Robust Smith Predictor Design for Time-Delay Systems with H∞ Performance

A new method for robust fixed-order H∞ controller design for uncertain time-delay systems is presented. It is shown that the H∞ robust performance condition can be represented by a set of convex constraints with respect to the parameters of a linearly parameterized primary controller in the Smith predictor structure. Systems with uncertain dead-time and with multimodel and frequency-domain uncertainty can be considered straightforwardly in the proposed approach. Furthermore, it is shown that the design method can also be extended to design of robust gain-scheduled dead-time compensators. The performance of the method is illustrated by simulation examples.