KR100707984B1 - Device and Method for motion analysis with bio-impedance - Google Patents

Abstract

The present invention comprises a constant current source consisting of an oscillation frequency circuit and a voltage current conversion circuit for generating a weak current; A stimulating current electrode for flowing the weak current from one point of the living body to another selected point; At least two voltage detection electrodes measuring a voltage at a predetermined portion of the living body in which the weak current flows; A demodulator for demodulating the voltage measured at the voltage detection electrode; A signal gain and offset adjuster for adjusting a gain and an offset of the signal passing through the demodulator; And an insulation amplifier for isolating a power supply and a signal. According to the present invention, by attaching a skin electrode, it is possible to simply measure the change in motion of the joint without limiting the activity of the subject.

Bioimpedance, motion analysis, joint angle

Description

Device and method for analyzing motion using bioimpedance {Device and Method for motion analysis with bio-impedance}

1 is a view showing a bioimpedance measuring device according to an embodiment of the present invention,

2 is an electrode arrangement diagram for positioning of an optimal electrode for detecting a change in bioimpedance in the lower extremity joint according to an embodiment of the present invention,

3 is an electrode arrangement diagram for positioning an optimal electrode for detecting a change in bioimpedance in the upper limb joint according to an embodiment of the present invention,

4 is a block diagram of an electrode and system for the analysis of joint motion during walking according to an embodiment of the present invention,

5 is a view showing an example of the lower extremity movement;

6 is a comparison of an electronic goniometer and a bioimpedance measurement signal for measuring ankle motion (ankle) movement angle according to an embodiment of the present invention,

7 is a comparison of an electronic goniometer and a bioimpedance measurement signal for measuring a knee (knee) movement angle according to an embodiment of the present invention,

8 is a comparison of the electronic goniometer and the bioimpedance measurement signal for measuring the hip joint (hip joint) movement angle according to an embodiment of the present invention,

9 is a view showing an example of an experimental method for selecting the optimum electrode during each joint movement,

10 is a definition of a signal-to-noise ratio for selecting an optimal electrode;

11 is a view showing an avatar corresponding to the lower extremity exercise according to an embodiment of the present invention.

The present invention relates to an apparatus and method for analyzing motion using bioimpedance, and more particularly, to an apparatus and method for analyzing motion using bioimpedance according to joint motion at a predetermined position of a living body in which weak current flows.

Human motion analysis has been mainly conducted on the gait of the lower extremities. Observational analysis, image analysis method, EMG, goniometer, and force plate analysis have been conducted.

Observational analysis has the disadvantage of not producing accurate data because it must be read by the human eye.

In the image analysis method, a reflector is attached to a part of a body to obtain a position value of several infrared cameras, and the data is calculated by a computer to obtain data for gait analysis. The data obtained in this way is relatively accurate, but the cost of building the system is too high and the space is limited.

EMG using bio-signals is not suitable for accurately and continuously measuring joint changes, such as goniometers and image analyzers, because it observes the state of muscle, that is, muscle activity, as the source of movement, rather than direct information about the movement of the human body.

In the case of a goniometer, it is the most accurate method because it attaches to a joint and analyzes the motion of the joint directly. However, there is a disadvantage that continuous measurement is difficult and the movement is limited.

 Image analysis method and force plate measurement method is limited in the place that can be used only in the place where the device is large and the equipment is installed. There is also a pressure gauge made of a shoe type to measure the pressure distribution, such as the force plate, but each subject has to prepare shoes according to the foot, there is a problem in attaching to the foot when walking.

  Accordingly, the technical problem to be achieved by the present invention is to provide a bioimpedance measuring apparatus using a bioimpedance, which is less limited in the measurement space and the operation of the subject, easier to measure, and has a higher time resolution than conventional methods for analyzing the biomechanical behavior. have.

Another technical problem of the present invention is to provide a method for measuring change in bioimpedance using an optimal electrode selection method according to joint motion.                         

Another technical problem of the present invention is to provide a joint motion analysis system using bioimpedance.

The present invention to achieve the above technical problem is composed of an oscillation frequency circuit and a voltage current conversion circuit and a constant current source for generating a weak current; A stimulating current electrode for flowing the weak current from one point of the living body to another selected point; At least two voltage detection electrodes measuring a voltage at a predetermined portion of the living body in which the weak current flows; A demodulator for demodulating the voltage measured at the voltage detection electrode; A signal gain and offset adjuster for adjusting a gain and an offset of the signal passing through the demodulator; And an insulation amplifier for insulating a power supply and a signal.

The present invention to achieve the above another technical problem is a process of generating a predetermined weak current by a constant current source; Flowing the weak current from one point of the living body to another selected point; A combination of _{m and} m (m is a natural number of two or more) points on each interval line separated by 1 / n (n is a natural number) interval between the joint and the joint of the living body in which the weak current flows ( _m C _{2 =} L) Selecting L electrode pairs (two electrodes) using the method, impedance from the electrode pairs (LK = J) except for the electrode pairs (K) located on the same line among the selected L electrode pairs at predetermined cycles Detecting; In addition, the present invention provides a method of measuring a change in bioimpedance using an optimal electrode selection method according to a joint motion including selecting one electrode pair having the largest value of the impedance change detected at each predetermined period.

In order to achieve the above another technical problem, the present invention comprises a constant current source consisting of an oscillation frequency circuit and a voltage current conversion circuit for generating a weak current; A stimulating current electrode for flowing the weak current from one point of the living body to another selected point; A first channel comprising at least two voltage detection electrodes, a demodulator, a gain and offset regulator, an insulation amplifier, positioned at a predetermined location between the hip and the knee, and positioned at a predetermined location between the hip and ankle joint, At least two voltage detection electrodes for detecting voltage, a demodulator, a second channel including a gain and offset regulator, and an insulation amplifier, and at least two voltage detection electrodes and demodulators for detecting a voltage located at predetermined portions between the knee joint and the ankle joint; And a third channel comprising a gain and offset regulator, an insulator, and at least two voltage detection electrodes, demodulators, gain and offset regulators, and insulators, which are located in a predetermined region between the knee and the toe and detect voltage. A fourth channel; An A / D converter converting output values of the first to fourth channels into digital signals; And it provides a joint motion analysis system comprising a control unit for calculating the angle change of the signals of each channel from the A / D converter.

Hereinafter, with reference to a preferred embodiment according to the present invention will be described in detail. These examples are only for illustrating the present invention, and the protection scope of the present invention is not limited by these examples.

1 is a view showing a bioimpedance measuring device according to an embodiment of the present invention. Referring to FIG. 1, the voltage sensing module 10 and the stimulation current module 20 are separately configured in consideration of the expandability of the multi-channel. The weak current is generated by the oscillator 110 and the voltage current converter 120.

In consideration of electrical safety, the constant current source flows a weak current of 50 KHz and 300 uA to the lower surface (not shown) through the stimulating current electrode. Since the impedance of the living body by the 50 kHz band has a small reactance component and mostly has a resistance component, the impedance measurement system measures only the resistance component.

When a constant current source is applied to the lower limb of the living body, the voltage can be detected by the voltage detecting electrode due to the intrinsic electrical resistance component of the muscle part constituting the lower limb of the living body. That is, the principle of detecting the impedance change due to the change in the cross-sectional area of the muscle and the cross-sectional area of the blood vessel as the main muscle (main muscle) of the joint constituting the lower limb of the living body contracts and relaxes.

Impedance measurement has been used since Swanson's formula, which is mathematically simplified since Nyboer's formula for blood flow measurement, has been used. Unlike blood flow measurement, the impedance change factor is assumed to be the change of muscle cross-sectional area and blood flow. When the distance of the voltage sensing electrode is constant as shown in Equation (1), the voltage measured by the constant current source is proportional to the specific resistance and the distance of the measurement site, and inversely proportional to the cross-sectional area of the muscle and blood vessel. Therefore, when the muscle contracts or relaxes, the impedance changes due to the change in the cross-sectional area of the muscle and the cross-sectional area of the blood vessel. In Equation (1), Zm and Zb are muscle impedance and blood impedance, respectively.

The demodulator 210 demodulates a signal whose amplitude is modulated by the 50 KHz oscillator 110.

Adding a low pass filter between the demodulator 210 and the gain and offset adjuster 220 of FIG. 1 removes muscle noise and motion artifect in addition to the impedance signal that changes as the joint moves. Can be. Preferably the low pass filter uses a sixth order butterworth (cutoff frequency 10 Hz).

The gain and offset controller 220 may adjust the impedance offset for each channel to obtain a wide range of impedance change.

The insulation amplifier 230 was isolated and separated using a DC-DC converter (PPD10-5-1515, NEMIC-LAMBDA) and an isolation amplifier (ISO100, Burrbrown), respectively, in consideration of the electrical safety of the power supply and the signal.

In addition, the gain and offset adjuster 240 may adjust the gain and offset from the outside of the system. Through this system, the bioimpedance signal according to the joint motion is obtained.

Referring to FIG. 1, four channels of Ch1, Ch2, Ch3, and Ch4 are illustrated, but the number of channels is not limited thereto. In each channel, the impedance signal obtained at the detection electrode is obtained.

2 is an electrode arrangement diagram for positioning an optimal electrode for detecting a change in bioimpedance in the lower extremity joint according to an embodiment of the present invention.

Referring to FIG. 1, an attachment position of a voltage detecting electrode in consideration of the anatomical positions of agonists, antagonists, and synergists according to changes in the angular motion of the hips, knees, and ankles of the lower limbs Fifteen were selected and stimulation current electrodes were attached to the lower abdomen and foot. And the position of the electrode showing the best correlation between the impedance change measurement value and the electronic photometer measurement value according to the lower limb movement was observed. This electrode arrangement detects changes in bioimpedance due to joint motion.

In FIG. 2, the part indicated by (C) is a stimulation current electrode for flowing a stimulus constant current source to the living body, and V + and V- shown on the left side of the demodulator 21 of FIG. 1 are two voltage detecting electrodes attached to the living body. do. However, the number of voltage detection electrodes is not limited thereto. The interval between electrodes was set so that it may apply to every subject in common.

Since the relationship between the changes in the muscle contraction and relaxation of the ankle, the knee and the hip joint according to the contraction and relaxation and the impedance change is not linear, the impedance change according to the motion of each joint and the joint Measurement or data analysis that reflects angles is required. The optimum electrode position satisfying these conditions was selected as shown in FIG. From the ankle joint, the total length of the knee joint was measured as H, and the distance between the voltage sensing electrodes was attached to H / 4, and the impedance change due to the change of the angle of the ankle joint was measured. Also, the distance from the knee joint to the hip joint was measured as W so that the distance between the voltage sensing electrodes was W / 3, and the impedance change due to the change in the angle between the knee joint and the hip joint was measured. As the electrode, Ag-AgCl (RedDot, 3M) having a diameter of 10 mm was used. Finally, in order to measure the angle of each joint, a combination of potentiometer and goniometer was used to make an electronic goniometer. The angles of the ankle, knee and hip joints were measured and the measured impedance measurements were corrected for the joint angles.

The posterior flexion of the ankle is the gastrocnemius, and the tibialis anterior of the dorsal flexion. Therefore, the measuring electrode for detecting the joint angle change during flexion and extension movement of the ankle joint is measured by electrode 1, electrode 2, electrode 3, electrode 4, electrode 5, electrode 6. However, the number of measuring electrodes is not limited thereto. Since the impedance change is not measured when the direction of the voltage sensing electrode and the direction in which the current flows are perpendicular, the position of the electrode should be appropriately selected in consideration of this point. In the case where the electrodes are parallel, since the electrical impedance change is 0, the pair of electrodes located in the horizontal direction is excluded during the measurement. After all, the number of measurement electrodes during ankle movement is a probability of selecting two out of six (electrodes 1, 2, 3, 4, 5, 6), and thus 6C2 = 15 using a combination. Since the parallel electrode pair electrodes (1 and 2), electrodes (3 and 4), and electrodes (5 and 6) are excluded, the number of cases is 12 (15-3 = 12). Therefore, in order to find the optimal electrode position according to the ankle movement, the electrodes are placed according to the number of 12 cases (1-3), (1-4), (1-5), and (1-6). ), (2-3), (2-4), (2-5), (2-6), (3-5), (3-6), (4-5), (4-6) Each of the 12 pieces is measured to select the position of one electrode pair having the largest impedance change value due to joint motion.

Electrode 5, electrode 6, electrode 7, electrode 8, electrode 9, electrode 10, electrode 11, electrode 12, electrode 13, and electrode 14 were used to detect the change of joint angle during flexion and extension movement of the knee joint. However, the number of measuring electrodes is not limited thereto. As in the case of the ankle movement, the electrical impedance change of the measuring electrode is zero when the electrodes are parallel, so the pair of electrodes located in the horizontal direction is excluded during the measurement. Therefore, the electrode pairs shown in Fig. 2, i.e., electrodes (5 and 6), (7 and 8), (7 and 9), (7 and 10), (8 and 9), (8 and 10), (9 and 10), (11 and 12), (11 and 13), (11 and 14), (12 and 13), (12 And 14), and (13 and 14) are excluded. As a result, the number of measurement electrodes during knee joint movement is 10C2 = 45 since the probability of selecting two out of ten (electrodes 5, 6, 7, 8, 9, 10, 11, 12, 13, 14). Since 13 pairs of parallel electrodes are excluded here, the number of cases becomes 32 (45-13 = 32). In other words, it is necessary to find the optimal position through experiments with 32 electrode positions. In order to find the optimal electrode position according to the knee joint movement, the electrodes are placed according to the number of 32 cases (5-7), (5-8), (5-9), (5-10), (5-11), (5-12), (5-13), (5-14), (6-7), (6-8), (6-9), (6-10), (6 -11), (6-12), (6-13), (6-14), (7-11), (7-12), (7-13), (7-14), (8-11 ), (8-12), (8-13), (8-14), (9-11), (9-12), (9-13), (9-14), (10-11), Each of 34 (10-12), (10-13), and (10-14) is measured, and the position of one electrode pair having the largest impedance change according to the knee joint motion is selected.

A total of eight measuring electrodes were used to detect the change of the joint angle during flexion and extension movement of the hip joint. The electrode 7, electrode 8, electrode 9, electrode 10, electrode 11, electrode 12, electrode 13, and electrode 14 were used. However, the number of measuring electrodes is not limited thereto. As in the case of knee joint movement, the electrical impedance change of the measuring electrode is zero when the electrodes are parallel, so the pair of electrodes located in the horizontal direction is excluded from the measurement. Therefore, the electrodes (7 and 8), the electrodes (7 and 9), the electrode (7 and 10) pairs, (8 and 9), and the electrode (8 and 10) shown in FIG. , Electrode (Nos. 9 and 10), (No. 11 and 12), electrodes (No. 11 and 13), electrode (No. 11 and 14), pairs (No. 12 and 13), and electrodes (No. 12 And 14), except for the electrode (13 and 14) pairs. As a result, the number of measurement electrodes during hip motion is 8C2 = 28 because the probability of selecting two out of eight (electrodes 7, 8, 9, 10, 11, 12, 13, 14) is 8, and the parallel Since 12 pairs of electrodes are excluded, the number of cases becomes 16 (28-12 = 16). That is, the optimum position is found through experiments according to the electrode position in 16 cases. In order to find the optimal electrode position according to the hip joint movement, the electrode is placed according to the number of 16 cases (7-11), (7-12), (7-13), (7-14) and (8). -11), (8-12), (8-13), (8-14), (9-11), (9-12), (9-13), (9-14), (10-11 ), (10-12), (10-13), and (10-14) are measured for each of 16 pairs, and the position of one electrode pair having the largest impedance change according to hip joint motion is selected.

In order to detect the heel strike and toe off, which is a phenomenon occurring during the walking cycle, the ground contact point is detected using a bioimpedance method instead of the piezoelectric sensor. The measuring electrode for detecting the ground contact between the heel and the toe corresponds to electrode 15, electrode 1, electrode 2, electrode 3, and electrode 4. However, the number of measuring electrodes is not limited thereto. In this case, since the electrical impedance change is 0 when the electrodes are parallel, the electrode pair located in the horizontal direction is excluded during the measurement. Therefore, the electrode pairs 1 and 2 and the pair of electrodes 3 and 4 shown in FIG. 2 are excluded. In the end, the number of measuring electrodes is the probability of selecting two out of five (electrodes 15, 1, 2, 3, 4), so the combination is 5C2 = 10, except for the two pairs of parallel electrodes described above. Therefore, the number is 8 (10-2 = 8). In order to find the optimum electrode position for detecting the impedance change of the joint during the ground contact between the heel and the toe, the electrode attachment position is determined according to the number of eight cases (15-1), (15-2), (15-3), (15-4), (1-3), (1-4), (2-3), and (2-4) for each of the eight pairs of measurements, each of the heel and toes The position of one electrode pair having the largest impedance change value of the lower limb muscle according to the ground contact motion is selected.

3 is an electrode arrangement diagram for positioning of an optimal electrode for detecting a change in bioimpedance in the upper limb joint according to an embodiment of the present invention.

In the description of FIG. 2, when replacing the ankle joint with the elbow joint, the elbow joint with the elbow joint, and the hip joint with the shoulder joint, the electrode arrangement for positioning the optimal electrode for detecting the change in the bioimpedance is also applied to the upper limb joint. Furthermore, the electrode arrangement for positioning the optimal electrode in the lower extremity or upper limb joint can also be applied to other animals with joints.

Figure 4 is a block diagram of the electrode and system for the analysis of joint motion during walking according to an embodiment of the present invention.

Referring to FIG. 4, a weak current is generated in a constant current source including an oscillator 11 and a voltage current converter 12 for joint motion and ground contact measurement of the foot during walking. Attach and flow the electrode.

In this way, after a weak current flows to the measurement site, when the muscle contracts and relaxes according to the movement of various joints of the lower limb, the impedance is measured at each voltage detection electrode located at a predetermined site. Preferably, the predetermined portion is the impedance change according to the joint movement is the most position, that is, the optimum electrode position.

The measured voltage is delivered to the A / D converter 35 through channels 1, 2, 3, and 4, including a demodulator, gain and offset regulator, and isolation amplifier. Each channel can be delivered to the A / D converter via wire as well as wireless.

The A / D converter 35 converts the impedance signal 31 of each channel into a digital signal. Preferably, the A / D converter 35 used DT9801.

The controller 36 processes the measured bioimpedance change according to each joint angle during walking and the bioimpedance signal according to the ground contact of the foot, calculates the change in angle, and processes the values for the flexion and extension of the joint. The process of converting the resistance value obtained from the bioimpedance signal into an angle is as follows.

Assuming that the flexion and extension range of the joints are statistically similar, the ankle / flexion range of the ankle joint is 70 degrees / 30 degrees, the knee extension / flexion range is 0 degrees / 90 degrees, and the hip extension / flexion range is 50 degrees / 110 degrees. do. Through experiments, we can infer the impedance value according to the angle of the joint, and assume that the bioimpedance value obtained by maximizing extension / flexion of the ankle joint is, for example, 1 ohm to 30 ohm. The maximum extension / flexion angle of the ankle ranges from 70 degrees to 0 degrees / 0 degrees to 30 degrees, ie 70 degrees +30 degrees = 100 degrees. Therefore, 1 ohm = 70 degrees (extension) and 30 ohm = 30 degrees (flexion). (Angle) / (bioimpedance value) is 100 degrees / 30 ohms = 3.333 degrees / 1 ohms. Therefore, if the calculation is made to change by 3.333 degrees according to the 1 ohm increase and decrease, the values for the flexion / extension according to the impedance change can be calculated.

In the case of the knee joint, the hip joint, and the ground contact of the foot, the flexion / extension values can be calculated in this way. Furthermore, in the case of a living body having a joint, the angle value can be calculated using the impedance signal as described above.

5 is a view showing an example of the lower extremity movement operation. That is, an example of joint motion of the lower limb joint is shown. In Figure 4 ankle flexion and extension (51), ankle extensor and adduction (52), knee flexion and extension (53), knee joint rotation and internal rotation (54), hip joint rotation and internal rotation (55) and the like.

FIG. 6 is a comparison of an electronic goniometer and a bioimpedance measurement signal for measuring ankle movement (ankle) motion angle according to an embodiment of the present invention.

Referring to FIG. 6, the change in angle during ankle flexion movement was measured by (a) an electronic potentiometer, (b) measured by 2-5 pairs of impedance electrodes, (c ) Is a value measured with 1-3 pairs of impedance electrodes, and (d) is a value measured with 1-4 pairs of impedance electrodes.

The present invention is to measure the joint angle change without using the electronic goniometer. Therefore, the method of obtaining the angular value of the vertical axis of FIG. 6 includes attaching an electronic goniometer and a pair of bioimpedance electrodes to the ankle joint at the same time, and then changing the voltage and the bio impedance of the electronic goniometer according to the change of the angle of the joint. By simultaneously measuring the change value, it is possible to convert the change in bioimpedance into an angular value.

By analyzing the interference effects of other joint movements in addition to the ankle joint movement, the signal of the electrode with the smallest interference effect and the signal with the highest correlation coefficient was selected as the optimum electrode position. The position of the electrode with the highest correlation between the ankle flexion and the angular change of extension motion measured by the electronic goniometer was found to be the electrode (No. 2 and No. 5), and the correlation coefficient was -0.913. Correlation coefficient flexed / extended the ankle joint for 10 seconds, obtained the bioimpedance according to the goniometer and joint movement simultaneously, and obtained Pearson's correlation coefficient and polynomial coefficient.

The reason why the electronic goniometer is compared with the bioimpedance is to indicate that the joint angle change can be easily measured using only the bioimpedance.

FIG. 7 is a comparison of an electronic goniometer and a bioimpedance measurement signal for measuring a knee motion angle according to an embodiment of the present invention.

Referring to FIG. 7, a change in angle during knee flexion / extension movement was measured (a) using an electronic goniometer, (b) measured with 5-7 pairs of impedance electrodes, and (c) The value measured with 5-8 pairs of impedance electrodes, (d) is the value measured with 5-9 pairs of impedance electrodes. By analyzing the interference effects of other joint movements in addition to the knee joint motion, the signal from the electrode with the smallest interference effect and the highest correlation coefficient with the signal by the electronic goniometer was selected as the optimum electrode position.

It can be seen that the bioimpedance change signal most similar to the value measured by the electronic goniometer in FIG. 7 is the value by the electrodes 5-7 (b). Through these experiments, it is confirmed that the optimum electrode positions for detecting the knee motion are electrodes 5 and 7 as illustrated in FIG. 2.

FIG. 8 is a comparison of an electronic goniometer and a bioimpedance measurement signal for measuring a hip motion angle according to an embodiment of the present invention. 8 is a measurement of the change of the angle during the flexion extension movement of the hip joint (a) is measured with an electronic goniometer, (b) is measured with 10-12 pairs of impedance electrodes, (c) is an impedance electrode 9- (D) is the value measured with 9-10 pairs of impedance electrodes. It can be seen that the bioimpedance change signal most similar to the value measured by the electronic goniometer in FIG. 8 is the value by the electrodes 9-13 (C). Through these experiments, it is confirmed that the optimal electrode positions for detecting the ankle movements are electrodes 9 and 13 as illustrated in FIG. 2.

As described above, the motion of the lower limb may be detected by using the bioimpedance signal corresponding to the change of the lower limb movement. Ankle flexion and extension movements can be detected by impedance changes of the gastrocnemius and forearm muscles. Knee flexion and extension movements can be detected by impedance changes of the quadriceps and femoral biceps. We can see that commutation is the main influence. Comparison with the goniometer confirms that each correlation is very high.

9 is a view showing an example of an experimental method for selecting the optimum electrode during each joint movement. In Figure 9, lower limb movement is ankle flexion and extension, knee flexion and extension, hip flexion and extension, and foot contact.

Referring to FIG. 9, the meaning of the interval of 15 seconds of exercise time in FIG. 9 is to measure impedance change in a pair of measuring electrodes attached to the ankle joint for 75 seconds in the case of ankle flexion / extension experiment. 1) The first 15 seconds (i.e. 0-15 seconds) bend / extend the ankle joint (2) and the second 15 seconds (i.e. 15-30 seconds) do not move the knee joint. Flex / extend; 3) the next 15 seconds (i.e. 30-45 seconds) do not move the ankles and flex / extend the hip. 4) For the next 15 seconds (ie 45 to 60 seconds), the ankles are not moving and the hip joint is rotated. 5) For the next 15 seconds (ie 60 to 75 seconds), flexion / extension of the ankles is performed.

As such, as each movement is performed over time, signals are extracted from the electronic goniometer attached to the joint and the electrodes attached to obtain the bioimpedance signal. Among the extracted signals, the position of the electrode detecting the signal having the highest correlation with the electronic goniometer is selected as the position of the optimum electrode. Here, the correlation means the degree of similarity with the result measured by the electronic goniometer according to the change of the angle of the joint and the result according to the embodiment of the present invention.

10 is a definition of a signal-to-noise ratio for selecting an optimum electrode. The reason for this definition is to select the optimal electrode position for each joint movement in which each joint movement excludes interference signals caused by movements of other joints. First, during ankle flexion and extension movement, the impedance wave form according to ankle flexion and extension movement becomes a signal, and the interference waveform according to flexion and extension of the knee becomes noise, which is according to SNR1 (signal-to-noise ratio 1), ankle flexion and extension movement The impedance waveform becomes a signal, and the interference waveform of joint motion due to hip flexion and extension is noise. The impedance waveform of SNR2 (signal-to-noise ratio 2) and the attached electrode according to the ankle movement is a signal, and the impedance waveform according to the rotation of the hip joint is noise. This is defined as SNR3 (signal-to-noise ratio 3).

SNR4 (signal-to-noise ratio 4) that uses the impedance waveform of the attached electrode according to the knee flexion and extension movement as the signal, and the impedance waveform according to the flexion and extension of the knee joint as a signal, and the knee flexion and extension movement SNR5 (signal-to-noise ratio 5) which uses the impedance waveform of the electrode as the signal, and the impedance waveform according to the flexion and extension of the hip joint, and the impedance waveform of the electrode according to the knee movement during the knee flexion and extension movement. It is defined as SNR6 (signal-to-noise ratio 6) in which the impedance waveform according to the rotation of the signal is noise.

SNR7 (signal-to-noise ratio 7), which uses the impedance waveform of the electrode attached to the hip joint movement as the signal during the flexion and extension movement of the hip joint, and the impedance waveform according to the flexion and extension of the knee joint, and the impedance waveform of the attached electrode according to the hip joint movement. SNR8 (signal-to-noise ratio 8), which is a signal, and an impedance waveform according to flexion and extension of the ankle, and an impedance waveform of an electrode attached to the hip joint movement as a signal, and SNR9, which is an impedance waveform according to the rotation of the hip joint, as a signal. Signal to noise ratio 9).

SNR10 (signal-to-noise ratio 10) which uses the impedance waveform of the electrode attached to the ground contact movement of the foot as the signal and the impedance waveform according to the flexion and extension of the knee as a signal during the ground contact movement of the foot, SNR11 (signal-to-noise ratio 11), which uses the impedance waveform as the signal, and the impedance waveform according to the flexion and extension of the hip, and the impedance waveform of the attachment electrode according to the ground contact movement of the foot as the signal, and the impedance waveform according to the rotation of the hip joint is noise. This is defined as SNR11 (signal-to-noise ratio 11).

Based on the signal-to-noise ratio defined above, an electrode pair having the least influence of the interference signal, that is, the signal-noise ratio having the best signal is determined as the optimum electrode.

11 is a view showing an avatar corresponding to the lower extremity exercise according to an embodiment of the present invention.

That is, an example of a lower limb motion analysis program designed to monitor and analyze the angle change of each joint step by step or continuously according to the lower limb movement of the subject is shown.

The bioimpedance signal refers to a change in bioimpedance at the optimal electrode position of the hip, knee and ankle according to the lower limb movement of the subject. The bioimpedance signal is shown on the right side of FIG.

The program was written in Sense8's WTKTM (ver.9) and Visual C ++. According to the prepared program, the lower limbs and the lower limb movements shown in FIG. 11 were controlled to control the avatars of the lower limbs in response to the bioimpedance signals acquired through the actual three channels.

The menu can be executed by selecting a shortcut key in the program. You can use the hotkey P to perform continuous animation, the hotkey L to play once, and the hotkey F to analyze the joint changes at every moment. The shortcut key R is used to reset the animation. Here, the menu is displayed on the left side of FIG. 11, where 'P' is Play animation, 'L' is Loop animation, 'F' is Play animation by Frame, 'R' is Reset Animation, and 'E' is Reset Environment. it means.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. For example, the range of the living body may be applied to the motion analysis of animals having joints as well as the lower limbs and upper extremities of the human body shown in the drawings according to an embodiment of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

According to the present invention, in the case of lower limb motion measurement, the angle change of each joint according to the ankle joint, the knee joint and the hip joint movement (flexion and extension, etc.) could be detected as the impedance change. In addition, it was confirmed that each correlation is very high as r = 0.94 or more as compared with the conventional electronic goniometer. The correlation coefficient r = 0.94 is obtained by cross-correlating the measured signal of the electronic goniometer with the change of the bioimpedance according to the change of the joint angle.

In addition, a high correlation coefficient (-0.97) between the derivative value of the lower arm's impedance change and the elbow angular velocity can be obtained, and the correlation coefficient (0.79) between the lower arm's impedance change and the arm's speed change can be obtained. The possibility of seeing the pattern was presented.

The effect of the present invention is, first, by attaching a skin electrode can easily measure the change in motion of the joint without limiting the activity of the subject. Compared with the mechanical method, it has less space constraint, enables long time motion analysis, and has high temporal resolution. In addition, compared to the conventional EMG method using a bio-signal, the calculation amount is much smaller and the signal-to-noise ratio has the advantage. Unlike the conventional method by image analysis, it is possible to overcome the limitations in the analysis of the fast motion and to measure accurately. Therefore, it is possible to replace expensive motion analysis and exercise performance analysis system.

Second is the acceleration of the development of the study by the development of motion analysis and exercise performance analysis system. In other words, it contributes to the clarification of the movement mechanism of human body including walking, automatic analysis by real-time interaction between developed hardware system and computer model, and induction of systemization and quantification for clinical application by software development.

Third, it contributes to the development of optimal training programs in the field of sports science. That is, in the field of sports training, it is possible to improve the athletic performance and improve the posture and exercise performance of many sports by improving walking style, running and various sports movements.

Fourth, the spread of an efficient analysis system that can replace expensive motion analysis equipment in the field of rehabilitation medicine. That is, it can be used as a gait analysis system by bioimpedance measurement and EMG measurement technology.

Fifth, it is used for remote control of robots using only pure bio signals, and it is a substitute for expensive motion capture system used in virtual reality and animation fields.

Sixth, the development of a low-cost system that simultaneously obtains operation information on operation and load is expected to improve the existing problems and contribute to the improvement of national health through the expansion and expansion of related institutions in Korea.

Seventh, additional channels can be expanded for more diverse and detailed analysis of lower extremity movements, such as gait analysis. In addition, unlike wireless goniometers and video image analyzers, which can measure only in certain spaces, wireless applications will likely be useful in sports and sports applications that require a lot of spatial movement and continuous measurement over long periods of time.

Claims (19)

delete delete delete delete delete delete delete Generating a predetermined weak current by a constant current source; Flowing the weak current from one point of the living body to another selected point; A combination of _{m and} m (m is a natural number of two or more) points on each interval line separated by 1 / n (n is a natural number) interval between the joint and the joint of the living body in which the weak current flows ( _m C _{2 =} L) Selecting L electrode pairs (two electrodes) using Detecting an impedance at predetermined intervals from the electrode pairs (L-K = J) except for the electrode pairs (K) positioned on the same line among the selected L electrode pairs; And Joint motion analysis method characterized in that for measuring the change in the bio-impedance using an optimal electrode selection method according to the joint motion comprising the step of selecting one electrode pair having the largest value of the impedance change detected in each predetermined period . The method of claim 8, The weak current is 50 KHz, 300 kW joint motion analysis method characterized in that. The method of claim 8, The m points Between the ankle and the knee joint of the living body in which the weak current flows is divided into quarter intervals and two points on the quarter interval line separated from the ankle joint, two points on the 2/4 interval line and 3/4 interval line Joint motion analysis method using the optimal electrode selection method according to the ankle motion, characterized in that two points of. The method of claim 8, The m points Separating between the ankle joint and the knee joint of the living body in which the weak current flows by a quarter interval, and two points on the line 3/4 interval from the separated ankle joint, between the knee joint and the hip joint at 1/3 intervals Joint motion analysis method using the method of selecting the optimum electrode according to the knee motion, characterized in that four points on the line 1/3 interval from the knee joint and four points on the line 2/3 interval. The method of claim 8, The m points Hip motion between the knee joint and the hip joint of the living body in which the weak current flows, wherein the joint is divided into four points on the 1/3 interval line and four points on the 2/3 interval line Joint motion analysis method using optimal electrode selection method according to. The method of claim 8, The m points Between the ankle and the knee joint of the living body in which the weak current flows is divided into quarter intervals and two points on the quarter interval line separated from the ankle joint, two points on the 2/4 interval line and predetermined between the ankle and the toe Joint motion analysis method using the optimal electrode selection method according to the heel and toe ground contact movement, characterized in that the point of. A constant current source composed of an oscillation frequency circuit and a voltage current conversion circuit and generating weak current; A stimulating current electrode for flowing the weak current from one point of the living body to another selected point; A first channel located at a predetermined portion between the hip and the knee and including at least two voltage detection electrodes for detecting voltage, a demodulator, a gain and offset regulator, and an insulation amplifier; A second channel located at a predetermined area between the hip joint and the ankle joint, the second channel including at least two voltage detection electrodes for detecting voltage, a demodulator, a gain and offset regulator, and an insulation amplifier; A third channel located at a predetermined region between the knee joint and the ankle joint and including at least two voltage detection electrodes for detecting voltage, a demodulator, a gain and offset regulator, and an insulation amplifier, A fourth channel positioned at a predetermined region between the knee and the toe and including at least two voltage detection electrodes for detecting voltage, a demodulator, a gain and offset regulator, and an insulation amplifier; An A / D converter converting output values of the first to fourth channels into digital signals; And Joint motion analysis system using a change in the body impedance according to the motion of the joint including a control unit for calculating the angle change of the signals of each channel from the A / D converter. The method of claim 14, And a display unit for expressing a value input by the controller and a value calculated by the controller. The method of claim 14, The control unit has a maximum flexion range of X degrees at the maximum extension of the joint and a bioimpedance variation range of the maximum flexion at the maximum extension of the joint is Yohm, and the angle change value according to the increase or decrease of 1 ohm is X degrees / Yohm = Z degrees / Joint motion analysis system, characterized in that for calculating the angular change of the biological impedance signal of each channel by ohm. The method of claim 14, The predetermined part is a joint motion analysis system, characterized in that the position where the impedance change according to the joint movement is the largest. The method of claim 16, The control unit And displaying an avatar corresponding to the joint motion on the display unit by using a bioimpedance signal corresponding to the joint motion and a predetermined analysis program. The method of claim 18, The control unit And a menu and a bioimpedance signal for monitoring and analyzing joint motion are further provided on the display unit.

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