Control of Systems with Time-Varying Delay: An Algebraic Approach vs. Modified Smith Predictors

The main aim of this paper is to compare three different control design methods which are applied to a continuous-time single-input single-output (SISO) system with harmonically time-varying delay. The first technique uses a modified PI-PD Smith predictor in combination with standard forms for minimum of integral squared time error (ISTE). The second methodology is also based on modified Smith predictor and on design by Coefficient Diagram Method (CDM). And finally, the third approach to synthesis is grounded in general solutions of Diophantine equations in the ring of proper and Hurwitz-stable rational functions (RPS) for 1DOF or 2DOF control system. The comparison of methods is performed and illustrated on a simulation example.