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EN
This paper presents an active disturbances rejecter controller (ADRC) for position and path following control of a fully actuated autonomous underwater vehicle (AUV). The unmodeled, undesirable dynamics and disturbances reduce the performances of classical controllers and complicate the design of appropriate and efficient controllers. In the proposed approach, the different modeling complexities; such as uncertain parameters, non-linearities, and external disturbances are considered all as a part of disturbance which is estimated in real-time by the extended state observer ESO, and effectively compensated from the control law. The ESO is also able to estimate the position and velocity of the system in real-time, in case where the full state measurement of the AUV is not possible during experiments. Computer simulations demonstrate the high ability of the AUV tracking control based on ADRC, to follow the desired trajectory in the horizontal plane and space with high precision, and showed high robustness and efficiency in rejecting the external and internal disturbances caused by significant changes in parameters of the system, and the added position disturbances.
EN
We consider a stochastic variant of the single machine total weighted tardiness problem jobs parameters are independent random variables with normal or Erlang distributions. Since even deterministic problem is NP-hard, it is difficult to find global optimum for large instances in the reasonable run time. Therefore, we propose tabu search metaheuristics in this work. Computational experiments show that solutions obtained by the stochastic version of metaheuristics are more stable (i.e. resistant to data disturbance) than solutions generated by classic, deterministic version of the algorithm.
EN
The paper presents new and improved numerical methods designed for analysis of mechanical systems with uncertain parameters. Uncertain parameters in mechanical systems are described using possibility theory. The main representatives of this theory are fuzzy and interval numbers. Algorithms using interval and fuzzy numbers are incorporated into the analysis. The possibilities and efficiency of suggested methods and algorithms are tested by programs created in the environment of the software package MATLAB.
4
Content available remote Numerical study of large scale truss construction with structural uncertainties
EN
The paper deals with efficiency and usability problem for the chosen solution methods for mechanical systems with structural uncertainties. They are significantly influencing the analysis results and the analysis itself. An application of the chosen approaches will be presented – the first one, a simple combination of only inf-values or only sup-values; the second one presents full combination of all inf-sup values; the third one uses the optimizing process as a tool for finding out an inf-sup solution and last one is Monte Carlo method as a comparison tool.
EN
The paper presents the spectral analysis of the beam’s vibration with uncertain parameters under a random train of moving forces which forms a filtered Poisson process. It is assumed that natural frequencies of the bridge beam are uncertain and are modelled by fuzzy numbers, random variables or fuzzy random variables. In order to obtain general solutions for the spectral density function of the beam’s response the normal mode dynamic influence function has been introduced. As an example the spectral density functions of a bridge modelled as a simple supported beam are determined.
PL
W pracy zaprezentowano analizę widmową drgań belki o niepewnych parametrach, poddanej działaniu losowej serii ruchomych sił. Siły te tworzą proces Poissona. W analizie przyjęto, że niepewność wielkości częstości własnych można uwzględnić, uznając je za liczby rozmyte, zmienne losowe lub rozmyte zmienne losowe. Wprowadzono dynamiczną funkcję wpływu o charakterze losowo-rozmytym, dzięki której można otrzymać wygodne dla dalszych rozważań i obliczeń numerycznych związki, które określają funkcję gęstości widmowej drgań belki.
EN
The paper considers a set of linear discrete-time systems with uncertain parameters. A method of synthesis of robust control which simultaneously stabilizes all the systems from this set is proposed. This method consists of two steps. First, a set of stochastic comparison systems with multiplicative noises is constructed such that if the stochastic system from this set is mean square stable then the corresponding system with uncertain parameters from the original set is robustly stable. Second, the simultaneous stabilization problem for the comparison system is solved. To find a gain matrix of the simultaneously stabilizing controller in the case of state feedback an LMI based algorithm is given and in the case of static output feedback a new method and convergent iteration algorithm are obtained.
EN
This paper concerns a control system for a resource distribution in a complex of parallel operations. The operations are described by relational knowledge representation with uncertain parameters characterized by an expert. The knowledge obtained from an expert is further corrected online by applying an adaptation process. Three particular adaptive control algorithms are suggested, of which two use an artificial neural network. The paper presents selected results of simulations showing that the proposed concepts and algorithms may be practically useful.
PL
W pracy rozpatrzono problem badania odpornej stabilności liniowych obwodów elektrycznych o niepewnych parametrach. Dokonano krótkiej ogólnej charakterystyki metod badania odpornej stabilności oraz dokładniej rozpatrzono dwie komputerowe metody: uogólnioną metodę Hurwitza oraz metodę przestrzeni niepewnych parametrów. Rozważania zilustrowano przykładem.
EN
The paper considers the problem of robust stability analysis of linear electrical circuits with uncertain parameters. A short review of methods for robust stability analysis is given. Two methods: the generalised Hurwitz method and the method of the space of uncertain parameters are described. Considerations are illustrated by an example.
PL
Metoda perturbacji pozwala na szybkie oszacowanie wartości własnych w układach poddanych zaburzeniom. Uogólniając tę metodę na liczby przedziałowe, można wykorzystać ją do oszacowania wszystkich wartości własnych przedziałowego zadania własnego [A]x = lambda[B]x, a także zadania własnego drugiego stopnia lambda do potęgi 2[A]x + lambda[B]x+[C]x=0. W teorii konstrukcji tę metodę możemy wykorzystać do oszacowania częstości drgań własnych wielowymiarowych układów dynamicznych o parametrach niepewnych oraz częstości drgań swobodnych w układach z tłumieniem.
EN
Method of perturbation makes possible quick estimation of eignvalues of systems under disturbances. Extension of this method over interval numbers gives possibility to estimate all eigenvalues of interval generalized eigenvalue problem [A]x = lambda[B]x and second degree eigenvalue problem lambda power 2 [A]x + lambda[B]x + [C]x = 0. In theory of structures this method can be used for eigenfrequency estimation of multidimensional dynamic systems with interval parameters and frequency of free vibration in systems with damping.
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