Розробка методу навчання штучних нейронних мереж для інтелектуальних систем підтримки прийняття рішень

A method for training artificial neural networks for intelligent decision support systems has been developed. The method provides training not only of the synaptic weights of the artificial neural network, but also the type and parameters of the membership function, architecture and parameters of an individual network node. The architecture of artificial neural networks is trained if it is not possible to ensure the specified quality of functioning of artificial neural networks due to the training of parameters of an artificial neural network. The choice of architecture, type and parameters of the membership function takes into account the computing resources of the tool and the type and amount of information received at the input of the artificial neural network. The specified method allows the training of an individual network node and the combination of network nodes. The development of the proposed method is due to the need for training artificial neural networks for intelligent decision support systems, in order to process more information, with unambiguous decisions being made. This training method provides on average 10–18 % higher learning efficiency of artificial neural networks and does not accumulate errors during training. The specified method will allow training artificial neural networks, identifying effective measures to improve the functioning of artificial neural networks, increasing the efficiency of artificial neural networks through training the parameters and architecture of artificial neural networks. The method will allow reducing the use of computing resources of decision support systems, developing measures aimed at improving the efficiency of training artificial neural networks and increasing the efficiency of information processing in artificial neural networksРазработан метод обучения искусственных нейронных сетей для интеллектуальных систем поддержки принятия решений. Метод проводит обучение не только синаптических весов искусственной нейронной сети, но и вида и параметров функции принадлежности; архитектуры и параметров отдельного узла сети. В случае невозможности обеспечить заданное качество функционирования искусственных нейронных сетей за счет обучения параметров искусственной нейронной сети происходит обучение архитектуры искусственных нейронных сетей. Выбор архитектуры, вида и параметров функции принадлежности происходит с учетом вычислительных ресурсов средства и с учетом типа и количества информации, поступающей на вход искусственной нейронной сети. Указанный метод позволяет проводить обучение отдельного узла сети и осуществлять комбинирование узлов сети. Разработка предложенного метода обусловлена необходимостью проведения обучения искусственных нейронных сетей для интеллектуальных систем поддержки принятия решений, с целью обработки большего количества информации, при однозначности решений, которые принимаются. Указанный метод обучения обеспечивает в среднем на 10–18% более высокую эффективность обучения искусственных нейронных сетей и не накапливает ошибок в ходе обучения. Указанный метод позволит проводить обучение искусственных нейронных сетей; определить эффективные меры для повышения эффективности функционирования искусственных нейронных сетей; повысить эффективность функционирования искусственных нейронных сетей за счет обучения параметров и архитектуры искусственных нейронных сетей. Метод позволит уменьшить использование вычислительных ресурсов систем поддержки и принятия решений; выработать меры, направленные на повышение эффективности обучения искусственных нейронных сетей; повысить оперативность обработки информации в искусственных нейронных сетяхРозроблено метод навчання штучних нейронних мереж для інтелектуальних систем підтримки прийняття рішень. Метод проводить навчання не тільки синаптичних ваг штучної нейронної мережі, але й виду та параметрів функції належності; архітектури та параметрів окремого вузла мережі. В разі неможливості забезпечити задану якість функціонування штучних нейронних мереж за рахунок навчання параметрів штучної нейронної мережі відбувається навчання архітектури штучних нейронних мереж. Вибір архітектури, виду та параметрів функції належності відбувається з врахуванням обчислювальних ресурсів засобу та з врахуванням типу та кількості інформації, що надходить на вхід штучної нейронної мережі. Зазначений метод дозволяє проводити навчання окремого вузла мережі та здійснювати комбінування вузлів мережі. Розробка запропонованого методу обумовлена необхідністю проведення навчання штучних нейронних мереж для інтелектуальних систем підтримки прийняття рішень, з метою обробки більшої кількості інформації, при однозначності рішень, що приймаються. Зазначений метод навчання забезпечує в середньому на 10–18 % більшу високу ефективність навчання штучних нейронних мереж та не накопичує помилок в ході навчання. Зазначений метод дозволить проводити навчання штучних нейронних мереж; визначити ефективні заходи для підвищення ефективності функціонування штучних нейронних мереж; підвищити ефективність функціонування штучних нейронних мереж за рахунок навчання параметрів та архітектури штучних нейронних мереж. Метод дозволить зменшити використання обчислювальних ресурсів систем підтримки та прийняття рішень; виробити заходи, що спрямовані на підвищення ефективності навчання штучних нейронних мереж; підвищити оперативність обробки інформації в штучних нейронних мережа

U-model based predictive control for nonlinear processes with input delay

In this paper, a general control scheme is proposed for nonlinear dynamic processes with input delay described by different models, including polynomial models, state-space models, nonlinear autoregressive moving average with eXogenous inputs (NARMAX) models, Hammerstein or Wiener type models. To tackle the input delay and nonlinear dynamics involved with the control system design, it integrates the classical Smith predictor and a U-model based controller into a U-model based predictive control scheme, which gives a general solution of two-degree-of-freedom (2DOF) control for the set-point tracking and disturbance rejection, respectively. Both controllers are analytically designed by proposing thedesired transfer functions for the above objectives in terms of a linear system expression with the U-model, and therefore are independent of the process model for implementation. Meanwhile, the control system robust stability is analyzed in the presence of process uncertainties. To demonstrate the control performance and advantage, three examples from the literature are conducted with a user-friendly step by step procedure for the ease of understanding by readers

Hysteresis Modeling in Iron-Dominated Magnets Based on a Multi-Layered Narx Neural Network Approach

A full-fledged neural network modeling, based on a Multi-layered Nonlinear Autoregressive Exogenous Neural Network (NARX) architecture, is proposed for quasi-static and dynamic hysteresis loops, one of the most challenging topics for computational magnetism. This modeling approach overcomes drawbacks in attaining better than percent-level accuracy of classical and recent approaches for accelerator magnets, that combine hybridization of standard hysteretic models and neural network architectures. By means of an incremental procedure, different Deep Neural Network Architectures are selected, fine-tuned and tested in order to predict magnetic hysteresis in the context of electromagnets. Tests and results show that the proposed NARX architecture best fits the measured magnetic field behavior of a reference quadrupole at CERN. In particular, the proposed modeling framework leads to a percent error below 0.02% for the magnetic field prediction, thus outperforming state of the art approaches and paving a very promising way for future real time applications

Development of U-model enhansed nonlinear systems

Nonlinear control system design has been widely recognised as a challenging issue where the key objective is to develop a general model prototype with conciseness, flexibility and manipulability, so that the designed control system can best match the required performance or specifications. As a generic systematic approach, U-model concept appeared in Prof. Quanmin Zhu’s Doctoral thesis, and U-model approach was firstly published in the journal paper titled with ‘U-model based pole placement for nonlinear plants’ in 2002.The U-model polynomial prototype precisely describes a wide range of smooth nonlinear polynomial models, defined as a controller output u(t-1) based time-varying polynomial models converted from the original nonlinear model. Within this equivalent U-model expression, the first study of U-model based pole placement controller design for nonlinear plants is a simple mapping exercise from ordinary linear and nonlinear difference equations to time-varying polynomials in terms of the plant input u(t-1). The U-model framework realised the concise and applicable design for nonlinear control system by using such linear polynomial control system design approaches.Since the first publication, the U-model methodology has progressed and evolved over the course of a decade. By using the U-model technique, researchers have proposed many different linear algorithms for the design of control systems for the nonlinear polynomial model including; adaptive control, internal control, sliding mode control, predictive control and neural network control. However, limited research has been concerned with the design and analysis of robust stability and performance of U-model based control systems.This project firstly proposes a suitable method to analyse the robust stability of the developed U-model based pole placement control systems against uncertainty. The parameter variation is bounded, thus the robust stability margin of the closed loop system can be determined by using LMI (Linear Matrix Inequality) based robust stability analysis procedure. U-block model is defined as an input output linear closed loop model with pole assignor converted from the U-model based control system. With the bridge of U-model approach, it connects the linear state space design approach with the nonlinear polynomial model. Therefore, LMI based linear robust controller design approaches are able to design enhanced robust control system within the U-block model structure.With such development, the first stage U-model methodology provides concise and flexible solutions for complex problems, where linear controller design methodologies are directly applied to nonlinear polynomial plant-based control system design. The next milestone work expands the U-model technique into state space control systems to establish the new framework, defined as the U-state space model, providing a generic prototype for the simplification of nonlinear state space design approaches.The U-state space model is first described as a controller output u(t-1) based time-varying state equations, which is equivalent to the original linear/nonlinear state space models after conversion. Then, a basic idea of corresponding U-state feedback control system design method is proposed based on the U-model principle. The linear state space feedback control design approach is employed to nonlinear plants described in state space realisation under U-state space structure. The desired state vectors defined as xd(t), are determined by closed loop performance (such as pole placement) or designer specifications (such as LQR). Then the desired state vectors substitute the desired state vectors into original state space equations (regarded as next time state variable xd(t) = x(t) ). Therefore, the controller output u(t-1) can be obtained from one of the roots of a root-solving iterative algorithm.A quad-rotor rotorcraft dynamic model and inverted pendulum system are introduced to verify the U-state space control system design approach for MIMO/SIMO system. The linear design approach is used to determine the closed loop state equation, then the controller output can be obtained from root solver. Numerical examples and case studies are employed in this study to demonstrate the effectiveness of the proposed methods

Proceedings. 24. Workshop Computational Intelligence, Dortmund, 27. - 28. November 2014

Dieser Tagungsband enthält die Beiträge des 24. Workshops "Computational Intelligence" des Fachausschusses 5.14 der VDI/VDE-Gesellschaft für Mess- und Automatisierungstechnik (GMA), der vom 27. - 28. November 2014 in Dortmund stattgefunden hat. Die Schwerpunkte sind Methoden, Anwendungen und Tools für Fuzzy-Systeme, Künstliche Neuronale Netze, Evolutionäre Algorithmen und Data-Mining-Verfahren sowie der Methodenvergleich anhand von industriellen Anwendungen und Benchmark-Problemen

Analysis of derived features for the motion classification of a passive lower limb exoskeleton

Analysis of Derived Features for the Motion Classification of a PassiveLowerLimbExoskeleton The recognition of human motion intentions is a fundamental requirement to control efficiently an exoskeleton system. The exoskeleton control can be enhanced or subsequent motions can be predicted, if the current intended motion is known. At H2T research has been carried out with a classification system based on Hidden Markov Models (HMMs) to classify the multi-modal sensor data acquired from a unilateral passive lower-limb exoskeleton. The training data is formed of force vectors, linear accelerations and Euler angles provided by 7 3D-force sensors and 3 IMUs. The recordings consist of data of 10 subjects performing 14 different types of daily activities, each one carried out 10 times. This master thesis attempts to improve the motion classification by using physical meaningful derived features from the raw data aforementioned. The knee vector moment and the knee and ankle joint angles, which respectively give a kinematic and dynamic description of a motion, were the derived features considered. Firstly, these new features are analysed to study their patterns and the resemblance of the data among different subjects is quantified in order to check their consistency. Afterwards, the derived features are evaluated in the motion classification system to check their performance. Various configurations of the classifier were tested including different preprocessors of the data employed and the structure of the HMMs used to represent each motion. Some setups combining derived features and raw data led to good results (e.g. norm of the moment vector and IMUs got 89.39% of accuracy), but did not improve the best results of previous works (e.g. 2 IMUs and 1 Force Sensor got 90.73% of accuracy). Although the classification results are not improved, it is proved that these derived features are a good representation of their primary features and a suitable option if a dimensional reduction of the data is pursued. At the end, possible directions of improvement are suggested to improve the motion classification concerning the results obtained along the thesis.Outgoin

Learning optimal control policies from data: a partially model-based actor-only approach

This dissertation presents new algorithms for learning optimal feed-back controllers directly from experimental data, considering the plant to be controlled as a black-box source of streaming input and output data. The presented methods fall in the Reinforcement Learning “actor-only” family of algorithms, employing a represen-tation (policy parameterization) of the controller as a function of the feedback values and of a set of parameters to be tuned. The optimization of a policy parameterization corresponds to the search of the set of parameters associated with the best value of a chosen performance index. Such a search is carried on via numerical opti-mization techniques, such as the Stochastic Gradient Descent algo-rithm and related techniques. The proposed methods are based on a combination of the data-driven policy search framework with some elements of the model-based scenario, in order to mitigate some of the drawbacks presented by the purely data-driven approach, while retaining a low modeling effort, as compared to the typical identif-cation and model-based control design scenario. In particular, we initially introduce an algorithm for the search of smooth control policies, considering both the online scenario (when new data are collected from the plant during the iterative policy syn-thesis, while the plant is also under closed-loop control) and the of-fine one (i.e. from open-loop data that were previously collected from the plant). The proposed method is then extended to learn non-smooth control policies, in particular hybrid control laws, op-timizing both the local controllers and the switching law directly from data. The described methods are then extended in order to be employed in a collaborative learning setup, considering multi-agent systems characterized by heavy similarities, exploiting a cloud-aided scenario to enhance the learning process by sharing information