Guaranteed cost control of uncertain discrete-time delay systems using dynamic output feedback

Guaranteed cost control problems for discrete-time systems with uncertainties and time delays are addressed in this paper. The delays may simultaneously appear not only in the state, but in control input and measurement output. Also, parametric uncertainties may exist in all system matrices of the systems considered in this paper. First, a new linear matrix inequality (LMI)-based approach is developed to construct dynamic guaranteed cost controllers for delay systems without uncertainties. Then this result is extended to discrete-time delay systems with uncertainties in linear fractional form in all system matrices. The solvability of these robust control problems for uncertain delay systems can be reduced to that for certain auxiliary systems without uncertainty. Numerical examples are provided to show the effectiveness of our approach.