Danica Rosinova

Modeling of magnetic levitation system

The paper is devoted to modeling and parameter identification for Magnetic Levitation System (MLS) from Inteco. MLS belongs to challenging modelling and control problems due to its unstability and nonlinearity. We concern several modeling details not sufficiently described in user manual, a correction of nonlinear model, and present the corresponding measurement results. The obtained nonlinear model parameters and corresponding linearized model fits the real data much better than parameters provided in the reference.

Robust control of coupled two tank system via LMI

The paper compares several methods for robust state-feedback controller design via LMI for a two tank coupled system and discusses qualities of the respective LMI solutions. LMI approach is used to design a controller guaranteeing quadratic or parameter dependent robust stability, H2 and Hinf performance specification for uncertain linearized model of two tank system. The results obtained using LMI and SeDuMi solvers are compared.

Robust decentralized PID controller design: A case study

Robust stability is an important aspect in control of real world systems, since uncertainties have to be considered in dynamic system models. The basic required quality of the system is its stability in the whole uncertainty domain called robust stability. This paper studies the robust decentralized controller design for a quadruple tank process, [3,4]. For this case study, several important aspects of system analysis are shown (pairing, stabilizability via decentralized control). The main contribution is the decentralized PID controller design in both frequency and time domains, analysis and comparison of results. The obtained results are supported by simulations used to demonstrate and compare the different approaches.

Robust PI controller design for Coupled-Tank process: LMI approach

This paper proposes an approach to a robust PI controller design for real uncertain Coupled-Tank process in time domain. Only the first independent tank is considered (single-input single-output system). Polytopic model of uncertain system is considered as a plant model to be controlled. Stability and performance of the closed loop system is determined through the LMI region, where the closed loop poles of whole uncertainty domain are placed. A robust stability condition based on the parameter-dependent Lyapunov function (PDLF) is used.

Robust control for a discrete-time uncertain system novel LMI based approach

In the paper, a novel robust controller design method is developed for discrete-time parameter varying system using matrix inequalities. Auxiliary matrices are used to reduce conservatism of the proposed robust stability conditions. The resulting design method is illustrated on examples.

Robust decentralized control for a boiler — turbine unit

Performance control of a boiler-turbine unit is of great importance due to demands on the economical operations of power plants and environmental awareness. In this paper, a robust decentralized control of nonlinear multi input-multi output (MIMO) model of a utility boiler-turbine unit is designed. Drum pressure, generator electric output and drum water level (as the output variables) are controlled by manipulation of valves position for fuel, feedwater and steam flows.

Decentralized controller for nonlinear drum boiler: Youla parametrization approach

In this paper, we focus on robust decentralized controller design for Benchmark PID problem brought recently by Morilla [5]: nonlinear drum boiler, having integration term and significant right half plane (RHP) zero in the interaction. We present the linearized uncertain model identified for the working area determined by working points. Robust decentralized controller is designed by Equivalent Subsystem Method approach, using Youla parametrization on subsystem level. We compare decentralized controller design with and without prescribing the designed controller structure. We derive the respective relations and filter, which guarantee the PI structure of controller. After controller design we check the robust stability condition for the determined working area. All controllers are verified on nonlinear boiler model [5].

Robust PID controller design using BMI

The new BMI based method for robust stabilizing PID controller design for linear uncertain system is proposed. The general constrained structure of controller matrix is considered which is appropriate both for output feedback and decentralized control. The developed control design scheme aims at robust stabilization with guaranteed cost. The extended quadratic performance index is used including the first derivative of the state vector to damp oscillations. The obtained results use parameter-dependent Lyapunov function to reduce conservatism of robust stability conditions.