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Using simulation for the design of semi-autonomous vehicle systems

IFAC Proceedings Volumes 2000年第20期33卷 351-356页

作者： Sandor Ujvari Philip R. Moore Centre for Intelligent Automation Department of Engineering Science Högskolan Skövde SE-541 28 Skövde Sweden Faculty of Computing Sciences and Engineering De Montfort University Leicester LE1 9BH United Kingdom

The paper describes the development of Semi-Autonomous Vehicles (SAVS) in the context of Automated Guided Vehicle Systems (AGVS). During the design process of a complete material handling AGV-system many variables must be decided. A two-stage simulation approach of discrete event simulation and continuous path simulation, improves development and testing of SAVS. Decisions need to be made e. g. what main navigation sensor to use, how many vehicles are needed for the task. The interrelation of these parameters makes it difficult to find optimum or near-optimum values. Because of this, simulation is a very useful tool to design and evaluate AGV-systems.

关键词： Simulation Automated Guided Vehicles

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Application of a neural predictive controller in boost converter input current control

Application of a neural predictive controller in boost conve...

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IEEE International Symposium on Intelligent Control (ISIC)

作者： I. Petrovic M. Baric A. Magzan N. Peric Fac. of Electr. Eng. Zagreb Univ. Croatia Faculty of Electrical Engineering and Computing Department of Control and Computer Engineering in Automation University of Zagreb Zagreb Croatia College of Electrical Engineering Polytechnics College of Zagreb Zagreb Croatia

The application of a nonlinear predictive controller in the cascade control structure of a boost converter is investigated. The neuro-predictive controller is realized as a nonlinear optimizer, using the Levenberg-Marquardt unconstrained optimization procedure. For the prediction of future process responses, two MLP neural networks are used. One network is used for modeling the converter dynamics and the other for online estimation of the converter's input voltage. This structure ensures good system performance in all operating regions and inherent compensation of ripples in the converter's input current caused by variations of the input voltage. The advantages of the proposed control structure are demonstrated through experimental comparison with a linear GPC with manually adjusted feedforward compensator.

关键词： Current control Voltage control Control systems Automatic control Pulse width modulation Switches Rail transportation Current measurement Electric current control Application software

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Adaptive Fuzzy Ship Autopilot for Track-Keeping

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IFAC Proceedings Volumes 2000年第21期33卷 129-134页

作者： Jasmin Velagic Zoran Vukic Edin Omerdic University of Sarajevo Faculty of Electrical Engineering Skenderija 70 BH-71000 Sarajevo Bosnia and Herzegovina fax : (+387 71) 654 972 University of Zagreb Faculty of Electrical Engineering and Computing Department of Control and Computer Engineering in Automation Unska 3 HR-10000 Zagreb Croatia fax : (+385 1) 612 98 09 University of Tuzla Faculty of Electrical and Mechanical Engineering Franjevacka 2 BH-75000 Tuzla Bosnia and Herzegovina

We develop in this paper an adaptive fuzzy gain autopilot for ship track-keeping. This autopilot is composed of Sugeno fuzzy type autopilot in an ordinary feedback loop and adjustable scaling factors mechanism in an additional feedback loop. The adjustment mechanism represents a fuzzy controller that changes scaling factors of the base fuzzy autopilot. The control system for the track-keeping is completely described. For the track-keeping problem, the maneuver of way-point turning and ship guiding through a complex path (trajectory) are presented. The influence of sea current and wave disturbances on track-keeping performance was also considered. We first present simulation results obtained by the Sugeno fuzzy type autopilot. Then, we compare those results with ones obtained by an adaptive fuzzy autopilot.

关键词： Adaptive fuzzy control track-keeping fuzzy gain concept disturbance rejection ship control

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MD simulation of heterogeneous vapor nucleation on a solid surface

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AIP Conference Proceedings 2000年第1期534卷 253-256页

作者： K. T. Kholmurodov K. Yasuoka X. C. Zeng 1Computational Science Division Advanced Computing Center The Institute of Physical and Chemical Research (RIKEN) Hirosawa 2-1 Wako Saitama 351-0198 Japan 4Laboratory of Computing Techniques and Automation Joint Institute for Nuclear Research Dubna Moscow region 141980 Russia 2Department of Mechanical Engineering Keio University Yokohama 223-8522 Japan 3Department of Chemistry University of Nebraska-Lincoln Lincoln Nebraska 68588

Molecular dynamics simulations of nucleation of a supersaturated Lennard-Jones vapor confined between parallel solid walls have been performed. The walls in the system, unlike the structure-less one [K. Yasuoka, G. T. Gao, and X. C. Zeng, J. Chem. Phys. 112, pp. 4279–4285 (2000)], are simulated in a more realistic fashion. The particles in the vapor and the solid walls are exactly the same and are described by the same Lennard-Jones potential. The walls are fixed in place in an fcc lattice structure by a combination of the restoring tethering forces and constraint mechanism. The restoring potential confines wall atoms to their lattice sites at the equilibrium state. The walls during simulations are thermostatted, so the heat being dissipated through conduction to the walls, as it is in an experiment [S. T. Cui, P. T. Cummings, and H. D. Cochran, J. Chem. Phys. 111, pp. 1273–1280 (1999)]. Condensation of a supersaturated vapor on a solid surface is investigated with the increasing strength of the wall-vapor interaction. The wall surfaces are the same (100) surface, but with the different strengths of the attraction of vapor atoms: strongly adsorbing wall (with ε1=ε ) and weakly adsorbing wall (with ε2=0.1ε ). Transition from a metastable supersaturated vapor phase to a stable condensed state is studied by monitoring the molecular dynamics configurations of the system in real time and identifying the short-lived droplet nucleus.

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Automatic contingency selection based on a pattern analysis approach

Automatic contingency selection based on a pattern analysis ...

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1999 International Conference on Electric Power engineering, PowerTech Budapest 1999

作者： Rodrigues, M.S. Souza, J.C.S. Filho, M.B. Do Coutto Schilling, M.Th. Department of Electrical Engineering Applied Computing and Automation Fluminense Federal University - UFF Brazil

ISBN: (纸本)0780358368

During power system operation, it is important that load demands be met without violations of system operational constraints. Besides, for a given operating condition, the system should be capable of resisting the loss of any component, with no operational problems. Thus, contingency analysis plays an important role in real-Time power system security evaluation. Contingency analysis comprises the simulation of a set of contingencies in which the system behavior is observed. Each post- contingency scenario is evaluated in order to detect operational problems and the severity of violations. The most common operational problems are transmission equipment overloads and inadequate voltage levels at system buses. In static security analysis the identification of operational constraints violation involves the solution of an AC load flow problem, described by a set of nonlinear equations, that has to be solved for each post-contingency scenario. This procedure leads to a high computational effort, which is not desirable for real-Time applications. Some approximate models have been proposed for realtime power system static security evaluation [1J. These models reduce computational effort, but they may not classify system contingencies accurately. It is not possible to analyze system performance considering all contingencies. It is necessary to reduce the number of contingencies to only those that are more likely to occur. These form the critical contingencies set, which is in general defined based on system operation past experience and/or off-line simulations. The need for computational efficiency in real-Time contingency analysis can make not possible the analysis even for the critical contingencies set. Then, it becomes necessary to select in the critical set the contingencies that can really lead the system to an emergency state, with operational constraints violations. It is important to note that, as system operating conditions change, the harmful contingencies may als

关键词： Neural networks

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Comparative analysis of Mamdani and Sugeno type fuzzy autopilots for ships

Comparative analysis of Mamdani and Sugeno type fuzzy autopi...

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1999 European Control Conference, ECC 1999

作者： Vukic, Z. Velagic, J. University of Zagreb Faculty of Electrical Engineering and Computing Department of Control and Computer Engineering in Automation Unska 3 ZagrebHR-10000 Croatia University of Sarajevo Faculty of Electrical Engineering Skenderija 70 SarajevoBH-71000 Bosnia and Herzegovina

ISBN: (纸本)9783952417355

In this paper a comparative analysis of Mamdani and Sugeno type fuzzy autopilots for ships is given. Both autopilots have two inputs: the heading signal and the yaw rate signal, and only one output: command rudder angle. Input variable fuzzification, fuzzy associative memory (FAM) rules, and output set defuzzification are described. The control system for the course-keeping composed of the nonlinear ship, the steering gear servo system, fuzzy autopilot and wave disturbance is described. Both autopilots are compared in three different sailing conditions: without wave disturbance, with wave disturbance and with wave disturbance and wave filtering. The notch filter was used for filtering of second-order wave disturbances. The influence of wave disturbance on course-keeping performance was analyzed. Even though the obtained performance in simulations are very similar, authors prefer Sugeno type fuzzy autopilot, due to less strain of the steering gear servo system and faster and more accurate heading obtained. © 1999 EUCA.

关键词： Ships

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Friction compensation methods in position and speed control systems

Friction compensation methods in position and speed control ...

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IEEE International Symposium on Industrial Electronics (ISIE)

作者： D. Stajic N. Peric J. Deur Faculty of Electrical Engineering and Computing Department or Control and Computer Engineering in Automation University of Zagreb Zagreb Croatia

Friction appears in the bearings and reduction gear of controlled electrical drives and affects the quality of the position, speed or force control. The servosystem performance can be improved by implementation of acceleration feedback. For the reason that acceleration measurement is often either not possible or practical, the implementation of acceleration estimation by an observer or differentiation of speed is proposed. Another approach to friction influence compensation is based on the disturbance observer. Its advantage is that it can be applied generally to the estimation of various disturbances. This paper deals with these friction compensation methods which are not based on friction model, but on the compensation of friction as a disturbance. The efficiency of these methods in a servodrive with Stribeck friction is compared by computer simulation and experimentally on a servosystem laboratory model.

关键词： Friction Velocity control Force control Servosystems Acceleration Accelerometers Gears Feedback Computer simulation Laboratories

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Automatic contingency selection based on a pattern analysis approach

Automatic contingency selection based on a pattern analysis ...

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International Conference on Electric Power engineering, PowerTech Budapest

作者： M.S. Rodrigues J.C.S. Souza M.B. Do Coutto Filho M.Th. Schilling Applied Computing & Automation Department of Electrical Engineering Fluminense Federal University (UFF) Brazil

Summary form only given. This paper presents a method for power systems automatic contingency selection and static security evaluation. It is possible to identify potentially harmful contingencies in a very short computational time, being the risk of false alarms and contingency misses. The method is tested for many different operating conditions and simulated with the IEEE 24 bus test system. Classification rates for contingency selection and static security evaluation are also provided.

关键词： Pattern analysis Power system security Power system analysis computing Power system simulation Power system modeling Computational modeling Artificial neural networks Power system planning Power engineering and energy Systems engineering and theory

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Frequency domain analysis of B-spline interpolation

Frequency domain analysis of B-spline interpolation

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IEEE International Symposium on Industrial Electronics (ISIE)

作者： Z. Mihajlovic A. Goluban M. Zagar Department of Electronics Microelectronics Computer and Intelligent Systems Faculty of Electrical Engineering and Computing University of Zagreb Zagreb Croatia Department of Control and Computer Engineering in Automation Faculty of Electrical Engineering and Computing University of Zagreb Zagreb Croatia

This paper describes B-spline interpolation and compares it with other reconstruction methods, especially in three-dimensional space. We first consider the B-spline bases in the terms of convolution in signal processing. The presented analysis requires careful usage of continuous and discrete representation of B-spline. Emphasis is given to the important difference between B-spline interpolation and approximation. The difference is shown through frequency domain analysis, so we derive frequency responses of the B-spline interpolation and approximation. We conclude by demonstrating the use of several reconstruction filters and appropriate gradient estimators in volume rendering. Exact reconstruction in volume visualization is very important in many industrial applications, such as material cavity control.

关键词： Frequency domain analysis Spline Interpolation Image reconstruction Convolution Filters Polynomials Data visualization Frequency response Microelectronics

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The B-spline interpolation in visualization

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Journal of computing and Information Technology 1999年第3期7卷 245-253页

作者： Mihajlović, Željka Goluban, Alan Department of Electronics Microelectronics Computer and intelligent Systems Faculty of Electrical Engineering arid Computing University of Zagreb Unska 3 Zagreb10 000 Croatia Department of Control and Computer Engineering in Automation Faculty of Electrical Engineering and Computing University of Zagreb Unska 3 Zagreb10 000 Croatia

The volume data is generally in the form of the large array of numbers. In order to render the object hidden in the volumetric data, we need to reconstruct or interpolate data values between the samples. The novelty presented in this paper is B-spline interpolation in the volumetric space. We show that this approach is better than currently used methods. We also present a hybrid approach, analyze this approach in frequency domain and compare it to B-spline interpolation. To enhance the quality during the volume visualization process it is important to enhance the quality of the reconstruction. It is of crucial importance to explore different undesired effects. If better reconstruction is performed the more accurate result of volume visualization process is achieved.

关键词： Volume rendering

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