Improved gait cycle counting method based on hip joint gait stress data

Abstract

The application discloses an improved step counting method based on hip gait stress data, and is characterized in that stress step range and stress step number of the improved step counting method are preset based on hip gait stress data characteristics; stress steps crossed by gait stress data are sequentially judged according to a counting principle of the improved step counting method, and the number of the crossed stress steps is counted; and the crossed stress steps are combined into a stress cycle according to a stress cycle determination method of the improved step counting method, so that the amplitude and the average of the stress cycle are obtained. The method overcomes the problems of poor real-time performance and loss of time sequence information in the data counting process of the traditional fatigue counting method, effectively saves the time sequence information of femoral structure gait stress, and improves the accuracy of the artificial hip joint structure fatigue life analysis result.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hip biomechanics, in particular to an improved step count method based on hip gait stress data. BACKGROUND

[0002] The hip joint is the largest ball-and-socket joint in the human body, which is composed of the femoral head and the acetabulum. Its main functions are weight-bearing and movement. Due to its morphological and functional characteristics, the hip joint is prone to wear and tear, causing joint pain and functional limitations, which seriously affects the patient's quality of life. Total hip arthroplasty is the most effective method to solve hip joint diseases. However, due to the lack of theoretical basis, the selection of prostheses by orthopedic surgeons relies mainly on clinical surgical experience, which leads to frequent complications such as femoral atrophy, prosthesis damage, and prosthesis loosening and sinking caused by changes in mechanical distribution after replacement, reducing the service life of artificial hip joints. Traditional research on hip joint fatigue life cannot meet the design requirements of prosthetic hip joints because it does not consider gait load. In order to accurately count the fatigue cycles under gait load and effectively apply to engineering practice, it is imperative to propose a fatigue counting method based on hip gait stress data.

[0003] Compared with fatigue analysis under static load of the hip joint, there have been some progress in fatigue research under gait load, but many problems still need to be solved. The existing counting methods are mostly based on the analysis and extraction of load information within a specific time history, which cannot perform real-time fatigue counting on load data and cannot effectively save the timing information of gait load on the femoral structure. Therefore, there is an urgent need for a counting method based on hip gait stress timing data. In order to effectively predict the fatigue life of artificial hip joints and optimize the structure of prostheses in the design of prosthetic structures. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application proposes an improved step count method based on hip gait stress data.

[0005] The technical solution of the present application is as follows:

[0006] An improved step count method based on hip gait stress data, comprising the following steps:

[0007] (1) Based on the characteristics of hip gait stress data, the stress level range and the number of stress levels of the improved step count method are preset, and the reference stress and stress level increment are obtained.

[0008] (1-1) Based on the characteristics of hip gait stress data, the stress level range [0, σ max ] is preset, and the number of stress levels is m;

[0009] (1-2) Determine the reference stress ref and stress level increment k based on the stress level range and the number of stress levels, and the determination formula of the reference stress and stress level increment is as follows:

[0010] ref = σ max / 2

[0011] k = σ max / (m-1).

[0012] (2) Real-time reading of hip gait stress data, according to the counting principle of the improved level crossing counting method, the stress levels crossed by the gait stress data are sequentially judged, and the number of stress levels crossed is obtained.

[0013] (2-1) Read the hip gait stress data D[1,2,…,n] sequentially, starting from the second collection point, and judge the stress level num crossed by each data collected. The determination formula of the stress level value is as follows:

[0014] num(i) = ref + i*k

[0015] Where i represents the i-th level, and the integer in the range of -m / 2≤i≤m / 2.

[0016] (2-2) Determine the difference Δ n , Δ n+1 of each stress level between adjacent data points, and judge the stress level crossed by the data. No matter what slope the stress level is crossed, it is counted once. The formula for judging the stress level crossed by the data is as follows:

[0017] Δ n+1 = D(n+1)-num(i)

[0018] Δ n = D(n)-num(i)

[0019] Where n represents the n-th data point; sequentially try each stress level value num(i), when Δ n+1 · Δ n ≤0, the stress level crossed is counted once; according to the gait loading sequence, the stress levels crossed by the hip gait stress data and their numbers are counted.

[0020] (3) According to the stress cycle determination method of the improved level crossing counting method, the stress levels crossed are combined into a stress cycle, and the amplitude and mean value of the stress cycle are obtained.

[0021] (3-1) Read the hip gait stress data sequentially, determine the trough of the data, and the determination formula of the trough is as follows:

[0022] D(n-1)-D(n)≥0 and D(n+1)-D(n)≥0

[0023] (3-2) Based on the stress level composition stress cycle of the improved stress level counting method, the stress level composition stress cycle of the first wave trough of the gait stress data is crossed twice, the number of load levels participating is reduced by 2, and the unused load level is reserved for use in the next cycle; in this way, until the hip joint gait stress data collection stops.

[0024] (3-3) The maximum stress σ max and the minimum stress σ min of each stress cycle are counted. a The amplitude σ m and the mean σ a of each stress cycle are obtained. The determination formula of the amplitude and the mean is as follows:

[0025] σ a = max-min;

[0026] σ m = (max+min) / 2;

[0027] Compared with the prior art, the beneficial effects of the present application are as follows:

[0028] 1. The present application is aimed at the problem of hip joint gait stress data, based on the characteristics of hip joint gait stress data, the stress level range and the number of stress levels of the improved stress level counting method are preset; the stress levels crossed by the gait stress data are judged in turn according to the counting principle of the improved stress level counting method, and the number of stress levels crossed is counted; the crossed stress levels are composed into stress cycles according to the stress cycle determination method of the improved stress level counting method, and the amplitude and the mean of the stress cycle are obtained.

[0029] 2. The method of the present application overcomes the problems of weak real-time performance and loss of time sequence information in the data counting process of the traditional fatigue counting method, realizes the effective preservation of the time sequence information of the femoral structure gait stress, and improves the accuracy of the artificial hip joint structure fatigue life analysis result. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The flowchart of the improved stress level counting method based on the hip joint gait stress time sequence data in the embodiment of the present application.

[0031] Figure 2 The stress level diagram crossed by the gait stress data in the embodiment of the present application.

[0032] Figure 3 The stress level diagram crossed by the gait stress data in the embodiment of the present application.

[0033] Figure 4 The stress cycle counting result diagram in the embodiment of the present application. DETAILED DESCRIPTION

[0034] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0035] This invention proposes an improved gait stress data-based method for gait level counting, such as... Figure 1 As shown, it includes the following steps:

[0036] Step 1: Preset the stress level range and number of stress levels for the improved stress level counting method to obtain the reference stress and stress level increment.

[0037] In this embodiment, based on the characteristics of hip joint gait stress data, a preset stress level range [0, σ] is defined. max The number of stress levels is m.

[0038] The reference stress ref and stress level increment k are determined based on the stress level range and the number of stress levels, as shown in formulas (1) and (2):

[0039] ref=σ max / twenty one)

[0040] k = σ max / (m-1) (2)

[0041] Step 2: Based on the counting principle of the improved traversal counting method, determine the stress levels traversed by the gait stress data in sequence to obtain the number of stress levels traversed.

[0042] Step 2.1: Read the hip joint gait stress data D[1,2,…,n] sequentially. Starting from the second acquisition point, determine the stress level num that the data traverses for each data point. The stress level value is determined as shown in formula (3):

[0043] num(i) = ref + i*k (3)

[0044] Where i represents the i-th level, and is an integer in the range of -m / 2 ≤ i ≤ m / 2.

[0045] Step 2.2: Determine the difference Δ between two adjacent data points and each stress level. n Δ n+1 As shown in formulas (4) and (5).

[0046] Δ n+1 =D(n+1)-num(i) (4)

[0047] Δ n =D(n)-num(i) (5)

[0048] Where n represents the nth data point; determine the stress level that the data point traverses. Count the stress level traversed regardless of the slope.

[0049] Try each stress level value num(i) in turn, determine data across stress level, when Δ n+1 ·Δ n ≤0, across the stress level count once, get gait stress data across the stress level as shown in Figure 2 .

[0050] According to the gait loading sequence statistics hip gait stress data across the stress level and its frequency, the statistical results as shown in Figure 3 .

[0051] Step 3: according to the improved stress cycle determination method of level counting method to cross the stress level composition stress cycle, get the amplitude and mean of stress cycle.

[0052] Step 3.1: read the hip gait stress data in turn, determine the trough of data, as shown in formula (6) to determine the trough position:

[0053] D(n-1)-D(n)≥0 and D(n+1)-D(n)≥0 (6)

[0054] Step 3.2: based on the stress level statistics of improved level counting method to form a stress cycle:

[0055] The first trough of gait stress data across 2 times of stress level to form a stress cycle, the number of load levels involved is reduced by 2, and the unused load level is reserved for the next cycle;

[0056] In this way, until the hip gait stress data collection stops. Stress cycle statistics results as shown in Figure 4 .

[0057] Step 3.3: statistics of each stress cycle maximum stress σ max and minimum stress σ min , get the amplitude σ a and mean σ m of each stress cycle, as shown in formula (7) and (8):

[0058] σ a =max-min (7)

[0059] σ m =(max+min) / 2 (8)

[0060] The improved gait stress level counting method based on the hip joint gait stress data in the above embodiment is based on the gait stress data characteristics, pre-sets the stress level range and the stress level number of the improved gait stress level counting method; the stress levels crossed by the gait stress data are sequentially judged according to the counting principle of the improved gait stress level counting method, and the stress level crossing times are counted; the stress levels crossed are composed into a stress cycle according to the stress cycle determination method of the improved gait stress level counting method, and the amplitude and the mean value of the stress cycle are obtained. The method in the above embodiment overcomes the problems of poor real-time performance and loss of time sequence information in the data counting process of the traditional fatigue counting method, effectively saves the gait stress time sequence information of the femur structure, and improves the accuracy of the artificial hip joint structure fatigue life analysis result.

[0061] The above embodiments are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. For the researchers in the field, other different forms of improvements can be made on the basis of the above description, and all the embodiments cannot be exhausted here. Any obvious changes or variations derived from the technical solutions of the present application are still within the protection scope of the present application.

Claims

1. An improved gait counting method based on hip joint gait stress data, characterized in that, Includes the following steps: (1) Based on the characteristics of hip joint gait stress data, the stress level range and number of stress levels of the improved piercing level counting method are preset to obtain the reference stress and stress level increment; (2) Read hip joint gait stress data in real time, and determine the stress level traversed by the gait stress data in sequence according to the counting principle of the improved traversal counting method, so as to obtain the number of stress levels traversed; (3) Based on the improved stress cycle determination method of the traversal counting method, the stress levels traversed are grouped into stress cycles to obtain the amplitude and mean of the stress cycles; Step (1) includes the following steps: (1-1) Based on the characteristics of hip joint gait stress data, the preset stress level range is [0, The number of stress levels is m; (1-2) The reference stress ref and stress level increment k are determined based on the stress level range and the number of stress levels. The formulas for determining the reference stress and stress level increment are as follows: ； The counting principle of the improved tiered counting method in step (2) is as follows: (2-1) Read hip joint gait stress data sequentially Starting from the second data collection point, for each data point collected, the stress level num that the data point traverses is determined. The formula for determining the stress level value is as follows: ； Where represents the i-th level, and its size is... Integers within the range; (2-2) Determine the difference between two adjacent data points and each stress level. To determine the stress level that the data passes through, the stress level is counted once regardless of the slope at which it passes through. The formula for determining the stress level that the data passes through is as follows: ； Where n represents the nth data point; each stress level value is tried sequentially. ,when At any given time, the stress level traversed is counted once; the stress levels traversed and the number of times are counted based on the gait loading sequence; The stress cycle determination method of the improved penetration counting method in step (3) is as follows: (3-1) Read the hip joint gait stress data sequentially and determine the troughs of the data. The formula for determining the troughs is as follows: ； (3-2) Based on the improved step counting method, stress levels are composed of stress cycles. Stress levels that are crossed twice before the first trough of gait stress data are combined into a stress cycle. The number of load levels involved is reduced by 2, and unused load levels are retained for the next cycle. This process continues until the hip joint gait stress data collection stops. (3-3) Calculate the maximum stress for each stress cycle. max and minimum stress min The amplitude of each stress cycle is obtained. and mean The formulas for determining the amplitude and mean are as follows: 。

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