidean transformation.

Rigid body transformations R and t may be obtained by satisfying [Equation 1].

[Equation 1]

Here, the p _i is the estimated marker center point, the q _i is the true value of the center point position of the global coordinate system reference marker, and the w _i is set to be the same or set using an error value calculated in the process of estimating each marker center point. can be a value.

The coordinate system alignment unit 120 may primarily convert the coordinate system of the ground reaction forcer and the coordinate system of the depth camera into a global coordinate system by using the rigid body transformations R and t.

Also, the coordinate system aligning unit 120 may estimate the plane using the points classified as the first transformed ground reaction force region.

Thereafter, the coordinate system aligning unit 120 may calculate the projection marker center point by projecting the point classified as the first-transformed marker area onto the estimated plane.

Also, the coordinate system aligning unit 120 may sample and select points classified as the ground reaction force region based on the position of the center point of the projection marker.

Also, the coordinate system aligning unit 120 may assign a weight to the center point of the projection marker and the point of the sampled ground reaction forcer region.

_{In addition, the coordinate system aligning unit 120 uses the second rigid body transformation R 2} and t ₂ calculated according to the projection marker center point, the sampled point of the ground reaction force region, and the weight to the marker region. Each of the classified points and the points classified as the ground reaction force region may be secondarily transformed into a global coordinate system.

That is, the coordinate system aligning unit 120 unifies the coordinate system of the ground reaction forcer and the coordinate system of the depth camera into a single coordinate system, so that the data obtained from the depth camera of the ground reaction forcer becomes a value under the same coordinate system. .

The analysis unit 130 analyzes the three-dimensional joint center position data and the ground reaction force data, and calculates the joint reaction force and torque acting on the lower extremity joint of the user. That is, the analysis unit 130 uses the three-dimensional joint center position data and the ground reaction force data, which are shown as a single coordinate system, to calculate the physical force applied to the lower extremity joints when the user is walking or when the user is standing. can

The joint repulsion force is a reaction force against the forces produced by muscle activity, the stretched connective tissue around the joint, and body weight. The joint connecting the rigid body (segment) bends in a certain direction according to the user's walking, It could mean repulsion.

Also, the torque may refer to a rotational force, and may refer to a force that a walking user momentarily exerts while walking.

In calculating the joint reaction force and torque, the analysis unit 130 may express the user's lower extremities (body below the waist) as a free body diagram.

The free body diagram is a kind of sketch representing the interaction between the body and the environment, and may be a diagram in which vectors of all related forces acting on the user's lower extremities are indicated by arrows or the like.

That is, the analysis unit 130 may represent the user's lower extremities as n rigid bodies, and assuming that the joints connecting the n rigid bodies are hinges, the free body diagram may be expressed. Here, n may be defined as a natural number of 7 or more counted including at least the user's pelvis, both thighs, both calves, and both feet.

The analysis unit 130 divides the user's lower extremities into seven equal parts to subdivide the rigid body, and shows the subdivided rigid body and the joints connecting each of these rigid bodies to represent the free body diagram.

Thereafter, the analysis unit 130 may calculate the moment of inertia I _cg of a specific rigid body in the free body diagram by satisfying [Equation 2] and [Equation 3].

[Equation 2]

k _cg = K _cg L

[Equation 3]

I _cg = m _segment k ² _cg

The K _cg may be defined as a ratio of the rotation radius of the rigid body, L may be defined as the length of the rigid body, the k _cg may be defined as the rotation radius at the center of mass, and the m _segment may be defined as the mass of the rigid body.

The moment of inertia indicates the magnitude of the property of an object rotating about its axis of rotation to continue to rotate, and may refer to the amount of energy that the rotating object tries to maintain at that time.

In addition, the analysis unit 130 may use the moment of inertia I _cg to calculate a joint repulsion force for each joint and a torque for each joint for a joint connecting the specific rigid body.

That is, the analysis unit 130 may obtain the moment of inertia for each joint, and through this, calculate the joint reaction force and torque of the corresponding joint.

For example, the analysis unit 130 may include an 'ankle joint' connecting the user's calf and foot, a 'knee joint' connecting the user's thigh and calf, and a 'hip joint' connecting the user's pelvis and thigh, respectively. It is possible to calculate the joint reaction force for each joint and the torque for each joint.

More specifically, when the specific rigid body is a 'foot', the analysis unit 130 calculates the joint repulsion force F _Ankle and the joint torque T _Ankle of the ankle joint connected to the 'foot', [Equation 4] ] and [Equation 5] can be satisfied.

[Equation 4]

F _Ankle = M _Foot A _Foot - F _GRF - W _Foot

Here, the M _Foot may be defined as the mass of the foot, the A _Foot may be defined as the acceleration of the center of mass of the foot, the F _GRF may be defined as a ground reaction force measured by a pressure sensor, and the W _Foot may be defined as self-weight due to the mass of the foot.

[Equation 5]

T _Ankle = I _Foot α _Foot + w _Foot * I _Foot w _Foot

- V _CoM-GRF * F _GRF

- T _GRF - V _CoM-Ankle * F _Ankle

Here, the I _Foot is the moment of inertia of the foot with respect to the ankle, the α _Foot is the angular acceleration of the foot, the w _Foot is the angular velocity of the foot, the V _CoM-GRF is the distance vector from the center of mass of the foot to the ground reaction force action point, and T _GRF is the ground The torque caused by the reaction force, V _CoM-Ankle, can be defined as a distance vector from the center of mass of the foot to the ankle.

In summary, the analysis unit 130 may calculate the joint reaction force and torque for the 'ankle joint' through [Equation 2] to [Equation 5] described above.

Thereafter, the analysis unit 130 may apply [Equation 2] to [Equation 5] in the same manner to the 'knee joint' and the 'hip joint' to calculate the joint repulsion force for each joint and the torque for each joint, respectively.

After calculating the joint repulsion force for each joint and the joint torque for each of the 'ankle joint', 'knee joint', and 'hip joint', the analysis unit 130 adds up the calculated joint repulsion force for each joint, and the joint repulsion force F _{Calculate Hip, Knee, Ankle} , and add up the calculated torque for each joint to calculate the torque T _{Hip, Knee, and Ankle} .

The output unit 140 outputs the rate of change of shape with respect to the posture of the user by presenting the correlation coefficient between the joint repulsion force and the reference value and the correlation coefficient between the torque and the reference value as a percentage. That is, the output unit 140 compares the joint reaction force F _{Hip, Knee, Ankle} and the torque T _{Hip, Knee, Ankle} with a set reference value, and numerically shows the correlation coefficient regarding the degree of similarity according to the comparison result. It can play a role of visually showing how different from the normal form the gait or standing posture of the person changes.

In another embodiment, the biomechanical-based balance analysis apparatus 100 of the present invention may evaluate the user's balance ability.

The measuring unit 110 measures vertical ground reaction force data regarding the walking or standing posture of the user from the ground reaction force device. The measurement unit 110 may serve to stand up the user on the FSR pressure mat as a ground reaction force and obtain information on the walking or standing posture sensed by the FSR pressure mat.

The FSR pressure mat may be a means for arranging a plurality of Force Sensing Resistor (FSR) sensors and producing information by classifying the pressing force sensed by these FSR sensors for each sensing position.

The vertical ground reaction force data is a ground reaction force (GRF) that pushes the user's lower extremities, feet, etc. vertically (z-axis direction) with respect to the user standing on the FSR pressure mat.

That is, the measurement unit 110 may acquire the vertical ground reaction force data of the user taking a walking or standing posture through the FSR pressure mat.

The three-dimensional joint center position data measured from the depth camera and the vertical ground reaction force data measured from the FSR pressure mat as a ground reaction force are displayed in accordance with the coordinate system set in the device. Needs to be.

This calibration can be performed by the coordinate system alignment unit 120, and the process is to convert the coordinate system of the above-mentioned ground reaction forcer and the depth camera to a global coordinate system, and calibrate the depth camera and the ground reaction force. replaced, and omitted here.

After obtaining the vertical ground reaction force data, the analysis unit 130 analyzes the three-dimensional joint center position data and the vertical ground reaction force data, and calculates the joint reaction force acting on the lower extremity joint of the user. That is, the analysis unit 130 may calculate the physical force applied to the lower extremity joint while the user is walking or standing by using the three-dimensional joint center position data and the vertical ground reaction force data, which are shown as a single coordinate system.

Specifically, the analysis unit 130, the asymmetry of the force distributed due to the joint repulsion force F Thigh on the left and right thighs of the lower _{extremities, and the joint repulsion force F Leg} on the left and right calves of each of the lower extremities ( asymmetric) can be expressed as a coefficient of variation (CoV).

That is, the analysis unit 130 calculates the joint repulsion force for each thigh and calf, generated from the FSR pressure mat, to the left and right for the user in a walking or standing posture, and the degree to which these joint repulsion forces are not symmetrical with respect to the left and right can be digitized and calculated as a coefficient of variation (CoV).

The coefficient of variation (CoV) represents the size of an arbitrary standard deviation as a percentage of the average value, where multiple standard deviations for _{the joint reaction force F Thigh} for each thigh on the left and right and the joint reaction force F for the left and right calves F _Leg can be defined as the value divided by the average value.

The analysis unit 130 represents the difference between the coefficient of variation CoV _Thigh associated with the thigh, the joint repulsion force F _L,Thigh on the left thigh and the joint reaction force F _R,Thigh on the right thigh, and also the coefficient of variation associated with the calf The CoV _Leg can be expressed as the difference between the joint reaction force F _L,Leg on the left calf and the joint reaction force F _{R,Leg on the right calf.}

That is, the analysis unit 130 may calculate the difference between the left and right joint repulsion forces of the thigh and calf as a coefficient of variation.

The output unit evaluates the balance ability of the user through a coefficient of variation (CoV) appearing from the joint reaction force. That is, the output unit 140 may play a role of diagnosing the level of the balance ability for a specific body part (rigid body) by using the coefficient of variation (CoV).

_{As before, in the state where the coefficient of variation CoV Thigh} associated with the thigh and the coefficient of _{variation CoV Leg} associated with the calf are calculated, the output unit 140 compares these coefficients of variation with each other, and according to the comparison result, balance ability can be assessed.

That is, the output unit 140 may _{compare the coefficient of variation CoV Thigh} and the coefficient of variation CoV _Leg , and evaluate the low balancing ability for a rigid body having a relatively low coefficient of variation. For example, by comparing the variation coefficient CoV _Thigh and variation coefficient CoV _Leg, variation coefficient CoV _Thigh is lower than the coefficient of variation CoV _Leg, the output unit 140 for thighs related to the variation coefficient CoV _Thigh, to evaluate the low Balance there is.

According to an embodiment, the output unit 140 may _{compare the coefficient of variation CoV Thigh} with the coefficient of variation CoV _Leg , and output a message recommending strength training for a rigid body having a relatively low coefficient of variation.

In the above-described example in which the _{coefficient of variation CoV Thigh} is lower than the coefficient of variation CoV _Leg , the output unit 140 writes and outputs a message recommending, for example, a skirt exercise for strengthening muscle strength, for the thigh related to the _{coefficient of variation CoV Thigh.} .

According to an embodiment of the present invention, it is possible to provide a biomechanical-based balance analysis method and apparatus, which enables biomechanical analysis to be performed using a depth camera that is inexpensive and practical compared to a conventional optical motion capture system.

In addition, according to an embodiment of the present invention, it is possible to evaluate not only the kinematic shape of the outside of the body, but also the kinetic evaluation of the inside of the body considering the forces acting inside the human body, so that more professional clinical trials are possible. can be used for

In addition, according to an embodiment of the present invention, it is possible to propose an automation algorithm for converting the coordinate system of the depth camera and the ground reaction force to the global coordinate system.

In addition, according to an embodiment of the present invention, it is possible to perform global coordinate system transformation robust to scan noise of the depth camera by performing estimation of the marker center point and fusing the planar characteristics of the ground reaction force.

In addition, according to an embodiment of the present invention, by performing biomechanical analysis, it is possible to compare the force and torque of the left/right joints, and through this, it is possible to quantify and train balance ability in walking and standing postures. .

The present invention uses a ground reaction force and a depth camera (kinect) to measure the ground reaction force data in the axial direction acting on the human body on the ground during walking or standing posture, the center of pressure, and the position of the joint It may include a configuration for

In the present invention, the coordinate system of the ground reaction force and the depth camera to which a spherical marker is attached can be matched.

The present invention performs at least one stride, and the ground measured according to the gait event from 0% of the step (right heel fold, heel contact) to 100% of the step (right toe lifted, toe off) Dynamic dynamic analysis can be performed using the data of the reaction force, the data of the depth camera, and the height and weight of the subject.

In addition, in the present invention, it is possible to output the axial results that are analyzed and output for each lower extremity joint as a time series graph.

Through this, the present invention compares the contact force and torque values in each joint known as normal gait with the calculated values, calculates a correlation coefficient between them, and presents it as a percentage, thereby comparing the current gait and normal gait and It can be used to evaluate the similarity level of

The present invention can be utilized to confirm the level of recovery of dynamic function in patients who have undergone treatment such as knee and hip replacement surgery and Chuna treatment.

In general, the system used for gait analysis is very expensive and only considers the kinematic form of the outside of the body, but the system of the present invention takes into account the forces acting inside the body as well as the kinetic It can be evaluated and used in more professional clinical trials.

In addition, in the case of using the FSR pressure mat as a ground reaction force, the subject's balance ability can be evaluated.

The configuration of the system by the FSR pressure mat enables the implementation of the system relatively simply.

In the existing balance ability evaluation, only the evaluation was performed to measure the movement of the center of mass and pressure, which are changes outside the human body in the standing posture, but with a simplified system like the present invention, the internal left/right lower extremity rigid body (segmental) force and torque value, and the joint contact force can be calculated.

In addition, the present invention can be utilized as an index for evaluating balance ability by calculating the asymmetric of the forces distributed to the left / right lower extremities.

In addition, in the present invention, by using the depth camera together with the ground reaction force, it is possible to highlight spatial and price strengths in posture analysis.

In particular, in the case of musculoskeletal disease patients who have undergone joint replacement surgery and chuna treatment, gait analysis is mainly used for dynamic function evaluation before and after surgery. Only the joint angle and range of motion measured kinematically during walking according to the gait analysis, the lower extremity angle Since the magnitude and shape of the force acting inside the joint cannot be confirmed, it may be necessary to perform clinical evaluation using the simplified system according to the present invention.

In addition, the system according to the present invention can evaluate the balance ability for the user, and it is also possible to implement the system relatively simply.

In the existing balance ability evaluation, only the evaluation was performed considering the distribution or movement of the center of pressure in the standing posture, but in this simplified system, torque values and joint contact forces can be calculated for each rigid body (segment) of the left and right lower extremities.

In particular, in the system of the present invention, it can be used as an index to evaluate the balance ability by calculating the asymmetric value of the force and torque applied to the joint distributed to the left and right lower extremities as a coefficient of variation.

2 is a schematic diagram of a biomechanical analysis system according to an embodiment of the present invention.

As shown in Figure 2, the depth camera measures the three-dimensional joint center position data of the human body using kinect 2.0 (Microsoft, US) and kinect for windows SDK 2.0, which are commercialized systems. The three-dimensional joint center position data may be represented based on _{a unique coordinate system (X c} , Y _c , Z _{c ) of the depth camera.}

In the force plate as a ground reaction force device synchronized with the sampling frequency, the ground reaction force data values of 6 axes (x, y, z-axis force & moment) are measured. The 6-axis ground reaction force data value may be expressed based on _{the unique coordinate system (X g} , Y _g , Z _{g ) of the ground reaction force machine.}

In order to evaluate the standing posture balance ability, a pressure mat including a simplified FSR pressure sensor (FSR Matrix) can be used. The FSR pressure sensor is a sensor that detects the pressing force, reduces the resistance when pressed, and operates on the principle of maintaining the resistance when not pressed.

The pressure mat MS9705 (Large Area FSR Matrix Array Sensor (Kitronyx, Korea)), which has 2,304 FSR pressure sensors arranged in 48 × 48, can measure the vertical ground reaction force in the user's standing posture. The measurable area of the pressure mat MS9705 is 384 × 384 (mm), the area of each FSR pressure sensor is 8 × 8 (mm), and the pressure sensing range is 0.22 to 1.78.

The Analysis System receives data from the pressure mat MS9705 controlled by the controller and analyzes the data. The controller MC1509 (Force Controller (Kitronyx, Korea)) is connected to the pressure mat MS9705, and the force measurement value can be obtained from the pressure mat MS9705 with 8 bit resolution.

The analysis system is powered by a USB serial port and may include a communication interface as a configuration.

The analysis system calculates the velocity and acceleration of the hip joint, knee, and ankle joint center using the lower limb joint position data (force measurement value) received from the controller MC1509, and receives the subject's height and weight information and anthropometric data can be applied to obtain the length, mass, center of mass, and moment of inertia of the rigid body of the lower extremities to perform dynamic dynamic analysis of walking and standing postures.

3 is a diagram illustrating an example of a marker for constructing an FSR pressure mat and a global coordinate system.

In order to create a global coordinate system at the joint position of the free body diagram, five markers attached to the ground reaction force can be used as shown in FIG. 3(a).

In FIG. 3(b), it is exemplified that the second marker is defined as the origin among the markers arranged in the ground reaction force of FIG. 3(a).

The '3D joint center position data' of the depth camera and the 'ground reaction force data (or vertical ground reaction force data) according to the pressure center of both feet of the ground reaction machine must be converted into a global coordinate system to create a model.

For dynamic dynamics analysis, the human lower extremities are composed of 7 rigid bodies without deformation: the pelvis, both thighs, both calves, and both feet, and the joints connecting each rigid body are assumed to be frictionless hinges. (free body diagram).

The length, mass, center of mass, and moment of inertia of each rigid body required for calculating the dynamic dynamics of the lower extremities are anthropometric data of the known paper Winter (DA Winter, Biomechanics of human movement, John Wiley & Sons, New York, 1979.). can be applied using

Anthropometric data is presented as a ratio of rigid body (segment) length and weight, as shown in Table 1, and can be used to calculate 3D moment of inertia by measuring the rigid body (segment) length and weight of each subject.

The 3D moment of inertia is Table 2 disclosed in the known paper De Leva (P. De Leva, "Adjustments to Zatsiorsky- Seluyanov's segment inertia parameters," J. Biomechanics, vol. 29, no. 9, pp. 1223-1230, 1996). It can be calculated through [Equation 2] and [Equation 3] using the rotation radius ratio of .

Table 1 is a table that records human segment variables.

[Table 1]

*segment mass as proportion of total body mass

**location of center of gravity from proximal ends of segment as proportion of segment's length

Table 2 is a table that records the rotation radius ratio of human body segments.

[Table 2]

[Equation 2]

k _cg = K _cg L

[Equation 3]

I _cg = m _segment k ² _cg

K _cg is the rotation radius ratio of the rigid body, L is the length of the rigid body, k _cg is the rotation radius at the center _{of mass, m segment} is the mass of the rigid body, and I _cg is the moment of inertia of the rigid body.

In the present invention, joint reaction force acting on lower extremity joints by applying the three-dimensional joint center position data of the depth camera and ground reaction force data or vertical ground reaction force data according to the pressure center of both feet of the ground reaction force to the modeled biomechanical model. and torque were calculated.

The present invention can calculate joint repulsion force and torque in the order of ankle, knee, and hip joint through the free body diagram of each rigid body.

4 is a view for explaining a lower extremity free body diagram according to an embodiment of the present invention.

Fig. 4 (a) shows an example of a free body diagram for a rigid body 'foot', Fig. 4 (b) shows an example of a free body diagram for a rigid body 'calf', and Fig. 4 (c) shows an example of a free body diagram for a rigid body 'calf'. An example of a free-body diagram for 'thigh' is shown.

Of these, [Equation 4] and [Equation 5] for calculating _{the repulsive force F Ankle} and the torque T _Ankle of the ankle joint in the free-body diagram of FIG. 4(a) can be derived as follows.

[Equation 4]

F _Ankle = M _Foot A _Foot - F _GRF - W _Foot

[Equation 5]

T _Ankle = I _Foo t α _Foot + w _Foot * I _Foot w _Foot

- V _CoM-GRF * F _GRF

- T _GRF - V _CoM-Ankle * F _Ankle

M _Foot is the mass of the foot, A _Foot is the acceleration of the center of mass of the foot, F _GRF is the ground reaction force measured by the pressure sensor, and W _Foot is the self-weight due to the mass of the foot.

In addition, I _Foot is the moment of inertia of the foot with respect to the ankle, α _Foot is the angular acceleration of the foot, w _Foot is the angular velocity of the foot, V _CoM-GRF is the distance vector from the center of mass of the foot to the point of application of the ground reaction force, T _GRF is the torque by the ground reaction force, V _CoM-Ankle can represent the distance vector from the center of mass of the foot to the ankle.

In the dynamic dynamics calculation of the standing posture, the ground reaction force is measured with a pressure sensor, and T _GRF is not measured and is therefore ignored.

M _Foot A _Foot is the force caused by acceleration, F _GRF is an externally applied force, W _Foot is the mass of the foot _{, and the repulsive force F Ankle} applied to the ankle is the same as the sum of these forces.

Similarly, the torque T _{Ankle applied} to the ankle can be expressed as the sum of the other torques shown in the free body diagram.

I _Foot α _Foot + w _Foot * I _Foot w _Foot is the amount of change in angular momentum and has the same role as acceleration in force, V _CoM-GRF * F _GRF is torque due to external force, V _CoM-Ankle * F _Ankle is the mass of the foot The torque caused by T _GRF is the ground reaction force torque, and all torques indicated on the free body diagram are indicated.

In the present invention, calculation formulas for the repulsive force and torque of the knee and hip joints can be derived in the same manner. At this time, the ground reaction force action point position and the ground reaction force can be calculated by replacing the position of the previous joint in the opposite direction of the repulsion force and torque.

_{According to the present invention, joint repulsion force F Hip, Knee, Ankle} and torque T _{Hip, Knee, Ankle,} which are the contact force of each lower extremity joint calculated by diagnosis using this system before joint replacement surgery and chuna treatment, are secured, and treatment and treatment are performed. When the correlation coefficient (r) with the result obtained by repeated measurement is calculated and presented as a percentage, the rate of change in the form of walking can be confirmed.

In addition, when a generally known normal gait graph is used as a reference, according to the present invention, it is possible to check the current gait state compared to the normal gait.

In addition, in the present invention, for the evaluation of the user's balance ability, a simplified system using the FSR pressure sensor as a ground reaction force can be configured.

The configured system may acquire data when the subject closes their eyes and maintains a standing posture for 1 minute.

In general, the balance ability contributes to the visual, vestibular, and somatic senses, and among them, the balance, which is arbitrarily reduced by blocking the most representative balance element, can be evaluated.

At this time, in the present invention, left (F _L) / right (F _R) side leg (F _Thigh) and calf (F _Leg) asymmetry (asymmetric) of force, the coefficient of variation (coefficient of variation, CoV) is dispersed in the It can be used as an index to evaluate balance ability.

In the evaluation of the balance ability, the present invention evaluates that the lower the coefficient of variation, the poorer the balance ability.

Accordingly, the present invention compares the coefficient of variation of the thigh and calf muscles of the lower extremities and considers a relatively low part not to be used for standing posture balance, so that strength training can selectively improve balance ability.

The method and procedure for calculating the standing balance ability evaluation result are as follows 1)~3).

1) |F _Hip - F _Knee | = F _Thigh , |F _Knee - F _Ankle | = F _Leg

2) CoV _Thigh and CoV _{Leg of |F R.Thigh} - F _L.Thigh | and |F _R.Leg - F _L.Leg | were calculated from the 1 minute standing posture measurement data.

3) If CoV _Thigh < Co _VLeg , thigh selective strength training is performed.

Conversely, if CoV _Thigh > CoV _Leg , calf selective strength training is performed.

In order to perform biomechanical analysis, it is necessary to convert the coordinate system of the ground reaction forcer and the coordinate system of the depth camera. That is, the position of the joint measured by the depth camera and the position of the marker defined in the ground reaction force are values based on the camera coordinate system, and the rigid body transformation R,t (R: 3-dimensional rotation, t: 3-dimensional) that transforms them into the global coordinate system. translation) should be obtained.

As shown in FIG. 2 above, it is assumed that the true values of positions are known in advance on the basis of the global coordinate system for predefined spherical markers 1 to 5 . For example, if marker No. 2 is defined as the origin of the global coordinate system and the horizontal and vertical grid intervals of each marker are known as measured values, it can be assumed that the true values of the center points of all markers are known in advance.

If the true value of the center point position of markers 1 to 5 is known based on the global coordinate system, the rigid body transformation R, t that moves the center point position based on the camera coordinate system of markers 1 to 5 to the global coordinate system is the estimated value of the center point of the marker observed in the camera coordinate system. Through , it can be obtained by methods such as singluar value decomposition.

In the above [Equation 1], p _i is the estimated values of the center point of the marker observed in the camera coordinate system, q _i is the true value of the center point position of the global coordinate system reference marker, and w _i may be a weight indicating the importance of each point. The problem of minimizing the error of [Equation 1] can be solved by a method such as singluar value decompostion. _ is a weight indicating the importance of each point.

In fact, since the 3D points corresponding to the marker surface observed by the depth camera are very noisy, the error in the estimation of the center point of each marker is large. Therefore, there is a need for a method to obtain accurate R,t while being robust to noise.

Since it is difficult to obtain a rigid body transformation using only 3D points on the noisy marker surface, we present a method of using the point information of the ground reaction force region assumed to be flat. In general, the number of points in the ground reaction forcer region is much greater than the number of marker regions, and since the ground reaction forcer is flat, rigid body transformation can be performed robustly against noise using the proposed method.

5 is a view for explaining an example of converting the coordinate system of the ground reaction force and the depth camera into the global coordinate system.

In step 501, the input 3D point cloud is a set of points observed by the depth camera, including the ground reaction force and the marker area.

Step 502 is a process of classifying points into markers and ground reaction force regions using K-Means, a color-based classification method, and the like.

Step 503 is a process of estimating the marker center point with respect to the marker area points.

Step 504 is a process of obtaining the first-order rigid body transformation R1,t1 by solving [Equation 1] using the correspondence relationship between the estimated marker center point and the true value defined in the global coordinate system.

In [Equation 1], p _i is the estimated center point of the marker, q _i is the true value of the center point position of the global coordinate system reference marker, and w _i is the same, or using the error value calculated in the process of estimating the center point of each marker. can be set.

Step 505 is a process of first transforming all of the points into the global coordinate system by applying the first rigid body transformation to the points corresponding to the marker and the ground reaction force region.

Step 506 is a process of performing plane fitting using points corresponding to the ground reaction force region. In step 506, an equation of a three-dimensional plane may be obtained, and outlier points located farther than a certain threshold value from the plane of the ground reaction force may be removed.

Step 507 is a process of calculating the projected marker center point on the plane by projecting the marker center point of step 505 onto the plane obtained in step 506 .

Step 508 is a process of sampling and selecting points corresponding to the ground reaction force region based on the projected marker center point position calculated in step 507 . For example, in step 508 , the points of the ground reaction forcer region may be sampled so as to be uniformly distributed on a plane by defining horizontal and vertical grid intervals. Also, the true position value of each point can be easily set by defining the grid interval.

Step 509 is a process of allocating a _{weight, w i ,} to the projected marker center point and points in the ground reaction force region. For example, marker centroids may be assigned a higher weight if the marker centroid estimate has been made reliable. Alternatively, a relatively low weight may be allocated to the marker center point as the error of the first rigid body transformation result obtained only with the marker center point is greater.

Step 510 is a process of completing transformation into the global coordinate system by obtaining the second-order rigid body transformation R2,t2 using the projected marker center point, the sampled points of the GRF region, and the corresponding weight value, and performing the transformation.

Hereinafter, a work flow of the biomechanical-based balance analysis apparatus 100 according to embodiments of the present invention will be described in detail with reference to FIG. 6 .

6 is a flowchart illustrating a biomechanical-based balance analysis method according to an embodiment of the present invention.

The biomechanical-based balance analysis method according to the present embodiment may be performed by the biomechanical-based balance analysis apparatus 100 .

First, the biomechanical-based balance analysis apparatus 100 measures the user's three-dimensional joint center position data from a depth camera ( 610 ). Step 610 may be a process of scanning the user's skeleton with a depth camera and acquiring the 3D joint center position data from the depth information of the skeleton according to the scan. The three-dimensional joint center position data may be motion data related to a movement of a skeleton by recognizing a gesture taken by a user.

In addition, the biomechanical-based balance analysis apparatus 100 measures the ground reaction force data regarding the user from the ground reaction force device ( 620 ). Step 620 may be a process of acquiring information on the gait of a user walking on the ground reaction force or the balance posture of the user standing on the ground reaction force.

The ground reaction force device is a device for measuring the reaction force when a force is applied to the ground, and may be a means to determine the degree of absorption of an impact or foot received by the human body through ground reaction force analysis, for example, running, walking, jumping, etc.

Specifically, a ground reaction force device is a sensor capable of measuring ground reaction force data, and herein may refer to a force plate and a force sensing register (FSR) pressure mat. The force plate measures the force and the moment of each of the x-axis, y-axis, and z-axis according to the marker according to the marker, and the moment of each of the x-axis, y-axis, and z-axis, and the FSR pressure mat is the z-axis force can only be measured.

The three-dimensional joint center position data measured from the depth camera and the ground reaction force data measured from the ground reaction force device display values according to the coordinate system individually set in the device, so calibration is required to show it as an integrated single coordinate system. may be needed

To this end, the biomechanical-based balance analysis apparatus 100 converts the coordinate system of the three-dimensional joint center position data and the ground reaction force data into a global coordinate system ( 630 ). Step 630 may be a process of calibrating the depth camera and the ground reaction force by converting the coordinate system of the ground reaction forcer and the coordinate system of the depth camera into a global coordinate system.

According to an embodiment, the biomechanical-based balance analysis apparatus 100 uses K-Means or a color-based classification method for points in an input 3D point cloud registered in association with the depth camera, It is classified into a marker area and a ground reaction force area. That is, the biomechanical-based balance analysis apparatus 100 may classify the points scanned as the input 3D point cloud into points related to the marker region and points related to the ground reaction force region through clustering.

In addition, the biomechanical-based balance analysis apparatus 100 estimates a marker center point for the points classified as the marker regions. That is, the biomechanical-based balance analysis apparatus 100 may assume a central point between points of the marker region.

_{In addition, the biomechanical-based balance analysis apparatus 100 uses the first rigid body transformations R 1} and t ₁ calculated according to the correspondence between the marker center point and the true value defined in the global coordinate system, and classifies it into the marker region. Each of the points and the points classified into the ground reaction force region are first transformed into a global coordinate system.

Rigid body transformation may be a model representing transformation using translation and Euclidean transformation.

Rigid body transformations R and t may be obtained by satisfying [Equation 1].

[Equation 1]

Here, the p _i is the estimated marker center point, the q _i is the true value of the center point position of the global coordinate system reference marker, and the w _i is set to be the same or set using an error value calculated in the process of estimating each marker center point. can be a value.

The biomechanics-based balance analysis apparatus 100 may primarily convert the coordinate system of the ground reaction forcer and the coordinate system of the depth camera into a global coordinate system by using the rigid body transformations R and t.

In addition, the biomechanical-based balance analysis apparatus 100 may estimate a plane by using the points classified as the first transformed ground reaction force region.

Thereafter, the biomechanical-based balance analysis apparatus 100 may calculate a projection marker center point by projecting a point classified as the first-transformed marker region on the estimated plane.

Also, the biomechanical-based balance analysis apparatus 100 may sample and select points classified as the ground reaction force region based on the position of the center point of the projection marker.

In addition, the biomechanical-based balance analysis apparatus 100 may allocate weights to the center point of the projection marker and the point of the sampled ground reaction force region.

_{In addition, the biomechanical-based balance analysis apparatus 100 uses the second rigid body transformation R 2} and t ₂ calculated according to the projection marker center point, the sampled ground reaction force region, and the weight. Each of the points classified as the marker region and the points classified as the ground reaction force region may be secondarily transformed into a global coordinate system.

That is, the biomechanical-based balance analysis apparatus 100 unifies the coordinate system of the ground reaction forcer and the depth camera into a single coordinate system, so that the data obtained from the depth camera of the ground reaction forcer becomes a value under the same coordinate system. can do.

Subsequently, the biomechanical-based balance analysis apparatus 100 analyzes the three-dimensional joint center position data and the ground reaction force data, and calculates the joint reaction force and torque acting on the lower extremity joint of the user ( 640 ). Step 640 may be a process of calculating the physical force applied to the lower extremity joint when the user walks or the user's standing posture by using the three-dimensional joint center position data and ground reaction force data, which are shown as a single coordinate system.

The joint repulsion force is a reaction force against the forces produced by muscle activity, the stretched connective tissue around the joint, and body weight. The joint connecting the rigid body (segment) bends in a certain direction according to the user's walking, It could mean repulsion.

Also, the torque may refer to a rotational force, and may refer to a force that a walking user momentarily exerts while walking.

In calculating the joint repulsion force and torque, the biomechanical-based balance analysis apparatus 100 may express the user's lower extremities (body below the waist) as a free body diagram.

The free body diagram is a kind of sketch representing the interaction between the body and the environment, and may be a diagram in which vectors of all related forces acting on the user's lower extremities are indicated by arrows or the like.

That is, the biomechanical-based balance analysis apparatus 100 may represent the user's lower extremities as n rigid bodies, and assuming that the joints connecting the n rigid bodies are hinges, they may be expressed as free-body diagrams. Here, n may be defined as a natural number of 7 or more counted including at least the user's pelvis, both thighs, both calves, and both feet.

The biomechanical-based balance analysis apparatus 100 may represent a free-body diagram by dividing the user's lower extremities into seven equal parts and subdividing them into rigid bodies, showing the subdivided rigid bodies and joints connecting each of these rigid bodies.

Thereafter, the biomechanical-based balance analysis apparatus 100 may calculate the moment of inertia I _cg of a specific rigid body in the free body diagram by satisfying [Equation 2] and [Equation 3].

[Equation 2]

k _cg = K _cg L

[Equation 3]

I _cg = m _segment k ² _cg

The K _cg may be defined as a ratio of the rotation radius of the rigid body, L may be defined as the length of the rigid body, the k _cg may be defined as the rotation radius at the center of mass, and the m _segment may be defined as the mass of the rigid body.

The moment of inertia indicates the magnitude of the property of an object rotating about its axis of rotation to continue to rotate, and may refer to the amount of energy that the rotating object tries to maintain at that time.

In addition, the biomechanical-based balance analysis apparatus 100 may use the moment of inertia I _cg to calculate a joint repulsion force for each joint and a torque for each joint for joints connecting the specific rigid body.

That is, the biomechanical-based balance analysis apparatus 100 may obtain the moment of inertia for each joint and calculate the joint reaction force and torque of the corresponding joint through this.

For example, the biomechanical-based balance analysis apparatus 100 includes an 'ankle joint' connecting the user's calf and foot, a 'knee joint' connecting the user's thigh and calf, and a 'knee joint' connecting the user's pelvis and thigh It is possible to calculate the joint repulsion force and torque for each joint for each 'hip joint'.

More specifically, when the specific rigid body is a 'foot', the biomechanical-based balance analysis apparatus 100 calculates the joint repulsion force F _Ankle and the joint torque T _Ankle of the ankle joint connected to the 'foot', It can be calculated by satisfying [Equation 4] and [Equation 5].

[Equation 4]

F _Ankle = M _Foot A _Foot - F _GRF - W _Foot

Here, the M _Foot may be defined as the mass of the foot, the A _Foot may be defined as the acceleration of the center of mass of the foot, the F _GRF may be defined as a ground reaction force measured by a pressure sensor, and the W _Foot may be defined as self-weight due to the mass of the foot.

[Equation 5]

T _Ankle = I _Foot α _Foot + w _Foot * I _Foot w _Foot

- V _CoM-GRF * F _GRF

- T _GRF - V _CoM-Ankle * F _Ankle

Here, the I _Foot is the moment of inertia of the foot with respect to the ankle, the α _Foot is the angular acceleration of the foot, the w _Foot is the angular velocity of the foot, the V _CoM-GRF is the distance vector from the center of mass of the foot to the ground reaction force action point, and T _GRF is the ground The torque caused by the reaction force, V _CoM-Ankle, can be defined as a distance vector from the center of mass of the foot to the ankle.

In summary, the biomechanical-based balance analysis apparatus 100 may calculate the joint reaction force and torque for the 'ankle joint' through [Equation 2] to [Equation 5] described above.

Thereafter, the biomechanical-based balance analysis apparatus 100 applies [Equation 2] to [Equation 5] in the same way for the 'knee joint' and the 'hip joint', and calculates the joint repulsion force for each joint and the torque for each joint, respectively. can be calculated

After calculating the joint repulsion force for each joint and the torque for each joint for each of the 'ankle joint', 'knee joint', and 'hip joint', the biomechanical-based balance analysis apparatus 100 adds up the calculated joint repulsion force for each joint, , calculate the joint reaction force F _{Hip, Knee, and Ankle} , and add up the calculated torques for each joint to calculate the torque T _{Hip, Knee, and Ankle} .

In addition, the biomechanical-based balance analysis apparatus 100 outputs the rate of change of shape with respect to the posture of the user by presenting the correlation coefficient between the joint repulsion force and the reference value and the correlation coefficient between the torque and the reference value as a percentage. (650). In step 650, the joint reaction force F _{Hip, Knee, Ankle} and the torque T _{Hip, Knee, Ankle} are compared with a set reference value, and the correlation coefficient regarding the degree of similarity according to the comparison result is digitized and shown. It may be a process of visually showing how different the standing posture changes from the normal form.

In another embodiment, the biomechanical-based balance analysis apparatus 100 of the present invention may evaluate the user's balance ability.

The biomechanical-based balance analysis apparatus 100 measures vertical ground reaction force data regarding the user's walking or standing posture from the ground reaction forcer. The biomechanical-based balance analysis apparatus 100 may serve to stand up the user on the FSR pressure mat as a ground reaction force and obtain information on the walking or standing posture sensed by the FSR pressure mat.

The FSR pressure mat may be a means for arranging a plurality of Force Sensing Resistor (FSR) sensors and producing information by classifying the pressing force sensed by these FSR sensors for each sensing position.

The vertical ground reaction force data is a ground reaction force (GRF) that pushes the user's lower extremities, feet, etc. vertically (z-axis direction) with respect to the user standing on the FSR pressure mat.

That is, the biomechanical-based balance analysis apparatus 100 may acquire vertical ground reaction force data of a user taking a walking or standing posture through the FSR pressure mat.

The three-dimensional joint center position data measured from the depth camera and the vertical ground reaction force data measured from the FSR pressure mat as a ground reaction force are displayed in accordance with the coordinate system set in the device. Needs to be.

This calibration may be performed by the biomechanical-based balance analysis apparatus 100, and the process converts the coordinate system of the above-described ground reaction forcer and the depth camera into a global coordinate system, and calibrates the depth camera and the ground reaction force. description, and will be omitted here.

After obtaining the vertical ground reaction force data, the biomechanical-based balance analysis apparatus 100 analyzes the three-dimensional joint center position data and the vertical ground reaction force data, and calculates the joint reaction force acting on the lower extremity joint of the user. . That is, the biomechanical-based balance analysis apparatus 100 calculates the physical force applied to the lower extremity joint while the user walks or stands by using the three-dimensional joint center position data and the vertical ground reaction force data, which are shown as a single coordinate system. can

Specifically, the biomechanical-based balance analysis apparatus 100 is a force distributed due _{to the joint repulsion force F Thigh on the left and right thighs of the lower extremities, and the joint repulsion force F Leg} pertaining to the left and right calves of the lower extremities, respectively. can be expressed as a coefficient of variation (CoV).

That is, the biomechanical-based balance analysis apparatus 100 calculates the joint repulsion force for each thigh and calf, generated from the FSR pressure mat, to the left and right for a user in a walking or standing posture, and these joint repulsion forces are each other for the left and right. The degree of non-symmetry can be quantified and calculated as a coefficient of variation (CoV).

The coefficient of variation (CoV) represents the size of an arbitrary standard deviation as a percentage of the average value, where multiple standard deviations for _{the joint reaction force F Thigh} for each thigh on the left and right and the joint reaction force F for the left and right calves F _Leg can be defined as the value divided by the average value.

The biomechanical-based balance analysis apparatus 100 represents the difference between the coefficient of variation CoV _Thigh associated with the thigh, the joint repulsion force F _L,Thigh on the left thigh and the joint repulsion force F _R,Thigh on the right thigh, and also the calf The coefficient of variation associated with CoV _Leg can be expressed as the difference between the joint reaction force F _L,Leg on the left calf and the joint reaction force F _{R,Leg on the right calf.}

That is, the biomechanical-based balance analysis apparatus 100 may calculate the difference between the left and right joint repulsion forces of the thigh and calf as a coefficient of variation.

The output unit evaluates the balance ability of the user through a coefficient of variation (CoV) appearing from the joint reaction force. That is, the biomechanical-based balance analysis apparatus 100 may play a role in diagnosing the degree of balance ability for a specific body part (rigid body) by using the coefficient of variation (CoV).

_{As before, in the state where the coefficient of variation CoV Thigh} associated with the thigh and the coefficient of _{variation CoV Leg} associated with the calf are calculated, the biomechanical-based balance analysis apparatus 100 compares these coefficients of variation with each other, and a specific body part according to the comparison result Balance ability can be evaluated for (rigid body).

That is, the biomechanical-based balance analysis apparatus 100 may _{compare the coefficient of variation CoV Thigh} and the coefficient of variation CoV _Leg to evaluate a low balance ability for a rigid body having a relatively low coefficient of variation. For example, by comparing the _{coefficient of variation CoV Thigh} and the coefficient of variation CoV _Leg , when the coefficient of variation _{CoV Thigh is lower than the coefficient of variation CoV Leg} , the biomechanical-based balance analysis apparatus 100 provides a low balance for the thigh associated with the _{coefficient of variation CoV Thigh.} ability can be assessed.

According to an embodiment, the biomechanical-based balance analysis apparatus 100 _{compares the coefficient of variation CoV Thigh} with the coefficient of variation CoV _Leg , and outputs a message recommending strength training for a rigid body having a relatively low coefficient of variation. there is.

In the _{above example where the coefficient of variation CoV Thigh} is lower than the coefficient of variation CoV _Leg , the biomechanical-based balance analysis device 100 writes a message to recommend, for example, a skirt exercise to strengthen muscle strength, for the thigh related to the _{coefficient of variation CoV Thigh,} can be printed out.

According to an embodiment of the present invention, it is possible to provide a biomechanical-based balance analysis method and apparatus, which enables biomechanical analysis to be performed using a depth camera that is inexpensive and practical compared to a conventional optical motion capture system.

In addition, according to an embodiment of the present invention, it is possible to evaluate not only the kinematic shape of the outside of the body, but also the kinetic evaluation of the inside of the body considering the forces acting inside the human body, so that more professional clinical trials are possible. can be used for

In addition, according to an embodiment of the present invention, it is possible to propose an automation algorithm for converting the coordinate system of the depth camera and the ground reaction force to the global coordinate system.

In addition, according to an embodiment of the present invention, it is possible to perform global coordinate system transformation robust to scan noise of the depth camera by performing estimation of the marker center point and fusing the planar characteristics of the ground reaction force.

In addition, according to an embodiment of the present invention, by performing biomechanical analysis, it is possible to compare the force and torque of the left/right joints, and through this, it is possible to quantify and train balance ability in walking and standing postures. .

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the embodiment, or may be known and available to those skilled in the art of computer software. Examples of the computer-readable recording medium include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic such as floppy disks. - includes magneto-optical media, and hardware devices specially configured to store and carry out program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

The software may comprise a computer program, code, instructions, or a combination of one or more thereof, which configures a processing device to operate as desired or is independently or collectively processed You can command the device. The software and/or data may be any kind of machine, component, physical device, virtual equipment, computer storage medium or device, to be interpreted by or to provide instructions or data to the processing device. , or may be permanently or temporarily embody in a transmitted signal wave. The software may be distributed over networked computer systems, and stored or executed in a distributed manner. Software and data may be stored in one or more computer-readable recording media.

As described above, although the embodiments have been described with reference to the limited drawings, those skilled in the art may apply various technical modifications and variations based on the above. For example, the described techniques are performed in a different order than the described method, and/or the described components of the system, structure, apparatus, circuit, etc. are combined or combined in a different form than the described method, or other components Or substituted or substituted by equivalents may achieve an appropriate result.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

100: biomechanical-based balance analysis device
110: measurement unit 120: coordinate system alignment unit
130: analysis unit 140: output unit

Claims (19)

Measuring the user's three-dimensional joint center position data from the depth camera;
measuring, from the ground reaction force device, ground reaction force data about the user; and
Analyzing the three-dimensional joint center position data and the ground reaction force data, calculating the joint reaction force and torque acting on the lower extremity joint of the user
A biomechanical-based balance analysis method comprising a. According to claim 1,
Outputting the shape change rate for the posture of the user by presenting the correlation coefficient between the joint repulsion force and the reference value, and the correlation coefficient between the torque and the reference value as a percentage
A biomechanical-based balance analysis method further comprising a. According to claim 1,
The ground reaction force device, as a sensor for measuring the ground reaction force data,
a force plate for measuring a force and a moment in each of the x-axis, y-axis, and z-axis according to the marker; and
FSR (force sensing register) pressure mat that measures the force in the z-axis
A biomechanical-based balance analysis method comprising a. According to claim 1,
classifying points in an input 3D point cloud registered in association with the depth camera into a marker region and a ground reaction force region using K-Means or a color-based classification method;
estimating a marker center point for the points classified as the marker regions; and
Points classified into the marker area using the _{first-order rigid body transformation R 1} (three-dimensional rotation) and t ₁ (three-dimensional translation) calculated according to the correspondence between the marker center point and the true value defined in the global coordinate system. and first transforming each of the points classified into the ground reaction force region into a global coordinate system.
A biomechanical-based balance analysis method further comprising a. 5. The method of claim 4,
estimating a plane using the points classified as the first transformed ground reaction force region;
calculating a projection marker center point by projecting a point classified as the first-order transformed marker region onto the estimated plane;
sampling and selecting points classified as the ground reaction force region based on the location of the center point of the projection marker;
allocating weights to the center point of the projection marker and the point of the sampled ground reaction force region; and
_{Using the second-order rigid body transformation R 2} and t ₂ calculated according to the projection marker center point, the sampled point of the ground reaction force region, and the weight, a point classified into the marker region, and the ground reaction force region region Secondary transformation of each point classified as
A biomechanical-based balance analysis method further comprising a. According to claim 1,
Measuring vertical ground reaction force data about the user from the ground reaction force;
analyzing the three-dimensional joint center position data and the vertical ground reaction force data, calculating a joint reaction force acting on the lower extremity joint of the user; and
Evaluating the user's balance ability through a coefficient of variation (CoV) appearing from the joint repulsion force
A biomechanical-based balance analysis method further comprising a. 7. The method of claim 6,
The coefficient of variation (CoV) is the asymmetric force distributed due _{to the joint repulsion force F Thigh} on the left and right thighs of the lower _{extremity and the joint repulsion force F Leg per} each calf on the left and right sides of the lower extremity. step represented by
A biomechanical-based balance analysis method further comprising a. 8. The method of claim 7,
_{representing the coefficient of variation CoV Thigh} associated with the thigh as a difference between the joint repulsion force F _L,Thigh on the left thigh and the joint repulsion force F _R,Thigh on the right thigh; and
_{Representing the coefficient of variation CoV Leg} associated with the calf as the difference between the joint repulsion force F _L,Leg on the left calf and the joint repulsion force F _{R,Leg on the right calf}
further comprising,
The step of evaluating the user's balance ability,
Comparing the coefficient of variation CoV _Thigh and the coefficient of variation CoV _Leg to evaluate a low balancing ability for a rigid body having a relatively low coefficient of variation
A biomechanical-based balance analysis method comprising a. 9. The method of claim 8,
The step of evaluating the user's balance ability,
Comparing the coefficient of variation CoV _Thigh with the coefficient of variation CoV _Leg , outputting a message recommending strength training for a rigid body having a relatively low coefficient of variation
A biomechanical-based balance analysis method further comprising a. a measurement unit for measuring the three-dimensional joint center position data of the user from the depth camera, and measuring the ground reaction force data for the user from the ground reaction force; and
An analysis unit that analyzes the three-dimensional joint center position data and the ground reaction force data to calculate the joint reaction force and torque acting on the lower extremity joint of the user
A biomechanical-based balance analysis device comprising a. 11. The method of claim 10,
By presenting the correlation coefficient between the joint repulsion force and the reference value and the correlation coefficient between the torque and the reference value as a percentage, an output unit for outputting a rate of change of shape for the user's posture
A biomechanical-based balance analysis device further comprising a. 11. The method of claim 10,
The ground reaction force device, as a sensor for measuring the ground reaction force data,
a force plate for measuring a force and a moment in each of the x-axis, y-axis, and z-axis according to the marker; and
FSR (force sensing register) pressure mat that measures the force in the z-axis
A biomechanical-based balance analysis device comprising a. 11. The method of claim 10,
Points in the input 3D point cloud registered in association with the depth camera are classified into a marker region and a ground reaction force region using K-Means or a color-based classification method, and a marker is applied to the points classified as the marker region. _{Estimating the center point, using the first rigid body transformation R 1} and t 1 calculated according to the correspondence between the marker center point and the true value defined in the global coordinate system, the point classified into the marker area, and the ground reaction force A coordinate system aligning unit that first transforms each point classified into a base region into a global coordinate system
A biomechanical-based balance analysis device further comprising a. 14. The method of claim 13,
The coordinate system alignment unit,
Estimate the plane using the points classified as the first transformed ground reaction force region,
Projecting a point classified as the first-transformed marker area onto the estimated plane, calculating a projection marker center point,
Based on the location of the center point of the projection marker, sampling and selecting points classified as the ground reaction force region,
allocating a weight to the center point of the projection marker and the point of the sampled ground reaction force region;
_{Using the second-order rigid body transformation R 2} and t ₂ calculated according to the projection marker center point, the sampled point of the ground reaction force region, and the weight, the point classified into the marker region, the ground reaction force region Each of the points classified as
Biomechanical-based balance analysis device. 11. The method of claim 10,
The measurement unit,
Measuring vertical ground reaction force data about the user from the ground reaction force,
The analysis unit,
By analyzing the three-dimensional joint center position data and the vertical ground reaction force data, the joint reaction force acting on the lower extremity joint of the user is calculated,
The biomechanical-based balance analysis device,
An output unit that evaluates the user's balance ability through the coefficient of variation (CoV) appearing from the joint repulsion force
A biomechanical-based balance analysis device further comprising a. 16. The method of claim 15,
The analysis unit,
The coefficient of variation (CoV) is the asymmetric force distributed due _{to the joint repulsion force F Thigh} on the left and right thighs of the lower _{extremity and the joint repulsion force F Leg per} each calf on the left and right sides of the lower extremity. represented by
Biomechanical-based balance analysis device. 17. The method of claim 16,
The analysis unit,
The coefficient of variation CoV _Thigh associated with the thigh is expressed as the difference between the joint repulsion force F _L,Thigh on the left thigh and the joint repulsion force F _{R,Thigh on the right thigh, and the coefficient of variation CoV Leg} associated with the calf is expressed on the left calf It is expressed as the difference between the joint repulsion force F _L,Leg and the joint repulsion force F _{R,Leg on the right calf,}
the output unit,
By comparing the coefficient of variation CoV _Thigh and the coefficient of variation CoV _Leg, for a rigid body with a relatively low coefficient of variation, low balancing ability
Biomechanical-based balance analysis device. 18. The method of claim 17,
the output unit,
Comparing the coefficient of variation CoV _Thigh with the coefficient of variation CoV _Leg , outputting a message recommending strength training for a rigid body with a relatively low coefficient of variation
Biomechanical-based balance analysis device. A computer-readable recording medium recording a program for executing the method of any one of claims 1 to 9.

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