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Uncertain Linear Systems (uncertain + linear_system)

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Selected Abstracts

Reliable State Feedback Control Synthesis For Uncertain Linear Systems

ASIAN JOURNAL OF CONTROL, Issue 2 2003
Guang-Hong Yang
ABSTRACT This paper is concerned with the problem of designing reliable state- feedback control for a class of uncertain linear systems with norm bounded uncertainty. A procedure for designing reliable state-feedback control is presented for the case of actuator faults that can be modeled by a scaling factor. In the design, the performance of the normal system (without fault) is optimized, as the considered system operates under the normal condition most of the time. In addition, when actuator faults occur, the closed-loop system retains robust stability and satisfies a known quadratic performance bound. A numerical example is provided to illustrate the effectiveness of the proposed design method. [source]

Reduced-order robust adaptive control design of uncertain SISO linear systems

INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 7 2008
Qingrong Zhao
Abstract In this paper, a stability and robustness preserving adaptive controller order-reduction method is developed for a class of uncertain linear systems affected by system and measurement noises. In this method, we immediately start the integrator backstepping procedure of the controller design without first stabilizing a filtered dynamics of the output. This relieves us from generating the reference trajectory for the filtered dynamics of the output and thus reducing the controller order by n, n being the dimension of the system state. The stability of the filtered dynamics is indirectly proved via an existing state signal. The trade-off for this order reduction is that the worst-case estimate for the expanded state vector has to be chosen as a suboptimal choice rather than the optimal choice. It is shown that the resulting reduced-order adaptive controller preserves the stability and robustness properties of the full-order adaptive controller in disturbance attenuation, boundedness of closed-loop signals, and output tracking. The proposed order-reduction scheme is also applied to a class of single-input single-output linear systems with partly measured disturbances. Two examples are presented to illustrate the performance of the reduced-order controller in this paper. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Robust quadratic performance for time-delayed uncertain linear systems

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 2 2003
Fen WuArticle first published online: 20 DEC 200
Abstract In this paper, the analysis and control synthesis problems were studied for a general class of uncertain linear systems with variable time delay. It is assumed that the structured time-varying parametric uncertainties enter the system state-space description in a linear fractional fashion. The generic quadratic performance metric encompasses many types of dynamic system performance measure. In the context of delay-independent stability, it was shown that the analysis and state-feedback synthesis problems for such time-delayed uncertain systems can be formulated equivalently as linear matrix inequality (LMI) optimization problems using the mechanism of full block multipliers. However, the solvability condition to output-feedback problem was given as bilinear matrix inequality (BMI), which leads to a non-convex optimization problem. A numerical example is provided to demonstrate the advantages of newly proposed control synthesis condition for time-delayed uncertain systems over existing approaches. Copyright © 2002 John Wiley & Sons, Ltd. [source]

A convex optimization procedure to compute ,2 and ,, norms for uncertain linear systems in polytopic domains

OPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 4 2008
Ricardo C. L. F. Oliveira
Abstract In this paper, a convergent numerical procedure to compute ,2 and ,, norms of uncertain time-invariant linear systems in polytopic domains is proposed. The norms are characterized by means of homogeneous polynomially parameter-dependent Lyapunov functions of arbitrary degree g solving parameter-dependent linear matrix inequalities. Using an extension of Pólya's Theorem to the case of matrix-valued polynomials, a sequence of linear matrix inequalities is constructed in terms of an integer d providing a Lyapunov solution for a given degree g and guaranteed ,2 and ,, costs whenever such a solution exists. As the degree of the homogeneous polynomial matrices increases, the guaranteed costs tend to the worst-case norm evaluations in the polytope. Both continuous- and discrete-time uncertain systems are investigated, as illustrated by numerical examples that include comparisons with other techniques from the literature. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Reliable State Feedback Control Synthesis For Uncertain Linear Systems

ASIAN JOURNAL OF CONTROL, Issue 2 2003
Guang-Hong Yang
ABSTRACT This paper is concerned with the problem of designing reliable state- feedback control for a class of uncertain linear systems with norm bounded uncertainty. A procedure for designing reliable state-feedback control is presented for the case of actuator faults that can be modeled by a scaling factor. In the design, the performance of the normal system (without fault) is optimized, as the considered system operates under the normal condition most of the time. In addition, when actuator faults occur, the closed-loop system retains robust stability and satisfies a known quadratic performance bound. A numerical example is provided to illustrate the effectiveness of the proposed design method. [source]