CN115577245B - Data distribution balancing method and system for RUL prediction of rotating assembly - Google Patents

Data distribution balancing method and system for RUL prediction of rotating assembly Download PDF

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CN115577245B
CN115577245B CN202211547913.6A CN202211547913A CN115577245B CN 115577245 B CN115577245 B CN 115577245B CN 202211547913 A CN202211547913 A CN 202211547913A CN 115577245 B CN115577245 B CN 115577245B
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CN115577245A (en
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刘夏丽
邓耀华
张紫琳
唐佳敏
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Guangdong University of Technology
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Abstract

The invention discloses a data distribution balancing method and system for RUL prediction of a rotating assembly, wherein the method comprises the following steps: and carrying out feature transformation on original signals of the source domain data set and the target domain data set, applying an Autoencoder feature extraction network to carry out feature dimension reduction, introducing a domain classifier, retraining the feature extraction network in the RUL prediction model according to the public property, the self-association and the correspondence requirements of the target features and combining the label data of the source domain and the label-free data of the target domain, and realizing the data distribution balance of the target domain and the source domain through iterative updating of the domain classifier and the feature extractor. According to the invention, self-correlation and correspondence constraint are added in the training process, so that the extraction capability of public features is improved, the capability of the model for processing complex working condition data sample distribution balancing is enhanced, and the migration application of the model under different working conditions is realized.

Description

Data distribution balancing method and system for RUL prediction of rotating assembly
Technical Field
The invention relates to the technical field of information, in particular to a data distribution balancing method and system for RUL prediction of a rotating assembly.
Background
The rotating component is an important component of high-end precise electronic manufacturing equipment, is critical to the normal operation of the equipment, has great influence on the performance of the equipment due to the normal working condition, and is easy to cause secondary damage to the associated component once fatigue failure occurs, thereby causing paralysis of the whole system. Therefore, it is of great practical importance to make predictions of remaining useful life for a rotating multi-component system.
Currently, most deep learning residual life (RUL) predictive models are based on a large number of data samples and the data distribution of the sample data training set and the test set are consistent. In an actual operation scene, the working conditions change frequently due to different environments such as the working load, the rotating speed and the temperature, the data distribution between the training data and the prediction data is unbalanced, and the labeled data in the actual scene is high in acquisition difficulty, small in sample size and incapable of acquiring a sufficient number of labeled data retraining models, so that the feature extractor and the RUL predictor obtained by training a source domain are directly used for a target domain prediction task, and the RUL prediction accuracy is low. Therefore, the capability of the model for processing the distribution balance of the complex working condition data sample is enhanced, and the prediction accuracy of the RUL model under the complex working condition is improved, so that the problem to be solved is urgent at present.
Disclosure of Invention
In order to solve the technical problems, the invention provides a data distribution balancing method and system for RUL prediction of a rotating assembly.
The first aspect of the present invention provides a data distribution balancing method for RUL prediction of a rotating assembly, comprising:
dividing an original signal of a rotating component into a source domain data set and a target domain data set, and carrying out feature transformation through short-time Fourier transformation;
introducing a domain classifier network into an Autoencoder feature extraction network, and constructing an countermeasure migration model with balanced data distribution by combining a circulating neural network based on attention mechanism intervention;
feature dimension reduction is carried out through an countermeasure migration model, a domain classifier and a feature extractor are subjected to countermeasure migration training, and a feature extraction network is retrained by combining tag data of a source domain data set and untagged data of a target domain data set;
and (3) realizing the data distribution balancing of the target domain and the source domain through the iterative updating of the domain classifier and the feature extractor, and predicting the residual service life of the rotating assembly through the data after the data distribution balancing.
In this scheme, the migration countermeasure model is composed of a feature extractor, a decoder, a domain classifier and an RUL predictor, specifically:
The feature extractor
Figure DEST_PATH_IMAGE001
The encoder part of the Autoencoder feature extraction network comprises a 3-layer convolution layer and a 2-layer full-connection layer, is a training object for transfer learning, and is used for extracting common features of a source domain and a target domain;
the decoder
Figure 507246DEST_PATH_IMAGE002
The decoder part of the Autoencoder feature extraction network comprises 3 deconvolution layers and 2 full connection layers, and is used for reconstructing the features extracted by the encoder into time-frequency features, and the self-correlation of the features in the migration process is kept between the specific gravity features and the original input features;
the domain classifier
Figure DEST_PATH_IMAGE003
Is a classification network comprising 2 layers of full connection layers and 1 layer of classification layers for distinguishing whether the extracted features belong to source domain or target domain, and a feature extractor
Figure 127977DEST_PATH_IMAGE001
The method comprises the steps of countertraining, alternately and iteratively updating, wherein the countertraining is used for reducing the data distribution difference between a source domain and a target domain;
the RUL predictor
Figure 35759DEST_PATH_IMAGE004
The RUL prediction network based on the Attention-GRU comprises an SVM classification layer, a 2-layer A-GRU network and a 2-layer full-connection layer, and is a backbone functional network for predicting the residual service life, and the backbone functional network is used for keeping the distinguishing property of public features extracted by a model.
In the scheme, the anti-migration training process is divided into two parts, namely target domain training and source domain training according to data sources, and specifically comprises the following steps:
The target domain training comprises three main body modules of a feature extractor, a decoder and a domain classifier, wherein the feature extractor adjusts network parameters according to errors of the decoder and the domain classifier, and when the feature extractor and the decoder finish updating, the other main body domain classifier of the countermeasure training is updated;
the source domain training comprises two steps of health data training and degradation data training, wherein in the source domain training process, a feature extractor respectively receives errors from an RUL predictor and a domain classifier to adjust network parameters, and the RUL predictor adjusts the network parameters of the RUL predictor;
and when the feature extractor and the RUL predictor finish optimization, the domain classifier is continuously updated and adjusted, and three networks gradually tend to be balanced through iterative training.
In this scheme, the target domain training specifically includes:
the target domain training comprises three main body modules of a feature extractor, a decoder and a domain classifier, wherein data of a target domain is projected to a new feature space in the target domain training, data alignment is carried out on the data of the source domain in the new feature space, and the common features of the source domain and the target domain are learned through the data alignment;
The feature extractor adjusts network parameters according to errors of the decoder and the domain classifier, the decoder receives the errors of the decoder to adjust, when the feature extractor and the decoder finish updating, the domain classifier of the other main body of the countermeasure training is updated along with the updating, and the domain classifier improves the classification accuracy through sample data with domain labels and training times;
the method comprises the steps of selecting and adopting earlier-stage operation data of a rotating assembly system and health data of a source domain to conduct data alignment, and using a loss function when a target domain is used for training to be:
Figure 312413DEST_PATH_IMAGE006
wherein ,
Figure DEST_PATH_IMAGE007
to use the target domain for training the loss function,
Figure 534316DEST_PATH_IMAGE008
respectively, feature extractor
Figure 732255DEST_PATH_IMAGE001
Decoder
Figure 968195DEST_PATH_IMAGE002
Domain classifier
Figure 260374DEST_PATH_IMAGE003
Is used for the network parameters of the (a),
Figure DEST_PATH_IMAGE009
as a loss function of the decoder,
Figure 351214DEST_PATH_IMAGE010
defining domain labels as loss functions of domain classifiers
Figure DEST_PATH_IMAGE011
The source domain label is 0, the target domain label is 1, and the source domain labeled data set is
Figure 851597DEST_PATH_IMAGE012
The target domain unlabeled dataset is
Figure DEST_PATH_IMAGE013
In this scheme, the objective of the domain classifier is to minimize classification errors, and to train with the feature extractor alternately, specifically:
in the training of the domain classifier, the MSE is adopted as a loss function, the training process is optimized through an Adam algorithm, a gradient inversion layer is introduced in the back propagation, and the optimization process of network parameters is as follows:
Figure DEST_PATH_IMAGE015
Figure DEST_PATH_IMAGE017
Figure DEST_PATH_IMAGE019
wherein ,
Figure 461701DEST_PATH_IMAGE020
is the learning rate of the gradient descent algorithm,
Figure DEST_PATH_IMAGE021
Figure 273799DEST_PATH_IMAGE022
Figure DEST_PATH_IMAGE023
respectively, feature extractor
Figure 355281DEST_PATH_IMAGE001
Encoder
Figure 179012DEST_PATH_IMAGE002
Domain classifier
Figure 943705DEST_PATH_IMAGE003
Is an optimization of the Adam of (c),
Figure 148159DEST_PATH_IMAGE009
as a loss function of the decoder,
Figure 203971DEST_PATH_IMAGE010
as a loss function of the domain classifier,
Figure 131476DEST_PATH_IMAGE024
is that
Figure 127725DEST_PATH_IMAGE010
A loss function after gradient inversion layer conversion.
In this scheme, the source domain training specifically includes:
the source domain training comprises three main body modules of a feature extractor, an RUL predictor and a domain classifier, and aims to improve RUL prediction capacity of common features, and is divided into health data training and degradation data training;
in the source domain training process, the feature extractor respectively receives errors from the RUL predictor and the domain classifier to adjust network parameters, the RUL predictor also adjusts the network parameters of the RUL predictor, and a mapping relation between new public features and RUL labels is searched;
after the feature extractor and the RUL predictor finish optimization, the domain classifier is continuously updated and adjusted, three networks gradually tend to be balanced through iterative training, and the optimal values of the overall loss function and the parameters of the source domain training are as follows:
Figure 524202DEST_PATH_IMAGE026
Figure 367393DEST_PATH_IMAGE028
Figure 398672DEST_PATH_IMAGE030
wherein ,
Figure DEST_PATH_IMAGE031
to use the source domain for training the loss function,
Figure 114955DEST_PATH_IMAGE032
respectively, feature extractor
Figure 296931DEST_PATH_IMAGE001
RUL predictor
Figure 694546DEST_PATH_IMAGE004
Domain classifier
Figure 331063DEST_PATH_IMAGE003
Is used for the network parameters of the (a),
Figure DEST_PATH_IMAGE033
as a loss function of the RUL predictor,
Figure 716783DEST_PATH_IMAGE010
as a loss function of the domain classifier,
Figure 822273DEST_PATH_IMAGE034
the gradient inversion layer is represented by a gradient,
Figure DEST_PATH_IMAGE035
and
Figure 56202DEST_PATH_IMAGE036
a health dataset and a degradation dataset of the source domain tagged dataset respectively,
Figure DEST_PATH_IMAGE037
respectively, feature extractor
Figure 625855DEST_PATH_IMAGE001
RUL predictor
Figure 339733DEST_PATH_IMAGE004
Domain classifier
Figure 962213DEST_PATH_IMAGE003
Is used to determine the optimum value of the network parameter,
Figure 154160DEST_PATH_IMAGE038
as a function of the loss,
Figure DEST_PATH_IMAGE039
feature extractors in source domain respectively
Figure 47161DEST_PATH_IMAGE001
Domain classifier
Figure 449716DEST_PATH_IMAGE003
Optimum values of network parameters;
the parameter updating and optimizing method comprises the following steps:
Figure DEST_PATH_IMAGE041
Figure DEST_PATH_IMAGE043
Figure 920012DEST_PATH_IMAGE044
wherein ,
Figure 430497DEST_PATH_IMAGE020
is the learning rate of the gradient descent algorithm,
Figure 896113DEST_PATH_IMAGE021
Figure DEST_PATH_IMAGE045
Figure 499264DEST_PATH_IMAGE023
respectively, feature extractor
Figure 315910DEST_PATH_IMAGE001
RUL predictor
Figure 355717DEST_PATH_IMAGE004
Domain classifier
Figure 144682DEST_PATH_IMAGE003
Is an optimization of the Adam of (c),
Figure 387576DEST_PATH_IMAGE033
as a loss function of the RUL predictor,
Figure 691518DEST_PATH_IMAGE010
is the loss function of the domain classifier.
The second aspect of the present invention also provides a data distribution balancing system for RUL prediction of a rotating assembly, the system comprising: the system comprises a memory and a processor, wherein the memory comprises a rotating assembly RUL predicted data distribution balance method program, and the rotating assembly RUL predicted data distribution balance method program realizes the following steps when being executed by the processor:
dividing an original signal of a rotating component into a source domain data set and a target domain data set, and carrying out feature transformation through short-time Fourier transformation;
Introducing a domain classifier network into an Autoencoder feature extraction network, and constructing an countermeasure migration model with balanced data distribution by combining a circulating neural network based on attention mechanism intervention;
feature dimension reduction is carried out through an countermeasure migration model, a domain classifier and a feature extractor are subjected to countermeasure migration training, and a feature extraction network is retrained by combining tag data of a source domain data set and untagged data of a target domain data set;
and (3) realizing the data distribution balancing of the target domain and the source domain through the iterative updating of the domain classifier and the feature extractor, and predicting the residual service life of the rotating assembly through the data after the data distribution balancing.
The invention discloses a data distribution balancing method and system for RUL prediction of a rotating assembly, wherein the method comprises the following steps: and carrying out feature transformation on original signals of the source domain data set and the target domain data set, applying an Autoencoder feature extraction network to carry out feature dimension reduction, introducing a domain classifier, retraining the feature extraction network in the RUL prediction model according to the public property, the self-association and the correspondence requirements of the target features and combining the label data of the source domain and the label-free data of the target domain, and realizing the data distribution balance of the target domain and the source domain through iterative updating of the domain classifier and the feature extractor. According to the invention, self-correlation and correspondence constraint are added in the training process, so that the extraction capability of public features is improved, the capability of the model for processing complex working condition data sample distribution balancing is enhanced, and the migration application of the model under different working conditions is realized.
Drawings
FIG. 1 is a flow chart illustrating a method of data distribution balancing for rotating assembly RUL prediction in accordance with the present invention;
FIG. 2 illustrates a block diagram of a data distribution balancing method of rotating assembly RUL prediction of the present invention;
FIG. 3 is a schematic diagram of a migration training process in accordance with the present invention;
FIG. 4 illustrates a block diagram of a data distribution balancing system of the rotating assembly RUL prediction of the present invention.
Detailed Description
In order that the above-recited objects, features and advantages of the present invention will be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description. It should be noted that, in the case of no conflict, the embodiments of the present application and the features in the embodiments may be combined with each other.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those described herein, and therefore the scope of the present invention is not limited to the specific embodiments disclosed below.
FIGS. 1 and 2 are a flow chart and block diagram illustrating a data distribution balancing method for rotating assembly RUL prediction according to the present invention.
As shown in fig. 1 and 2, a first aspect of the present invention provides a data distribution balancing method for RUL prediction of a rotating assembly, including:
S102, dividing an original signal of a rotating assembly into a source domain data set and a target domain data set, and performing feature transformation through short-time Fourier transformation;
s104, introducing a domain classifier network into an Autoencoder feature extraction network, and constructing an countermeasure migration model with balanced data distribution by combining a circulating neural network based on attention mechanism intervention;
s106, performing feature dimension reduction through an anti-migration model, performing anti-migration training on the domain classifier and the feature extractor, and retraining the feature extraction network by combining the label data of the source domain data set and the label-free data of the target domain data set;
s108, realizing data distribution balancing of the target domain and the source domain through iterative updating of the domain classifier and the feature extractor, and predicting the residual service life of the rotating assembly through data after data distribution balancing.
It should be noted that, firstly, the feature transformation is performed on the original signals (the source domain data set and the target domain data set) through short-time fourier transform (STFT), and then the Autoencoder feature extraction network is applied to further reduce the dimension of the features, so as to obtain the health index of the rotating multi-component system. The rotating component performance state evolution stage is divided by an SVM, and then each part of input data is given different weights by adopting a variant network A-GRU (Gated Recurrent Unit) of a circulating neural network with Attention mechanism (Attention) intervention, so that more key and more important information is extracted for the residual service life prediction of the multiple components.
In the process of reducing the dimension of the features by an Autoencoder feature extraction network, a domain classifier network (Domain Classifier) is introduced
Figure 497800DEST_PATH_IMAGE003
And retraining a feature extraction network in the RUL prediction model according to the public, self-association and correspondence requirements of the target features by combining the label data of the source domain and the label-free data of the target domain, and realizing the data distribution balance of the target domain and the source domain through iterative updating of the domain classifier and the feature extractor.
The anti-migration model is composed of a feature extractor, a decoder, a domain classifier and an RUL predictor, and specifically comprises the following steps: the feature extractor
Figure 452855DEST_PATH_IMAGE001
The encoder part of the Autoencoder feature extraction network comprises a 3-layer convolution layer and a 2-layer full-connection layer, is a training object for transfer learning, and is used for extracting common features of a source domain and a target domain; the decoder
Figure 850339DEST_PATH_IMAGE002
The decoder part of the Autoencoder feature extraction network comprises 3 deconvolution layers and 2 full connection layers, and is used for reconstructing the features extracted by the encoder into time-frequency features, and the self-correlation of the features in the migration process is kept between the specific gravity features and the original input features; the domain classifier
Figure 392309DEST_PATH_IMAGE003
Is a classification network comprising a 2-layer full connection layer and a 1-layer classification layer for distinguishing extraction The obtained features belong to the source domain or the target domain, and a feature extractor
Figure 533441DEST_PATH_IMAGE001
The method comprises the steps of countertraining, alternately and iteratively updating, wherein the countertraining is used for reducing the data distribution difference between a source domain and a target domain; the RUL predictor
Figure 611512DEST_PATH_IMAGE004
The RUL prediction network based on the Attention-GRU comprises an SVM classification layer, a 2-layer A-GRU network and a 2-layer full-connection layer, is a main functional network for predicting the residual service life, and aims to enable the network to obtain prediction capacity similar to that of a source domain in a target domain scene, and the role in a migration process is to keep the distinguishing property of public features extracted by the model.
Feature extractor
Figure 383159DEST_PATH_IMAGE001
Through a decoder
Figure 412426DEST_PATH_IMAGE002
Domain classifier
Figure 357248DEST_PATH_IMAGE003
RUL predictor
Figure 21316DEST_PATH_IMAGE004
The three networks are used for adjusting the countermeasure training, and the purposes of adjustment are three, firstly, the accurate classification of the source domain data set is realized, the distinguishing property of the characteristics is ensured, and the minimization of classification errors is realized; secondly, the public features of the source domain data and the target domain data are extracted, so that the maximization of domain classification errors is realized; thirdly, the corresponding relation between the extracted features and the original data is ensured, the minimization of the reconstruction error is realized, and the self-association of the features is ensured.
The self-association of the features means that the features extracted by the network can be reconstructed and correspond to the original data, and because the data of the target domain has no label, whether the extracted features correspond to the original data is difficult to judge, the constraint of the self-association can keep the structural information of the features, and the phenomenon that the feature extractor performs indiscriminate compression extraction on the data is avoided. The distinguishing of the features means that the extracted features do not lose the capability of classification prediction, and the association with the sample label is still reserved. The feature commonality means that the features extracted from the source domain and the target domain can remove domain bias information and have the same edge probability distribution.
Fig. 3 shows a schematic diagram of a migration training procedure in the present invention.
It should be noted that, the challenge migration training process is divided into two parts of target domain training and source domain training according to the data source, the target domain training includes three main body modules of a feature extractor, a decoder and a domain classifier, the feature extractor adjusts network parameters according to errors of the decoder and the domain classifier, and when the feature extractor and the decoder complete updating, another main body domain classifier of the challenge training is updated accordingly;
the source domain training comprises two steps of health data training and degradation data training, wherein in the source domain training process, a feature extractor respectively receives errors from an RUL predictor and a domain classifier to adjust network parameters, and the RUL predictor adjusts the network parameters of the RUL predictor;
and when the feature extractor and the RUL predictor finish optimization, the domain classifier is continuously updated and adjusted, and three networks gradually tend to be balanced through iterative training.
The target domain training comprises three main body modules of a feature extractor, a decoder and a domain classifier, wherein data of a target domain is projected to a new feature space in the target domain training, data alignment is carried out on the data of the source domain in the new feature space, and the common features of the source domain and the target domain are learned through the data alignment;
The feature extractor adjusts network parameters according to the errors of the decoder and the domain classifier, which means that the data distribution difference between the target domain and the source domain in the new feature mapping space is reduced, and the recognition degree of the data is maintained. The decoder receives the error of the decoder to adjust, namely, the decoder adapts to the reconstruction relation between the new public features and the original data by adjusting the network parameters of the network, and after the feature extractor and the decoder finish updating, the domain classifier of the other main body of the countermeasure training is updated accordingly, and the domain classifier improves the classification accuracy by the sample data with the domain labels and the training times;
in the migration scene, the target domain data are all unlabeled, and in order to ensure that the corresponding relation between the features obtained by the feature extractor and the original data exists, the features are reconstructed through a decoder, and an encoder-decoder structure is formed with the feature extractor to realize self-supervision constraint. If the full life cycle data of the rotating multi-component system is used for extracting the common features, due to the missing label, the mismatching with the source domain data can be caused, and the negative migration phenomenon occurs. The rotating multi-component system is in a healthy state at the initial stage of operation, so that the common characteristics are extracted more accurately, the convergence rate of training is accelerated, the data alignment is carried out by selecting the front-stage operation data of the rotating component system and the healthy data of the source domain, and the loss function when the target domain is used for training is as follows:
Figure 26181DEST_PATH_IMAGE046
wherein ,
Figure 277165DEST_PATH_IMAGE007
to use the target domain for training the loss function,
Figure 556837DEST_PATH_IMAGE008
respectively, feature extractor
Figure 78341DEST_PATH_IMAGE001
Decoder
Figure 535999DEST_PATH_IMAGE002
Domain classifier
Figure 789126DEST_PATH_IMAGE003
Is used for the network parameters of the (a),
Figure 590597DEST_PATH_IMAGE009
as a loss function of the decoder,
Figure 979990DEST_PATH_IMAGE010
defining domain labels as loss functions of domain classifiers
Figure 280653DEST_PATH_IMAGE011
The source domain label is 0, the target domain label is 1, and the source domain labeled data set is
Figure 755496DEST_PATH_IMAGE012
The target domain unlabeled dataset is
Figure 832430DEST_PATH_IMAGE013
It should be noted that, the objective of the domain classifier is to minimize the classification error, and the feature extractor is to confuse the domain classifier to maximize the classification error, where the optimization paths of the two networks for the classification error are opposite, and usually, one network needs to be fixed first and the other network needs to be trained; in the training of the domain classifier, the MSE is adopted as a loss function, the training process is optimized through an Adam algorithm, a gradient inversion layer is introduced in the back propagation, and the optimization process of network parameters is as follows:
Figure 76330DEST_PATH_IMAGE015
Figure 344631DEST_PATH_IMAGE017
Figure 306771DEST_PATH_IMAGE019
wherein ,
Figure 184466DEST_PATH_IMAGE020
is the learning rate of the gradient descent algorithm,
Figure 282872DEST_PATH_IMAGE021
Figure 518812DEST_PATH_IMAGE022
Figure 171511DEST_PATH_IMAGE023
respectively, feature extractor
Figure 398703DEST_PATH_IMAGE001
Encoder
Figure 820457DEST_PATH_IMAGE002
Domain classifier
Figure 430561DEST_PATH_IMAGE003
Is an optimization of the Adam of (c),
Figure 367293DEST_PATH_IMAGE009
as a loss function of the decoder,
Figure 852370DEST_PATH_IMAGE010
as a loss function of the domain classifier,
Figure 925368DEST_PATH_IMAGE024
is that
Figure 706374DEST_PATH_IMAGE010
A loss function after gradient inversion layer conversion.
The source domain training comprises three main body modules of a feature extractor, an RUL predictor and a domain classifier, and aims to improve RUL prediction capacity of common features, and is divided into health data training and degradation data training; because the label data is trained, the health state of the data is not needed to be distinguished by a network model, the SVM classifier is skipped in the source domain training process, and the network parameters of the SVM classifier are updated after the training of the feature extractor and the RUL predictor is completed. In an actual scene, the target domain only selects the early-stage operation data of the rotary multi-component system for transfer learning, and the early-stage data is health data, so that the data of the health tag is also selected for data alignment in source domain training, and effective public features are extracted.
In the source domain training process, the feature extractor respectively receives errors from the RUL predictor and the domain classifier to adjust network parameters, the RUL predictor also adjusts the network parameters of the RUL predictor, and a mapping relation between new public features and RUL labels is searched; after the feature extractor and the RUL predictor finish optimization, the domain classifier is continuously updated and adjusted, three networks gradually tend to be balanced through iterative training, and the overall loss function of source domain training is as follows:
Figure 68085DEST_PATH_IMAGE026
according to the objective function of the network parameter optimization of the feature extractor and the RUL predictor, the network parameter optimal value is obtained, and the objective function is as follows:
Figure 576427DEST_PATH_IMAGE028
Figure 21708DEST_PATH_IMAGE030
wherein ,
Figure 222882DEST_PATH_IMAGE031
to use the source domain for training the loss function,
Figure 884939DEST_PATH_IMAGE032
respectively, feature extractor
Figure 196971DEST_PATH_IMAGE001
RUL predictor
Figure 493829DEST_PATH_IMAGE004
Domain classifier
Figure 865905DEST_PATH_IMAGE003
Is used for the network parameters of the (a),
Figure 952941DEST_PATH_IMAGE033
as a loss function of the RUL predictor,
Figure 68664DEST_PATH_IMAGE010
as a loss function of the domain classifier,
Figure 222959DEST_PATH_IMAGE034
the gradient inversion layer is represented by a gradient,
Figure 765935DEST_PATH_IMAGE035
and
Figure 137005DEST_PATH_IMAGE036
a health dataset and a degradation dataset of the source domain tagged dataset respectively,
Figure 56419DEST_PATH_IMAGE037
respectively, feature extractor
Figure 62290DEST_PATH_IMAGE001
RUL predictor
Figure 979431DEST_PATH_IMAGE004
Domain classifier
Figure 87064DEST_PATH_IMAGE003
Is used to determine the optimum value of the network parameter,
Figure 295323DEST_PATH_IMAGE038
as a function of the loss,
Figure 906433DEST_PATH_IMAGE039
feature extractors in source domain respectively
Figure 308988DEST_PATH_IMAGE001
Domain classifier
Figure 107180DEST_PATH_IMAGE003
Optimum values of network parameters;
The parameter updating and optimizing method comprises the following steps:
Figure 853550DEST_PATH_IMAGE041
Figure 584746DEST_PATH_IMAGE043
Figure 155274DEST_PATH_IMAGE019
wherein ,
Figure 706341DEST_PATH_IMAGE020
is the learning rate of the gradient descent algorithm,
Figure 318719DEST_PATH_IMAGE021
Figure 904421DEST_PATH_IMAGE045
Figure 371481DEST_PATH_IMAGE023
respectively, feature extractor
Figure 409844DEST_PATH_IMAGE001
RUL predictor
Figure 763597DEST_PATH_IMAGE004
Domain classifier
Figure 469384DEST_PATH_IMAGE003
Is an optimization of the Adam of (c),
Figure 381714DEST_PATH_IMAGE033
pre-preparation for RULThe loss function of the meter is determined,
Figure 907374DEST_PATH_IMAGE010
is the loss function of the domain classifier.
FIG. 4 illustrates a block diagram of a data distribution balancing system of the rotating assembly RUL prediction of the present invention.
The second aspect of the present invention also provides a data distribution balancing system for RUL prediction of a rotating assembly, the system comprising: the system comprises a memory and a processor, wherein the memory comprises a rotating assembly RUL predicted data distribution balance method program, and the rotating assembly RUL predicted data distribution balance method program realizes the following steps when being executed by the processor:
dividing an original signal of a rotating component into a source domain data set and a target domain data set, and carrying out feature transformation through short-time Fourier transformation;
introducing a domain classifier network into an Autoencoder feature extraction network, and constructing an countermeasure migration model with balanced data distribution by combining a circulating neural network based on attention mechanism intervention;
feature dimension reduction is carried out through an countermeasure migration model, a domain classifier and a feature extractor are subjected to countermeasure migration training, and a feature extraction network is retrained by combining tag data of a source domain data set and untagged data of a target domain data set;
And (3) realizing the data distribution balancing of the target domain and the source domain through the iterative updating of the domain classifier and the feature extractor, and predicting the residual service life of the rotating assembly through the data after the data distribution balancing.
It should be noted that, firstly, the feature transformation is performed on the original signals (the source domain data set and the target domain data set) through short-time fourier transform (STFT), and then the Autoencoder feature extraction network is applied to further reduce the dimension of the features, so as to obtain the health index of the rotating multi-component system. The rotating component performance state evolution stage is divided by an SVM, and then each part of input data is given different weights by adopting a variant network A-GRU (Gated Recurrent Unit) of a circulating neural network with Attention mechanism (Attention) intervention, so that more key and more important information is extracted for the residual service life prediction of the multiple components.
In the process of reducing the dimension of the features by an Autoencoder feature extraction network, a domain classifier network (Domain Classifier) is introduced
Figure 64817DEST_PATH_IMAGE003
And retraining a feature extraction network in the RUL prediction model according to the public, self-association and correspondence requirements of the target features by combining the label data of the source domain and the label-free data of the target domain, and realizing the data distribution balance of the target domain and the source domain through iterative updating of the domain classifier and the feature extractor.
The anti-migration model is composed of a feature extractor, a decoder, a domain classifier and an RUL predictor, and specifically comprises the following steps: the feature extractor
Figure 828373DEST_PATH_IMAGE001
The encoder part of the Autoencoder feature extraction network comprises a 3-layer convolution layer and a 2-layer full-connection layer, is a training object for transfer learning, and is used for extracting common features of a source domain and a target domain; the decoder
Figure 648955DEST_PATH_IMAGE002
The decoder part of the Autoencoder feature extraction network comprises 3 deconvolution layers and 2 full connection layers, and is used for reconstructing the features extracted by the encoder into time-frequency features, and the self-correlation of the features in the migration process is kept between the specific gravity features and the original input features; the domain classifier
Figure 927490DEST_PATH_IMAGE003
Is a classification network comprising 2 layers of full connection layers and 1 layer of classification layers for distinguishing whether the extracted features belong to source domain or target domain, and a feature extractor
Figure 623044DEST_PATH_IMAGE001
The method comprises the steps of countertraining, alternately and iteratively updating, wherein the countertraining is used for reducing the data distribution difference between a source domain and a target domain; the RUL predictor
Figure 37845DEST_PATH_IMAGE004
The RUL prediction network based on the Attention-GRU comprises an SVM classification layer, a 2-layer A-GRU network and a 2-layer full-connection layer, is a main functional network for predicting the residual service life, and aims to enable the network to obtain prediction capacity similar to that of a source domain in a target domain scene, and the role in a migration process is to keep the distinguishing property of public features extracted by the model.
Feature extractor
Figure 26399DEST_PATH_IMAGE001
Through a decoder
Figure 526650DEST_PATH_IMAGE002
Domain classifier
Figure 25896DEST_PATH_IMAGE003
RUL predictor
Figure 295203DEST_PATH_IMAGE004
The three networks are used for adjusting the countermeasure training, and the purposes of adjustment are three, firstly, the accurate classification of the source domain data set is realized, the distinguishing property of the characteristics is ensured, and the minimization of classification errors is realized; secondly, the public features of the source domain data and the target domain data are extracted, so that the maximization of domain classification errors is realized; thirdly, the corresponding relation between the extracted features and the original data is ensured, the minimization of the reconstruction error is realized, and the self-association of the features is ensured.
The self-association of the features means that the features extracted by the network can be reconstructed and correspond to the original data, and because the data of the target domain has no label, whether the extracted features correspond to the original data is difficult to judge, the constraint of the self-association can keep the structural information of the features, and the phenomenon that the feature extractor performs indiscriminate compression extraction on the data is avoided. The distinguishing of the features means that the extracted features do not lose the capability of classification prediction, and the association with the sample label is still reserved. The feature commonality means that the features extracted from the source domain and the target domain can remove domain bias information and have the same edge probability distribution.
It should be noted that, the challenge migration training process is divided into two parts of target domain training and source domain training according to the data source, the target domain training includes three main body modules of a feature extractor, a decoder and a domain classifier, the feature extractor adjusts network parameters according to errors of the decoder and the domain classifier, and when the feature extractor and the decoder complete updating, another main body domain classifier of the challenge training is updated accordingly;
the source domain training comprises two steps of health data training and degradation data training, wherein in the source domain training process, a feature extractor respectively receives errors from an RUL predictor and a domain classifier to adjust network parameters, and the RUL predictor adjusts the network parameters of the RUL predictor;
and when the feature extractor and the RUL predictor finish optimization, the domain classifier is continuously updated and adjusted, and three networks gradually tend to be balanced through iterative training.
The target domain training comprises three main body modules of a feature extractor, a decoder and a domain classifier, wherein data of a target domain is projected to a new feature space in the target domain training, data alignment is carried out on the data of the source domain in the new feature space, and the common features of the source domain and the target domain are learned through the data alignment;
The feature extractor adjusts network parameters according to the errors of the decoder and the domain classifier, which means that the data distribution difference between the target domain and the source domain in the new feature mapping space is reduced, and the recognition degree of the data is maintained. The decoder receives the error of the decoder to adjust, namely, the decoder adapts to the reconstruction relation between the new public features and the original data by adjusting the network parameters of the network, and after the feature extractor and the decoder finish updating, the domain classifier of the other main body of the countermeasure training is updated accordingly, and the domain classifier improves the classification accuracy by the sample data with the domain labels and the training times;
in the migration scene, the target domain data are all unlabeled, and in order to ensure that the corresponding relation between the features obtained by the feature extractor and the original data exists, the features are reconstructed through a decoder, and an encoder-decoder structure is formed with the feature extractor to realize self-supervision constraint. If the full life cycle data of the rotating multi-component system is used for extracting the common features, due to the missing label, the mismatching with the source domain data can be caused, and the negative migration phenomenon occurs. The rotating multi-component system is in a healthy state at the initial stage of operation, so that the common characteristics are extracted more accurately, the convergence rate of training is accelerated, the data alignment is carried out by selecting the front-stage operation data of the rotating component system and the healthy data of the source domain, and the loss function when the target domain is used for training is as follows:
Figure DEST_PATH_IMAGE047
wherein ,
Figure 316642DEST_PATH_IMAGE007
to use the target domain for training the loss function,
Figure 851660DEST_PATH_IMAGE008
respectively, feature extractor
Figure 653131DEST_PATH_IMAGE001
Decoder
Figure 42525DEST_PATH_IMAGE002
Domain classifier
Figure 139925DEST_PATH_IMAGE003
Is used for the network parameters of the (a),
Figure 349189DEST_PATH_IMAGE009
as a loss function of the decoder,
Figure 691702DEST_PATH_IMAGE010
defining domain labels as loss functions of domain classifiers
Figure 201181DEST_PATH_IMAGE011
The source domain label is 0, the target domain label is 1, and the source domain labeled data set is
Figure 469482DEST_PATH_IMAGE012
The target domain unlabeled dataset is
Figure 166043DEST_PATH_IMAGE013
It should be noted that, the objective of the domain classifier is to minimize the classification error, and the feature extractor is to confuse the domain classifier to maximize the classification error, where the optimization paths of the two networks for the classification error are opposite, and usually, one network needs to be fixed first and the other network needs to be trained; in the training of the domain classifier, the MSE is adopted as a loss function, the training process is optimized through an Adam algorithm, a gradient inversion layer is introduced in the back propagation, and the optimization process of network parameters is as follows:
Figure 309317DEST_PATH_IMAGE015
Figure 407723DEST_PATH_IMAGE048
Figure 50188DEST_PATH_IMAGE044
wherein ,
Figure 499624DEST_PATH_IMAGE020
is the learning rate of the gradient descent algorithm,
Figure 135005DEST_PATH_IMAGE021
Figure 945309DEST_PATH_IMAGE022
Figure 352150DEST_PATH_IMAGE023
respectively are provided withIs a feature extractor
Figure 272571DEST_PATH_IMAGE001
Encoder
Figure 242801DEST_PATH_IMAGE002
Domain classifier
Figure 332111DEST_PATH_IMAGE003
Is an optimization of the Adam of (c),
Figure 565646DEST_PATH_IMAGE009
as a loss function of the decoder,
Figure 241871DEST_PATH_IMAGE010
as a loss function of the domain classifier,
Figure 15792DEST_PATH_IMAGE024
is that
Figure 412138DEST_PATH_IMAGE010
A loss function after gradient inversion layer conversion.
The source domain training comprises three main body modules of a feature extractor, an RUL predictor and a domain classifier, and aims to improve RUL prediction capacity of common features, and is divided into health data training and degradation data training; because the label data is trained, the health state of the data is not needed to be distinguished by a network model, the SVM classifier is skipped in the source domain training process, and the network parameters of the SVM classifier are updated after the training of the feature extractor and the RUL predictor is completed. In an actual scene, the target domain only selects the early-stage operation data of the rotary multi-component system for transfer learning, and the early-stage data is health data, so that the data of the health tag is also selected for data alignment in source domain training, and effective public features are extracted.
In the source domain training process, the feature extractor respectively receives errors from the RUL predictor and the domain classifier to adjust network parameters, the RUL predictor also adjusts the network parameters of the RUL predictor, and a mapping relation between new public features and RUL labels is searched; after the feature extractor and the RUL predictor finish optimization, the domain classifier is continuously updated and adjusted, three networks gradually tend to be balanced through iterative training, and the overall loss function of source domain training is as follows:
Figure 832887DEST_PATH_IMAGE026
According to the objective function of the network parameter optimization of the feature extractor and the RUL predictor, the network parameter optimal value is obtained, and the objective function is as follows:
Figure 478632DEST_PATH_IMAGE028
Figure 259506DEST_PATH_IMAGE030
wherein ,
Figure 821943DEST_PATH_IMAGE031
to use the source domain for training the loss function,
Figure 397281DEST_PATH_IMAGE032
respectively, feature extractor
Figure 281054DEST_PATH_IMAGE001
RUL predictor
Figure 600040DEST_PATH_IMAGE004
Domain classifier
Figure 767716DEST_PATH_IMAGE003
Is used for the network parameters of the (a),
Figure 766153DEST_PATH_IMAGE033
as a loss function of the RUL predictor,
Figure 652069DEST_PATH_IMAGE010
as a loss function of the domain classifier,
Figure 774746DEST_PATH_IMAGE034
the gradient inversion layer is represented by a gradient,
Figure 547661DEST_PATH_IMAGE035
and
Figure 464801DEST_PATH_IMAGE036
a health dataset and a degradation dataset of the source domain tagged dataset respectively,
Figure 821702DEST_PATH_IMAGE037
respectively, feature extractor
Figure 482491DEST_PATH_IMAGE001
RUL predictor
Figure 359180DEST_PATH_IMAGE004
Domain classifier
Figure 463533DEST_PATH_IMAGE003
Is used to determine the optimum value of the network parameter,
Figure 58463DEST_PATH_IMAGE038
as a function of the loss,
Figure 522942DEST_PATH_IMAGE039
feature extractors in source domain respectively
Figure 506335DEST_PATH_IMAGE001
Domain classifier
Figure 30857DEST_PATH_IMAGE003
Optimum values of network parameters;
the parameter updating and optimizing method comprises the following steps:
Figure 598236DEST_PATH_IMAGE041
Figure 928723DEST_PATH_IMAGE043
Figure 763693DEST_PATH_IMAGE044
wherein ,
Figure 459116DEST_PATH_IMAGE020
is the learning rate of the gradient descent algorithm,
Figure 966321DEST_PATH_IMAGE021
Figure 320073DEST_PATH_IMAGE045
Figure 25861DEST_PATH_IMAGE023
respectively, feature extractor
Figure 892186DEST_PATH_IMAGE001
RUL predictor
Figure 189482DEST_PATH_IMAGE004
Domain classifier
Figure 674821DEST_PATH_IMAGE003
Is an optimization of the Adam of (c),
Figure 749962DEST_PATH_IMAGE033
as a loss function of the RUL predictor,
Figure 52768DEST_PATH_IMAGE010
is the loss function of the domain classifier.
In the several embodiments provided in this application, it should be understood that the disclosed apparatus and method may be implemented in other ways. The above described device embodiments are only illustrative, e.g. the division of the units is only one logical function division, and there may be other divisions in practice, such as: multiple units or components may be combined or may be integrated into another system, or some features may be omitted, or not performed. In addition, the various components shown or discussed may be coupled or directly coupled or communicatively coupled to each other via some interface, whether indirectly coupled or communicatively coupled to devices or units, whether electrically, mechanically, or otherwise.
The units described above as separate components may or may not be physically separate, and components shown as units may or may not be physical units; can be located in one place or distributed to a plurality of network units; some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in each embodiment of the present invention may be integrated in one processing unit, or each unit may be separately used as one unit, or two or more units may be integrated in one unit; the integrated units may be implemented in hardware or in hardware plus software functional units.
Those of ordinary skill in the art will appreciate that: all or part of the steps for implementing the above method embodiments may be implemented by hardware related to program instructions, and the foregoing program may be stored in a computer readable storage medium, where the program, when executed, performs steps including the above method embodiments; and the aforementioned storage medium includes: a mobile storage device, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk or an optical disk, or the like, which can store program codes.
Alternatively, the above-described integrated units of the present invention may be stored in a computer-readable storage medium if implemented in the form of software functional modules and sold or used as separate products. Based on such understanding, the technical solutions of the embodiments of the present invention may be embodied in essence or a part contributing to the prior art in the form of a software product stored in a storage medium, including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the methods described in the embodiments of the present invention. And the aforementioned storage medium includes: a removable storage device, ROM, RAM, magnetic or optical disk, or other medium capable of storing program code.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (3)

1. A method for predicting the remaining useful life of a rotating assembly, comprising the steps of:
dividing an original signal of a rotating component into a source domain data set and a target domain data set, and carrying out feature transformation through short-time Fourier transformation;
introducing a domain classifier network into an Autoencoder feature extraction network, and constructing an countermeasure migration model with balanced data distribution by combining a circulating neural network based on attention mechanism intervention;
feature dimension reduction is carried out through an countermeasure migration model, a domain classifier and a feature extractor are subjected to countermeasure migration training, and a feature extraction network is retrained by combining tag data of a source domain data set and untagged data of a target domain data set;
the data distribution balance of the target domain and the source domain is realized through the iterative updating of the domain classifier and the feature extractor, and the residual service life of the rotating assembly is predicted through the data after the data distribution balance;
the anti-migration training process is divided into two parts, namely target domain training and source domain training according to data sources, and specifically comprises the following steps:
the target domain training comprises three main body modules of a feature extractor, a decoder and a domain classifier, wherein the feature extractor adjusts network parameters according to errors of the decoder and the domain classifier, and when the feature extractor and the decoder finish updating, the other main body domain classifier of the countermeasure training is updated;
The source domain training comprises two steps of health data training and degradation data training, wherein in the source domain training process, a feature extractor respectively receives errors from an RUL predictor and a domain classifier to adjust network parameters, and the RUL predictor adjusts the network parameters of the RUL predictor;
the method comprises the following steps of training a target domain, wherein after the feature extractor and the RUL predictor finish optimization, updating and adjusting the domain classifier are continuously carried out, and three networks gradually tend to be balanced through iterative training;
the target domain training specifically comprises the following steps:
the target domain training comprises three main body modules of a feature extractor, a decoder and a domain classifier, wherein data of a target domain is projected to a new feature space in the target domain training, data alignment is carried out on the data of the source domain in the new feature space, and the common features of the source domain and the target domain are learned through the data alignment;
the feature extractor adjusts network parameters according to errors of the decoder and the domain classifier, the decoder receives the errors of the decoder to adjust, when the feature extractor and the decoder finish updating, the domain classifier of the other main body of the countermeasure training is updated along with the updating, and the domain classifier improves the classification accuracy through sample data with domain labels and training times;
The method comprises the steps of selecting and adopting earlier-stage operation data of a rotating assembly system and health data of a source domain to conduct data alignment, and using a loss function when a target domain is used for training to be:
Figure QLYQS_1
wherein ,
Figure QLYQS_3
loss function for training using the target domain, +.>
Figure QLYQS_6
Feature extractor->
Figure QLYQS_7
Decoder->
Figure QLYQS_4
Domain classifier->
Figure QLYQS_8
Network parameters of->
Figure QLYQS_9
For the loss function of the decoder, < >>
Figure QLYQS_10
For the loss function of the domain classifier, the domain label is defined as +.>
Figure QLYQS_2
The source domain label is 0, the target domain label is 1, and the target domain unlabeled dataset is +.>
Figure QLYQS_5
The objective of the domain classifier is to minimize classification errors, and to train with feature extractors alternately, specifically:
in the training of the domain classifier, the MSE is adopted as a loss function, the training process is optimized through an Adam algorithm, a gradient inversion layer is introduced in the back propagation, and the optimization process of network parameters is as follows:
Figure QLYQS_11
Figure QLYQS_12
;/>
Figure QLYQS_13
wherein ,
Figure QLYQS_14
is the learning rate of the gradient descent algorithm, +.>
Figure QLYQS_18
,/>
Figure QLYQS_21
,/>
Figure QLYQS_16
Feature extractor->
Figure QLYQS_17
Decoder->
Figure QLYQS_20
Domain classifier->
Figure QLYQS_23
Adam optimizer of->
Figure QLYQS_15
For the loss function of the decoder, < >>
Figure QLYQS_19
For the loss function of the domain classifier, +.>
Figure QLYQS_22
Is->
Figure QLYQS_24
A loss function converted by the gradient inversion layer;
the source domain training is specifically as follows:
the source domain training comprises three main body modules of a feature extractor, an RUL predictor and a domain classifier, and aims to improve RUL prediction capacity of common features, and is divided into health data training and degradation data training;
In the source domain training process, the feature extractor respectively receives errors from the RUL predictor and the domain classifier to adjust network parameters, the RUL predictor also adjusts the network parameters of the RUL predictor, and a mapping relation between new public features and RUL labels is searched;
after the feature extractor and the RUL predictor finish optimization, the domain classifier is continuously updated and adjusted, three networks gradually tend to be balanced through iterative training, and the optimal values of the overall loss function and the parameters of the source domain training are as follows:
Figure QLYQS_25
Figure QLYQS_26
Figure QLYQS_27
wherein ,
Figure QLYQS_38
loss function for training using source domain, +.>
Figure QLYQS_30
Feature extractor->
Figure QLYQS_34
RUL predictor->
Figure QLYQS_31
Domain classifier->
Figure QLYQS_36
Network parameters of->
Figure QLYQS_39
For the loss function of the RUL predictor, +.>
Figure QLYQS_44
For the loss function of the domain classifier, +.>
Figure QLYQS_35
Representing gradient inversion layer, ">
Figure QLYQS_40
and />
Figure QLYQS_28
Health data set and degradation data set of source domain tagged data set, respectively, < >>
Figure QLYQS_33
Separate feature extractor->
Figure QLYQS_42
RUL predictor->
Figure QLYQS_45
Domain classifier->
Figure QLYQS_43
Optimized value of network parameter, +.>
Figure QLYQS_46
For loss function->
Figure QLYQS_29
Feature extractor in source domain>
Figure QLYQS_32
Domain classifier->
Figure QLYQS_37
Optimum values of network parameters, definition fieldsThe label is->
Figure QLYQS_41
The parameter updating and optimizing method comprises the following steps:
Figure QLYQS_47
Figure QLYQS_48
Figure QLYQS_49
wherein ,
Figure QLYQS_50
is the learning rate of the gradient descent algorithm, +. >
Figure QLYQS_53
,/>
Figure QLYQS_55
,/>
Figure QLYQS_52
Feature extractor->
Figure QLYQS_56
RUL predictor->
Figure QLYQS_57
Domain classifier->
Figure QLYQS_58
Adam optimizer of->
Figure QLYQS_51
For the loss function of the RUL predictor, +.>
Figure QLYQS_54
Is the loss function of the domain classifier.
2. The method for predicting the remaining service life of a rotating assembly according to claim 1, wherein the migration countermeasure model is composed of a feature extractor, a decoder, a domain classifier and a RUL predictor, specifically:
the feature extractor
Figure QLYQS_59
The encoder part of the Autoencoder feature extraction network comprises a 3-layer convolution layer and a 2-layer full-connection layer, is a training object for transfer learning, and is used for extracting common features of a source domain and a target domain;
the decoder
Figure QLYQS_60
The decoder part of the Autoencoder feature extraction network comprises 3 deconvolution layers and 2 full connection layers, and is used for reconstructing the features extracted by the encoder into time-frequency features, and the self-correlation of the features in the migration process is kept between the specific gravity features and the original input features;
the domain classifier
Figure QLYQS_61
Is a classification network comprising 2 layers of full connection layers and 1 layer of classification layers for distinguishing whether the extracted features belong to a source domain or a target domain, and a feature extractor +.>
Figure QLYQS_62
The method comprises the steps of countertraining, alternately and iteratively updating, wherein the countertraining is used for reducing the data distribution difference between a source domain and a target domain;
The RUL predictor
Figure QLYQS_63
Is RUL prediction network based on attention mechanism intervention cyclic neural network, and comprises SVM classification layer and 2The layer A-GRU network and the 2-layer full-connection layer are backbone functional networks for predicting the residual service life and are used for keeping the distinguishing property of the public features extracted by the model.
3. A system for predicting the remaining useful life of a rotating assembly, the system comprising: the system comprises a memory and a processor, wherein the memory comprises a rotating assembly RUL predicted data distribution balance method program, and the rotating assembly RUL predicted data distribution balance method program realizes the following steps when being executed by the processor:
dividing an original signal of a rotating component into a source domain data set and a target domain data set, and carrying out feature transformation through short-time Fourier transformation;
introducing a domain classifier network into an Autoencoder feature extraction network, and constructing an countermeasure migration model with balanced data distribution by combining a circulating neural network based on attention mechanism intervention;
feature dimension reduction is carried out through an countermeasure migration model, a domain classifier and a feature extractor are subjected to countermeasure migration training, and a feature extraction network is retrained by combining tag data of a source domain data set and untagged data of a target domain data set;
The data distribution balance of the target domain and the source domain is realized through the iterative updating of the domain classifier and the feature extractor, and the residual service life of the rotating assembly is predicted through the data after the data distribution balance;
the anti-migration training process is divided into two parts, namely target domain training and source domain training according to data sources, and specifically comprises the following steps:
the target domain training comprises three main body modules of a feature extractor, a decoder and a domain classifier, wherein the feature extractor adjusts network parameters according to errors of the decoder and the domain classifier, and when the feature extractor and the decoder finish updating, the other main body domain classifier of the countermeasure training is updated;
the source domain training comprises two steps of health data training and degradation data training, wherein in the source domain training process, a feature extractor respectively receives errors from an RUL predictor and a domain classifier to adjust network parameters, and the RUL predictor adjusts the network parameters of the RUL predictor;
the method comprises the following steps of training a target domain, wherein after the feature extractor and the RUL predictor finish optimization, updating and adjusting the domain classifier are continuously carried out, and three networks gradually tend to be balanced through iterative training;
the target domain training specifically comprises the following steps:
The target domain training comprises three main body modules of a feature extractor, a decoder and a domain classifier, wherein data of a target domain is projected to a new feature space in the target domain training, data alignment is carried out on the data of the source domain in the new feature space, and the common features of the source domain and the target domain are learned through the data alignment;
the feature extractor adjusts network parameters according to errors of the decoder and the domain classifier, the decoder receives the errors of the decoder to adjust, when the feature extractor and the decoder finish updating, the domain classifier of the other main body of the countermeasure training is updated along with the updating, and the domain classifier improves the classification accuracy through sample data with domain labels and training times;
the method comprises the steps of selecting and adopting earlier-stage operation data of a rotating assembly system and health data of a source domain to conduct data alignment, and using a loss function when a target domain is used for training to be:
Figure QLYQS_64
wherein ,
Figure QLYQS_67
loss function for training using the target domain, +.>
Figure QLYQS_70
Feature extractor->
Figure QLYQS_72
Decoder->
Figure QLYQS_66
Domain classifier/>
Figure QLYQS_68
Network parameters of->
Figure QLYQS_71
For the loss function of the decoder, < >>
Figure QLYQS_73
For the loss function of the domain classifier, the domain label is defined as +.>
Figure QLYQS_65
The source domain label is 0, the target domain label is 1, and the target domain unlabeled dataset is +. >
Figure QLYQS_69
The objective of the domain classifier is to minimize classification errors, and to train with feature extractors alternately, specifically:
in the training of the domain classifier, the MSE is adopted as a loss function, the training process is optimized through an Adam algorithm, a gradient inversion layer is introduced in the back propagation, and the optimization process of network parameters is as follows:
Figure QLYQS_74
Figure QLYQS_75
Figure QLYQS_76
wherein ,
Figure QLYQS_78
is the learning rate of the gradient descent algorithm, +.>
Figure QLYQS_81
,/>
Figure QLYQS_84
,/>
Figure QLYQS_79
Feature extractor->
Figure QLYQS_80
Encoder->
Figure QLYQS_83
Domain classifier->
Figure QLYQS_86
Adam optimizer of->
Figure QLYQS_77
For the loss function of the decoder, < >>
Figure QLYQS_82
For the loss function of the domain classifier, +.>
Figure QLYQS_85
Is->
Figure QLYQS_87
A loss function converted by the gradient inversion layer;
the source domain training is specifically as follows:
the source domain training comprises three main body modules of a feature extractor, an RUL predictor and a domain classifier, and aims to improve RUL prediction capacity of common features, and is divided into health data training and degradation data training;
in the source domain training process, the feature extractor respectively receives errors from the RUL predictor and the domain classifier to adjust network parameters, the RUL predictor also adjusts the network parameters of the RUL predictor, and a mapping relation between new public features and RUL labels is searched;
after the feature extractor and the RUL predictor finish optimization, the domain classifier is continuously updated and adjusted, three networks gradually tend to be balanced through iterative training, and the optimal values of the overall loss function and the parameters of the source domain training are as follows:
Figure QLYQS_88
Figure QLYQS_89
Figure QLYQS_90
wherein ,
Figure QLYQS_102
loss function for training using source domain, +.>
Figure QLYQS_94
Feature extractor->
Figure QLYQS_98
RUL predictor->
Figure QLYQS_106
Domain classifier->
Figure QLYQS_108
Network parameters of->
Figure QLYQS_107
For the loss function of the RUL predictor, +.>
Figure QLYQS_109
For the loss function of the domain classifier, +.>
Figure QLYQS_101
Representing gradientsReversing layer(s)>
Figure QLYQS_105
and />
Figure QLYQS_93
Health data set and degradation data set of source domain tagged data set, respectively, < >>
Figure QLYQS_97
Feature extractor->
Figure QLYQS_99
RUL predictor->
Figure QLYQS_103
Domain classifier->
Figure QLYQS_100
Optimized value of network parameter, +.>
Figure QLYQS_104
For loss function->
Figure QLYQS_91
Feature extractor in source domain>
Figure QLYQS_95
Domain classifier->
Figure QLYQS_92
Optimal value of network parameter, domain label is defined as +.>
Figure QLYQS_96
The parameter updating and optimizing method comprises the following steps:
Figure QLYQS_110
Figure QLYQS_111
Figure QLYQS_112
wherein ,
Figure QLYQS_113
is the learning rate of the gradient descent algorithm, +.>
Figure QLYQS_118
,/>
Figure QLYQS_120
,/>
Figure QLYQS_114
Feature extractor->
Figure QLYQS_116
RUL predictor->
Figure QLYQS_119
Domain classifier->
Figure QLYQS_121
Adam optimizer of->
Figure QLYQS_115
For the loss function of the RUL predictor, +.>
Figure QLYQS_117
Is the loss function of the domain classifier. />
CN202211547913.6A 2022-12-05 2022-12-05 Data distribution balancing method and system for RUL prediction of rotating assembly Active CN115577245B (en)

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