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Monika Bakošová and Juraj Oravec

Abstract

The continuous stirred-tank reactor with uncertain parameters was stabilized in the open-loop unstable steady state using the robust model predictive control. The gain matrices of the robust state-feedback controller were designed using the nominal system optimization and the quadratic parameter-dependent Lyapunov functions. The controller was verified by simulations using the non-linear model of the reactor and compared with the robust model predictive controller designed using the worst-case system optimization. The values of the quadratic cost function and the consumption of coolant were observed. Both robust model predictive controllers stabilized the reactor despite constrained control inputs and states. The robust model predictive control based on the nominal system optimization improved control responses and decreased the consumption of coolant.

Open access

Anna Vasičkaninová and Monika Bakošová

Abstract

Possibilities of using robust controllers for a shell-and-tube heat exchanger control were studied, tested and compared by simulations and obtained results are presented in this paper. The heat exchanger was used to pre-heat petroleum by hot water; the controlled output was the measured output temperature of the heated fluid — petroleum, and the control input was the volumetric flow rate of the heating fluid — water. Robust controllers were designed using ℋ2, ℋ, ℋ2/ℋ strategies and μ-synthesis. A comparison with the classical PID control demonstrated the superiority of the proposed robust control especially in case when the controlled process is affected by disturbances.

Open access

Jana Závacká and Monika Bakošová

Abstract

The paper presents an approach for robust PI controller design for a system affected by parametric uncertainty. The method is based on plotting the stability boundary locus in the plane of controller parameters that is called (kp, ki)-plane. Designed robust PI controller is implemented for control of two counter-current tubular heat exchangers in series with uncertain parameters, in which kerosene as a product of distillation in a refinery has to be cooled by water. The controlled variable is the temperature of the outlet stream of the kerosene from the second heat exchanger and the control input is the volumetric flow rate of the inlet stream of the cold water in the second heat exchanger. Simulation results of robust PI control of heat exchangers are also presented.

Open access

Juraj Oravec and Monika Bakošová

Abstract

The paper addresses a case study of robust stabilization of a continuous stirred tank reactor using robust model-based predictive control with constrained input variables. One exothermic reaction runs in the reaction mixture and the reactor is modelled in the form of an uncertain polytopic system. The control approach is based on solution of a set of linear matrix inequalities. This formulation enables to use convex optimization methods to design a gain matrix of a state feedback controller in each control step. The task of stabilization is solved in assumed control conditions with respect to symmetric constraints on control inputs. The control performance achieved by robust constrained model-based predictive control is studied via simulations. Obtained results confirm that the robust constrained model-based predictive control ensures the stability demands and the quality requirements represented by chosen quadratic cost function.

Open access

Ayush Sharma, Miroslav Fikar and Monika Bakošová

Abstract

Continuous Stirred Tank Reactor (CSTR) is the productive part in different chemical and process industries, and hence there is a need to control this process at desired optimum conditions of temperature and concentration. This paper deals with modelling and constrained control of a CSTR that minimises the processing time. Modelling consisted in performing the mass and heat balances of the CSTR system. Different controllers (time optimal, PID) were then applied to this non-linear system and compared within the boundaries of the control input and states. A theoretical case study was solved numerically using the orthogonal collocations method and simulations, resulting in a comparison of different controllers.

Open access

Anna Vasičkaninová and Monika Bakošová

Abstract

This work deals with the design and the application of a robust control to a chemical reactor. The reactor is exothermic one. There are two parameters with only approximately known values in the reactor. These parameters are the reaction enthalpies. Because of the presence of uncertainty, the robust output feedback is designed. Two robust controllers are designed, the first one is based on the small gain theorem and the second one uses the H2/H control techniques. The presented experimental results confirm applicability of mentioned approaches to safe control of nonlinear processes.

Open access

Radek Matušů, Katarína Vaneková, Roman Prokop and Monika Bakošová

Design of Robust PI Controllers and their Application to a Nonlinear Electronic System

The principal aim of the paper is to present a possible approach to the design of simple Proportional-Integral (PI) robust controllers and subsequently to demonstrate their applicability during control of a laboratory model with uncertain parameters through the Programmable Logic Controller (PLC) SIMATIC S7-300 by Siemens Company. The proposed and utilized synthesis consists of two steps. The former one is determination of controller parameters area, which ensures the robustly stable control loop and is based on computing/plotting the stability boundary locus while the latter one lies in the final choice of the controller itself relying on algebraic techniques. The basic theoretical parts are followed by laboratory experiments in which the 3rd order nonlinear electronic model has been successfully controlled in various working points.