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1

Multi-agent system inspired distributed control of a serial-link robot

Soumya S., Guruprasad K. R.

Journal of Automation Mobile Robotics and Intelligent Systems

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2020

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Vol. 14, No. 1

29--38

EN

Inspired by the multi-agent systems, we propose a model-based distributed control architecture for robotic manipulators. Here, each of the joints of the manipulator is controlled using a joint level controller and these controllers account for the dynamic coupling between the links by interacting among themselves. Apart from the reduced computational time due to distributed computation of the control law at the joint levels, the knowledge of dynamics is fully utilized in the proposed control scheme, unlike the decentralized control schemes proposed in the literature. While the proposed distributed control architecture is useful for a general serial-link manipulator, in this paper, we focus on planar manipulators with revolute joints. We provide a simple model-based distributed control scheme as an illustration of the proposed distributed model-based control architecture. Based on this scheme, distributed model-based controller has been designed for a planar 3R manipulator and simulations results are presented to demonstrate that the manipulator successfully tracks the desired trajectory.

2

Bioprocess feedback control - a case study of the fed-batch biomass cultivation bioprocess

Ryniecki A., Wawrzyniak J., Gulewicz P., Horla D., Nowak D.

Przemysł Spożywczy

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2018

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T. 72, nr 8

34--39

EN

It is particularly difficult to control a biotechnological process because of significant sensitivity of living organisms cultured in bioreactors to process parameters and environmental conditions. Varying conditions of the process are also significant (a change in the chemical composition of the substrate or a change in the mass exchange conditions resulting from the modification of rheological parameters). The industrial biomass cultivation processes require the optimal biomass growth rate. In order to ensure it, it is necessary to analyze input variables, find the most representative output variables, and design an adequate automated control strategy, which should be tailored to a given bioprocess. The article analyzes selected automated control systems in fed-batch biomass cultivation bioprocesses presented in reference publications concerning bioprocess control. Open-loop and closed-loop control systems were taken into consideration. The research showed that open-loop control systems could not respond to process disturbances such as unexpected variations in input variables. Therefore, the authors analyzed closed-loop control systems in more detail, especially the feedback control systems with proportional-integral (PI) control action, which were used to stabilize the specific growth rate at a desired level. The authors presented equations which enable the online estimation of the specific growth rate on the basis of cellular metabolic heat. It has been noticed that the quality of automated control of bioprocesses can be further improved through improvement of control systems with a feedback.

PL

Kontrola przebiegu procesu biotechnologicznego jest szczególnie trudna ze względu na dużą wrażliwość hodowanych w bioreaktorach żywych organizmów – zarówno na parametry procesowe, jak i warunki środowiskowe. Nie bez znaczenia są również dynamicznie zmieniające się warunki prowadzenia procesu (zmiana składu chemicznego podłoża czy zmiana warunków wymiany masy jako efekt zmieniających się parametrów reologicznych). Procesy przemysłowej hodowli biomasy narzucają konieczność zapewnienia optymalnej szybkości wzrostu biomasy. Aby to zrealizować, niezbędne są: analiza wielkości wejściowych bioprocesu, znalezienie najbardziej reprezentatywnych wielkości wyjściowych oraz opracowanie odpowiedniej strategii sterowania automatycznego, która powinna być indywidualnie dobranado danego bioprocesu. W artykule poddano analizie wybrane systemy sterowania automatycznego procesem hodowli biomasy prowadzonej metodą okresową z zasilaniem – przedstawione w ostatnich latach w literaturze przedmiotu. Uwzględniono układy sterowania zarówno otwarte, jak i zamknięte. Stwierdzono, że sterowanie w układzie otwartym nie radzi sobie z zakłóceniami działającymi na bioprocess, takimi jak niespodziewane zmiany wartości wielkości wejściowych procesu. Dlatego autorzy z większą uwagą analizowali zamknięte układy sterowania, w szczególności te ze sprzężeniem zwrotnym wykorzystujące człon proporcjonalno-całkujący (PI), który posłużył do stabilizowania szybkości wzrostu biomasy na założonym poziomie. W pracy przedstawiono równania umożliwiające obliczanie on-line właściwej szybkości wzrostu biomasy na podstawie ciepła metabolizmu komórkowego. Zauważono, że możliwa jest dalsza poprawa jakości automatycznego sterowania bioprocesami poprzez doskonalenie systemów sterowania ze sprzężeniem zwrotnym.

3

Sterowanie poziomem cieczy przy pomocy regulatora wykorzystującego model neuronowy obiektu nieliniowego

Kula K.

Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

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2016

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Nr 51

87--92

PL

W pracy przedstawiono projekt układu regulacji poziomu wody w zespole zbiorników o swobodnym wypływie, który w swej strukturze wykorzystuje nieliniowe modele obiektu: neuronowy i model niskiego rzędu uwzględniający zależność stałych czasowych od wartości wielkości regulowanej. Tak przyjęta struktura pozwala realizować sterowanie w układzie otwartym z możliwością korekty wartości zadanej przy wystąpieniu zakłóceń na wejściu lub wyjściu obiektu.

EN

The paper presents the concept of a nonlinear control system, which is the liquid level control system of two tanks It is based on the use in controller structure a non-linear models of the plant: neural and low-order model takes into account the dependence of the time constants and steady state gain of the controlled variable. So adopted structure allows to perform the control in an open-loop system with the possibility of setpoint correction under the influence of disturbances on the input or output of the plant.

4

State of the Art in Predictive Control of Wheeled Mobile Robots

Harasim P., Trojnacki M.

Journal of Automation Mobile Robotics and Intelligent Systems

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2016

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Vol. 10, No. 1

34--42

EN

The paper is concerned with the problem of tracking control of wheeled mobile robots (WMRs) using predictive control systems. Various kinematic structures of WMRs important from the point of view of motion control are discussed. A hierarchical approach to the problem of motion control of this kind of robots is presented. The problems of trajectory tracking and path following control of WMRs are briefly discussed. The methods of predictive control of WMRs are described in detail and the following aspects relevant to predictive control are considered: kinematic structures of robots, slip of wheels and its compensation, assumed constraints, methods of optimization of the objective function, problems of model nonlinearity, linearization and discretization, stability of the control system and use of the state observers.

5

Design of the control system for canned-food sterilization

Ryniecki A., Wawrzyniak J., Danyluk B.

Przemysł Spożywczy

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2015

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T. 69, nr 8

62--64

EN

A properly designed control system for canned-food sterilization is able to achieve the final desired level of bacterial inactivation, irrespective of any disturbances, e.g. in the form of undesired changes of the heating- medium temperature, and with a minimum of over-processing. The feed-forward control system for canned- food sterilization was described in the article. The controller in such a system is able: (a) to anticipate the change of the final cumulative lethality in a situation when the disturbances of the process occurred during heating and (b) to take appropriate corrective actions that can eliminate such disturbances. The heating turn-off decisions in such a controller are based upon the prediction (in every second during heating) of cumulative lethality for the cooling stage. The prediction of the cooling phase is based on a simulation of temperature changes in the coldest point inside a can using the empirical m-th order step-response model.

PL

Właściwie zaprojektowany system sterowania procesem sterylizacji konserw mięsnych umożliwia osiągnięcie zadanego końcowego poziomu inaktywacji bakterii niezależnie od zakłóceń, np. w postaci niepożądanych zmian temperatury medium grzejnego, przy równoczesnym zachowaniu warunku minimum nadmiernego wyjałowienia konserw. W artykule przedstawiono system sterowania procesem sterylizacji ze sprzężeniem wyprzedzającym. Sterownik tego systemu umożliwia: (a) przewidywanie zmian końcowej letalności skumulowanej w sytuacji, gdy zakłócenia procesu występują w czasie ogrzewania, oraz (b) wprowadzenie odpowiednich sygnałów korekcyjnych, eliminujących te zakłócenia. W tym sterowniku, decyzje o zakończeniu ogrzewania podejmowane są w każdej sekundzie ogrzewania na podstawie przewidywania wartości sterylizacyjnej fazy chłodzenia. Przewidywanie to realizowane jest przy wykorzystaniu symulacji zmian temperatury w najmniej dogrzanym miejscu konserwy za pomocą empirycznego modelu inercyjnego m-tego rzędu.

6

Application of the simple additive modeling of the first principle model inaccuracies for the offset–free process control

Czeczot J., Łaszczyk P

Control and Cybernetics

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2014

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Vol. 43, no. 2

261--277

EN

In this paper, the method for simple additive modeling of the first principle model inaccuracies for the offset-free process control is presented. Starting from transformation of the general nonlinear state model into the input affine dynamical equation describing directly the controlled variable, it is shown how to compensate for the potential modeling inaccuracies by lumping them into a single additive parameter. Its on-line estimation procedure based only on the measurement data collected from the process is very simple and effective and the estimate converges without any additional excitation of the process. The discussion on how to apply the suggested model as a basis for the chosen model-based control techniques is presented, and for the processes of the higher relative order, the practical simplification of this approach is shown. The experimental results show the practical applicability of the considered approach for the synthesis of the open loop InternalModel Controller (IMC) and of the Balance-Based Adaptive Controller (B-BAC).

7

Noise sensitivity of selected kinematic path following controllers for a unicycle

Libal U., Płaskonka J.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2014

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Vol. 62, nr 1

3--13

EN

In the paper a path following problem for a wheeled mobile robot of (2,0) type has been considered. The kinematic model of the robot was derived with respect to the Serret-Frenet frame. Two kinematic control algorithms - Samson and Morin-Samson - have been tested taking into account their sensitivity to a white noise with a zero mean appearing in the one of state variables. The properties of path following errors have been analysed using statistical techniques. The conclusions related to an acceptable level of noise and a range of applicability of the presented algorithms have been reached.

8

Model-based centralized AMB control with position and current feedback and nonlinear observer

Jastrzębski R., Pyrhönen O.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 1a

253-256

EN

Over the last decade, the model-based position controllers have been investigated in an effort to extend the applicability of the active magnetic bearing (AMB) technology in rotating machinery. This work proposes a very efficient solution to improve the performance of the classical centralized model-based position controller. The article discusses the linear and nonlinear AMB controllers for rigid and flexible rotor models with position and current feedback signals.

PL

Na przesterzeni ostatniego dziesięciolecia prowadzono badania centralnego sterowania układu zawieszenia magnetycznego w celu zwiększenia zastosowań w aplikacjach maszyn wirujących. Praca ta proponuje skuteczne rozwiązanie, które poprawia sprawność klasycznego centralnego sterownika położenia bazującego na modelu zmiennych stanu. W artykule przedstawione są sterowniki liniowe i nieliniowe dla sztywnego i elastycznego wału oparte na pomiarach położenia i prądu.

9

Wireless communication for control of manipulation systems

Belda K., Rychnovský V., Píša P.

Archives of Control Sciences

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2012

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Vol. 22, no. 1

29-41

EN

The paper deals with a novel application of the wireless data communication for a continual control of the distributed manipulation systems. The solution is intended for industrial robotic plants. A considered way of the wireless communication is based on ZigBee protocol. The protocol is tested for a real time bidirectional data communication within a manipulation system. The system consists of several moving manipulation units, several stationary auxiliary units and one control computer. The computer provides the cooperation of all units in the system in relation to the user requirements. The system is controlled by a simple feedback multi-level control realized in MATLAB - Simulink environment. The paper is focused on the realization of the boards of power electronics, transmitters, optical positional sensors, optical gates and their networking in accordance with ZigBee protocol definition. The behavior of the ZigBee is illustrated by several records from real experiments.

10

Inverse heat transfer problem in digital temperature control in plate fin and tube heat exchangers

Taler D., Sury A.

Archives of Thermodynamics

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2011

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Vol. 32, no. 4

17-32

EN

The aim of the paper is a steady-state inverse heat transfer problem for plate-fin and tube heat exchangers. The objective of the process control is to adjust the number of fan revolutions per minute so that the water temperature at the heat exchanger outlet is equal to a preset value. Two control techniques were developed. The first is based on the presented mathematical model of the heat exchanger while the second is a digital proportional-integral-derivative (PID) control. The first procedure is very stable. The digital PID controller becomes unstable if the water volumetric flow rate changes significantly. The developed techniques were implemented in digital control system of the water exit temperature in a plate fin and tube heat exchanger. The measured exit temperature of the water was very close to the set value of the temperature if the first method was used. The experiments showed that the PID controller works also well but becomes frequently unstable.

11

O optymalnym sterowaniu temperaturą i stężeniem dwutlenku węgla w szklarni

Stankiewicz A.

Inżynieria Rolnicza

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2009

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R. 13, nr 8

189-198

PL

Systemy sterowania klimatem we współczesnych szklarniach to złożone struktury wykorzystujące model matematyczny sterowanego procesu i nowoczesne koncepcje sterowania. W pracy rozważa się zadanie równoczesnej stabilizacji temperatury powietrza i stężenie dwutlenku węgla wewnątrz szklarni przy odcinkami stałych wartościach zadanych. Zaproponowano nowy system sterowania typu feedback-feedforward, który pozwala w torze sprzężenia "wprzód" skutecznie i szybko niwelować skutki szybkozmiennych zakłóceń, a w torze sprzężenia zwrotnego od stanu procesu zapewnia szybkie zanikanie błędu sterowania. Macierz regulatora dobrano optymalnie w sensie wskaźnika z mnożnikiem czasowym.

EN

The optimal control of greenhouse climate has received considerable attention in agricultural engineering research. In this paper a new feedback-feedforward control system is proposed for the state variables stabilization on piecewise constant user-desired or computed by the upper level set-points for temperature and CO2 concentration. The proposed control structure consists of two main parts: a model based feedforward compensation of external disturbances and the model based optimal feedback simultaneous control of the greenhouse temperature and CO2 concentration. The applied decomposition is able to deal with rapidly fluctuating deterministic external inputs or disturbances acting on the system by feedforward static compensation and guarantee the fast decay of the control error due to the static state feedback with constant gain matrix optimal in the sense of timemultiplied quadratic index. In a forthcoming paper, the simulation experiments will be conducted for the known in the literature example of the production of a lettuce crop by the use of the Simulink toolbox of Matlab in order to demonstrate the effectiveness of the control system proposed.

12

Application of reduced order phenomenological model to pH nonlinear control

Stebel K., Metzger M.

Archives of Control Sciences

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2005

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Vol. 15, no. 2

199-216

EN

Changes in process sensitivity with pH make the design of the conventional controllers difficult. pH processes are very hard to control because of strong nonlinearity and usually time varying characteristics. A lot of work has been done in the field of phenomenological modelling of the pH processes. However, there is a need to simplify the model to have it suitable for control purposes. This follows from the fact that the internal model for the controllers must be as simple as possible. Wiener models consisting of a linear dynamic element followed by a static nonlinear element are considered to be perfect to represent a wide range of nonlinear processes. The proposed reduced order phenomenological model of pH has a similar form as the Wiener models but includes bilinear reduced order phenomenological dynamic element. This model was validated using the real world pilot plant. The possibility of combining the phenomenological and arbitrary approaches occurred. The aim of this paper is to present reduced order model of pH process which can be used for simulation purposes and to design process model based controller.

13

Model following control (MFC) - nowe struktury układów regulacji i ich właściwości

Skoczowski S.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Elektryka

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2000

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Z. 36

63-70

PL

Analizuje się właściwości struktur dwupętlowych z wykorzystaniem modelu tzw. MFC z punktu widzenia odporności na pertrubacje obiektu i wpływ zakłóceń w porównaniu z klasyczną pętlą ujemnego sprzężenia zwrotnego. Zwraca się uwagę na przydatności tych układów w regulacji temperatury obiektów o zmiennych parametrach na przykładzie pieca rezystancyjnego.

EN

The paper deals with properties of a two-loop structure of a model following control system containing the nominal model of controlled plant and two controllers. Special attention is paid to high robustness of the considered control structure to perturbations of the controlled plant and to good suppression of disturbances commonly met in industrial practice. Compared to the classic negative feedback loop, the system proposed offers a much better control quality in case of perturbed plant; in doing so both time constants and plant gain and process order may be perturbed.

14

Problems and practice of pH process modelling and control in stirred tank reactors

Jutila P., Hyotyniemi H., Ylen J.

Archives of Control Sciences

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1999

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Vol. 9, no. 3/4

5-31

EN

The control of pH processes in stirred tank reactors includes a wide variety of different types and levels of control tasks. The possible difficulties may arise from the quality of process or reagent liquids, the type and size of the mixing reactor, the accuracy of the instrumentation, the (perhaps time-variant) nonlinearity of the process, and last but not least the difficulties in the measurement of the pH value. In this paper these different aspects are discussed. The applications of pH control have a wide spectrum in different types of engineering problems. In this paper the environmental, chemical, and algorithmic aspects are given the main emphasis, and less attention is paid to the problems of device technology and pH measurement.