Balance stability limit test system and method

Abstract

The invention belongs to the field of balance function evaluation, and particularly relates to a balance stability limit test system and method. Comprising a human body gravity center angle calculation module, a maximum movement distance calculation module, a reaction time measurement module, an end point offset calculation module, a movement speed calculation module, a direction control calculation module and a comprehensive score calculation module. According to the invention, the stability limit of the testee is evaluated from multiple aspects and multiple angles of coordination ability, motion ability and control ability. The balance function of the testee can be visually fed back through the tested data, and the accuracy and efficiency of evaluation are improved.

Description

Technical Field

[0001] The invention belongs to the field of balance function evaluation, and in particular relates to a balance stability limit testing system and method. Background Art

[0002] All kinds of actions in human life depend on balance function, and many diseases (such as limb movement dysfunction) can cause balance disorders. Balance function assessment can effectively understand the degree of balance dysfunction of the test subject and the training effect after balance rehabilitation training.

[0003] At present, balance function assessment basically includes stability limit test. Some stability limit tests only show the pressure center trajectory and real-time pressure value, while others further give the length of the pressure center trajectory. Some use the pressure distribution in the plantar area for assessment and give the moving distance of the plantar pressure center.

[0004] In the prior art, the trajectory of the pressure center is used to calculate the maximum distance that a human body can move in eight directions (front, right front, right, right rear, rear, left rear, left, and left front) in a stable state. The disadvantages are: 1. The influence of individual differences in the human body on the moving distance of the pressure center is not avoided, especially the influence of height. Medical experiments and mechanical force analysis show that different heights have a linear relationship with the moving distance of the human pressure center; 2. There is only one moving trajectory of the pressure center and the maximum pressure center offset distance, and the feedback information is relatively small. Some human factors and abnormal factors are not excluded, and there will be a large difference between the evaluation results and the actual situation. The effectiveness and accuracy of the stability limit test are insufficient. Summary of the invention

[0005] The object of the present invention is to provide a balance stability limit testing system and method.

[0006] In order to achieve the above objectives, the technical solution adopted by the present invention is as follows: a balance stability limit test system, including a human body center of gravity angle calculation module, a maximum moving distance calculation module, a reaction time measurement module, an end point offset calculation module, a moving speed calculation module, a direction control calculation module and a comprehensive score calculation module;

[0007] The human body center of gravity angle calculation module calculates the human body center of gravity angle according to the position coordinates G (x, y) of the human body pressure center trajectory point and the height;

[0008] The maximum moving distance calculation module is used to calculate the maximum effective moving distance that the human body can reach in each target direction;

[0009] The reaction time measurement module is used to measure the time it takes for the subject to make movement feedback after the target appears;

[0010] The end point deviation calculation module is used to calculate the effective value of the farthest distance that the test subject reaches in the target direction for the first time;

[0011] The moving speed calculation module is used to calculate the average moving speed of the test subject's body center of gravity between 5% and 95% of the offset distance from the end point;

[0012] The direction control calculation module is used to calculate the direction control scores of all front and rear target directions;

[0013] The comprehensive score calculation module is used to calculate the comprehensive scores of the moving speed, end point offset distance, and maximum moving distance in the four directions of front, back, left, and right, and / or calculate the comprehensive scores of the reaction time and direction control in the four directions of front, back, left, and right.

[0014] In a preferred embodiment, in the human body center of gravity angle calculation module, the calculation formulas for x and y in the position coordinates G (x, y) of the human body pressure center trajectory point are:

[0015]

[0016] FA, FB, FC, FD are the pressure values ​​detected by the four sensors; (xA, yA), (xB, yB), (xC, yC), (xD, yD) are the positions of the four sensors, xA = xB = -xC = -xD = L, yA = yB = -yC = -yD = M, G is the weight of the person being tested;

[0017] The body's center of gravity angle includes the x-direction center of gravity inclination angle θx and the y-direction center of gravity inclination angle θy;

[0018] θx=arc sin(X / H)

[0019] θy=arc sin(Y / H) Formula (2)

[0020] H=k*height, k=0.55-0.56, X, Y are x, y in G(x, y) respectively.

[0021] When the human body moves toward a target direction, the four pressure sensors are sampled at regular intervals (for example, 10ms). Therefore, there are four pressure value data at each sampling moment. G(x, y) at that moment is calculated based on the pressure value data, and then θx and θy at that moment are calculated based on G(x, y). The θx and θy values ​​at each moment constitute the trajectory of the human body's center of gravity.

[0022] Furthermore, the steps performed by the maximum moving distance calculation module are:

[0023] A is the initial position of the human body's center of gravity, B is the target center, C is a point on the trajectory of the human body's center of gravity, and D is the point C on the straight line L.AB projection on;

[0024] The equation of the straight line AB is y = -1*(xx A ), where x A =0,y A = 0, the slope is represented by k, k = ±1; y = -kx; the product of the slopes of the two vertical lines AB and CD = -1; y is θy; x is θx;

[0025] Since the slope of line AB is k, we know that the slope of line CD is -1 / k, so the equation of line CD is:

[0026] Solving the simultaneous equations yields:

[0027]

[0028] Then line segment L AD The effective moving distance of the center of gravity of the human body in the direction AB is:

[0029]

[0030] When the initial position of the human body's center of gravity is not at zero, calculate the mapping point E of the initial position of the human body's center of gravity, then the line segment L ED The effective moving distance of the center of gravity of the human body in the direction AB is:

[0031]

[0032] Line segment L CD The ineffective moving distance of the center of gravity of the human body in the direction AB is:

[0033]

[0034] The maximum effective moving distance among all effective moving distances of all center of gravity trajectory points in each target direction is the maximum moving distance corresponding to the target direction.

[0035] In a preferred embodiment, in the reaction time measurement module, when measuring the reaction time, the center of gravity swing amplitude is calculated.

[0036] The specific steps are as follows: find the maximum value Amax of the center of gravity swing amplitude within a certain time after the test starts; the target appears after a certain time after the test starts, and the time t0 is recorded at this time (that is, the time when the target appears is t0); the current center of gravity swing amplitude Ai of the human body is calculated in real time according to formula (7) and compared with Amax; when Ai>Amax, the time t1 is recorded at this time (that is, the sampling time corresponding to the first Ai greater than Amax after the target appears), and the reaction time of the subject is t=t1-t0.

[0037] In the end point offset calculation module, the center of gravity trajectory points collected after the target appears are used to calculate the effective moving distance of each center of gravity trajectory point in the corresponding direction on the center of gravity trajectory according to formula (3) or (4). When the effective moving distance of the next center of gravity trajectory point is shorter than that of the previous center of gravity trajectory point, L m-5 is the effective value of the longest distance reached for the first time in the target direction; L m-5 That is L 初次； The endpoint deviation scores of the subjects were:

[0038] The test subject's endpoint deviation score = L 初次 / Human body's range of motion in a specific direction*100% formula (8);

[0039] In the moving speed calculation module,

[0040] Movement Speed

[0041] T5 is the time corresponding to the center of gravity trajectory point whose effective moving distance is 5% of the end point offset distance, and T95 is the time corresponding to the center of gravity trajectory point whose effective moving distance is 95% of the end point offset distance.

[0042] In a preferred embodiment, in the direction control calculation module, the effective moving distance and the invalid moving distance of each point of the center of gravity trajectory are calculated according to formula (3) or (4) and formula (5).

[0043] Direction Control Score

[0044] i=1, 2, 3...n, where n is the total number of all points on the centroid trajectory.

[0045] In the comprehensive score calculation module, the comprehensive score algorithm for the moving speed in the front, back, left, and right directions, the end point offset, and the maximum moving distance is as follows:

[0046] forward:

[0047] right:

[0048] back:

[0049] Left:

[0050] θ LFy It represents the angle between the center of gravity trajectory point selected by the left front upward end point offset to reach the longest effective distance for the first time and the y-axis; S LF Indicates the score of the end point offset, moving speed or maximum moving distance in the left front direction; θFy It represents the angle between the center of gravity trajectory point that reaches the longest effective distance for the first time selected by the forward end point offset and the y-axis, S F The score representing the end point offset, moving speed or maximum moving distance in the forward direction; θ RFy It represents the angle between the center of gravity trajectory point selected by the right front upward end point offset to reach the longest effective distance for the first time and the y-axis, S RF The score representing the end point offset, moving speed or maximum moving distance in the right front direction; θ RFx The angle between the center of gravity trajectory point selected by the right front upward end point offset to reach the longest effective distance for the first time and the x-axis; θ Rx It represents the angle between the center of gravity trajectory point selected by the end point offset in the right direction and the x-axis. R Indicates the score of the end point offset, moving speed or maximum moving distance in the right direction; θ RBx It represents the angle between the center of gravity trajectory point selected by the end point offset of the right rear upward and the x-axis. RB The score representing the end point offset, moving speed or maximum moving distance in the right rear direction; θ LBy It represents the angle between the center of gravity trajectory point selected by the left rear upward end point offset to reach the longest effective distance for the first time and the y-axis, S LB Indicates the score of the end point offset, moving speed or maximum moving distance in the left rear direction; θ RBy It represents the angle between the center of gravity trajectory point selected by the end point offset in the right rear direction and the y-axis; θ LFx The angle between the center of gravity trajectory point selected by the left front upward end point offset to reach the longest effective distance for the first time and the x-axis; θ By It represents the angle between the center of gravity trajectory point selected by the end point offset in the rear direction and the y-axis. B The score representing the end point offset, moving speed or maximum moving distance in the backward direction; θ Lx It represents the angle between the center of gravity trajectory point selected by the end point offset in the left direction and the x-axis. L Indicates the score of the end point offset, moving speed or maximum moving distance in the left direction; θ LBx It represents the angle between the center of gravity trajectory point selected by the left rear upward end point offset that first reaches the farthest effective distance and the x-axis;

[0051] The comprehensive scoring algorithm for reaction time and direction control in the front, back, left, and right directions is as follows:

[0052] forward:

[0053] right:

[0054] back:

[0055] Left:

[0056] S LF Indicates the score of reaction time or direction control in the left front direction; S F Indicates the score of reaction time or direction control in the forward direction; S RF Indicates the score of reaction time or direction control in the right front direction; S R Indicates the score of reaction time or direction control in the right direction; S RB Indicates the score of reaction time or direction control in the right rear direction; S LB Indicates the score of reaction time or direction control in the left rear direction; S B Indicates the score of reaction time or direction control in the backward direction; S L Represents the score of reaction time or directional control in the left direction.

[0057] Another object of the present invention is to disclose a method for testing the balance stability limit using the aforementioned system.

[0058] Another object of the present invention is to provide a processor, the processor is used to run a computer program, and when the computer program is running, the balance stability limit test method as described above is executed.

[0059] The last object of the present invention is to provide a computer-readable medium having a computer program stored thereon, wherein the computer program is executed by a processor to implement the balance stability limit test method as described above.

[0060] Compared with the prior art, the present invention is beneficial in that the influence of height on the stability limit is taken into account, and the data obtained is more universal. The end point offset calculation excludes abnormal human factors and is mainly used to evaluate the extreme center of gravity movement range of the human body in a stable state. Reaction time and movement speed can provide feedback on the coordination and athletic ability of the test subject; direction control can provide feedback on the control ability of the test subject. The present invention evaluates the stability limit of the test subject from multiple aspects and angles such as coordination ability, athletic ability, and control ability. The test data can intuitively provide feedback on the balance function of the test subject, thereby improving the accuracy and efficiency of the evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 This is the principle diagram of human body pressure center detection;

[0062] Figure 2Schematic diagram of the tilt angle of the center of gravity of the human body, A, schematic diagram of the change of the center of gravity of the human body, B, the tilt angle of the center of gravity of the human body;

[0063] Figure 3 This is a schematic diagram for calculating the maximum moving distance;

[0064] Figure 4 This is a schematic diagram of reaction time measurement;

[0065] Figure 5 This is a schematic diagram of the end point offset;

[0066] Figure 6 This is a schematic diagram of direction control calculation;

[0067] Figure 7 A schematic diagram of the angle between the center of gravity trajectory point that reaches the maximum effective distance for the first time selected for the end point offset and the x-axis;

[0068] Figure 8 It is a schematic diagram of the range of human activities;

[0069] Fig. 9 A scoring diagram. DETAILED DESCRIPTION

[0070] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0071] During the balance stability limit test, pressure sensors are installed on the four sides of the bottom of the four-point two-dimensional center of gravity plate. The testee stands on the corresponding area of ​​the center of gravity plate, and is required to stand in a symmetrical posture with both shoulders drooped. The pressure data detected by the pressure sensor is filtered, amplified by analog quantity, and converted to analog-to-digital, and then uploaded to the balance stability limit test system. The four-point two-dimensional center of gravity plate is adjusted to a horizontal level during installation, and the sensor deviation value caused by the weight W of the center of gravity plate is automatically subtracted when the test is started.

[0072] The present invention optimizes the calculation of the human body's pressure center into the calculation of the inclination angle of the human body's center of gravity. When standing (symmetrical standing posture with shoulders drooping), the human body's center of gravity is generally 7 cm in front of the upper edge of the third sacral vertebra on the median plane of the body. The relationship between the human body's center of gravity and height is k*height, k is 0.55-0.56 (preferably 0.5527), and the influence of height on the stability limit is taken into account.

[0073] The balance stability limit test system includes a human body center of gravity angle calculation module, a maximum moving distance calculation module, a reaction time measurement module, an end point offset calculation module, a moving speed calculation module, a direction control calculation module and a comprehensive score calculation module.

[0074] Human body center of gravity angle calculation module:

[0075] The four-point two-dimensional center of gravity plate is a popular device for testing the position of the human body's pressure center in the world. When the test subject stands on the detection platform (i.e., the four-point two-dimensional center of gravity plate), the four sensors on the detection platform are affected by the test subject's gravity and generate output signals. After filtering and amplification, they are converted into digital signals through A / D conversion and input into the human body center of gravity angle calculation module, i.e., FA, FB, FC, and FD. By analyzing these four data, the human body center of gravity angle calculation module can calculate the coordinates G (x, y) of the position of the human body's pressure center, as shown in Figure 1. Figure 1 shown.

[0076] The calculation formula of the coordinates G (x, y) of the position of the human body pressure center is simplified as follows (which is the prior art):

[0077]

[0078] Figure 1 Where G(x, y) is the coordinate of the pressure center of the human body relative to the center of gravity detection platform (i.e., the four-point two-dimensional center of gravity plate).

[0079] Specifically, according to the converted signals FA, FB, FC, and FD output by the sensors, we can find the coordinates of the human body's pressure center. Assume that the center of the detection platform is the coordinate origin o, the ox axis is the x-axis, and the oy axis is the y-axis. A (xA, yA), B (xB, yB), C (xC, yC), and D (xD, yD) are the positions of the four sensors, respectively, where xA = xB = -xC = -xD = L, and yA = yB = -yC = -yD = M. The forces on the sensors are FA, FB, FC, and FD, respectively. The weight of the detection platform is W, and the material of the detection platform is evenly distributed, so that the center of gravity of the detection platform coincides with the center O of the detection platform, and the weight of the platform does not generate a torque.

[0080] The force on the sensor changes with the position of the subject on the detection platform, that is, FA, FB, FC, and FD are functions of time t and the subject's weight G. The G(x, y) value at each moment is recorded and stored in the human body center of gravity angle calculation module. Then, θx and θy are calculated according to formula (2). The θx and θy values ​​at each moment are integrated into a human body center of gravity trajectory diagram (the diagram is a vertical mapping trajectory of the human body center of gravity on the horizontal plane).

[0081] The present invention provides feedback stability limits from multiple dimensions, and all dimensions of the feedback stability limits are measured in eight directions respectively:

[0082] a. Maximum moving distance calculation module

[0083] Maximum travel distance refers to the effective value of the farthest distance reached in the target direction (i.e., maximum effective travel distance). The maximum effective travel distance is the maximum distance (measured in vertical angle) that the subject can move or tilt his or her center of mass without losing balance or starting a step. A fall occurs when the movement of the center of mass exceeds the available sway envelope or stability limit.

[0084] Individual changes in height and foot length will also affect the theoretical limit of stability. Height and foot length change together. The stability limits (expressed in degrees) of people of different heights are similar. The range of human activity is 8° forward, 8° left, 8° right, and 4.5° backward. After conversion, the left front is 5.7°, the right front is 5.7°, the left rear is 3.9°, and the right rear is 3.9°. The height, a factor that has a greater impact on the position of the human pressure center on the center of gravity plate, is introduced. The human pressure center is converted into the inclination angle of the center of gravity, and is linked to the range of human activity for evaluation. Taking the target direction as the front as an example, after the subject moves as far as possible in the target direction, the line segment from the center of the subject's foot support area to the subject's current center of gravity is H( Figure 2 ).

[0085] like Figure 2 As shown in A in the figure, the COG inclination angle is the inclination angle of the center of gravity of the human body, taking the calculation of θx as an example. The line segment from the center point of the test subject's foot support area to the current center of gravity of the test subject is H, and this line segment forms an angle θx with the vertical projection line of the center of gravity of the human body in the x-axis direction. Similarly, this line segment forms an angle θy with the vertical projection line of the center of gravity of the human body in the y-axis direction. Since it is difficult for the human body to move very accurately in only one direction when moving, the center of gravity offset in the x-direction and the center of gravity offset in the y-direction generally exist at the same time.

[0086] The specific algorithm is as follows:

[0087] θx=arc sin(X / H)

[0088] θy=arc sin(Y / H) Formula (2)

[0089] X and Y are directly obtained from formula (1) (X is the x value calculated by formula (1), and Y is the y value calculated by formula (1)), which represents the position of the pressure center of the human body on the four-point two-dimensional center of gravity plate; H = k*height, which represents the center of gravity position of the human body. θx is the inclination angle of the center of gravity in the x direction (i.e., the angle value in the x direction), and θy is the inclination angle of the center of gravity in the y direction (i.e., the angle value in the y direction).

[0090] The present invention sets eight target directions (adjacent directions are all 45° apart, front, back, left, right, left front, left back, right front, right back), the subject should try to move towards the target direction, collect the subject's body center of gravity trajectory through formula (2) (the positions of all body center of gravity trajectory points are represented by their corresponding θx and θy, the body center of gravity trajectory points are located in the plane composed of the x-axis formed by θx and the y-axis formed by θy, and the coordinate units of the x-axis and y-axis are both degrees), project the points of the body center of gravity trajectory to the points in the corresponding target direction, calculate the effective moving distance of the body center of gravity, and obtain the maximum effective moving distance of the center of gravity in the target direction through the maximum value method, as shown in FIG. Figure 3 , take the second direction (45° to the left) of the eight directions of equal angles as an example, and use points A and B to determine the target direction and target distance. A is the initial position of the center of gravity of the human body, B is the center of the target, C is a point on the trajectory of the center of gravity of the human body, and D is the point C on the straight line L. AB Projection on.

[0091] The equation of the straight line AB is y = -1*(xx A ), where x A =0,y A = 0, for generality, the slope is represented by k, k = ± 1 (such as Figure 3 As shown, the k of the centroid locus point of quadrant 1 is 1, and the k of the centroid locus point of quadrant 2 is -1); y = -kx; the product of the slopes of the two vertical lines = -1;

[0092] Since the slope of line AB is k, we know that the slope of line CD is -1 / k, so the equation of line CD is:

[0093] Wherein, x is θx calculated by equation (2), and y is θy calculated by equation (2).

[0094] Solving the simultaneous equations yields:

[0095]

[0096] Then line segment L AD The effective moving distance of the center of gravity of the human body in the direction AB is:

[0097]

[0098] For generality, when the initial position of the human body's center of gravity is not at zero (i.e., the mapping point of the initial position of the human body's center of gravity on the xoy plane is not zero), the mapping point E of the initial position of the human body's center of gravity is calculated (i.e., the mapping point of the initial position of the human body's center of gravity on the xoy plane). The method for determining points B, C, and D is the same as that in the calculation of the aforementioned formula (3). Then the line segment L ED The effective moving distance of the center of gravity of the human body in the direction AB is:

[0099]

[0100] Regardless of whether the initial position of the human body's center of gravity is zero, the line segment L CD The invalid moving distance of the center of gravity of the human body in the direction AB (for direction control algorithm):

[0101]

[0102] x D is the coordinate value of point D in the x-axis direction; y D is the coordinate value of point D in the y-axis direction; x C is the coordinate value of point C in the x-axis direction; y C is the coordinate value of point C in the y-axis direction; x E is the coordinate value of point E in the x-axis direction; y E is the coordinate value of point E in the y-axis direction. The above coordinate values ​​are all in degrees, and all refer to the inclination angle of the center of gravity of the corresponding point in the x-axis or y-axis direction.

[0103] The effective moving distance and invalid moving distance of the center of gravity trajectory point in other directions can be measured by referring to the above method.

[0104] The effective moving distances corresponding to all the center of gravity trajectory points in each direction are stored in the maximum moving distance calculation module, and the maximum value Lmax is calculated by the bubble method, which is the maximum moving distance of the center of gravity in that direction. That is, when testing a certain direction, the effective moving distance is calculated for each center of gravity trajectory point.

[0105] The ratio to the range of human activity (percentage value) can provide intuitive feedback on the activity ability of the person being tested.

[0106]

[0107] like Figure 8 As shown, the range of human activity in a specific direction refers to 8° forward, 8° left, 8° right, 4.5° backward, 5.7° left forward, 5.7° right forward, 3.9° left backward, and 3.9° right backward (the same below). For example, the maximum moving distance score (in %) of the target direction - left front is used as the maximum effective moving distance (in degrees) corresponding to all the center of gravity trajectory points when moving to the left front. max , divided by 5.7° corresponding to the left forward tilt and then multiplied by 100%.

[0108] b. Reaction time measurement module

[0109] Reaction time is the time it takes for the subject to make a movement feedback after the target appears. Reaction time indicates the delay in the subject's ability to move according to instructions or intentions, and is measured in seconds. It is an important indicator for measuring balance function. During the test, after the target appears, the subject is required to move the body's center of gravity in the direction of the target as quickly as possible. After the test begins, the target needs to be delayed for two seconds. The purpose is to collect the subject's body center of gravity in a stable state before the target appears, so as to avoid large fluctuations caused by the subject's unstable center of gravity, and the system mistakenly recognizes that the subject has responded to the target. After the test starts, the subject tries to remain stable, and the system collects the subject's center of gravity movement. Referring to formula (2), the point where the center of gravity is mapped on the plane is calculated, and the amplitude of the center of gravity swing is calculated according to the Pythagorean theorem.

[0110] Specifically, the maximum amplitude (i.e., the center of gravity swing amplitude) Amax within 2 seconds after the start of the test (i.e., during the period of 0-2s) is obtained by the bubbling method (the corresponding θx, θy and A can be calculated for each sampling moment, and the maximum value of all A values ​​at different moments in 0-2s is Amax). Two seconds after the start of the test, the target appears. At this time, the system time t0 is recorded. According to formula (7), the current human center of gravity swing amplitude Ai is calculated in real time and compared with Amax. When Ai>Amax, the system time t1 is recorded (i.e., the sampling moment corresponding to the first Ai greater than Amax after the target appears). The reaction time of the subject is t=t1-t0( Figure 4 ). The measured reaction time t is used as the reaction time score, and the unit of the score is second.

[0111] c. End point offset calculation module

[0112] like Figure 5 As shown, the end point offset distance refers to: the effective value of the farthest distance initially reached in the target direction (i.e., the maximum effective moving distance initially reached in the target direction). When calculating the end point offset value, the factor of the test subject increasing the moving distance of the center of gravity through repeated impact in the maximum moving distance is filtered out.

[0113] End excursion provides a measure of how far the subject is willing to move toward the target on the first attempt. End excursion distance represents the individual's perception of their own safety limit. Maximum movement distance represents the distance the subject actually moved the body's center of mass. End excursion distances significantly lower than maximum movement distance may indicate fear, anxiety, pain, or effort during the center of mass shift because the subject is performing a self-contracting movement on the first attempt. End excursion helps identify potential system impairments and serves as a strong outcome measure for rehabilitation of specific potential body system impairments. The algorithm is as follows:

[0114] After the target appears, the center of gravity trajectory points collected are used to calculate the effective moving distance L of each center of gravity trajectory point in the corresponding direction on the center of gravity trajectory according to formula (3) or formula (4): j (j represents the jth centroid trajectory point obtained by the jth sampling and calculation, L j represents the effective moving distance of the jth center of gravity trajectory point), when it occurs five times in a row for the first time - the effective moving distance of the next center of gravity trajectory point is less than that of the previous center of gravity trajectory point, where the last center of gravity trajectory point used for comparison is the mth center of gravity trajectory point, L m-4 <L m-5 , L m-3 <L m-4 , L m-2 <L m-3 , L m-1 <L m-2 , L m <L m-1 That is, it meets the condition that the effective moving distance of the next center of gravity trajectory point is smaller than that of the previous center of gravity trajectory point for five consecutive times), L m-5 (i.e. L 初次 ) is the effective value of the longest distance initially reached in the target direction; and L m-5 It is the first value that meets the conditions among the center of gravity trajectory points collected after the target appears, and m is an integer at least greater than 5. The end point deviation score of the test subject is:

[0115]

[0116] The reason for the five consecutive comparisons is that: when approaching the end point offset position, the moving speed is very slow, and the acquisition time is short (for example, 10 milliseconds for acquisition). Factors such as circuit acquisition accuracy and electromagnetic interference will cause fluctuations in sensor values. In order to prevent abnormal conditions such as circuit system accuracy and data conversion accuracy from causing the collected data to jump to a value smaller than the previous one and be misjudged as the end point offset, multiple consecutive comparisons can prevent misjudgment. When the effective moving distance of a center of gravity trajectory point after five consecutive occurrences is less than that of the previous center of gravity trajectory point, it means that the human body has reached the farthest distance for the first time, and it shows a slight movement back in the five consecutive measurements after reaching the farthest distance for the first time.

[0117] The range of human activity in a specific direction refers to 8° forward, 8° left, 8° right, 4.5° backward, 5.7° left front, 5.7° right front, 3.9° left back, and 3.9° right back. For example, the target direction - the end point deviation score (in %) of the left front is used as the effective value of the farthest distance reached in the target direction for the first time when moving to the left front (in degrees) as L 初次 , divided by 5.7° corresponding to the left forward tilt and then multiplied by 100%.

[0118] d. Moving speed calculation module

[0119] The average moving speed of the test subject's body center of gravity between 5% and 95% of the offset distance from the end point is calculated. The purpose of taking 5% to 95% is to remove the reaction time in the early stage of the movement of the human body's center of gravity (that is, to exclude the acceleration component) and to remove the time of the center of gravity shaking in the later stage of the movement (that is, to exclude the deceleration component), so as to prevent the two from causing inaccurate calculation of the moving speed.

[0120] Movement speed: quantifies the average movement speed of the patient's body center of gravity from 5% to 95% of the offset distance from the end point, in degrees per second, so the acceleration and deceleration components are excluded in the calculation. The calculation method is as follows:

[0121] According to formula (3) or formula (4), the effective moving distance L of each center of gravity trajectory point in the corresponding direction is calculated: i (i represents the i-th center of gravity trajectory point), compare it with the value of the end point offset distance * 5%, find out the center of gravity trajectory point whose effective moving distance is the end point offset distance * 5%, read the system time T5 (i.e. sampling time, also called sampling moment, referred to as moment or time) of this point in the human body center of gravity angle calculation module, and similarly find out the system time T95 of the center of gravity trajectory point whose effective moving distance is 95% of the end point offset distance, and the algorithm for obtaining the moving speed is as follows:

[0122] Movement Speed

[0123] T5 is the time corresponding to the center of gravity trajectory point whose effective moving distance is 5% of the end point offset distance, and T95 is the time corresponding to the center of gravity trajectory point whose effective moving distance is 95% of the end point offset distance.

[0124] The measured moving speed S is equal to the moving speed score, and the score unit is degree / second.

[0125] e. Direction control calculation module

[0126] Directional control: The quality of movement control is quantified by directional control. Directional control is the amount of movement of the subject in the intended direction, i.e., the amount of movement towards the target compared to the amount of movement away from the target, expressed as a percentage (%). The value can be interpreted as the percentage of accuracy of self-initiated movement. The algorithm is as follows:

[0127] According to formula (3) or formula (4) and formula (5), the effective moving distance and invalid moving distance of each point of the center of gravity trajectory are calculated.

[0128] Direction Control Score

[0129] i=1, 2, 3...n, where n is the total number of points on the center of gravity trajectory, and the unit of the direction control score is %.

[0130] like Figure 6 As shown, X C3 ,y C3 , X D3 ,y D3 Refer to formula (3), formula (4), formula (5) in which X C ,y C , X D ,y D The subscript plus 3 represents the third centroid trajectory point; similarly, X Ci ,y Ci , X Di ,y Di Refer to (3), (4), (5) where X C ,y C , X D ,y D The subscript plus i represents the i-th centroid trajectory point.

[0131] In each module in the above ae, scores are calculated separately for each of the eight directions. The eight directions are front, back, left, right, left front, right front, left back, and right back. The angle between adjacent directions is 45°, dividing a circle equally.

[0132] f. Comprehensive score calculation module

[0133] After the scores in the eight directions are obtained respectively, the comprehensive scores in the four directions of front, back, left and right are calculated through an algorithm.

[0134] The combined directional scores from the three forward components (front, right front, and left front) are combined to provide an average forward score. The combined directional scores from the three backward components (back, right rear, and left rear) are combined to provide an average backward score. The combined directional scores from the three rightward components (right, right front, and right rear) are combined to provide an average rightward score. The scores from the three leftward components (left, left front, and left rear) are combined to provide an average leftward score.

[0135] The comprehensive scoring algorithm for the moving speed in each direction, the end point offset and the maximum moving distance is as follows:

[0136] forward:

[0137] right:

[0138] back:

[0139] Left:

[0140] θ LFy It represents the angle between the center of gravity trajectory point selected by the left front upward end point offset to reach the longest effective distance for the first time and the y-axis; S LF Indicates the score of the end point offset, moving speed or maximum moving distance in the left front direction; θ Fy It represents the angle between the center of gravity trajectory point that reaches the longest effective distance for the first time selected by the forward end point offset and the y-axis, S F The score representing the end point offset, moving speed or maximum moving distance in the forward direction; θ RFy It represents the angle between the center of gravity trajectory point selected by the right front upward end point offset to reach the longest effective distance for the first time and the y-axis, S RF The score representing the end point offset, moving speed or maximum moving distance in the right front direction; θ RFx The angle between the center of gravity trajectory point selected by the right front upward end point offset to reach the longest effective distance for the first time and the x-axis; θ Rx It represents the angle between the center of gravity trajectory point selected by the end point offset in the right direction and the x-axis. R Indicates the score of the end point offset, moving speed or maximum moving distance in the right direction; θ RBx It represents the angle between the center of gravity trajectory point selected by the end point offset of the right rear upward and the x-axis. RB The score representing the end point offset, moving speed or maximum moving distance in the right rear direction; θ LBy It represents the angle between the center of gravity trajectory point selected by the left rear upward end point offset to reach the longest effective distance for the first time and the y-axis, S LB Indicates the score of the end point offset, moving speed or maximum moving distance in the left rear direction; θ RBy It represents the angle between the center of gravity trajectory point selected by the end point offset in the right rear direction and the y-axis; θ LFx The angle between the center of gravity trajectory point selected by the left front upward end point offset to reach the longest effective distance for the first time and the x-axis; θ By It represents the angle between the center of gravity trajectory point selected by the end point offset in the rear direction and the y-axis. B The score representing the end point offset, moving speed or maximum moving distance in the backward direction; θ Lx It represents the angle between the center of gravity trajectory point selected by the end point offset in the left direction and the x-axis. L Indicates the score of the end point offset, moving speed or maximum moving distance in the left direction; θ LBxIt represents the angle between the center of gravity trajectory point selected by the left rear upward end point offset that first reaches the farthest effective distance and the x-axis;

[0141] All θ and S(S LF , S LB , S L , S F , S RF , S R , S RB , S B ) subscripts correspond to: the eight directions that divide a circle equally, with the angles between adjacent directions being 45° ( Figure 3 , Figure 7 ).

[0142] The comprehensive scores of the moving speed, end point offset and maximum moving distance in each direction are calculated separately. For example, when calculating the comprehensive score of the moving speed in the left direction, all S(S LF , S LB , S L ) represent the scores of the moving speed in the corresponding directions respectively; when calculating the comprehensive score of the end point offset in the forward direction, all S(S LF , S F , S RF ), all refer to the scores of the end point deviation in the corresponding direction; when calculating the comprehensive score of the maximum moving distance in the right direction, all S(S RF , S R , S RB ) refers to the score of the maximum moving distance in a specific direction. The same applies to other directions.

[0143] The specific meaning of 2.414 is: in an ideal state, the left front, left rear, right front, and right rear directions correspond to sin45° or cos45°. The front, back, left, and right directions all correspond to cos0°=1. In an ideal state, the target value is

[0144] The comprehensive scoring algorithm for reaction time and direction control in each direction is as follows:

[0145] forward:

[0146] right:

[0147] back:

[0148] Left:

[0149] S LF Indicates the score of reaction time or direction control in the left front direction; SF Indicates the score of reaction time or direction control in the forward direction; S RF Indicates the score of reaction time or direction control in the right front direction; S R Indicates the score of reaction time or direction control in the right direction; S RB Indicates the score of reaction time or direction control in the right rear direction; S LB Indicates the score of reaction time or direction control in the left rear direction; S B Indicates the score of reaction time or direction control in the backward direction; S L Represents the score of reaction time or directional control in the left direction.

[0150] All S(S LF , S LB , S L , S F , S RF , S R , S RB , S B ) subscripts correspond to: the eight directions that divide a circle equally, with the angles between adjacent directions being 45° ( Figure 3 , Figure 7 ).

[0151] The reaction time and direction control comprehensive score of each direction are calculated separately. For example, when calculating the comprehensive score of the reaction time of the rear direction, all S(S RB , S LB , S B ), all refer to the reaction time in a specific direction; when calculating the comprehensive score of the directional control in the front direction, all S(S LF , S F , S RF ), all refer to the score of directional control in a specific direction. The same applies to other directions.

[0152] The test subject's moving speed, end point deviation, maximum moving distance, reaction time, scores of eight directions of directional control, and comprehensive scores of front, back, left, and right can be compared with the test subject's own scores in different directions or with the scores of previous tests in different periods to evaluate the changes in his or her balance function. It can also be compared with the score data of people with normal balance and stability function or with different degrees of balance and stability function defects.

[0153] The comprehensive score results are as follows Fig. 9 As shown (for example).

[0154] The calculation of the inclination angle of the human body's center of gravity takes into account the influence of height on the stability limit, and the resulting data is more universal. The calculation of the end point offset excludes abnormal human factors and is mainly used to evaluate the extreme center of gravity movement range of the human body in a stable state. The evaluation needs to filter out the situation where the test subject obtains a larger movement range through short-term human instability. The maximum distance reached by the human body's center of gravity for the first time solves this problem. The data of multiple tests on the same test subject are basically consistent, which can truly reflect the test subject's balance ability and is a good supplement to the maximum movement distance parameter. The comparison of these two data can reflect the test subject's activity status. Reaction time and movement speed can reflect the strength of the test subject's coordination and athletic ability; direction control can reflect the strength of the test subject's control ability.

[0155] In summary, the stability limit of the subject can be evaluated from multiple angles, including coordination ability, motor ability, and control ability. The test data can provide intuitive feedback on the subject's balance function, improving the accuracy and efficiency of the evaluation.

[0156] The above embodiments are only used to illustrate the technical solutions of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation shall fall within the protection scope of the present invention.

Claims

1. A balance stability limit test system, characterized in that: It includes a human body center of gravity angle calculation module, a maximum moving distance calculation module, a reaction time measurement module, an end point offset calculation module, a moving speed calculation module, a direction control calculation module and a comprehensive score calculation module; The body center of gravity angle calculation module calculates the body center of gravity angle according to the position coordinates G (x, y) of the body pressure center trajectory point and the body height; The maximum moving distance calculation module is used to calculate the maximum effective moving distance that the human body can reach in each target direction; The reaction time measurement module is used to measure the time it takes for the subject to make movement feedback after the target appears; The end point deviation calculation module is used to calculate the effective value of the farthest distance that the test subject reaches in the target direction for the first time; The moving speed calculation module is used to calculate the average moving speed of the test subject's body center of gravity between 5% and 95% of the offset distance from the end point; The direction control calculation module is used to calculate the direction control scores of all target directions; The comprehensive score calculation module is used to calculate the comprehensive scores of the moving speed, end point offset, and maximum moving distance in the four directions of front, back, left, and right, and / or calculate the comprehensive scores of the reaction time and direction control in the four directions of front, back, left, and right.

2. A balance stability limit test system according to claim 1, characterized in that: In the human body center of gravity angle calculation module, the calculation formulas for x and y in the position coordinates G(x, y) of the human body pressure center trajectory point are: FA, FB, FC, and FD are the pressure values ​​detected by the four sensors; (xA, yA), (xB, yB), (xC, yC), and (xD, yD) are the positions of the four sensors, xA = xB = -xC = -xD = L, yA = yB = -yC = -yD = M, and G is the weight of the person being tested; The body's center of gravity angle includes the x-direction center of gravity inclination angle θx and the y-direction center of gravity inclination angle θy; θx=arc sin(X / H) θy=arc sin(Y / H) Formula (2) H = k*height, k = 0.55-0.56, X, Y are x, y in G(x,y) respectively; The θx and θy values ​​at each moment constitute the trajectory of the human body's center of gravity.

3. A balance stability limit test system according to claim 1, characterized in that: The steps performed by the maximum moving distance calculation module are: A is the initial position of the human body's center of gravity, B is the target center, C is a point on the trajectory of the human body's center of gravity, and D is the point C on the straight line L. AB projection on The equation of the straight line AB is y = -1*(xx A ), where x A =0,y A = 0, the slope is represented by k, k = ± 1; y = -kx; the product of the slopes of the two vertical lines AB and CD = -1; where y is θy; x is θx; Since the slope of line AB is k, we know that the slope of line CD is -1 / k, and the equation of line CD is: Solving the simultaneous equations yields: Then line segment L AD The effective moving distance of the center of gravity of the human body in the direction AB is: When the initial position of the human body's center of gravity is not at zero, calculate the mapping point E of the initial position of the human body's center of gravity, then the line segment L ED The effective moving distance of the center of gravity of the human body in the direction AB is: Line segment L CD The ineffective moving distance of the center of gravity of the human body in the direction AB is: The maximum effective moving distance among all effective moving distances of all center of gravity trajectory points in each target direction is the maximum moving distance corresponding to the target direction.

4. A balance stability limit test system according to claim 1, characterized in that: In the reaction time measurement module, when measuring the reaction time, the center of gravity swing amplitude is calculated The specific steps are as follows: find the maximum value Amax of the center of gravity swing amplitude within a certain time after the test starts; the target appears after a certain time after the test starts, and the time t0 is recorded at this time; the current center of gravity swing amplitude Ai is calculated in real time according to formula (7) and compared with Amax; when Ai>Amax, the time t1 is recorded at this time, and the reaction time of the subject is t=t1-t0.

5. A balance stability limit test system according to claim 1, characterized in that: In the end point offset calculation module, the center of gravity trajectory points collected after the target appears are used to calculate the effective moving distance of each center of gravity trajectory point in the corresponding direction on the center of gravity trajectory according to formula (3) or formula (4). When the effective moving distance of the next center of gravity trajectory point is less than that of the previous center of gravity trajectory point for five consecutive times, L m-5 is the effective value of the longest distance reached for the first time in the target direction; L m-5 That is L 初次； The endpoint deviation scores of the subjects were: The test subject's endpoint deviation score = L 初次 / Human body's range of motion in a specific direction*100% formula (8); In the moving speed calculation module, Movement Speed T5 is the time corresponding to the center of gravity trajectory point whose effective moving distance is 5% of the end point offset distance, and T95 is the time corresponding to the center of gravity trajectory point whose effective moving distance is 95% of the end point offset distance.

6. A balance stability limit test system according to claim 1, characterized in that: In the direction control calculation module, the effective moving distance and invalid moving distance of each point on the center of gravity trajectory are calculated according to equation (3) or (4) and equation (5). Direction Control Score i=1, 2, 3...n, where n is the total number of all points on the centroid trajectory.

7. A balance stability limit test system according to claim 1, characterized in that: In the comprehensive score calculation module, the comprehensive score algorithm for the moving speed in the front, back, left, and right directions, the end point offset, and the maximum moving distance is as follows: forward: right: back: left: θ LFy It represents the angle between the center of gravity trajectory point selected by the left front upward end point offset to reach the longest effective distance for the first time and the y-axis; S LF Indicates the score of the end point offset, moving speed or maximum moving distance in the left front direction; θ Fy Indicates the angle between the center of gravity trajectory point that reaches the longest effective distance for the first time selected by the forward end point offset and the y-axis, s F The score representing the end point offset, moving speed or maximum moving distance in the forward direction; θ RFy It represents the angle between the center of gravity trajectory point selected by the right front upward end point offset to reach the longest effective distance for the first time and the y-axis, S RF The score representing the end point offset, moving speed or maximum moving distance in the right front direction; θ RFx The angle between the center of gravity trajectory point selected by the right front upward end point offset to reach the longest effective distance for the first time and the x-axis; θ Rx It represents the angle between the center of gravity trajectory point selected by the end point offset in the right direction and the x-axis. R Indicates the score of the end point offset, moving speed or maximum moving distance in the right direction; θ RBx It represents the angle between the center of gravity trajectory point selected by the end point offset of the right rear upward and the x-axis. RB The score representing the end point offset, moving speed or maximum moving distance in the right rear direction; θ LBy It represents the angle between the center of gravity trajectory point selected by the left rear upward end point offset to reach the longest effective distance for the first time and the y-axis, S LB Indicates the score of the end point offset, moving speed or maximum moving distance in the left rear direction; θ RBy It represents the angle between the center of gravity trajectory point selected by the end point offset in the right rear direction and the y-axis; θ LFx The angle between the center of gravity trajectory point selected by the left front upward end point offset to reach the longest effective distance for the first time and the x-axis; θ By It represents the angle between the center of gravity trajectory point selected by the end point offset in the rear direction and the y-axis. B The score representing the end point offset, moving speed or maximum moving distance in the backward direction; θ Lx It represents the angle between the center of gravity trajectory point selected by the end point offset in the left direction and the x-axis. L Indicates the score of the end point offset, moving speed or maximum moving distance in the left direction; θ LBx It represents the angle between the center of gravity trajectory point selected by the left rear upward end point offset that first reaches the farthest effective distance and the x-axis; The comprehensive scoring algorithm for reaction time and direction control in the front, back, left, and right directions is as follows: forward: right: back: left: S LF Indicates the score of reaction time or direction control in the left front direction; S F Indicates the score of reaction time or direction control in the forward direction; S RF Indicates the score of reaction time or direction control in the right front direction; S R Indicates the score of reaction time or direction control in the right direction; S RB Indicates the score of reaction time or direction control in the right rear direction; S LB Indicates the score of reaction time or direction control in the left rear direction; S B Indicates the score of reaction time or directional control in the backward direction; S L Represents the score of reaction time or directional control in the left direction.

8. A method for testing the balance stability limit of a system according to any one of claims 1 to 7.

9. A processor for running a computer program, characterized in that: The computer program executes the balance stability limit testing method as claimed in claim 8 when it is run.

10. A computer readable medium having a computer program stored thereon, characterized in that: The computer program is executed by a processor to implement the balance stability limit test method as claimed in claim 8.

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