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1

ANFIS based inverse controller design for liquid level control of a spherical tank

Akca Talha Burak, Ulu Cenk, Obut Salih

Przegląd Elektrotechniczny

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2023

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R. 99, nr 2

32--36

EN

In this study, an adaptive neuro fuzzy inference system (ANFIS) based inverse controller design is presented for liquid level control application of a spherical tank. First, an excitation signal is applied to the system and the corresponding output signal is obtained. ANFIS-based fuzzy model of the nonlinear spherical tank system is constructed by using this input-output data set. While constructing the fuzzy model, a fuzzy model structure with two inputs and one output is preferred considering design simplicity. The input-output data used for constructing the fuzzy model of the system are exchanged, and by using this new data set, an ANFIS based inverse controller is designed. To improve the control performance against disturbances and model mismatches, the inverse controller is used in an internal model control structure. The performance of the proposed controller is compared to that of classical PI and fuzzy PI controllers under set point variation and disturbance conditions. The results of comparisons reveal that the proposed inverse controller outperforms both the classical and fuzzy PI controllers.

PL

W niniejszym opracowaniu przedstawiono projekt regulatora odwrotnego opartego na adaptacyjnym neurorozmytym systemie wnioskowania (ANFIS) do zastosowania w kontroli poziomu cieczy w zbiorniku kulistym. Najpierw do systemu doprowadzany jest sygnał wzbudzenia i uzyskiwany jest odpowiedni sygnał wyjściowy. Oparty na ANFIS model rozmyty nieliniowego systemu zbiorników sferycznych jest tworzony przy użyciu tego zestawu danych wejściowych i wyjściowych. Podczas konstruowania modelu rozmytego preferowana jest struktura modelu rozmytego z dwoma danymi wejściowymi i jednym wynikiem, biorąc pod uwagę prostotę projektowania. Dane wejściowe-wyjściowe wykorzystywane do budowy modelu rozmytego systemu są wymieniane, a przy użyciu tego nowego zestawu danych projektowany jest sterownik odwrotny oparty na ANFIS. W celu poprawy wydajności sterowania w przypadku zakłóceń i niezgodności modelu, w wewnętrznej strukturze sterowania modelu zastosowano regulator odwrotny. Wydajność proponowanego regulatora jest porównywana z klasycznymi regulatorami PI i rozmytymi regulatorami PI w warunkach zmienności wartości zadanej i zakłóceń. Wyniki porównań pokazują, że proponowany regulator odwrotny przewyższa zarówno klasyczne, jak i rozmyte regulatory PI.

2

Analysis of the effects of recycling on process control

Silva Cássio R.A., Panuci Victor C., Coutinho Monica R., Conceição Wagner A.S., Andrade Cid M.G.

Polish Journal of Chemical Technology

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2023

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Vol. 25, nr 2

43--55

EN

The union of different devices in order to obtain a specific response for a process is commonly called a control system. For a control system, it is necessary to have one or more controllers. Among the most used in the industrial sector are the PID and PI controllers. Next to these controllers is the control software. Scilab is a good example of control software. It is characterized as free code software, with no cost for its acquisition, in addition to having a large computational power and integrated tools, such as Xcos, intended for modeling and simulation. For the union with Scilab, there is Arduino. Such a mixture can be used, for example, to control liquid levels in tanks. In this context, the present work aims to study the tank-level control system based on PID and PI controllers through the union between Scilab and Arduino. Phenomenological models were developed based on closed-loop control (feedback control system) of the process with two tanks not coupled with recycle. Furthermore, for comparison purposes, two approaches were used for each process: one considering the saturation of the manipulated variable and the other without the presence of such saturation. At first, there was a need to implement an anti-windup system. For tuning the controller parameters, the ISE method was used, executed through a programming code developed in Scilab. The parameters found for the two systems were tested on a made-up experimental bench. Therefore, using the block diagrams and the method here called “ISE method”, satisfactory values were obtained for the control parameters. These were ratified in the tests carried out in the experimental module. Level control was achieved with greater prominence for the PI controller since there is one less parameter to be tuned and processed by the system. This controller provided results close to the PID controller for cycles up to 50%. In general, the PI controller showed maximum response deviations smaller than the PID, such as deviations of 1.55 cm and 2.40 cm, respectively, for the case with 75% recycle. It was also clear the influence of the saturation of the manipulated variable on the system response, but not on the tuning of the controller parameterseters.

3

Performance Analysis of Power Boiler Drum Water Level Control Systems

Pawlak M.

Acta Energetica

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2016

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nr 4

81--89

EN

Described in the paper are the structures of water level controls in power boiler drums. A boiler drum’s function is very important for the power unit process, because this is where water separates from steam, which is then superheated and supplied to the turbine. A boiler drum’s dynamic properties as an object of regulation have been listed. The model has been identified on the basis of measurement data from a real object. In the described system the control and measurement devices’ working conditions are difficult due to high temperature and pressure. Incorrect operation of the control system could lead to a major accident. A performance analysis has been presented of three controller level structures, to ensure the system’s stable operation.

PL

Opisano struktury stosowanych regulatorów poziomu wody w walczaku kotła energetycznego. Walczak pełni bardzo odpowiedzialne funkcje w procesie technologicznym bloku energetycznego, ponieważ zachodzi tutaj proces oddzielania wody od pary, która po przegrzaniu jest doprowadzana do turbiny. Przedstawiono właściwości dynamiczne walczaka jako obiektu regulacji. Przeprowadzono identyfikację modelu na podstawie danych pomiarowych z rzeczywistego obiektu. W opisywanym układzie warunki pracy urządzeń regulacyjnych i pomiarowych są trudne ze względu na wysoką temperaturę i ciśnienie. Niepoprawna praca układu regulacji może doprowadzić do poważnej awarii. Zaprezentowano analizę pracy trzech struktur regulatora poziomu w celu zapewnienia stabilnej pracy układu.

4

Uogólnienie metody rzutowania naprzemiennego

Dylewski R.

Pomiary Automatyka Kontrola

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2011

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R. 57, nr 6

679-682

PL

W artykule przedstawiono różne modyfikacje metody rzutowania naprzemiennego (alternating projection method), wprowadzonej przez von Neumanna. Metody te służą do wyznaczania punktu ze zbioru A i punktu ze zbioru B takich, że jest odległością między zbiorami A i B. Wprowadzono uogólnienie prezentowanych metod projekcyjnych, które gwarantuje zbieżność także w przypadku, gdy przekrój zbiorów A i B jest pusty i odległość między zbiorami jest nieznana. W wielu praktycznych problemach mamy taką sytuację, np. w zagadnieniu tomografii komputerowej i zagadnieniu planowania radioterapii.

EN

In the paper there is presented modification of the von Neumann method of alternating projection (AP-method) where A and B are closed and convex subsets of The problem of finding and with if this infimum is attained is dealt with. It is known that in case of the sequence ( ) generated by the AP-method converges weakly to a fixed point of the operator of alternating projection [1]. If the distance is known, one can efficiency apply a modifica-tion of the von Neumann method, which has the form for (relaxation parameter) and (step size) depending on (RAP-method - relaxed alternating projection method) [3]. In this paper the authors propose a generalization of the RAP-method (GRAP-method - generalized relaxed alternating projection method), where it is not supposed that the value (Section 2) is known. Instead of , there is applied its approximation for (with changeable level parameter ) which is updated in each iteration (Section 3). The GRAP-method is also a generalization of the modified relaxed alternating projection method (MRAP-method) [6]. In Section 4 there are presented the results of numerical tests for two problems: (P1), where A, B are closed and convex subsets (Table 1) and (P2), where A is a closed and affine subspace, B is a closed and convex subset (Table 2). The preliminary numerical experiments confirm practical applicability of the GRAP-method even in case when the distance is unknown. These experiments show the superiority of the GRAP-method with respect to the RAP-method, if is unknown.

5

Sterowanie poziomem w metodach projekcyjnych dla problemów minimalizacji wypukłej nieróżniczkowalnej

Dylewski R.

Przegląd Elektrotechniczny

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2010

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R. 86, nr 9

141-144

PL

W artykule przedstawiono nową metodę sterowania poziomem ze zmiennym parametrem poziomu, używaną w metodach projekcyjnych dla problemow minimalizacji wypukłej, w ktorych funkcja celu nie musi być różniczkowalna. Pokazano, że metoda ta spenia warunki gwarantujące zbieżność do rozwiązania problemu. Uzyskane wyniki, dla problemow testowych, wskazują na możliwość zmniejszenia liczby wyznaczeń wartości funkcji celu i subgradientu potrzebnej do wyznaczenia rozwiązania [epsilon]optymalnego.

EN

In this paper we present a new method of level control with a changeable level parameter. We can use this method in projection methods for nonsmooth convex minimization problems. We also present numerical results for some test problems.

6

Use of neural networks for dynamic modelling and predictive control of power plant systems

Lazar C., Carari S., Vrabie D., Ivana D.

Systems Science

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2005

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Vol. 31, no 1

37-44

EN

Boiler drum is a critical power plant component having nonlinearities and a non-minimum phase response but, despite this fact, control structures with PID controllers are usually used in industrial applications. In the last decades, important efforts have been made to improve the closed loop performance of the drum level controller by using on-line self-tuning approaches. In this paper, such a method of on-line adaptation is presented based on a neuro-predictive technique of the authors of [4], [5]. In order to implement the neuro-predictive procedure a neural model was developed for drum level process. By means of simulation, a comparison between the obtained drum level controller's operation and that of a classic controller of the type PI under similar conditions is carried out.