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2008 American control Conference (ACC), vol.3

作者： E. Portillo M. Marcos I. Cabanes A. Zubizarreta J.A. Sanchez Department of Automatic Control and System Engineering University of Basque Country (UPV-EHU) Bilbao Spain Department of Mechanical Engineering E.T.S.I. de Bilbao University of Basque Country (UPV-EHU) Bilbao Spain

This paper presents the use of Artificial Neural Networks to diagnose degraded behaviours in Wire Electrical Discharge Machining (WEDM). The detection in advance of the degradation of the cutting process is crucial since this can lead to the breakage of the cutting tool (the wire), reducing the process productivity and the required accuracy. Concerning this, previous investigations have identified different types of degraded behaviors in two commonly used workpiece thicknesses (50 and 100 mm). This goal was achieved by monitoring different functions of the characteristic variables of the discharges. However, the thresholds achieved by these functions depended on the workpiece thickness. Consequently, the main objective of this work is to detect the process degradation in different workpiece thicknesses using one unique empirical model Since Neural network techniques are appropriate for stochastic and nonlinear nature processes, its use is investigated here to cope with different workpiece thicknesses. The results of this work show a satisfactory performance of the presented approach.

关键词： Artificial neural networks Machining Degradation Wire Neural networks Electrodes Dielectrics Productivity Stochastic processes Ionization

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Utilizing Model Structure for Efficient Simultaneous Localization and Mapping for a UAV Application

Utilizing Model Structure for Efficient Simultaneous Localiz...

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IEEE Conference on Aerospace

作者： Rickard Karlsson Thomas B. Schon David Tornqvist Gianpaolo Conte Fredrik Gustafsson Division of Automatic Control Department of Electrical Engineering Linköping University Linkoping Sweden Division of Artificial Intelligence and Integrated Computer System Department of Computer and Information Science Linköping University Linkoping Sweden

This contribution aims at unifying two recent trends in applied particle filtering (PF). The first trend is the major impact in simultaneous localization and mapping (SLAM) applications, utilizing the FastSLAM algorithm. The second one is the implications of the marginalized particle filter (MPF) or the Rao-Blackwellized particle filter (RBPF) in positioning and tracking applications. Using the standard FastSLAM algorithm, only low-dimensional vehicle models are computationally feasible. In this work, an algorithm is introduced which merges FastSLAM and MPF, and the result is an algorithm for SLAM applications, where state vectors of higher dimensions can be used. Results using experimental data from a UAV (helicopter) are presented. The algorithm fuses measurements from on-board inertial sensors (accelerometer and gyro) and vision in order to solve the SLAM problem, i.e., enable navigation over a long period of time.

关键词： Simultaneous localization and mapping Unmanned aerial vehicles Particle filters Filtering Particle tracking Computational modeling Helicopters Fuses Time measurement Sensor fusion

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Comparisons and combinations of interpolation methods with conventional predictive control

Comparisons and combinations of interpolation methods with c...

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2007 Mediterranean Conference on control and Automation, MED

作者： Ding, Yihang Rossiter, J.A. Automatic Control and System Engineering University of Sheffield United Kingdom

ISBN: (纸本)142441282X

Many papers have demonstrated that interpolation methods can often enlarge feasible regions significantly while also reducing computational complexity in MPC algorithms (Bacic et al, 2003;Rossiter et al, 2004). However, the simplest interpolations give non-convex feasible regions and thus may have limited benefit in some state directions. This paper presents a new interpolation method which combines the advantages of simple interpolations with conventional predictive control methods to enable a better compromise balance between the volume and shape of the feasible region and the number of degrees of freedom required. ©2007 IEEE.

关键词： Interpolation

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QFT control based on zero phase error compensation for flight simulator

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Journal of systems engineering and Electronics 2007年第1期18卷 125-131页

作者： Liu Jinkun He Yuzhu Dept. of Automatic Automatic Control Beijing Univ. of Aeronautics and Astronautics Beijing 100083 E R. China Dept. of Engineering System of Engineering Beijing Univ. of Aeronautics and Astronautics Beijing 100083 E R. China

To improve the robustness of high-precision servo systems, quantitative feedback theory （QFT） which aims to achieve a desired robust design over a specified region of plant uncertainty is proposed. The robust design problem can be solved using QFT but it fails to guarantee a high precision tracking. This problem is solved by a robust digital QFT control scheme based on zero phase error （ZPE） feed forward compensation. This scheme consists of two parts： a QFT controller in the closed-loop system and a ZPE feed-forward compensator. Digital QFT controller is designed to overcome the uncertainties in the system. Digital ZPE feed forward controller is used to improve the tracking precision. Simulation and real-time examples for flight simulator servo system indicate that this control scheme can guarantee both high robust performance and high position tracking precision.

关键词： Quantitative feedback theory Zero phase error Feed forward compensation Servo system Flight simulator

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Geometrical design of a multiple-source active noise control system using genetic algorithms

Geometrical design of a multiple-source active noise control...

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36th International Congress and Exhibition on Noise control engineering, INTER-NOISE 2007

作者： Jafferi, Noormaziah Tokhi, M.O. Department of Automatic Control and System Engineering University of Sheffield United Kingdom

ISBN: (纸本)9781605603858

This paper presents an investigation into the development of a noise cancellation system using genetic algorithms (GAs). A multi-input multi-output (MIMO) control structure and associated control algorithm are developed on the basis of optimum cancellation of noise at a set of observation points. The algorithm is realised using GA and its performance assessed in the cancellation of noise in a free-field medium. The global search technique of GA is used to select the system component configuration for enhanced performance of an active noise control (ANC) system. In this investigation, randomly selected parameters are optimized for different, arbitrarily chosen locations for system components by applying the working mechanism of GA. The percentage of reinforcement that occurs in the medium is adopted as the objective function value. The MIMO GA-ANC algorithm is implemented and simulation results are presented to asses the performance of the system, with single frequency noise. The results are presented for analysis using a graphical user interface, to allow the user asses the system design in an interactive manner.

关键词： Genetic algorithms

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Advanced concepts in Power control systems

Advanced concepts in Power Control Systems

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作者： Dumitrache, Ioan Iliescu, Sergiu Stelian Automatic Control and System Engineering Department Faculty Automatic of Control and Computers Politehnica University Bucharest Romania Automatic Control and Industrial Informatics Departament Faculty Automatic of Control and Computers Politehnica University Bucharest Romania

ISBN: (纸本)9783902661388

In this paper are presented some new concepts of control applied in Power systems. Are given the architectures and methodologies based on the agents theory. The complexity of Power systems is included into a new paradigm - Complex Adaptive systems - and the modelling and control of Power systems based on intelligent agents are considered. Some concepts on hierarchical and heterarchical architectures which include different intelligent techniques are also presented in this paper.

关键词： Multi agent systems

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Speed sensorless control with neuron MRAS estimator of an induction machine

Speed sensorless control with neuron MRAS estimator of an in...

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7th International Conference on Power Electronics and Drive systems, PEDS 2007

作者： Lei, Dong Dong, Yang Xiaozhong, Liao Department of Automatic Control Engineering Beijing Institute of Technology Key Laboratory of Complex System Intelligent Control and Decision Ministry of Education Beijing China

ISBN: (纸本)1424406455

In the high speed range, vector control of rotor flux orientation of an induction machine implements good performance. However, the performance in low speed rang deteriorates because of the inaccurate estimation of rotor flux and speed. In this paper, modified voltage model for rotor flux estimation and neuron model-reference adaptive system (MRAS) for speed estimation are used to improve the performance of speed sensorless vector control. To improve the accuracy of rotor flux estimation, the stator resistance is identified on-line. The experimental results show that the proposed scheme yields improved performance in low speed range. © 2007 IEEE.

关键词： Induction machine

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ADVANCED CONCEPTS IN POWER control systemS

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IFAC Proceedings Volumes 2007年第8期40卷 15-19页

作者： Ioan Dumitrache Sergiu Stelian Iliescu Automatic Control and System Engineering Department Automatic Control and Industrial Informatics Departament Faculty Automatic of Control and Computers Politehnica University of Bucharest

In this paper are presented some new concepts of control applied in Power systems. Are given the architectures and methodologies based on the agents theory. The complexity of Power systems is included into a new paradigm – Complex Adaptive systems – and the modelling and control of Power systems based on intelligent agents are considered. Some concepts on hierarchical and heterarchical architectures which include different intelligent techniques are also presented in this paper.

关键词： Eelectrical Ppower systems (EPS) Multi-Agent systems (MAS) Complex Adaptive systems (CAS)

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Optimization of RAMS+C for safety instrumented system design with diverse redundancy

Optimization of RAMS+C for safety instrumented system design...

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European Safety and Reliability Conference 2007, ESREL 2007 - Risk, Reliability and Societal Safety

作者： Torres-Echeverría, A.C. Martorell, S. Thompson, H.A. Department of Automatic Control and System Engineering University of Sheffield Sheffield United Kingdom Department of Chemical and Nuclear Engineering Polytechnic University of Valencia Valencia Spain

ISBN: (纸本)0415447860

This paper addresses the optimization of safety instrumented systems design based on a RAMS+C approach using a multi-objective genetic algorithm. The design includes optimization of safety and reliability measures against lifecycle cost, paying special attention to the effect that different diverse redundancy schemes have on common cause failure and thus how they affect the overall system objectives. The safety integrity requirements and modelling detail indicated by the standard IEC 61508 are addressed. The problem is approached as one of redundancy allocation with diversity and design variations. In order to include safety integrity, the Average Probability of Failure on Demand is one objective to optimize. This is complemented with the Spurious Trip Rate (safe failure) and Lifecycle Cost as additional objectives. For demonstration of the overall method, a practical example from chemical industry is used: a protection against high pressure and temperature for a chemical reactor. Three different technologies are available for use per subsystem to implement diversity, at the same time also modifying the diagnostic coverage. © 2007 Taylor & Francis Group.

关键词： systems analysis

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Spatiotemporal analysis of an agent-based model of a colony of keratinocytes: A first approach for the development of validation methods

Spatiotemporal analysis of an agent-based model of a colony ...

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7th IEEE International Conference on Bioinformatics and Bioengineering, BIBE

作者： Pichardo-Almarza, César Smallwood, Rod Billings, S.A. Department of Computer Science University of Sheffield Sheffield United Kingdom Department of Automatic Control and System Engineering University of Sheffield Sheffield United Kingdom

ISBN: (纸本)1424415098

Agent-based models are widely used for the simulation of systems from several domains (biology, economics, meteorology, etc). In biology agent-based models are very useful for predicting the social behaviour of systems;in particular they seem well adapted to model the behaviour of a cell population. In this paper an agent-based model, developed to study normal human keratinocytes (tissue cells), will be investigated. This kind of model exhibits probabilistic behaviour and the validation of simulation results is often done with a qualitative analysis by the experts (biologists). The main objective of this paper is to propose new variables and metrics that allow the comparison and a possible quantitative validation using numerical results from simulations. ©2007 IEEE.

关键词： Cell culture

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