Properties of optimal weighted sensitivity designs

Weighted sensitivity designs for a class of single-input/single-output, linear time-invariant systems are shown to have the property that the optimal controller has fewer right-half plane poles than the plant has right-half plane zeros. While weighted complementary sensitivity designs are shown to have the property that the optimal controller has fewer right-half plane zeros than the plant has right-half plane poles. Effects of various choices of weighting functions on the optimal solutions are described. >