Disclosure of Invention
The invention aims to provide a method for distinguishing people with balance ability disorder based on a gravity center shift model, and solves the problems that a traditional subjective method is too rough, and a scale evaluation method is too complex and too costly.
The invention adopts the technical scheme that the method for distinguishing the crowd with balance ability disorder based on the gravity center shift model comprises the following specific operation steps:
step 1, a lens of a camera is right opposite to the position between the front side and the side surface of a human body, namely, human body walking posture videos of normal people and abnormal people in a built virtual reality scene are collected from 45 degrees;
step 2, loading the two collected human body walking posture videos, respectively extracting video images into pictures, and then processing the pictures to respectively obtain the gravity center coordinates of the two types of human bodies;
and 3, extracting included angle of gravity data and mean square deviation of upper and lower centers of gravity of the human body according to the obtained coordinate data of the center of gravity, classifying the extracted included angle of gravity data through a Support Vector Machine (SVM) classifier, and judging the crowd with balance disorder by combining the included angle of gravity data and the mean square deviation of the upper and lower centers of gravity of the human body.
Yet another feature of the present invention is that,
the operation process of the step 2 is as follows:
step 2.1, reading the two collected human body posture videos by using a cvLoadImage function, setting the starting time and the ending time of the read-in videos, resetting the starting time and the ending time of the videos if the capture function does not read the videos containing the portrait, and carrying out the next step if the capture function reads the videos containing the portrait;
step 2.2, frames of the two groups of extracted videos are respectively removed through a CvCapture function in OpenCV, firstly, blank scenes in the two groups of videos are respectively extracted for picture storage, and then, one frame of the shot human body posture video is taken every two seconds and stored as a picture;
2.3, carrying out differential processing on the two groups of stored human body posture pictures and the blank scene respectively to obtain pictures only with human body postures;
step 2.4, carrying out image denoising on the image after the difference;
step 2.5, further carrying out image corrosion on the denoised picture to finally obtain a black and white image only with a human body image;
step 2.6, performing edge extraction on the image obtained after corrosion, processing the corroded image by using a Canny edge detection operator to obtain a connected region of the image, and performing convolution on the image by using a Gaussian filter to reduce the obvious noise influence on an edge detector; then, calculating the gradient strength and direction of each pixel point in the image, and applying non-maximum value inhibition to eliminate stray response caused by edge detection; finally, determining real and potential edges by using double-threshold detection, finally finishing edge detection by inhibiting isolated weak edges, and extracting a human body contour image by using findContours;
and 2.7, calculating the moment of the human body contour image, and calculating the barycentric coordinate of the human body through the moment of the contour image.
The specific process of the differential processing in step 2.3 is as follows:
firstly, carrying out binarization processing on two groups of stored human body posture pictures and blank scene pictures to enable all images to be black and white images;
then, carrying out difference processing on the two groups of binarized human body posture photos and blank scene pictures, and setting the image containing the human body extracted at the kth moment as xkThe image of the blank scene is xjAnd differentiating the two images to obtain a differential image delta xk:Δxk=xk-xj。
The image denoising process of the step 2.4 is as follows: and (2) replacing the pixel value of one point in the differential processing image by using a median filtering method to obtain a denoised image by using the pixel median of each point in the neighborhood of the point, wherein the specific process is that f (x, y) and g (x, y) are respectively the image subjected to differential processing and the image subjected to denoising, and the median filtering output is g (x, y) ═ med { f (x-k, y-l), (k, l ∈ W) }, wherein W is a two-dimensional template, and k and l are respectively rows and columns of the image.
The specific operation steps of step 2.5 are as follows: and corroding the image subjected to difference and denoising, defining the size of a corrosion window by a getStructuringElement function, selecting a rectangular window MORPH-RECT, selecting the size of a corrosion kernel by 3 multiplied by 3, and then performing corrosion operation by using an erode function through the corrosion window MORPH-RECT to obtain the image only containing the portrait.
The calculation method of the body weight center coordinates in step 2.7 is as follows:
firstly, calculating the moment of a human body contour image, taking a human body in a picture as a planar object, taking a pixel value of each point as the density of the point, taking an expected value of the point as the moment of the point, and calculating the barycentric coordinate of the human body by adopting the first moment of the image, as shown in formulas 1-3:
the coordinates of the center of gravity of the human body image are:
wherein, V (i, j) represents the gray value of the human body image at the point (i, j), when the image is a binary image and V (i, j) only has black and white, namely two values of 0 and 1, then M is00Expressed as the sum of white areas in the human body image, i.e. the area of the binary image, M10Representing the accumulation of the horizontal coordinate values of the white area in the image; in the same way, M01Representing the accumulation of ordinate values of white areas in the image, xcRepresents the abscissa of the center of gravity, ycRepresenting the ordinate of the center of gravity.
The operation steps of step 3 are as follows:
step 3.1, classifying the obtained gravity center seat as input data through an SVM classifier to obtain gravity center coordinate data of normal people and abnormal people with marks;
step 3.2, respectively extracting the gravity center included angle of the normal person and the abnormal person;
step 3.3, calculating the mean square error of the gravity centers of the normal person and the abnormal person respectively;
and 3.4, combining the steps 3.1-3.3 to obtain the barycentric coordinates, barycentric included angles and barycentric mean square deviations of the human body, and distinguishing the crowd with balance ability disorder.
The process of classification by the SVM classifier in step 3.1 is as follows:
firstly, loading a training data set and a testing data set, wherein the training data set comprises training data, training labels, testing data and testing labels, namely human body barycentric coordinate data and correct labels, dividing the training data and the testing data into two parts, obtaining the optimal parameters of current data through an SVMcgForRegress parameter optimizing function, and obtaining a trained model through the optimized parameters and training data through an svmtrain function; and finally, testing by using an svmpredict function to obtain barycentric coordinate data with a mark of '1' or '-1'.
The specific calculation process of step 3.2 is as follows:
by calculating the three barycentric coordinates of the upper, middle and lower parts of the human body, using the atan2 function and converting the barycentric coordinates into angles, the included angle of the upper, middle and lower barycentric coordinates can be calculated: let the coordinate of the upper center of gravity P1 be (x)1,y1) Center of gravity coordinates P2 (x)2,y2) The lower center of gravity P3 is represented by the coordinate (x)3,y3) When the angle of gravity center is theta, the radian of the angle between P1P2 and the positive direction of the x-axis is atan2 (y)2-y1,x2-x1) Angle of inclination theta1Is atan2 (y)2-y1,x2-x1) 180/pi, and the same principle, the angle theta between P3P2 and the positive direction of the x axis2Is atan2 (y)3-y2,x3-x2) 180/pi, and the angle of gravity theta is represented as theta1+θ2As formula 7, the included angle of the center of gravity of the normal person and the abnormal person is calculated respectively:
wherein n is the number of the extracted included angles of the center of gravity, p1.y、p2.y、p3.yIs the ordinate of three gravity points, p1.x、p2.x、p3.xThe abscissa of the three gravity points.
The specific process of step 3.3 is as follows:
extracting one frame of picture every two seconds from the human body walking video, wherein the 20 frames of pictures are total, and calculating the mean value and the variance of the vertical coordinates of the gravity centers of the upper half body and the lower half body extracted after calculation by using a formula 8:
wherein n is the number of experimental objects, and t is the element [1, n ]],
Represents the values of the upper and lower body barycentric ordinates at time t,
representing the mean value of the ordinate of the center of gravity, and CGS is the mean square error of the center of gravity;
step 3.4 the method for distinguishing people with balance ability disorder comprises the following steps:
judging according to the mark on the gravity center data, if the output balance capability is marked as '1', distinguishing as a normal person, and showing that the balance capability is good; if the output balance ability is marked as "-1", the person is distinguished as an abnormal person, which indicates that the balance ability is obstructed; the included angle value of the gravity center is relatively large, the balance capability is good, the included angle value of the gravity center is relatively small, and the balance capability is obstructed; the relatively large variance value of the center of gravity indicates that the larger and more unstable the fluctuation of the center of gravity of the human body, the worse the balance ability.
The method has the beneficial effects that the method for distinguishing the crowd with balance ability disorder based on the gravity center shift model solves the problems that the traditional subjective method is too rough, and the scale evaluation method is too complex and too costly. The method has the advantages that the gravity center data are obtained by processing the human body walking video, people with balancing obstacle ability are distinguished through the gravity center offset model without any balance measuring instrument, the balancing ability of the people or other people is objectively judged, the video and the image are processed through multiple steps, and the accuracy rate of final classification is guaranteed to be more than 85%.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
The method for distinguishing people with balance ability disorder based on the center-of-gravity shift model, disclosed by the invention, is shown in fig. 1 and fig. 2, and comprises the following specific operation steps:
when the camera lens is opposite to the front of the human body, the collection angle is defined to be 0 degrees, when the camera lens is opposite to the side face of the human body, the collection angle is defined to be 90 degrees, the camera lens is selected to be opposite to the position between the front and the side face of the human body, and the collection angle at the moment is defined to be 45 degrees.
Step 1, collecting human body walking posture videos of normal people and abnormal people in a built virtual reality scene from 45 degrees;
step 2, loading the two collected human body walking posture videos, respectively extracting video images into pictures, and then processing the pictures to respectively obtain the gravity center coordinates of the two types of human bodies;
and 3, extracting barycentric included angle data and mean square deviations of upper and lower barycentrics of the human body according to the obtained barycentric coordinate data, classifying the extracted barycentric data through an SVM classifier, and judging the crowd with balance ability obstacle by combining the barycentric included angle data and the mean square deviations of the upper and lower barycentrics of the human body.
The operation process of the step 2 is as follows:
step 2.1, reading posture videos of normal people and abnormal people by using a cvLoadImage function, setting the starting time and the ending time of the read-in video, resetting the starting time and the ending time of the video if the capture function does not read the video containing the portrait, and carrying out the next step if the capture function reads the video containing the portrait;
step 2.2, frames of the two groups of extracted videos are respectively removed through a CvCapture function in OpenCV, firstly, blank scenes in the two groups of videos are respectively extracted for picture storage, and then, one frame of the shot human body posture video is taken every two seconds and stored as a picture;
2.3, carrying out differential processing on the two groups of stored human body posture pictures and the blank scene respectively to obtain pictures only with human body postures;
step 2.4, carrying out image denoising on the image after the difference;
step 2.5, further carrying out image corrosion on the denoised picture to finally obtain a black and white image only with a human body image;
step 2.6, performing edge extraction on the image obtained after corrosion, processing the corroded image by using a Canny edge detection operator to obtain a connected region of the image, and performing convolution on the image by using a Gaussian filter to reduce the obvious noise influence on an edge detector; then, calculating the gradient strength and direction of each pixel point in the image, and applying non-maximum value inhibition to eliminate stray response caused by edge detection; finally, determining real and potential edges by using double-threshold detection, finally finishing edge detection by inhibiting isolated weak edges, and extracting a human body contour image by using findContours;
and 2.7, calculating the moment of the human body contour image, and calculating the barycentric coordinate of the human body through the moment of the contour image.
The specific process of the differential processing in step 2.3 is as follows:
firstly, carrying out binarization processing on two groups of stored human body posture pictures and blank scene pictures to enable all images to be black and white images;
then, carrying out difference processing on the two groups of binarized human body posture photos and blank scene pictures, and setting the image containing the human body extracted at the kth moment as xkThe image of the blank scene is xjAnd differentiating the two images to obtain a differential image delta xk:
Δxk=xk-xj
The image denoising process of the step 2.4 is as follows: and (2) replacing the pixel value of one point in the differential processing image by using a median filtering method to obtain a denoised image by using the pixel median of each point in the neighborhood of the point, wherein the specific process is that f (x, y) and g (x, y) are respectively the image subjected to differential processing and the image subjected to denoising, and the median filtering output is g (x, y) ═ med { f (x-k, y-l), (k, l ∈ W) }, wherein W is a two-dimensional template, and k and l are respectively rows and columns of the image.
The specific operation steps of step 2.5 are as follows: and corroding the image subjected to difference and denoising, defining the size of a corrosion window through a getStructuringElement function, selecting a rectangular window MORPH-RECT, selecting the size of a corrosion kernel by 3 multiplied by 3, and performing corrosion operation through the corrosion window by using an anode function through the corrosion window MORPH-RECT to obtain the image only containing the portrait.
The calculation method of the body weight center coordinates in step 2.7 is as follows:
firstly, calculating the moment of a human body contour image, taking a human body in a video picture as a planar object, taking a pixel value of each point as the density of the point, taking an expected value of the point as the moment of the point, and calculating the barycentric coordinate of the human body by adopting the first moment of the image, as shown in formula 1-3:
the coordinates of the center of gravity of the human body image are:
v (i, j) represents the gray value of the human body image at the point (i, j), and when the image is a binary image and the V (i, j) only has black and white, namely two values of 0 and 1, M is obtained00Expressed as the sum of white areas in the human body image, i.e. the area of the binary image, M10Representing the accumulation of the horizontal coordinate values of the white area in the image; in the same way, M01Representing the accumulation of ordinate values of white areas in the image, xcRepresents the abscissa of the center of gravity, ycRepresenting the ordinate of the center of gravity.
The operation steps of step 3 are as follows:
step 3.1, classifying the acquired barycentric coordinates as input data by an SVM classifier to obtain barycentric coordinate data of normal persons and abnormal persons with marks;
step 3.2, respectively extracting the gravity center included angle of the normal person and the abnormal person;
step 3.3, calculating the mean square error of the gravity centers of the upper and lower half bodies of the normal person and the abnormal person respectively;
and 3.4, combining the steps 3.1-3.3 to obtain the barycentric coordinates, barycentric included angles, barycentric mean values and variances of the human body, and classifying the pictures of normal people and abnormal people.
The process of classification by the SVM classifier in step 3.1 is as follows:
firstly, loading a training data set and a testing data set, wherein the training data set comprises training data, training labels, testing data and testing labels, namely, barycentric coordinate data and correct labels of a human body, dividing the training data set into two parts, namely training data and testing data, acquiring optimal parameters of current data through an SVMcgForRegress parameter optimizing function, and acquiring trained model through svmtrain function training data by using the acquired optimized parameters; and finally, testing by using an svmpredict function to obtain barycentric coordinate data with a mark of '1' or '-1'.
The basic principle of the SVM classifier is as follows: the support vector machine is a supervised learning method and is widely applied to statistical classification and regression analysis. In the experiment, the barycentric coordinates of the human body are mapped to a high-dimensional space, and a hyperplane with the maximum interval is searched for in the high-dimensional space
The coordinates x of the center of gravity of the human body of the experimental group
iAnd the coordinates x of the center of gravity of the human body in the contrast group
iSeparated from each other. Where W represents the hyperplane normal separating the characteristic vectors of the barycentric coordinates of the experimental group from the barycentric coordinates of the control group, and γ is the displacement interval added for the flexibility of the method. Make the characteristic vector of the barycentric coordinate of the human body in the contrast group satisfy
Characteristic vector satisfaction of human body barycentric coordinates of experimental group
When there are W and γ satisfying such a condition, such a feature vector is said to be divisible. In practical problems, it may not be possible to completely separate all feature vectors, and the best hyperplane is selected as the optimal solution. 1/omega is
And
finding the optimal hyperplane translates to minimizing ω. The mathematical expression is
Constraint of y
i[wx
i+γ]1, i ═ 1, 2. By utilizing the mature theory of convex quadratic programming, when the characteristic vector of the barycentric coordinate of the human body is not completely separable, a corresponding kernel function K can be selected, and a characteristic space formed by the barycentric coordinate of the input human body is implicitly mapped to a high-dimensional space, wherein the barycentric coordinate of the input human body is linearly separable in the high-dimensional space. According to the dual condition, the optimization problem can be converted into a corresponding dual problem to be solved.
The specific calculation process of step 3.2 is as follows:
by calculating the three barycentric coordinates of the upper, middle and lower parts of the human body, using the atan2 function and converting the barycentric coordinates into angles, the included angle of the upper, middle and lower barycentric coordinates can be calculated: let the coordinate of the upper center of gravity P1 be (x)1,y1) Center of gravity coordinates P2 (x)2,y2) The lower center of gravity P3 is represented by the coordinate (x)3,y3) When the angle of gravity center is theta, the radian of the angle between P1P2 and the positive direction of the x-axis is atan2 (y)2-y1,x2-x1) Angle of inclination theta1Is atan2 (y)2-y1,x2-x1) 180/pi, and the same principle, the angle theta between P3P2 and the positive direction of the x axis2Is atan2 (y)3-y2,x3-x2) 180/pi, and the angle of gravity theta is represented as theta1+θ2As formula 7, the included angle of the center of gravity of the normal person and the abnormal person is calculated respectively:
wherein n is the number of the extracted included angles of the center of gravity, p1.y、p2.y、p3.yIs the ordinate of three gravity points, p1.x、p2.x、p3.xThe abscissa of the three gravity points.
The specific calculation process of step 3.3 is as follows:
one frame of picture is extracted every two seconds from the human body walking video, 20 frames of pictures are totally extracted, and mean square deviations of the vertical coordinates of the gravity centers of the upper half body and the lower half body extracted after calculation are respectively calculated by using a formula 8:
wherein n is the number of pictures, t is the [1, n ]],
Represents the values of the upper and lower body barycentric ordinates at time t,
representing the mean value of the ordinate of the center of gravity, and CGS is the mean square error of the center of gravity;
step 3.4 the method for distinguishing people with balance ability disorder comprises the following steps:
as shown in fig. 3, the judgment is performed according to the output mark of the barycentric coordinate data, and after classification is performed by the SVM classifier, if the output balance capability is marked as "1", the classification is performed to be a normal person, which indicates that the balance capability is good; if the output balance ability is marked as "-1", the person is distinguished as an abnormal person, which indicates that the balance ability is obstructed;
the judgment is carried out according to the included angle of the gravity center, which is the posture control capability reflecting proprioception and refers to the size of the included angle between the upper, middle and lower gravity center points of the human body in the motion process. The relatively large included angle indicates that the balance capability is better; the smaller the included angle is, the weaker the human posture control capability is, the worse the balance capability is;
the judgment is carried out according to the gravity center variance, the gravity center variance reflects the discrete degree of variables in the group, and the larger the variance is, the larger and the more unstable the fluctuation of the gravity center of the human body is, and the poorer the balance capability is.
The invention designs a human body balance posture model based on the gravity center according to the shaking of the human body, as shown in figures 4-7, wherein P is1、P2、P3If the balance ability of a normal person is good, the included angle theta of the three gravity centers is larger, and the distance L of the gravity center to the middle axis is smaller. When the included angle of the center of gravity of a person is large, and the distance from the center of gravity to the central axis is small, the posture of the person tends to be a line, and the person is judged to be a normal person and has good balance capability. Factors influencing the balance of the human body are the included angle of the center of gravity, the mean value of the upper and lower centers of gravity and the variance of the upper and lower centers of gravity.
The included angle of the gravity centers of normal people in the virtual environment for balance training is larger than that of abnormal people, and the included angle of the gravity centers of normal people in the virtual environment for training is also higher than that of abnormal people. Meanwhile, due to the weak balance capability, the gravity center fluctuation of the training of the special person in the virtual environment is larger than that of a normal person, and the body shaking is obviously better than that of the normal person. Therefore, the mean value of the center of gravity of the upper and lower half bodies of a normal person is higher than that of an abnormal person in the training process, and the variance of the center of gravity of the upper and lower half bodies is generally smaller than that of a special person. Therefore, various decisions are integrated to measure the balance ability of the human body.
The specific implementation mode is as follows:
the implementation process of the method for classifying people with balance disorder based on the center-of-gravity shift model is described below by extracting the center of gravity and the included angle from a group of human walking videos.
TABLE 1 two-class test data and tags
Table 2 SVM test output label
Table 35 centre of gravity angle for normal person video analysis
|
Object A
|
Object B
|
Object C
|
Object D
|
Object E
|
Angle |
1
|
165.193
|
143.47
|
168.943
|
163.919
|
159.417
|
Angle 2
|
117.495
|
168.986
|
144.627
|
148.402
|
149.246
|
Angle 3
|
127.619
|
164.707
|
148.088
|
157.817
|
167.652
|
Angle 4
|
164.163
|
166.13
|
133.002
|
124.572
|
134.112
|
Angle 5
|
124.437
|
164.973
|
148.754
|
163.538
|
146.965
|
Angle 6
|
120.294
|
142.347
|
156.048
|
142.739
|
129.503
|
Angle 7
|
130.256
|
140.419
|
132.031
|
139.283
|
145.452
|
Angle 8
|
121.957
|
122.756
|
143.362
|
119.525
|
143.944
|
Angle 9
|
122.95
|
167.096
|
160.831
|
135.912
|
142.712
|
Angle 10
|
118.602
|
157.364
|
123.537
|
157.193
|
159.853
|
Angle 11
|
126.105
|
177.533
|
132.831
|
146.615
|
135.736
|
Angle 12
|
159.543
|
152.654
|
167.266
|
152.064
|
151.242
|
Angle 13
|
154.525
|
146.652
|
132.284
|
163.148
|
148.865
|
Angle 14
|
125.446
|
128.54
|
128.439
|
141.804
|
137.409
|
Angle 15
|
122.481
|
118.704
|
142.858
|
148.155
|
132.536
|
Angle 16
|
119.33
|
153.988
|
131.764
|
129.525
|
146.693
|
Angle 17
|
131.288
|
131.373
|
131.764
|
142.731
|
139.557
|
Angle 18
|
118.496
|
152.749
|
156.048
|
155.912
|
153.752
|
Angle 19
|
116.124
|
119.282
|
129.324
|
149.381
|
171.355
|
Angle 20
|
125.705
|
120.03
|
135.617
|
135.485
|
128.542 |
TABLE 45 Special person video analysis barycenter angle
|
Object A
|
Object B
|
Object C
|
Object D
|
Object E
|
Angle |
1
|
81.6148
|
111.057
|
116.515
|
118.419
|
121.318
|
Angle 2
|
109.372
|
112.516
|
113.043
|
105.832
|
128.467
|
Angle 3
|
120.73
|
109.153
|
114.948
|
127.089
|
112.709
|
Angle 4
|
100.799
|
107.415
|
104.563
|
105.07
|
102.759
|
Angle 5
|
109.668
|
108.88
|
101.023
|
124.502
|
106.706
|
Angle 6
|
72.7893
|
105.285
|
118.588
|
107.603
|
125.628
|
Angle 7
|
114.999
|
101.03
|
108.091
|
122.447
|
97.4247
|
Angle 8
|
104.504
|
104.219
|
112.477
|
106.48
|
115.254
|
Angle 9
|
112.66
|
109.335
|
95.686
|
106.073
|
124.882
|
Angle 10
|
133.608
|
123.346
|
105.898
|
114.945
|
116.532
|
Angle 11
|
122.385
|
118.258
|
107.626
|
103.139
|
128.328
|
Angle 12
|
103.523
|
119.35
|
106.692
|
123.779
|
113.849
|
Angle 13
|
86.4591
|
119.693
|
112.627
|
123.904
|
98.7091
|
Angle 14
|
131.69
|
104.884
|
120.48
|
126.066
|
122.961
|
Angle 15
|
121.503
|
107.016
|
119.959
|
125.433
|
118.74
|
Angle 16
|
109.578
|
110.361
|
116.628
|
96.6743
|
122.095
|
Angle 17
|
123.69
|
109.257
|
110.754
|
121.265
|
125.428
|
Angle 18
|
115.133
|
118.679
|
111.425
|
106.873
|
111.713
|
Angle 19
|
109.111
|
109.078
|
114.059
|
116.375
|
120.102
|
Angle 20
|
102.369
|
121.584
|
108.353
|
106.241
|
125.246 |
(1) Firstly, shooting three conditions of an empty scene, normal characters and abnormal characters from the positions of 0 degrees, 45 degrees and 90 degrees of included angles between a camera and a target respectively, and extracting pictures from a video; (2) differentiating the pictures, wherein the left side is a normal person, and the right side is an abnormal person, and the obtained result is shown in fig. 8; (3) performing median filtering and corrosion denoising on the differential picture, wherein the result is shown in fig. 9; (4) extracting the coordinates of the barycenter of the person as shown in fig. 10; (5) classifying the gravity coordinates by using an SVM, wherein the correct label of the test data is shown in table 1, the gravity data of a normal person is marked as 1, the gravity data of an abnormal person is marked as-1, and the label of the test data after SVM classification is shown in table 2; (6) calculating and analyzing the included angles of the centers of gravity of 5 normal persons and 5 abnormal persons, as shown in tables 3, 4 and 11, the included angles of the centers of gravity of the normal persons are all larger than 120 degrees, and the included angles of the centers of the abnormal persons are relatively smaller; (7) the mean value of the center of gravity and the variances of the upper and lower half bodies are analyzed and compared, as shown in fig. 12 and 13, the variances of the upper and lower centers of gravity of a normal person are generally smaller than those of an obstacle group in the walking process, which shows that the centers of gravity of three points of the normal person are close to the central axis, the body is not obviously shaken in the walking process, and the balance capability is good.