Application of bionic models for situation management O.M. Gerget1,2, N.A. Markova1 gerget@tpu.ru, markovana@tpu.ru 1 Tomsk Polytechnic University, Tomsk, Russia; 2 Siberian State Medical University, Tomsk, Russia The article discusses the concept of choosing the sequence of control actions in order to minimize the possibility of the system state transition to an adverse one. For this purpose, the bionic model based on the synthesis of information approach, neural networks and a genetic algorithm is developed. The functionality of each of the model elements and their interaction are presented in this paper. Special attention is paid to neuroevolutionary interaction. At the same time, information about control actions is encapsulated in the gene, which allowed increasing the functionality of the algorithm due to multidimensional data representation. The article describes the principle of data representation in bionic models, which differs from the existing ones by the possibility of explicit or implicit representation of the control action in the chromosome. In the explicit representation one neural network is formed, it describes the effect of any of the control actions involved in the training. An implicit view creates a set of models, each of which describes the effect of only one control action. A brief description of the software implemented in the Python programming language is provided. Keywords: information approach, neural networks, genetic algorithm, bionic model, choice of control actions. 1. Introduction 2. Information method for calculating the generalized indicator The development of information technologies for monitoring, prediction and situation modeling based on The application of the information approach in the the application of bionic principles is one of the most structure of the bionic model makes it possible to promising scientific directions [1-5]. Evolving over evaluate the state of the object of the study at the millions of years in biosystems, structures have been considered moments of time and to reveal deviations formed, in particular, genetic, immune, neural, providing from the stationary state. Of interest is the formation of a balanced development and availability of necessary single quantitative indicator [7, 8], which would allow to information means of control and adaptive control in a assess the reaction of the object of the study to changes changing environment. Attempts are currently being taking place under the influence of the internal and made to integrate artificial information processing external environment. systems that structurally reflect the functioning of On the basis of implementation and analysis of dynamic systems. Particular attention is paid to the methods for construction of generalized estimates in the development of models and methods that information system, the approach [9] which considers the comprehensively take into account the specifics of the information measure as a measure of preference of the object of the study. In the article we will focus on the behavior of the bioobject is used. concept of choosing the sequence of control actions in The choice is justified by the analysis of the results order to prevent the transition of the dynamic system to obtained by: an adverse state. For this purpose, we will consider the 1. The integral criterion based on the evaluation of bionic model proposed by the authors [6]. similarity measure of observed and preferred state By the bionic model we will mean the mathematical areas in feature space, where similarity measure is model, as well as its software implementation, built on normalized in Mahalanobis metric by intramultiple the principle of functioning and organization of distance of reference (steady) state area [10]. biosystems. 2. The integral criterion, in the basis of which Kulbak In order to implement situation management, namely, information measure is considered as a measure of to choose the best solution, evaluate and predict the effect bioobject behavior preference [9, 11]. of the application of control actions it is necessary to 3. The entropy method for detecting body response to have an adequate mathematical model. This role is impact [12]. performed by the bionic model of choosing the sequence of control actions of the following type: 3. Prediction of the state of the research object < 𝑁𝑁𝑁𝑁, 𝐺𝐺𝐺𝐺, 𝐼𝐼, 𝐴𝐴 > based on bionic models where 𝑁𝑁𝑁𝑁 - neural network models, 𝐺𝐺𝐺𝐺 - genetic Neural networks have been chosen as the basic algorithms, 𝐼𝐼 - information method for calculating the technology in the bionic model structure in order to generalized indicator of a biosystem, 𝐴𝐴 - model setting predict the values of features characterizing the state of algorithms. the system in dynamics, as well as when choosing a Synthesis of information approaches, neural networks particular control action. This is due to the high and genetic algorithms in bionic models allows systems efficiency of prediction; the possibility of implementing a to exchange information and transfer the values of their model ensemble and using recursive neural networks for characteristics as input to another subsystem which a variable structure vector [13, 14]. improves the quality of functioning and interpretability. Let us consider an object whose state is characterized by informative features xi … and the ways to influence Copyright Β© 2020 for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0) the state of the object U = (u1,...,ul), where l is the object and generalized indicators obtained on the basis of number of control actions. the information method. It is believed that the value of the i-th feature at a The implementation of the prediction algorithms is point of time t +1 is determined according to the formula: based on recurrent neural networks [4, 15, 16], through π‘₯π‘₯𝑖𝑖 (𝑑𝑑 + 1) = 𝑓𝑓(π‘₯π‘₯𝑖𝑖 (𝑑𝑑), π‘₯π‘₯𝑖𝑖 (𝑑𝑑 βˆ’ 1), … , π‘₯π‘₯𝑖𝑖 (𝑑𝑑 βˆ’ 𝑛𝑛), … , 𝑒𝑒𝑗𝑗 ). which it is possible to obtain an accurate identification of The problem comes down to solving the task of behavior. The main advantage of using this approach is predicting the time series. For this purpose, n neural the implementation of the "sequence-to-sequence networks are formed, each of which describes the effect learning" idea, namely the input and output vectors are of only one control action. Each of the neural networks not limited in size. You can put a vector of any length at takes only the vector of indicators of the study object as the input and get the corresponding vector at the output. an input, and the information about the type of the It should be noted that by analogy with the concept of simulated impact is presented in all weights of the model. time representation in dynamic neural networks a new The output of neural networks is the predicted values of principle of data representation in bionic models in the both variables characterizing the state of the research form of explicit (Fig. 1) and implicit representation of control actions (Fig. 2) is proposed in this case. Fig. 1. Machine learning with explicit representation of control actions Fig. 2. Machine learning with implicit representation of control actions When using an approach with explicit representation 4. Evolutionary approach in bionic model of control actions, the result of machine learning is the structure only model presented (singleton) describing the effect of The application of the evolutionary approach in the any of the control actions involved in learning. Such a structure of the bionic model has made it possible both to model takes as input not only the values of the indicators search for the most effective control actions and to describing the object of the study, but also the logical optimize hyperparameters of the models. In this case, variables in which the control action is encoded (0 - no control actions are presented in two forms: impact; 1 - impact is performed). - in case of explicit representation of control actions, In implicit representation, the result of machine the chromosome is constructed from genes, each of learning is a set of models, each describing the effect of which determines the set of control actions applied to only one control action. Each of the models accepts only the object of study at some point of time; the vector of indicators of the study object, and the - in case of implicit representation, the chromosome is information about the type of simulated impact is determined by genes characterizing certain implicitly presented (i.e. distributed) in all weights of the properties of the model (number of layers, neurons model. per a layer, short-term memory capacity, degree of The need to present information in two types is network connectivity, type of activation function, justified by the fact that the explicit representation allows type of dynamic network deployment, etc.). to regulate the "intensity" of the impact, but requires Fig. 3 shows a diagram for the general case where careful presetting of weights and regularization there are several dependent control actions on the test coefficients, which would determine the informativity of object at each time point. In this case, each chromosome the input neurons that take the values describing the involved in the formation of the population is a matrix control action to the input. (M)ij, where i is the type of action; j is the time point. When learning models with implicit representation of Two ways of presenting priori data were reflected control actions, there is no problem of loss of both in the construction of the chromosome and in the informativity of input neurons values. Each model defining of criterion function. contains fewer configurable parameters. However, the With explicit representation, a gene is a vector of type of impact and its β€œintensity” remain unchanged after logical variables, each of which determines the presence learning, and a large number of models result in huge or absence of the control action. When the function investment of time, compared to a model using explicit fitting is calculated, each gene is concatenated with a representation. vector of values of variables describing the state of the The approaches described above are applicable to a study object and it is input to some model. The output wide class of models, from linear regression to dynamic value of the model by means of a generalized assessment and deep neural networks. Optimization of deep neural reflects the effectiveness of situation management. network parameters is a computationally more complicated task as "layered" architectures contain combinations of nonlinearities defining a wide range of learning problems described by the general term β€œdeep learning”. Fig. 3. Chromosome type determined by the way control actions are presented in the model. Note: U = (u(1,) u2,...ul) is a vector of control actions; W = (w1,w2,...,wn) is a vector of neural model parameters; T = (t1,t2,...,tΟ„) are the time points In the implicit setting of control actions, each gene is developed which implemented the following procedure a vector of neural network model parameters describing a of actions: certain action. Thus, some "bank" of learnt models is 1. Loading of the table with integral criteria on tic formed, vectors of weights remain unchanged in the marks; course of the evolutionary process, but they participate in 2. Data separation into training and test samples chromosome formation. according to cross-validation conditions; Each gene, since it is a fully functional model, takes a 3. Neural network training in order to obtain a vector of variables describing the object of the study as predictive generalized assessment of the state of the study input, and its output is the predicted value of the object at the next point of time; generalized (integral) assessment of the dynamic system 4. Calculation of a prediction error; state depending on the control action. 5. Optimal selection of neural network hyperparameters using a genetic algorithm. 5. Methodological basis for choosing the The results of the prototype work made it possible to sequence of control actions during situation assess the accuracy of this approach and to conclude on management the need to develop a software complex based on the We summarize and note the functionality of each chosen algorithms. element of the bionic model of choosing the sequence of The prototype was developed in Matlab R2008b. control actions during situation management. Python, a high-level programming language relating Let us have a database that stores the values of the to freely distributed software, has been chosen as the properties of the study objects at the following moments main development tool. of time: prior and after some control action is applied. The program on Python consists of a main module 1. For each object at each moment of time, we and secondary modules that can be connected when calculate the values of the generalized indicator and running the main module code. Secondary modules are: evaluate their deviations from the norm. β€’ NumPy - data interpolation, statistical functions, 2. The control action on each object is modeled by a optimized calculations; neural network. As input data, values of variables β€’ Pandas - dataframe, loading and saving *.csv-files; characterizing the state of the research object before β€’ PyBrain - artificial neural networks, optimization applying the control action are used. As the desired methods, including genetic algorithm; responses, both the variable values and the generalized β€’ PyQt – components of the graphic interface. indicator (I) values are used after the control action is The selected tools allow you to move from the stage applied. The objective function to be minimized is of prototype development to the implementation of the defined as the deviation of the generalized indicator from finished software project quite quickly. the norm. The whole process will be divided into several stages: 3. The obtained set of neural network models forms a collection of primary data and secondary data obtained plurality of genes that can be specified by a vector of from the results of additional studies. After the neural network parameters (for an implicit form of calculation of integral indicators based on the control action) and a vector of logical variables in which information approach, a graph of changes in the state of the control action is encoded (in an explicit form). the research object in time is displayed. The cubic spline 4. The sequence of control actions is determined by interpolates the data and calculates the rate of change of known previous states (state variables) and predicted the variables characterizing the state of the research values of object state variables using genetic algorithm. object. In the process of genetic algorithm work the request to Further, the calculation of predicted values of each of neural networks for obtaining the predicted values of the the indicators is performed separately, and a predicted object state for all future time intervals is performed. integrated assessment of the state during the situation 5. The genetic algorithm forms and chooses new control period is given. The deviations between the generation by means of selection, crossover and prediction and the stationary (normal) values at each time mutation. point are determined and displayed on the graph. A 6. The values of the fitting function of the genetic sequence of control actions at which deviation is minimal algorithm are determined as deviations (from the norm) is formed. of the value of the generalized indicator predicted by the 7. Results neural network (by a gene). Among the set of control actions, defined by chromosomes, the one at which the Development and testing of the bionic model, which value of the fitting function will be minimal is chosen is based on the interaction of the information method, (the range is set [0,1; 1]). genetic algorithm and neural networks, allow for situation control based on correct choice of the sequence 6. Software implementation of control actions. The information method forms a At the first stage of development of information single integral indicator characterizing the state of the system in order to test the possibility of using artificial object of the study. Artificial neural networks enable to neural networks for predicting the state of dynamic obtain prediction of integral assessment of the object systems (the object of the study) a prototype was state depending on the chosen control actions. The genetic algorithm chooses a sequence of control actions [8] Alifirova V.M., Brasovsky K.S., Zhukova I.A., that reduce the possibility of transition to adverse states. Pecker J.S., Tolmachev I.V., Fokin V.A. 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