Disclosure of Invention
Therefore, the invention provides a myotonic assessment method and a myotonic assessment system based on a recursion diagram and width learning, which are used for solving the problem that the input myotonic signals are not classified accurately by the existing model.
According to an aspect of the present invention, there is provided a myotonic assessment method based on a recursive graph and a width learning, the method comprising the steps of:
step one, collecting muscular tension time series signals of different people, and preprocessing the muscular tension time series signals; wherein the time series signals of the muscular tension of different people comprise time series signals of the muscular tension corresponding to the patients with the mild myotonia, the patients with the severe myotonia and the normal people without the symptoms of the myotonia;
step two, constructing a recursion chart by using the preprocessed muscle tension time sequence signals;
extracting quantized features based on a recursion map, which correspond to muscular tension time series signals of different people;
inputting the quantized features into a classification model based on width learning for training, and obtaining a trained classification model;
and fifthly, extracting quantized features based on a recursion graph and corresponding to the muscle tension time sequence signals to be detected, and inputting the quantized features into a trained classification model to obtain a muscle rigidity prediction result.
Further, the preprocessing in the first step includes rejecting outliers present in the signal.
Further, the specific steps of the second step include: according to a time delay reconstruction principle, carrying out phase space reconstruction on the muscle tension time sequence signal; calculating the distance between any two points in the reconstructed phase space, wherein the distance corresponds to a recursion value; a two-dimensional recursion map is drawn using the plurality of recursion values.
Further, the quantization characteristic in the third step includes a recursion rate, a diagonal length entropy and a capturing time; wherein the recurrence rate is a measure of the density of recurrence points in the recurrence plot; the diagonal length entropy is shannon entropy of the diagonal distribution probability with the length of l in the recursion diagram; the capture time is a weighted average of the lengths of the vertical segments in the recursion chart.
Further, the recursive rate calculation formula is as follows:
wherein N represents the track length in the phase space; r is R i,j The recursive value is represented as a square matrix consisting of 0 and 1.
Further, the diagonal length entropy calculation formula is as follows:
wherein l represents the length of the diagonal line; p (l) represents the distribution probability of a diagonal of length l.
Further, the capturing time calculation formula is as follows:
wherein v represents a line segment perpendicular to the main diagonal, P (v) represents a probability of distribution of a perpendicular line segment of length v, v min Representing the minimum line segment length.
Further, the loss function of the classification model based on the width learning in the step four in the training process includes: the loss function is expressed as:
in the formula ,Zn Representing a mapping feature sequence obtained by nonlinear mapping; h m Representing a mapped feature layer sequence; w (W) m Representing an output weight matrix; λ represents a regularized term coefficient;representing the true value;
the corresponding output weight matrix when the loss function obtains the minimum value is:
wherein I represents an identity matrix.
Further, in the fourth step, the classification model based on the width learning improves the model performance by adding additional enhancement nodes in the training process, the enhancement nodes are generated according to the feature layer calculation, and the new enhancement layer is expressed as:
wherein ,generating a weight matrix and a deviation matrix of the new enhancement node by mapping the feature nodes; ζ represents a nonlinear function.
According to another aspect of the present invention, there is provided a myotonic assessment system based on a recursive graph and a width learning, the system comprising:
the data acquisition module is configured to acquire muscular tension time series signals of different people and preprocess the muscular tension time series signals; wherein the time series signals of the muscular tension of different people comprise time series signals of the muscular tension corresponding to the patients with the mild myotonia, the patients with the severe myotonia and the normal people without the symptoms of the myotonia;
a recurrence map construction module configured to construct a recurrence map using the preprocessed muscle tone time-series signal;
the characteristic extraction module is configured to extract quantized characteristics based on a recursion chart, which correspond to the muscular tension time series signals of different people;
the model training module is configured to input the quantized features into a classification model based on width learning for training, and obtain a trained classification model;
the prediction module is configured to extract quantized features based on a recursion graph corresponding to the muscle tension time sequence signals to be detected, and input the quantized features into a trained classification model to obtain a muscle rigidity prediction result.
The beneficial technical effects of the invention are as follows:
clinically, the degree of myotonia is usually given by doctors according to clinical experience, slight change of the muscle tension is easy to ignore, and the magnitude of the muscle tension is difficult to be quantified, and the invention designs the muscle tension detection device, and acquires muscle tension signals in the process of driving a certain part of a body to perform specific movement by external force so as to realize objective analysis of the muscle tension; the invention carries out quantitative analysis on the muscle tension signal based on a recursion diagram, and obtains the muscle tension characteristic parameter with obvious distinction degree while realizing time sequence visualization; the neural network with independent depth of width learning has the advantages of simple and flexible structure, high calculation speed and stronger nonlinearity, and can meet the requirements of evaluation accuracy and efficiency in the myotonic evaluation process.
Detailed Description
In order that those skilled in the art will better understand the present invention, exemplary embodiments or examples of the present invention will be described below with reference to the accompanying drawings. It is apparent that the described embodiments or examples are only implementations or examples of a part of the invention, not all. All other embodiments or examples, which may be made by one of ordinary skill in the art without undue burden, are intended to be within the scope of the present invention based on the embodiments or examples herein.
The invention provides a myotonia assessment method and a myotonia assessment system based on a recursion chart and width learning, which solve the problem that the change of the myotonia is difficult to objectively assess through quantitative analysis of a myotonia signal.
The embodiment of the invention provides a myotonic assessment method based on a recursion diagram and width learning, as shown in fig. 1, comprising the following steps:
step one, collecting muscular tension time series signals of different people, and preprocessing the muscular tension time series signals; wherein the time series signals of the muscular tension of different people comprise time series signals of the muscular tension corresponding to the patients with the mild myotonia, the patients with the severe myotonia and the normal people without the symptoms of the myotonia;
step two, constructing a recursion chart by using the preprocessed muscle tension time sequence signals;
extracting quantized features based on a recursion map, which correspond to muscular tension time series signals of different people;
inputting the quantized features into a classification model based on width learning for training, and obtaining a trained classification model;
and fifthly, extracting quantized features based on a recursion graph and corresponding to the muscle tension time sequence signals to be detected, and inputting the quantized features into a trained classification model to obtain a muscle rigidity prediction result.
In the first step, a muscle tension signal is collected, and an abnormal value existing in the data is preprocessed and removed.
According to an embodiment of the invention, for data acquisition: and acquiring muscle tension data of a tested person in the movement process of a specific part through a clinical experiment, and recording the blocked force and the position information of the blocked force of the device in the process of driving the body part to perform specific reciprocating movement by external force. The arm is straightened to be used as an initial position, and the motor is used for driving the upper arm to perform specific movements such as uniform low-speed movement, uniform high-speed movement and the like. The encoder is used for collecting the rotation angle of the arm, the output force of the motor when the motor drives the arm to move is equal to the resistance of the arm, and the hardware connection of the detection device is shown in fig. 2. Myotonia data was collected for right arms of healthy persons, mild myotonia, and severe patients.
For data preprocessing: because the data acquisition process inevitably has the reasons of noise, equipment failure, manual misoperation and the like, the acquired data usually has various problems to influence the data analysis result, so the data preprocessing is performed first, and the data quality is improved. Based on an abnormal value detection mode of statistical characteristics, motor output torque data of each tested person in the test process are checked, the absolute value average value of torque under each motion instruction is calculated, and if the average value of a certain period is larger than that of other periods, the motion data of the period is most likely to be influenced by the force actively applied by the tested person, and the motion data are removed.
In the second step, a recursive graph is constructed to analyze the muscle tension time series signal, and the specific steps include:
(1) Reconstructing a phase space: phase space reconstruction is carried out on the time sequence through a time delay reconstruction technology;
(2) And (3) calculating the distance: calculating the distance between any two points in the reconstructed phase space;
(3) And (3) calculating a recursive value: the distance between any two points in the phase space corresponds to a recursion value;
(4) And (3) drawing a recursion chart: the recursion values are plotted as a two-dimensional recursion map.
According to the embodiment of the invention, the time series signal of the muscle tension is made to be u i I=1, 2, n, constructing a recursion graph to analyze the muscle tension time series signal, the method comprises the following specific steps:
(1) Reconstructing a phase space: let x= { X 1 ,X 2 ,X 3 ,...,X N },X i =[u i ,u i+τ ,u i+2τ ,...,u i+(m-1)τ ]Where i=1, 2,..n, n=n- (m-1) τ, N is the track length of X in the reconstructed phase space. m is the embedding dimension, determined using a false nearest neighbor method, as shown in fig. 3 (a), m=3. τ is a delay time, and is a value corresponding to when the value of the mutual information function reaches the first minimum value in the average mutual information method, as shown in fig. 3 (b), τ=5.
(2) And (3) calculating the distance: calculating the distance r between any two points in the reconstructed phase space ij =||X i -X j I, where i, j=1, 2,..n, |·| represents a norm.
(3) And (3) calculating a recursive value: the distance between any two points in the phase space corresponds to a recursion value, R i,j =Θ(ε-||X i -X j ||)=Θ(ε-r ij ) Where i, j=1, 2,..where N, epsilon is a preset threshold distance, Θ (x) is a Heaviside function,
(4) And (3) drawing a recursion chart: r is R i,j Is an n×n square matrix composed of 0 and 1, and on a two-dimensional coordinate axis, i is an abscissa, and j is an ordinate. R is R i,j When 1, the pixel at the two-dimensional coordinate (i, j) is 0, R i,j When 0, the pixel at (i, j) is 255. The recursion chart of the muscular tension signal conversion of the three tested persons is shown in fig. 4.
From an analysis of fig. 4, it can be seen that the three categories of recursion have distinct diagonals parallel to the main diagonal, which corresponds to the period of a fixed instruction in the instruction set. The existence of vertical lines and horizontal lines in the recursion diagrams of healthy people and mild patients indicates that in a certain process, the system phase space track is in an approximately unchanged state, the change of moment values is small, and the moment values correspond to the pause time after the execution of each instruction is finished; more arcs appear in the recurrence plot for a severe patient, indicating that two close trajectories in the phase space have changed at some time.
In the third step, the quantized features based on the recursive graph corresponding to the muscular tension time series signals of different people are extracted, and the graphic features of the recursive graph are analyzed by using the recursive quantization. Some properties of the recursive graph are quantized based on the density of the recursive points of the recursive graph and structural features such as diagonal lines, vertical lines, etc. in the recursive graph. And reserving the recursion characteristics with higher discrimination.
According to the embodiment of the invention, some features of the recursion chart are subjected to recursion quantization analysis, and the result is shown in fig. 5, and the specific description of the features is as follows:
(1) The recurrence rate is a simple measure of the density of recurrence points in a recurrence plot, expressed asN is the track length in phase space.
(2) The diagonal length entropy is shannon entropy of the diagonal distribution probability of length l in the recursion diagram, expressed asP (l) represents the distribution probability of a diagonal of length l. Reflecting the complexity of the recursive diagram with respect to the diagonal, the entropy of the uncorrelated temporal sequences, such as white noise, is very low, indicating that the signal is very low in complexity.
(3) The capture time refers to a weighted average of the lengths of the vertical segments in the recursion map, usingRepresentation, where v denotes a line segment perpendicular to the main diagonal, P (v) is the probability of distribution of a vertical line segment of length v, v min Is the smallest segment length, typically taken as 2. The value reflects that the system is staying at a certain positionThe duration of a particular state can be used to evaluate the stability of the system.
As can be seen from fig. 5, the quantization characteristic of the muscle tension signal based on the recurrence map is well differentiated for three types of tested persons.
In the fourth step, the quantized features are input into a classification model based on width learning for training, and a trained classification model is obtained.
According to an embodiment of the present invention, a width learning model is first constructed. Inputting data X, obtaining a characteristic layer Zn through nonlinear mapping, obtaining a reinforcing layer Hm through the characteristic layer, and obtaining a predicted value output by a width learning model through parallel connection of the reinforcing layer and the characteristic layer by an output weight matrix Wm, namely, obtaining an evaluation result of myotonia. The network structure is shown in fig. 6.
(1) Let the input data be X, through nonlinear mappingObtaining a mapping feature, wherein->Nonlinear activation function, let-> and />The method is characterized in that an input weight matrix and a bias vector are randomly generated, and in order to enable the generated mapping characteristics to be more simplified, a sparse self-coding idea is introduced to optimize the input weight matrix +.>Let Z n =[Z 1 ,Z 2 ,...,Z n ]The random features are generated as a more sparse and compact feature layer.
(2) Mapping feature layer passesGenerating an increaseStrong node, wherein-> and />Is randomly generated, nonlinear function ζ (x) =1/(1+e) -x ) Let the mapping layer be H m =[H 1 ,H 2 ,...,H m ]。
(3) The enhancement layer and the mapping layer are connected in parallel and pass through an output weight matrix W m Obtain output byTo represent the true value, the predicted value y= [ Z ] of the width learning network n |H m ]W m 。
Then, dividing the data set, and training a width learning model; in the training process, a loss function is defined as the square of the difference between the predicted value and the true valueWeight matrix W m The solution is performed by means of a least squares method,to avoid [ Z ] n |H m ]For the case of large errors caused by non-rank full order matrix, the loss function is added with a regularization term based on the ridge regression theory, and isλ represents a regularized term coefficient; the corresponding output weight matrix when the loss function obtains the minimum value is +.>I represents an identity matrix.
In the training process, if the performance of the width learning does not meet the expectations, the model performance is improved by adding additional enhancement nodes, and the newly added nodes are generated according to the feature layer calculation. The new enhancement layer is expressed in the following way wherein />The weight matrix and the deviation matrix of the new enhancement node are generated by mapping the feature nodes.
The muscle tension signal recursion chart quantitative feature set is divided into a training set and a testing set by a five-fold cross validation method. Training the constructed width learning through the training set, and storing the number of nodes and the related numerical value of the output weight matrix when the network performance reaches the expected standard, and verifying the performance of the method by utilizing the data of the testing set. And counting the evaluation results of each test set, wherein the accuracy rate is 89.06%, the accuracy rate is 83.57%, the recall rate is 82.26%, and the confusion matrix is drawn as shown in fig. 7.
Another embodiment of the present invention provides a myotonic assessment system based on a recursive graph and a width learning, the system comprising:
the data acquisition module is configured to acquire muscular tension time series signals of different people and preprocess the muscular tension time series signals; wherein the time series signals of the muscular tension of different people comprise time series signals of the muscular tension corresponding to the patients with the mild myotonia, the patients with the severe myotonia and the normal people without the symptoms of the myotonia;
a recurrence map construction module configured to construct a recurrence map using the preprocessed muscle tone time-series signal;
the characteristic extraction module is configured to extract quantized characteristics based on a recursion chart, which correspond to the muscular tension time series signals of different people;
the model training module is configured to input the quantized features into a classification model based on width learning for training, and obtain a trained classification model;
the prediction module is configured to extract quantized features based on a recursion graph corresponding to the muscle tension time sequence signals to be detected, and input the quantized features into a trained classification model to obtain a muscle rigidity prediction result.
The function of the myotonic assessment system based on the recursion graph and the width learning in the embodiment of the present invention may be illustrated by the aforementioned myotonic assessment method based on the recursion graph and the width learning, so that the system embodiment is not described in detail, and reference may be made to the above method embodiment, which is not described herein.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of the above description, will appreciate that other embodiments are contemplated within the scope of the invention as described herein. The disclosure of the present invention is intended to be illustrative, but not limiting, of the scope of the invention, which is defined by the appended claims.