Wyniki wyszukiwania - BazTech

1

Elman neural network for modeling and predictive control of delayed dynamic systems

Wysocki A., Ławryńczuk M.

Archives of Control Sciences

|

2016

|

Vol. 26, no. 1

117--142

EN

The objective of this paper is to present a modified structure and a training algorithm of the recurrent Elman neural network which makes it possible to explicitly take into account the time-delay of the process and a Model Predictive Control (MPC) algorithm for such a network. In MPC the predicted output trajectory is repeatedly linearized on-line along the future input trajectory, which leads to a quadratic optimization problem, nonlinear optimization is not necessary. A strongly nonlinear benchmark process (a simulated neutralization reactor) is considered to show advantages of the modified Elman neural network and the discussed MPC algorithm. The modified neural model is more precise and has a lower number of parameters in comparison with the classical Elman structure. The discussed MPC algorithm with on-line linearization gives similar trajectories as MPC with nonlinear optimization repeated at each sampling instant.

2

Fractional order PI controllers for TCP packet flow ensuring given modulus margins

Krajewski W., Viaro U.

Control and Cybernetics

|

2014

|

Vol. 43, no. 4

493--505

EN

An Active Queue Management (AQM) robust control strategy for Traffic Control Protocol (TCP) data transfer is proposed. To this purpose, the TCP behaviour is first approximated by a second–order model with delayed input obtained from the linearization of an efficient and commonly used nonlinear fluid–based model. The adopted feedback control structure uses a fractional– order PI controller. To ensure the desired robustness, the parameter regions where such a controller guarantees a given modulus margin (inverse of the H1 norm of the sensitivity function) are derived. An example commonly used in the literature is worked out to show that the suggested graphically–based design technique is simple to apply while it limits the effects of disturbances and of the unmodelled dynamics.

3

Stan badań w zakresie teorii sterowania

Klamka J.

Pomiary Automatyka Kontrola

|

2011

|

R. 57, nr 11

1436-1440

PL

Niniejsze opracowanie poświęcone jest analizie aktualnego stanu badań oraz perspektywom rozwoju teorii sterowania w uczelniach i instytutach naukowych. Celem opracowania jest podjecie próby wytyczenia głównych kierunków działalności naukowo-badawczej oraz ich koordynacja. Teoria sterowania jest uprawiana w kilkunastu ośrodkach krajowych, w większości w wyższych uczelniach technicznych oraz w instytutach badawczych Polskiej Akademii Nauk. W artykule rozpatrywane są zarówno skończenie wymiarowe układy dynamiczne liniowe ciągłe i dyskretne jak i nieliniowe układy dynamiczne. W przypadku układów liniowych wyróżnia się miedzy innymi układy osobliwe oraz w przypadku układów dyskretnych układy o wielu zmiennych niezależnych. Przedstawione są także układy nieskończenie-wymiarowe opisane równaniami różniczkowymi cząstkowymi oraz skończenie wymiarowe układy dynamiczne z różnego typu opóźnieniami zarówno w stanie, jak i w sterowaniu.

EN

The presented paper is devoted to analysis of research in the domain of control theory and development perspectives of control theory in technical high schools and research institutes of the Polish Academy of Sciences. The main research directions in mathematical control theory are pointed out. It should be stressed that control theory is developed in several universities and institutes. The paper contains many remarks and comments concerning control theory of finite-dimensional dynamical systems both for linear continuous-time and discrete-time as well as nonlinear dynamical systems. In the case of linear systems there are distinguished, among others, singular systems and in the case of discrete-time systems - systems with many independent variables. Moreover, infinite-dimensional dynamical systems and systems with different types of delays in the state variables and in the admissible controls are also considered. There are also presented in the paper: linear finite-dimensional dynamical systems, multidimensional systems and automatic control, distributed parameter dynamical systems, shape optimisation, dynamical systems with delays, special flying machines, nonlinear dynamical systems, multi-criterion optimisation.

4

Sterowalność liniowych układów dynamicznych z opóźnieniem

Klamka J.

Pomiary Automatyka Kontrola

|

2010

|

R. 56, nr 5

377-380

PL

W niniejszej pracy zostaną sformułowane i udowodnione kryteria aproksymacyjnej sterowalności dla liniowego stacjonarnego układu dynamicznego o parametrach rozłożonych z jednym stałym skupionym opóźnieniem we współrzędnych stanu oraz jednym stałym skupionym opóźnieniem w sterowaniu. Rozpatrywany będzie układ dynamiczny opisany liniowym równaniem różniczkowym cząstkowym typu parabolicznego o jednej zmiennej przestrzennej z zerowymi warunkami brzegowymi typu Dirichleta oraz nieujemnymi sterowaniami dopuszczalnymi. Przedstawione będą warunki wystarczające aproksymacyjnej sterowalności przy założeniu, że sterowania dopuszczalne są nieujemne. Niniejsza praca stanowi rozszerzenie na przypadek układów dynamicznych o parametrach rozłożonych i ze skupionym opóźnieniem we współrzędnych stanu oraz ograniczonymi sterowaniami dopuszczalnymi, warunków sterowalności z nieograniczonymi sterowaniami dopuszczalnymi.

EN

In recent years controllability problems for linear retarded dynami-cal systems have been considered in many publications. However, most literature in this direction so far has been concerned with unconstrained controllability problems. Only a few papers deals with the so called constrained controllability problems, i.e. with the case when the controls are restricted to take their values in a given set. Moreover, it should be pointed out, that up to now constrained controllability of linear distributed parameter systems with delays has not been considered in the literature. Therefore, in order to fill this gap the present paper studies the constrained controllability problem for abstract retarded dynamical systems. The main purpose of the paper is to study constrained controllability problems for linear time-invariant distributed parameter dynamical systems with constant so called lumped delays in the state variables. Dynamical system is described by linear partial differential equation of parabolic type with zero Dirichlet boundary conditions More precisely, constrained relative approximate controllability and constrained absolute approximate controllability are considered. Using some general methods taken from the functional analysis, and specially from the spectral theory of linear unbounded operators, several conditions for these types of constrained controllability are formulated and proved. Finally, some remarks and comments on the relationships between relative and absolute constrained controllability are presented.

5

Optimal control for bilinear systems with delay on control

Eljai A., Karrakchou J., Rachik M., Lhous M.

Archives of Control Sciences

|

2001

|

Vol. 11, no. 1/2

23-55

EN

The quadratic optimal control for bilinear distributed systems with delays in the control is considered. A semigroup model which involves no explicit delays in control is introduced. In the case of continuous delay, the control operator is bounded and the classical results can be applied. The case of general delays can be considered as a distributed system with boundary control. With the aid of a family of approximating systems, it is shown that the optimal control is obtained as a limit of sequence which is solution of classical control problems.

6

On the asymptotic stability of nonlinear discrete systems

Rachik M., Lhous M., Tridane A.

Archives of Control Sciences

|

2000

|

Vol. 10, no. 3/4

125-140

EN

Discrete nonlinear systems are considered. Inspired by what was done in (Banks et al., 1996) and (Hong et al., 1994), we develop some sufficient conditions which assure the stability of discrete-time nonlinear varying systems. The problem for discrete delayed systems is also considered.