Output Feedback Control of Switched Nonlinear Systems: A Gain Scheduling Approach

Switched controller design for nonlinear continuous and discrete-time systems under an arbitrary switching signal using the gain scheduling approach is addressed in this paper. The obtained controller design procedures for continuous and discrete-time systems are in the bilinear matrix inequality form. The proposed design procedure ensures multi parameter-dependent quadratic stability of the switched gain scheduled plant which is associative to a nonlinear plant model and optimal performance defined by quadratic gain scheduled parameters weighting cost function. Example demonstrates the effectiveness of the proposed approaches

Robust exponential stability of a class of nonlinear systems

summary:The paper addresses the problem of design of a robust controller for a class of nonlinear uncertain systems to guarantee the prescribed decay rate of exponential stability. The bounded deterministic uncertainties are considered both in a studied system and its input part. The proposed approach does not employ matching conditions

Robust PI-D controller design for descriptor systems using regional pole placement and/or H2H_2 performance

summary:The paper deals with the problem of obtaining a robust PI-D controller design procedure for linear time invariant descriptor uncertain polytopic systems using the regional pole placement and/or $H_2$ criterion approach in the form of a quadratic cost function with the state, derivative state and plant input (QSR). In the frame of Lyapunov Linear Matrix Inequality (LMI) regional pole placement approach and/or $H_2$ quadratic cost function based on Bellman-Lyapunov equation, the designed novel design procedure guarantees the robust properties of closed-loop system with parameter dependent quadratic stability/quadratic stability. In the obtained design procedure the designer could use controller with different structures such as P, PI, PID, PI-D. For the PI-D's D-part of controller feedback the designer could choose any available output/state derivative variables of descriptor systems. Obtained design procedure is in the form of Bilinear Matrix Inequality (BMI). The effectiveness of the obtained results is demonstrated on two examples

Robust Decentralized Controller Design for Large Scale Systems: Subsystems Approach

The paper addresses the problem of the robust output feedback PI controller design for complex large-scale systems with stateoutput decentralized structure. The proposed design method is based on the Generalized Geršgorin Theorem and the V-K iterationmethod to design robust PI controller guaranteeing feasible performance achieved in subsystems level and for the full system. Theproposed method excludes limit of system order in LMI solution, while PI controller design procedure is feasible on the subsystemlevel. Finally, numerical example is given to illustrate the effectiveness of the proposed method

ROBUST CONTROL METHODS A SYSTEMATIC SURVEY

The paper addresses the problem how to recognize a level of robust controller design and is aimed show the difficulties of implementation for practical use. In the first part of paper we introduce the survey of robust controller design for SISO systems with generalization design procedure for structured and unstructured uncertainties. The second part of paper is devoted to MIMO systems. In the frequency domain robust controller design procedure we reduce to independent design of SISO subsystems and in time domain the LMI or BMI approaches with polytopic system description are favorable. K e y w o r d s: robust control, frequency domain, time domain, polytopic systems, Lyapunov function, linear system

A new Nyquist-based technique for tuning robust decentralized controllers

summary:An original Nyquist-based frequency domain robust decentralized controller (DC) design technique for robust stability and guaranteed nominal performance is proposed, applicable for continuous-time uncertain systems described by a set of transfer function matrices. To provide nominal performance, interactions are included in individual design using one selected characteristic locus of the interaction matrix, used to reshape frequency responses of decoupled subsystems; such modified subsystems are termed ``equivalent subsystems". Local controllers of equivalent subsystems independently tuned for stability and specified feasible performance constitute the decentralized controller guaranteeing specified performance of the full system. To guarantee robust stability, the $M-\Delta$ stability conditions are derived. Unlike standard robust approaches, the proposed technique considers full nominal model, thus reducing conservativeness of resulting robust stability conditions. The developed frequency domain design procedure is graphical, interactive and insightful. A case study providing a step-by-step robust DC design for the Quadruple Tank Process [K.H. Johansson: Interaction bounds in multivariable control systems. Automatica 38 (2002), 1045–1051] is included

ROBUST POWER SYSTEM STABILIZER VIA NETWORKED CONTROL SYSTEM

The paper presents a novel power system stabilizer (PSS) design for a multivariable power system. The proposed design procedure is based on the linear matrix inequalities and stabilization of controlled system with time-varying time delay

Independent design of decentralized controllers in the frequency domain

The paper presents an original frequency domain decentralized controller design technique for guaranteed performance. The novelty consists in that the designed decentralized controller guarantees the required performance for the full system. Interactions are considered in local designs by means of a chosen characteristic locus of the interaction matrix used to modify mathematical models of isolated subsystems thus defining the equivalent subsystems \cite ves. The developed graphical design method is insightful and promising from the viewpoint of further application in the robust control design \cite aves. Theoretical conclusions are supported with results obtained from the solution of several examples