CN106937872A - A kind of gait bilateral symmetric property evaluation method based on regression curve - Google Patents

Abstract

The invention discloses a kind of gait bilateral symmetric property evaluation method based on regression curve.First, foot 3-axis acceleration information when obtaining gait motion using acceleration transducer, and de-noising pretreatment is carried out to the acceleration information of acquisition；Secondly, the acceleration signal after de-noising is extracted, the bilateral symmetric property index of continuous gait cycle is calculated respectively, the quantitative analysis of gait symmetry is realized.The characteristics of gait bilateral symmetric property detection method of the present invention has easy, accurate, has broad application prospects in fields such as gait balanced capacity analyses.

Description

A kind of gait bilateral symmetric property evaluation method based on regression curve

Technical field

The invention belongs to mode identification technology, it is related to a kind of recognition methods of acceleration signal, it is more particularly to a kind of Bilateral gait symmetry evaluation method based on regression curve.

Background technology

Lower limb gait be human body in the process of walking, posture and state that both legs are shown, with periodically, continuity And the features such as repeatability.It is heelstrike complete for one with the time landed again to the batter from side in human walking procedure Whole gait cycle.In gait motion, human nerve maincenter by complicated, not transreplication control, show it is high-effect, Stable gait.Wherein, the main executive of gait motion is lower limb, and foot is used as the device contacted between human body and ground Official, has played important function in motion process, its move symmetrical analysis result, be widely used in training athlete, Healthy People is taken exercise, and walking disorder patient's functional rehabilitation etc. gait motion evaluation.

In the prior art, frequently with the symmetry of plantar pressure information research gait.Its method is when vola connects with ground When tactile, mutually extrude the plantar pressure of generation by measuring foot with ground to realize.But it is in what is swung back and forth in foot During gait process, it is impossible to obtain effective plantar pressure information.Therefore, the gait analysis based on plantar pressure, for it is complete, Continuous gait cycle has some limitations.Acceleration signal is produced by foot movement, with real-time, successional feature, Available for progress gait analysis.In the prior art, gait bilateral symmetric property analysis indexes include the statistical value of asymmetry, such as phase , there is random error greatly, the problem of data user rate is low in relation number, principal component, variance analysis and mean difference analysis etc..Example Such as, equal poor index are used to assess the translation in vertical direction, are easily influenceed by gait amplitude, random error is big.Separately Outside, range of movement only compares maximum in gait curve, minimum value, and have ignored the overall distribution situation of curve, has The low defect of data user rate.

The content of the invention

Data user rate is low in symmetry analysis of gait when the present invention is directed to current human body walking, random error asking greatly Topic, proposes a kind of gait bilateral symmetric property evaluation method based on Regression.

In order to realize above-mentioned target, the inventive method comprises the following steps：

Step 1, foot movement acceleration signal is obtained.

In experimental data collection, acceleration transducer is placed in during subject's foot front end, collection gait motion The foot 3-axis acceleration signal of generation, then carries out de-noising pretreatment to original foot 3-axis acceleration signal, isolates letter Number and noise, finally reconstruct de-noising after acceleration signal sample data, obtain gait motion foot acceleration information.

Step 2, the gait bilateral symmetric property index based on regression curve is calculated

The evaluation of gait bilateral symmetric property concentrates on the difference for calculating bilateral gait curve in one gait cycle of analysis.Its In, less bilateral curve difference represents higher symmetry.Every bit on curve subtracts and is worth to new curve, meter Calculate formula as follows：

Wherein,WithFor the initial data of left and right sides foot, Obtained by three axis accelerometer；WithFor the left and right curve point after conversion；WithFor the average of left and right curve.

The step state acceleration data being converted to will be calculated during upper oneWithIt is reconstructed into a matrixUnder its matrix M is constituted：

Its characteristic vector is calculated to matrix M application singular value decompositions, specific calculation procedure is as follows：

1) basis | λ E-MM^H|=0 obtains matrix MM^HEigenvalue λ₁、λ₂、...、λ_n, while singular value must can be corresponded toAssuming that having j singular value.Wherein E is unit matrix, M^HFor matrix M associate matrix, meter Calculate as follows：

Wherein,For r_o(i)-r_ave(i)Conjugate complex number.

2) eigenvalue λ is calculated respectively_iCorresponding characteristic vectorMeetWherein,

For the orthogonal basis in n-dimensional space.Here, matrix M characteristic vector represents all members in matrix The characteristic distributions of element, therefore along the direction of this feature vector, matrix aberration rate reaches maximum.

On the basis of calculating obtains matrix M characteristic vectors, according to triangle geometrical relationship further try to achieve characteristic vector with Angle between reference axis and x or y.According to the angle, matrix M each row is carried out it is rotationally-varying, be allowed to along x-axis or Y-axis is distributed.Rotation is calculated as follows：

Wherein,WithRespectively postrotational left and right gait curve；θ is matrix M characteristic vectors and x-axis or y-axis Angle.Postrotational gait curve is distributed along x-axis, and x-axis direction and the rate of change of gait curve on y-axis direction are calculated respectively. Transverse axis rate of change varX represents the distortion situation along characteristic vector direction gait curve, and the rate of change varY of y direction is represented Along the distortion situation on characteristic vector orthogonal direction, it is calculated as follows：

HereFor vectorMould,For vectorMould.Thus gait bilateral symmetric property desired value is obtained, Expression formula is varY/varX, is represented with a percentage, for evaluating gait symmetry during biped walking, wherein 0% table Show optimal symmetry.

A kind of method based on regression curve is proposed in the present invention, by calculating the data of complete gait cycle, a left side is obtained Right foot gait symmetric index value, the symmetry for evaluating body gait.Method random fluctuation in the present invention is small, symmetrically Property index value it is stable, convergence is higher.

Brief description of the drawings

Fig. 1 is present invention specific implementation flow chart；

Fig. 2 is continuous gait cycle bilateral symmetric property calculating process schematic diagram；

Fig. 3 is the gait curve and regression curve of a gait cycle；

Fig. 4 is gait bilateral symmetric property index.

Embodiment

The specific embodiment of the present invention is elaborated with reference to Figure of description：The present embodiment is with skill of the present invention It is lower premised on art scheme to be implemented, give detailed embodiment and specific operating process.But the protection model of the present invention Enclose and be not limited to following embodiments.

Such as Fig. 1, the implementation of the inventive method is mainly included the following steps that：

Step one, bilateral foot acceleration signal is gathered.During gait motion, added using three axles of Delsys companies Speedometer, its sample frequency is 150Hz.

In the present embodiment, the experimental subjects of selection is 24 ± 1.75 healthy males, double as gait using different leg speeds The foundation of side symmetry comparative evaluation, carries out level walking with 1.0m/s, 1.2m/s, 1.4m/s and 1.6m/s speed respectively Motion.The acceleration signal collected is transferred to PC by bluetooth module, and next gait is carried out on the basis of filter preprocessing Bilateral symmetric property analyzes link.

Step 2, calculates gait bilateral symmetric property index.When subject carries out gait experimental, left and right biped is in the cycle Property swing, alternately process forward, therefore the gait curve of left and right has certain phase difference.In order to analyze both sides foot gait Bilateral symmetric property between curve is, it is necessary to intercept the complete gait curve of not homonymy.Meanwhile, the gait curve for comparing calculating Between can not have phase difference.

In the present embodiment, a complete gait curve cycle is chosen as target, passage time translation is calculated every respectively Correlation during secondary translation, the bilateral curve to determine analytic trend symmetry value.Wherein, translation time and gait curvilinear correlation Relation between property is as shown in Figure 2.Wherein, a is translation time and difference linearity curve；B is the difference in translation time 500-700 Difference curve in dotted line frame A in curve, as Fig. 2 a；Black "+" number is represented in the interval in b, otherness minimum point, i.e. bilateral Gait curvilinear correlation peak.

As shown in Fig. 2 bilateral gait difference curve shows stronger periodicity.Take the lowest difference opposite sex in a cycle Value, based on this, the trend symmetry value between bilateral gait curve of the analysis based on regression curve, as shown in Figure 3.In figure, 3a is bilateral gait curve, on the left of the representative of point, and on the right side of the representative with point, g represents acceleration of gravity, is worth for 9.8m/s²； 3b dotted lines are regression curve, and solid line is characterized the direction of vector.By calculating in the vectorial both direction of parallel and vertical features Gait bilateral symmetric property index between curve variability, analysis left and right sides gait curve, for increase bilateral symmetric property evaluation Representativeness, the present embodiment have chosen the symmetrical desired value under 12 groups of different leg speeds, and calculate corresponding average value and variance Value, as shown in table 1.

The different gait conditional trends symmetry values of table 1

In the present embodiment, in order to make evaluation result more directly perceived, by the change of subject's gait bilateral symmetric property desired value Change trend represents with box diagram mode, as shown in Figure 4.Wherein, abscissa represent subject walking leg speed, respectively 1.0m/s, 1.2m/s, 1.4m/s and 1.6m/s.In figure, "+" represents outlier, shows that the value organizes other data with this and there is significance difference It is different；Horizontal line represents the 50th percentile, i.e. median；In addition, border from top to bottom is followed successively by the 90th, 75,25 and 10 Individual percentile, the flat degree of box represents the intensity of data；Finally, " * " represents the equal of this group of Bilateral Symmetry value It is worth position.

The bilateral symmetric property of movement human bilateral gait curve represents the difference degree of left and right curve, that is, works as symmetric index Be worth for 0 when, bilateral curve similarity highest, symmetry is optimal.In the definition of foundation symmetric index, such as Fig. 4, with subject Downward trend is presented in the raising of walking leg speed, gait bilateral symmetric property index, and the phenomenon illustrates, in this test scope, gait Bilateral symmetric property gradually strengthen with the raising of the speed of travel.In addition, in this process, in box diagram box domain with The raising of the speed of travel more they tends to flattening, and data distribution is more close, illustrates that its stochastic volatility diminishes, symmetric index is taken advantage of It is good.

Claims (1)

1. a kind of gait bilateral symmetric property evaluation method based on regression curve, it is characterised in that this method specifically includes following Step：

Step 1, foot movement acceleration signal is obtained；

In experimental data collection, acceleration transducer is placed in during subject's foot front end, collection gait motion and produced Foot 3-axis acceleration signal, then to original foot 3-axis acceleration signal carry out de-noising pretreatment, isolate signal with Noise, finally reconstructs the acceleration signal sample data after de-noising, obtains gait motion foot acceleration information；

Step 2, the gait bilateral symmetric property index based on regression curve is calculated

The evaluation of gait bilateral symmetric property concentrates on the difference for calculating bilateral gait curve in one gait cycle of analysis；Wherein, Less bilateral curve difference represents higher symmetry；Every bit on curve subtracts and is worth to new curve, calculates Formula is as follows：

$\left\{\begin{array}{c}{\stackrel{\→}{L}}_T\\ {\stackrel{\→}{R}}_T\end{array}\right\}=\left\{\begin{array}{c}{\stackrel{\→}{L}}_o\\ {\stackrel{\→}{R}}_o\end{array}\right\}-\left\{\begin{array}{c}{\stackrel{\→}{L}}_{ave}\\ {\stackrel{\→}{R}}_{ave}\end{array}\right\}---\left(1\right)$

Wherein,WithFor the initial data of left and right sides foot, pass through Three axis accelerometer is obtained；WithFor the left and right curve point after conversion；WithFor the average of left and right curve；

The step state acceleration data being converted to will be calculated during upper oneWithIt is reconstructed into a matrixUnder its matrix M is constituted：

$M={\left[\begin{array}{cc}{\stackrel{\→}{L}}_T& {\stackrel{\→}{R}}_T\end{array}\right]}_{n\×2}={\left[\begin{array}{cc}{l}_{o\left(1\right)}-l_{ave\left(1\right)}& r_{o\left(1\right)}-r_{ave\left(1\right)}\\ l_{o\left(2\right)}-l_{ave\left(2\right)}& r_{o\left(2\right)}-r_{ave\left(2\right)}\\ .& .\\ .& .\\ .& .\\ l_{o(n-1)}-l_{ave(n-1)}& r_{o(n-1)}-r_{ave(n-1)}\\ l_{o\left(n\right)}-l_{ave\left(n\right)}& r_{o\left(n\right)}-r_{ave\left(n\right)}\end{array}\right]}_{n\×2}---\left(2\right)$

Its characteristic vector is calculated to matrix M application singular value decompositions, specific calculation procedure is as follows：

1) basis | λ E-MM^H|=0 obtains matrix MM^HEigenvalue λ₁、λ₂、...、λ_n, while singular value must can be corresponded toAssuming that having j singular value；Wherein E is unit matrix, M^HFor matrix M associate matrix, meter Calculate as follows：

$M^H={\left[\begin{array}{ccccc}\stackrel{\‾}{l_{o\left(1\right)}-l_{ave\left(1\right)}}& \stackrel{\‾}{l_{o\left(2\right)}-l_{ave\left(2\right)}}& \mathrm{...}& \stackrel{\‾}{l_{o(n-1)}-l_{ave(n-1)}}& \stackrel{\‾}{l_{o\left(n\right)}-l_{ave\left(n\right)}}\\ \stackrel{\‾}{r_{o\left(1\right)}-r_{ave\left(1\right)}}& \stackrel{\‾}{r_{o\left(2\right)}-r_{ave\left(2\right)}}& \mathrm{...}& \stackrel{\‾}{r_{o(n-1)}-r_{ave(n-1)}}& \stackrel{\‾}{r_{o\left(n\right)}-r_{ave\left(n\right)}}\end{array}\right]}_{2\×n}---\left(3\right)$

Wherein,For r_o(i)-r_ave(i)Conjugate complex number；

2) eigenvalue λ is calculated respectively_iCorresponding characteristic vectorMeetWherein,Tieed up for n Orthogonal basis in space；Here, matrix M characteristic vector represents the characteristic distributions of all elements in matrix, thus along this The direction of characteristic vector, matrix aberration rate reaches maximum；

On the basis of calculating obtains matrix M characteristic vectors, characteristic vector and coordinate are further tried to achieve according to triangle geometrical relationship Angle between axle and x or y；It is according to the angle, matrix M each row progress is rotationally-varying, it is allowed to along x-axis or y-axis Distribution；Rotation is calculated as follows：

$\left\{\begin{array}{c}{\stackrel{\→}{L}}_{rot}\\ {\stackrel{\→}{R}}_{rot}\end{array}\right\}=\left[\begin{array}{cc}cos\mathrm{\θ}& sin\mathrm{\θ}\\ -sin\mathrm{\θ}& cos\mathrm{\θ}\end{array}\right]\left\{\begin{array}{c}{\stackrel{\→}{L}}_T\\ {\stackrel{\→}{R}}_T\end{array}\right\}---\left(5\right)$

Wherein,WithRespectively postrotational left and right gait curve；θ is the angle of matrix M characteristic vectors and x-axis or y-axis； Postrotational gait curve is distributed along x-axis, and x-axis direction and the rate of change of gait curve on y-axis direction are calculated respectively；Transverse axis becomes Rate varX represents the distortion situation along characteristic vector direction gait curve, and the rate of change varY of y direction is represented along feature Distortion situation on vectorial orthogonal direction, is calculated as follows：

$\mathrm{var}X=\left|{\stackrel{\→}{L}}_{rot}\right|=|{\stackrel{\→}{L}}_{T}cos\mathrm{\θ}+{\stackrel{\→}{R}}_T\sin \mathrm{\θ}|---\left(6\right)$

$\mathrm{var}Y=\left|{\stackrel{\→}{R}}_{rot}\right|=|-{\stackrel{\→}{L}}_{T}sin\mathrm{\θ}+{\stackrel{\→}{R}}_{T}cos\mathrm{\θ}|---\left(7\right)$

HereFor vectorMould,For vectorMould；Thus gait bilateral symmetric property desired value is obtained, is expressed Formula is varY/varX, is represented with a percentage, for evaluating gait symmetry during biped walking, wherein 0% represents most Good symmetry.