© 1998 by Institute of Mathematics and its Applications
A Lyapunov analysis of stability robustness for discrete linear descriptor systems
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1Department of Control Engineering, Faculty of Mechanical Engineering, University of Belgrade 27 Marta 80, 11000 Beograd, Yugoslavia
2Centre for Engineering Research, Technikon Natal P.O. Box 953, Durban 4000, Republic of South Africa
3System Control Group, Faculty of Technology and Metallurgy, University of Belgrade Karnegijeva 4, Beograd, Yugoslavia
Discrete descriptor systems are those for which the dynamics are governed by a mixture of algebraic and difference equations. This paper examines the existence of solutions that are attracted by the origin of the phase space, for regular and irregular discrete linear descriptor systems. By a suitable transformation, the original system is transformed to a convenient form that enables development and easy application of Lyapunov's direct method for the existence analysis of a subclass of solutions characterized by convergence to the origin. A potential (weak) domain of attraction of the origin is underestimated on the basis of a symmetric positive definite solution of a reduced-order discrete Lyapunov matrix equations. Also, it has been shown that the same result can be efficiently used in determining quantitative measures of robustness for a class of perturbed discrete linear descriptor systems.