H∞ control of systems with distributed delay: Discretized Lyapunov functional method

The discretized Lyapunov functional method is extended, for the first time, to H_∞ control of linear neutral type systems with both, (single) discrete and distributed delays. The coefficients associated with the distributed delay are assumed to be piecewise-constant. A new Bounded Real Lemma (BRL) is derived in terms of Linear Matrix Inequalities (LMIs) via descriptor approach. The analysis results are applied to state-feedback H_∞ control of linear neutral systems with discrete and distributed delays, where the controller may be either instantaneous or may contain discrete or distributed delay terms. In the numerical examples for retarded type systems, the resulting values of H_∞ -norm generally converge to the exact ones. The new method essentially improves the existing H_∞ control results. Moreover, it provides new tools for the important design problems, such as H_∞ control of systems, which are not stabilizable without delay.