ROBUST-CONTROL OF LINEAR TIME-INVARIANT PLANTS USING PERIODIC COMPENSATION

The use and design of linear periodic time-varying controllers for the feedback control of linear time-invariant discrete-time plants are discussed. It is shown that for a large class of robustness problems, periodic compensators are superior to time-invariant ones. Explicit design techniques which can be easily implemented are given. In the context of periodic controllers, consideration is also given to the strong and simultaneous stabilization problems. Finally, it is also shown that for the problem of weighted sensitivity minimization for linear time-invariant plants, time-varying controllers offer no advantage over the time-invariant ones.