Disclosure of Invention
In view of the above, the invention provides a method, medium and system for estimating the replacement time of a filter screen in the ABS production process, which can solve the technical problems of most of the prior art that the blocking degree of the filter screen is estimated according to experience of production personnel, and the replacement time of the filter screen is arranged according to production plan, and the limitation exists.
The invention is realized in the following way:
The first aspect of the invention provides a method for estimating the replacement time of a filter screen in an ABS production process, which comprises the following steps:
s10, collecting historical parameter data of a plurality of filter screen monitoring points on a plurality of ABS production lines, wherein the parameter data comprise filter screen pressure, filter screen deformation, material fluid temperature and material fluid flow;
s20, preprocessing the collected historical parameter data, including removing abnormal values, interpolating missing values and normalizing, so as to obtain standardized monitoring data;
S30, counting the change trend of historical parameter data of each monitoring point, and marking known filter screen replacement time as historical marking data;
S40, establishing and training a filter screen blocking machine learning model for each monitoring point based on the historical mark data;
s50, online predicting real-time data of the current filter screen by using the filter screen blocking machine learning model, and estimating the current filter screen blocking degree;
and S60, setting a threshold value of the blocking degree of the filter screen, and judging that the filter screen corresponding to any monitoring point needs to be replaced when the prediction result of the monitoring point exceeds the threshold value.
The specific implementation mode of collecting historical parameter data of a plurality of filter screen monitoring points on a plurality of ABS production lines in the step S10 comprises the steps of collecting parameter data such as historical filter screen pressure, filter screen deformation, material fluid temperature, material fluid flow and the like of each monitoring point from a plurality of monitoring sensors arranged on the ABS production lines, wherein the data cover key indexes of filter screen operation in the ABS production process, and provide basis for subsequent predictive modeling.
The specific implementation mode of preprocessing the collected historical parameter data in the step S20 comprises the steps of firstly detecting and removing abnormal values of the data to remove abnormal data points deviating from a normal range, then filling the missing data points by adopting methods such as interpolation to ensure the integrity of the data, and finally normalizing the index data to convert the index data into standardized monitoring data so as to meet the requirements of subsequent modeling and analysis.
The specific implementation mode of counting historical parameter data change trend and marking known filter screen replacement time in the step S30 comprises the steps of carrying out statistical analysis on standardized monitoring data collected by each monitoring point to find change rules of indexes such as pressure, deformation and the like of the filter screen in the using process, and marking the historically known filter screen replacement time by combining production reality to provide a reference basis for training of a subsequent machine learning model.
The specific implementation mode of the filter screen blockage machine learning model established and trained based on the historical marking data in the step S40 comprises the steps of selecting a neural network embedded with a physical model as a prediction model, wherein the model comprises key components such as a physical model module, a time sequence module, an attention module, a feature extraction module, a weight real-time updating module and the like, and establishing a foundation for subsequent online prediction through learning and modeling a filter screen blockage rule by the structured neural network.
The specific implementation mode of the filter screen blockage machine learning model in step S50 for carrying out online prediction on the real-time data of the current filter screen comprises the steps of receiving the parameter data such as pressure, deformation, temperature, flow and the like from each monitoring point in real time, and predicting the blockage degree of the current filter screen by utilizing a neural network model in combination with the trained physical model constraint so as to provide a basis for judging the subsequent filter screen replacement time.
The specific implementation mode of setting the filter screen blocking degree threshold and judging the filter screen replacing time in the step S60 comprises the steps of setting the filter screen blocking degree threshold to 70% -80% according to production practice and experience, and judging that the filter screen corresponding to any monitoring point needs to be replaced when the predicted blocking degree of the monitoring point exceeds the threshold so as to ensure the stability and the product quality of ABS production.
The filter screen at least comprises an extruder head filter screen, a die head filter screen and a filter screen of an ABS production line, wherein the filter screens play a key role in filtering in the ABS production process, and the blocking condition of the filter screens needs to be monitored and predicted in real time.
Wherein, the filter screen at least comprises an extruder head filter screen, a die head filter screen and a filter screen of an ABS production line.
The filter screen blocking machine learning model is a neural network embedded with a physical model, and the physical model is specifically based on an Ergun equation between a filter screen pressure difference and parameters of flow, temperature and viscosity, and is used for restraining the output of the neural network to conform to a physical rule.
Furthermore, the neural network further comprises a time sequence module, an attention module, a feature extraction module and a weight real-time updating module, wherein the weight real-time updating module is used for optimizing weights according to new filter screen replacement records, and the weight real-time updating module has a verification data screening function and is used for automatically selecting proper real-time monitoring data to be used for verifying and updating the weights of the filter screen blocking machine learning model.
Furthermore, the physical model adopts an Ergun equation, and specifically constructs physical constraint through a relation among the pressure difference of a filter screen, the flow, the viscosity of fluid and the blockage rate of the filter screen.
Further, the timing module is used for capturing the timing variation characteristics of each parameter, and the specific structure is a convolution LSTM network.
Further, the attention module is used for capturing the correlation between different characteristics, and the specific structure is a multi-head attention mechanism.
Further, the feature extraction module is used for extracting features from different parameters, and the specific structure is divided into two parts:
1) Extracting characteristics of the filter screen pressure, the material fluid temperature and the material fluid flow by using a one-dimensional convolution network;
2) Extracting characteristics of the deformation data of the filter screen by using a two-dimensional convolution network;
The weight real-time updating module is specifically structured to update model weights on line through Reptile th element learning algorithm.
A second aspect of the present invention provides a computer readable storage medium, where the computer readable storage medium stores program instructions, where the program instructions are configured to execute the above-mentioned method for estimating a screen replacement time in an ABS production process when the program instructions are executed.
A third aspect of the present invention provides a system for estimating a replacement time of a filter screen in an ABS production process, wherein the system includes the above computer-readable storage medium.
Compared with the prior art, the method, medium and system for predicting the replacement moment of the filter screen in the ABS production process have the beneficial effects that the scheme of the invention fully utilizes historical monitoring data collected on the production line, including a plurality of key indexes such as the pressure, deformation, material temperature and flow of the filter screen, and an intelligent filter screen blockage prediction system is established through the steps of data preprocessing, feature learning, dynamic modeling and the like. Compared with the prior art, the method has the following main advantages:
1. The method collects a plurality of monitoring indexes including the pressure, deformation, temperature, flow and the like of the filter screen, and comprehensively reflects the running state of the filter screen in the ABS production process. The fusion of the multi-source data is beneficial to improving the accuracy and the robustness of prediction, and the problem that a single index is difficult to accurately describe the blocking condition of the filter screen is solved.
2. The method combines the physical model with the neural network, on one hand, the output of the neural network is constrained by utilizing the physical rules such as the Ergun equation and the like to ensure that the prediction result accords with the physical rules, and on the other hand, the complex nonlinear relation hidden in the historical data can be excavated through the strong learning capacity of the neural network. The modeling strategy combining physical constraint and data driving ensures that the prediction model has good interpretability and can fully exert the prediction capability of data.
3. The method adopts a convolution LSTM network to capture the change characteristics of each monitoring parameter along with time, and can effectively model the dynamic evolution rule of the filter screen blocking condition. Compared with the existing method only focusing on single-moment prediction, the modeling mode based on time sequence data can better reflect the continuity and the dynamics of the actual operation of the filter screen.
4. The method has the capacity of on-line self-adaptive optimization, and realizes the real-time updating of the weights by adopting Reptile-unit learning algorithm on the basis of a trained prediction model. When a new filter screen replacement record appears, the model can automatically adjust parameters according to the latest sample, and continuously optimize the prediction performance, so that the model is suitable for the change of the production environment and provides guarantee for long-term stable application.
In summary, the invention solves the technical problems that most of the prior art estimates the blocking degree of the filter screen according to experience of production personnel, and arranges the filter screen replacement time according to production plan, and has limitation.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
As shown in FIG. 1, the invention provides a flowchart of a method for estimating the replacement time of a filter screen in an ABS production process, which comprises the following steps:
S10, collecting historical parameter data of a plurality of filter screen monitoring points on a plurality of ABS production lines, wherein the parameter data comprise filter screen pressure, filter screen deformation, material fluid temperature and material fluid flow;
s20, preprocessing the collected historical parameter data, including removing abnormal values, interpolating missing values and normalizing, so as to obtain standardized monitoring data;
S30, counting the change trend of historical parameter data of each monitoring point, and marking known filter screen replacement time as historical marking data;
S40, establishing and training a filter screen blocking machine learning model for each monitoring point based on the historical mark data;
S50, online predicting real-time data of the current filter screen by using a filter screen blocking machine learning model, and estimating the current filter screen blocking degree;
and S60, setting a threshold value of the blocking degree of the filter screen, and judging that the filter screen corresponding to any monitoring point needs to be replaced when the prediction result of the monitoring point exceeds the threshold value.
The following describes in detail the specific embodiments of the above steps:
step S10, collecting historical parameter data of a plurality of filter screen monitoring points on a plurality of ABS production lines:
The main purpose of this step is to collect and sort the relevant historical parameter data of the operation of the filter screen during the ABS production process. Specifically, it is desirable to collect historical monitoring data including a plurality of indicators of screen pressure, screen deformation, material fluid temperature, material fluid flow, etc. The data are derived from a plurality of monitoring points on the ABS production line, so that sufficient sample data are obtained, and a foundation is laid for the establishment of a subsequent prediction model.
Step S20, preprocessing the collected historical parameter data:
The raw monitoring data collected may have some outliers or missing values, and therefore, the data needs to be preprocessed. First, outlier detection and removal of the data is required to remove those outlier data points that deviate significantly from the normal range. Then, for the missing data points, interpolation or other methods can be adopted to fill in, so as to ensure the integrity of the data. And finally, carrying out normalization processing on each index data, and converting the index data into standardized monitoring data, so that preparation is made for subsequent modeling and analysis.
Step S30, counting the change trend of the historical parameter data, and marking the known filter screen replacement time:
Standardized monitoring data collected for each monitoring point requires careful analysis of its historical trend. Through statistical analysis of the data, the change rule of indexes such as pressure, deformation and the like of the filter screen in the using process can be found. Meanwhile, in combination with production practice, historically known filter screen replacement time is required to be marked, and a reference basis is provided for subsequent machine learning model training.
Step S40, based on the historical marking data, establishing and training a filter screen blockage machine learning model:
With the historical data and the marking information accumulated in the previous steps, a machine learning predictive model of filter screen plugging can be initially built and trained. A neural network embedded with a physical model is chosen as the predictive model. Specifically, this neural network model includes the following key modules:
1) And the physical model module is used for establishing the relation among the pressure difference, the flow, the fluid viscosity and the blockage rate of the filter screen based on the Ergun equation and is used for restricting the output of the neural network to conform to the physical rule.
2) And the time sequence module is used for capturing the change characteristics of each parameter along with time by adopting a convolution LSTM network.
3) And the attention module adopts a multi-head attention mechanism to learn the correlation among different features.
4) And the characteristic extraction module is used for extracting the characteristics of different types of input data (pressure, temperature, flow and deformation) by adopting different convolution networks.
5) And the weight real-time updating module adopts Reptile element learning algorithm to optimize the weight parameters of the neural network in real time according to the new filter screen replacement record.
Through the neural network model with rich structure and the combination of the supervised learning of the historical mark data, the filter screen blocking law can be well learned and modeled, and a foundation is laid for the follow-up online prediction.
Step S50, online prediction is carried out on real-time data of the current filter screen by utilizing a filter screen blocking machine learning model:
The trained filter screen blockage prediction model can be used for on-line prediction of real-time monitoring data of the filter screen on the current production line. Specifically, the model can receive parameter data such as pressure, deformation, temperature, flow and the like from each monitoring point in real time, and predicts the blocking degree of the current filter screen by combining physical model constraint. The prediction result provides an important basis for judging the subsequent filter screen replacement time.
Step S60, setting a threshold value of the blocking degree of the filter screen, and judging the replacing time of the filter screen:
After obtaining the predicted result of the clogging degree of the filter screen, a reasonable clogging degree threshold value needs to be set. When the predicted blocking degree of any monitoring point exceeds the threshold value, the filter screen corresponding to the monitoring point can be judged to need to be replaced. The threshold value is set by combining production practice and experience, and can be generally set to be 70% -80% of blocking degree. When this threshold is reached, screen changes should be made immediately to ensure the stability of ABS production and product quality.
In general, the method for estimating the replacement moment of the filter screen in the ABS production process fully utilizes historical monitoring data on a production line, and establishes a powerful online prediction system by combining machine learning and a physical model. The system can monitor the blocking state of the filter screen in real time, predict the preferable time for replacing the filter screen in advance, and greatly improve the automation level and the operation efficiency of ABS production.
A second aspect of the present invention provides a computer readable storage medium, where the computer readable storage medium stores program instructions, where the program instructions are configured to execute the above-mentioned method for estimating a screen replacement time in an ABS production process when the program instructions are executed.
A third aspect of the present invention provides a system for estimating a replacement time of a filter screen in an ABS production process, wherein the system includes the above computer-readable storage medium.
For a better understanding and implementation of the present invention, the following provides example 1 of specific steps of a computer readable program of the present invention running in a computer readable medium or a computer-like device, in this example 1, for step S10, historical parameter data of a plurality of screen monitoring points on a plurality of ABS production lines are collected, and the following variables may be defined:
indicating the number of ABS production lines, Indicating the number of screen monitoring points on each production line. For the firstFirst on strip production lineThe following historical parameter data are collected at each monitoring point:
The pressure of the filter screen;
Deformation of the filter screen;
The temperature of the material fluid;
material fluid flow;
Wherein the method comprises the steps of Representing a time series. By collecting the historical parameter data, the comprehensive information of the running state of the filter screen in the ABS production process is obtained.
When preprocessing the collected historical parameter data in step S20, it is first necessary to detect and remove an abnormal value. Assume that a certain monitoring point is at the momentPressure data of (2)The presence of an abnormality can be detected by:
;
Wherein the method comprises the steps of AndRespectively representAnd standard deviation. If it isThen judgeIs an outlier and is culled.
For missing data points, interpolation can be used to fill in. Assume that in a time intervalInternal presence ofThe missing values of (2) can be padded using a cubic spline interpolation method:
;
Wherein the method comprises the steps of Is the coefficient of a cubic polynomial by the known methodAndAnd determining derivative conditions.
Finally, to meet the requirement of subsequent modeling, normalization processing is required for each index data. Assume thatThe normalized filter screen pressure, deformation, temperature and flow data are:
;
;
;
;
In the formula, AndThe maximum and minimum of the corresponding terms, respectively.
Through the preprocessing step, standardized monitoring data are obtained, and a foundation is laid for subsequent analysis and modeling.
When the trend of the historical parameter data is counted and the known screen replacement time is marked in step S30, the following method may be adopted:
For each monitoring point First, theThe production line can calculate the change rate of each parameter along with time:
;
by analyzing the change rates, the change rule of each index of the filter screen in the use process can be found. At the same time, the historically known filter screen replacement time needs to be marked in combination with the actual production record Providing a reference basis for subsequent machine learning model training.
In step S40, a neural network embedded with a physical model is selected as a prediction model when the filter screen plugging machine learning model is built and trained based on the history flag data. Specifically, the model includes the following key components:
1. physical model module:
establishing a filter screen differential pressure by using an Ergun equation Flow rate and flow rateViscosity of fluidBlockage rateRelationship between:
;
Wherein, Is the aperture of the filter screen,Is the fluid density. The physical model is used for constraining the output of the neural network to conform to the physical rule.
2. A time sequence module:
The convolution LSTM network is adopted to capture the change characteristics of each parameter along with time. Specifically, for the first Strip production line NoEach monitoring point is input with the following sequenceWhereinIs the time window length. The convolutional LSTM network can extract these timing features to provide support for subsequent occlusion prediction.
3. Attention module:
and a multi-head attention mechanism is adopted to learn the correlation among different characteristics. For the first Strip production line NoThe monitoring points are at the momentCharacteristic representation of (a)The attention mechanism can be expressed as:
;
;
Wherein, Is a weight matrix that can be learned. The attention mechanism can capture the correlation between different characteristics and improve the expression capacity of the model.
4. And the feature extraction module is used for:
for different types of input data, different convolution networks are used for feature extraction.
For screen pressureTemperature of material fluidAnd flow rateWaiting for one-dimensional data, and extracting features by using a one-dimensional convolution network;
For deformation of the filter screen And (5) waiting for two-dimensional data, and extracting features by using a two-dimensional convolution network.
By the differentiated feature extraction method, the characteristics of different types of data can be better utilized.
5. And the weight real-time updating module is used for:
In order to enable the model to dynamically adjust parameters along with time and adapt to the change of the production environment, a Reptile-unit learning algorithm is adopted to optimize and update the model weight in real time. Specifically, when a new screen change record appears, it is used as a validation set, and model parameters are fine-tuned by Reptile algorithm to better fit the new sample distribution. Meanwhile, the module also has the function of automatically screening proper verification data, and the online learning effect is further improved.
Through the design of the neural network model and the combination of the constraint of the physical model, the historical monitoring data can be fully utilized, the filter screen blocking rule can be learned and modeled, and powerful support is provided for subsequent online prediction.
In step S50, when the filter screen blocking machine learning model is used for online prediction of the real-time data of the current filter screen, the pressure from each monitoring point is received in real timeDeformation ofTemperature (temperature)And flow rateAnd isoparametric data. The blocking degree of the current filter screen can be predicted by combining the neural network model trained in the step S40:
;
Wherein, Representing parameters of the model. The prediction result provides an important basis for judging the subsequent filter screen replacement time.
When the threshold value of the clogging degree of the screen is set and the screen replacement timing is judged in step S60, the threshold value of the clogging degree of the screen may be set according to production practice and experienceIs set to 70% -80%. When any monitoring pointIs the first of (2)Predicted degree of jam for strip production lineWhen the threshold value is exceeded, the filter screen corresponding to the monitoring point can be judged to need to be replaced:
;
by the method based on real-time monitoring and prediction, the filter screen blocking seedling can be found in time, decision support is provided for production management staff, and the stability of ABS production and the product quality are ensured.
In general, the method for estimating the replacement moment of the filter screen in the ABS production process fully utilizes historical monitoring data on a production line, combines physical model constraint and strong neural network prediction capability, and establishes an intelligent online monitoring and prediction system. The system can monitor the running state of the filter screen in real time, predicts the preferable time for replacing the filter screen in advance, and greatly improves the automation level and the operation efficiency of ABS production.
Specifically, the principle of the invention is to build an intelligent prediction system based on the combination of machine learning and physical model. The key of the system is that historical monitoring data collected on a production line is fully utilized, and a machine learning model capable of accurately predicting the blocking degree of the filter screen is finally obtained through the steps of data preprocessing, feature learning, dynamic modeling and the like. This predictive model contains the following key innovation points:
1. physical model constraint when the machine learning prediction model is established, the method is integrated with the physical models such as an Ergun equation and the like and is used for constraining the output of the neural network. The Ergun equation describes the relationship between the filter screen pressure differential, flow, fluid viscosity and plug rate, conforming to the laws of physics. The physical model is embedded into the neural network, so that the prediction result can be ensured not to violate the basic physical law, and the interpretation and reliability of the model are improved.
2. Modeling time sequence characteristics, namely, the blocking of a filter screen is a dynamic change process, and the change characteristics of each monitoring parameter along with time need to be considered. The method adopts a convolution LSTM network to capture the time sequence characteristics, and the network structure can effectively extract time dependency information contained in an input sequence and provide support for dynamic prediction. By means of the time sequence modeling mode, the blocking trend of the filter screen can be predicted more accurately, and the method is not limited to a state at a certain moment.
3. The multisource characteristic fusion is that the running state of the filter screen is the result of the combined action of a plurality of factors, and the blocking degree of the single monitoring index is difficult to comprehensively reflect. The method collects various heterogeneous data such as filter screen pressure, deformation, material temperature, flow and the like, and adopts a differential characteristic extraction method (a one-dimensional convolution network and a two-dimensional convolution network) to fully utilize the information of the multi-source data. The fusion of the multi-source features can provide richer and more comprehensive input and improve the generalization capability of the prediction model.
4. In the actual production, the running state of the filter screen can be changed to a certain extent due to the continuous change of the process conditions. In order to enable the prediction model to adapt to the changes, the method adopts Reptile-element learning algorithm to realize real-time optimization and update of model parameters. When a new filter screen replacement record appears, the model automatically adjusts the weight according to the latest sample, so that the prediction result can continuously track the actual running condition of the filter screen, and the accuracy and stability of prediction are improved.
In summary, the technical principle of the method is mainly characterized in that 1) the interpretability of the model is improved by combining with the constraint of a physical model, 2) a dynamic change rule is captured by adopting time sequence feature modeling, 3) the prediction capability is enhanced by utilizing multi-source feature fusion, and 4) the adaptability of the model is enhanced by self-adaption on-line optimization.
In order to better understand the invention, an embodiment 2 of a specific application scenario is designed below, wherein an enterprise has 3 ABS production lines, and each production line is provided with 5 filter screen monitoring points which are respectively positioned at key positions such as an extruder head, a die head, a filter and the like. The enterprise is always seeking to improve the automation level and the operation efficiency of the ABS production process, hopes to find the filter screen blocking seedling in time, and provides decision support for filter screen replacement. Based on the method, the enterprise decides to adopt the method for estimating the replacement time of the filter screen in the ABS production process, and the method is implemented as follows:
1. data collection
Firstly, the enterprise collects historical operation data of 5 filter screen monitoring points on 3 ABS production lines in the last 2 years, wherein the historical operation data comprise parameters such as filter screen pressure, filter screen deformation, material fluid temperature, material fluid flow and the like. Taking the 3 rd monitoring point of the 1 st production line as an example, the collected part of historical data is shown in table 1:
table 1 historical data table
Time of |
Filter screen pressure (MPa) |
Deformation of filter screen (mm) |
Material temperature (°c) |
Material flow (L/min) |
2022-01-0108:00 |
2.1 |
0.3 |
210 |
80 |
2022-01-0108:15 |
2.2 |
0.4 |
211 |
79 |
2022-01-0108:30 |
2.3 |
0.4 |
209 |
78 |
... |
... |
... |
... |
... |
2023-12-3123:45 |
3.2 |
0.8 |
215 |
72 |
Fig. 2-5 are graphs showing the trend of the screen monitoring data over time, showing the trend of four key parameters of screen pressure, deformation, material temperature and material flow over the period of 2022, 1/12/31/1/2022. Four sub-graphs are included in the graph, showing the variation of these parameters over time, respectively. The pressure and deformation of the filter screen can be observed to be in an ascending trend, the temperature of the material is relatively stable, and the flow rate of the material is in a descending trend. These trends intuitively reflect the process of gradual clogging of the screen. Through the collection of the historical data, enterprises accumulate rich filter screen running state samples, and a foundation is laid for subsequent predictive modeling.
2. Data preprocessing
The collected raw monitoring data inevitably has some abnormal values and missing values, so that necessary pretreatment is required. For the data of the 3 rd monitoring point of the 1 st production line, the specific preprocessing steps are as follows:
(1) Outlier detection and removal:
taking the pressure data of the filter screen as an example, calculating the standard fraction: ;
Wherein, As the mean value of the sample,Is the standard deviation of the samples. If it isThen the data point is determined to be an outlier and is culled. In this way, a total of 18 outlier pressure data points are removed.
(2) Filling up the missing value:
and filling the missing data points by adopting a cubic spline interpolation method. Taking the loss of the flow data in a certain period as an example, a loss interval is set as Then the following interpolation function can be constructed:
;
Wherein the method comprises the steps of For the undetermined coefficients, they can be determined by known boundary conditions. In this way, a total of 27 missing traffic data points are filled.
(3) Data normalization:
In order to eliminate the influence of dimension on subsequent modeling, the minimum-maximum normalization processing is carried out on each monitoring index data. Taking the filter screen pressure as an example, normalized pressure data The calculation is as follows:
;
the normalization processing mode of other indexes is similar. Through the preprocessing step, the enterprise obtains standardized monitoring data, and a foundation is laid for subsequent analysis and modeling.
3. Historical data analysis
After the data preprocessing is completed, the enterprise starts to analyze the change trend of the historical monitoring data of each monitoring point. Taking the 3 rd monitoring point of the 1 st production line as an example, the analysis result is as follows:
(1) The pressure of the filter screen gradually rises from the initial 2.1MPa to 3.2MPa, and the rising amplitude reaches 52%.
(2) The deformation of the filter screen is gradually increased from 0.3mm to 0.8mm, and the increase is 167%.
(3) The temperature of the material is basically kept stable and fluctuates between 209 ℃ and 215 ℃.
(4) The material flow rate is gradually reduced from the initial 80L/min to 72L/min, and the reduction is 10%.
Meanwhile, the enterprise marks 3 times of screen replacement time in the history of the monitoring point in the production record, which respectively occur on the day of 2022, the day of 2023, the day of 2021, the day of 10, and the day of 2023, the day of 7, and the day of 5. Through analysis of the historical data, enterprises master basic change rules of the running state of the monitoring point filter screen, and an important basis is provided for the establishment of a subsequent prediction model.
4. Predictive model training
Based on the foregoing historical data analysis results, the enterprise began to set up a predictive model of screen plugging. Considering that screen plugging is a complex process involving multiple physical factors, enterprises decide to use a neural network embedded with a physical model as a predictive model, which specifically includes the following key modules:
(1) Physical model module-Enterprise describes the pressure difference of the filter screen by adopting an Ergun equation Flow rate and flow rateViscosity of fluidBlockage rateThe relation between the two is taken as a constraint condition: Wherein, the method comprises the steps of, Is the aperture of the filter screen,Is the fluid density. The physical model is embedded into the neural network, so that the output result is ensured to accord with the physical rule.
(2) And the time sequence module is used for capturing the change characteristics of each monitoring parameter along with time, and an enterprise adopts a convolution LSTM network as a time sequence characteristic extraction module. The input of the module is the pastSequences of monitored data within time steps, e.g.WhereinNormalized pressure, deformation, temperature and flow data, respectively. The convolution LSTM network can effectively extract these timing characteristics and provide support for subsequent occlusion prediction.
(3) Attention module in order to capture the correlation between different monitoring indexes, the enterprise integrates a multi-head attention mechanism in the model. Specifically, for time of dayCharacteristic representation of timeThe attention module calculates as follows:
;
;
Wherein, Is a weight matrix that can be learned. The attention mechanism can adaptively give different weights to different features, and the capturing capacity of the model on key features is enhanced.
(4) And the characteristic extraction module is used for extracting different characteristics of enterprises according to different types of monitoring data. For one-dimensional pressure, temperature and flow data, a one-dimensional convolution network is used for extracting features, and for two-dimensional deformation data, a two-dimensional convolution network is used for extracting features. By means of the differentiated feature extraction, the characteristics of various data can be better utilized, and high-quality input features are provided for subsequent blockage prediction.
(5) And the weight real-time updating module is used for enabling the model to dynamically adjust parameters along with time, adapting to the change of the production environment, and enabling the enterprise to integrate Reptile-element learning algorithm in the prediction model to realize real-time optimization of the weight. Specifically, whenever a new screen change record occurs, the enterprise will use it as a validation set to fine tune the model parameters through Reptile algorithm to better fit the new sample distribution. Meanwhile, the module also has the function of automatically screening proper verification data, and the online learning effect is further improved.
With the model design, the enterprise trains and verifies the model by using the historical data of the 3 rd monitoring point of the 1 st production line. In the training process, the enterprise adopts a layered sampling strategy, so that the proportion of samples in various blocking states is balanced, and the generalization of the model is improved. And finally, obtaining a machine learning model capable of accurately predicting the blocking degree of the filter screen of the monitoring point through repeated iterative optimization.
5. On-line prediction and decision-making, namely, a trained prediction model is provided, and enterprises start to apply in real time on a production line. Taking the 3 rd monitoring point of the 1 st production line as an example, the specific process is as follows:
(1) And acquiring real-time data, namely acquiring the data of the pressure, deformation, material temperature and material flow of the filter screen of the monitoring point by a sensor arranged on the production line in real time, and transmitting the data to a prediction model.
(2) The blockage degree prediction is that a prediction model receives the monitoring data in real time and predicts the current blockage degree of the filter screen of the monitoring point according to the mechanisms such as physical constraint, time sequence characteristic, multi-source characteristic fusion and the like introduced above。
(3) Decision support, namely, enterprises threshold the blocking degree of a filter screen according to production practice experienceSet at 80%. Predictive occlusion degree at any one monitoring pointWhen this threshold is exceeded, a screen change decision is triggered.
As shown in fig. 6, the screen clogging degree prediction results during 2023, 11, 1, to 2023, 12, 31 are shown. In the figure, a blue solid line indicates an actual clogging degree, a red dotted line indicates a predicted clogging degree, a green dotted line indicates a replacement threshold value (0.8), and a yellow hatched area indicates an early warning area. It can be seen from the graph that the predicted result is very close to the actual blocking degree, when the predicted blocking degree exceeds the threshold value, the filter screen is required to be replaced by entering the early warning area, in the practical application, the enterprise finds that the predicted blocking degree of the 3 rd monitoring point of the 1 st production line reaches 82% after 2 hours and exceeds 80% of the threshold value, and after receiving the early warning signal, production management staff immediately arranges the filter screen corresponding to the monitoring point to be replaced, so that the production interruption and the product quality problem caused by the blocking of the filter screen are avoided.
Through continuous real-time monitoring and prediction, enterprises find out that certain differences exist in the filter screen blocking condition of each monitoring point. For example, the 4 th monitoring point of the 2 nd production line has slower changes of the pressure and deformation of the filter screen due to the adjustment of the process parameters, and the predicted blocking degree does not exceed the threshold. The 1 st monitoring point of the 3 rd production line shows a faster blocking trend, and the enterprise correspondingly changes the filter screen earlier. Figure 7 compares the plugging trend of three different monitoring points (line 1-point 3, line 2-point 4, line 3-point 1) throughout 2023. As can be seen from the graph, there is a significant difference in the rate of occlusion at the different monitoring points. The line 3-point 1 is plugged at the fastest rate, while the line 2-point 4 is plugged at the slowest rate. The black dashed line indicates the replacement threshold (0.8). The comparison graph is helpful for production management personnel to know the blocking characteristics of different monitoring points, so that a more targeted maintenance strategy is formulated.
In general, by adopting the method, enterprises can realize intelligent monitoring and prediction of the state of the filter screen in the ABS production process, and timely and accurate decision support is provided for filter screen replacement. The production stability and the product quality are improved, and the manpower and the resource consumption for replacing the filter screen are greatly saved. Meanwhile, a large amount of monitoring and predicting data accumulated by the method also provides valuable data support for further optimizing ABS production process parameters.
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.