A LOOP-SHAPING TECHNIQUE FOR FEEDBACK-CONTROL DESIGN

In this paper, a generalized loop-shaping method is developed to deal with various uncertainty descriptions for robust control design. The m ethod is based on the proposition that the singular values of a feedba ck system matrix can be shaped by the addition of a perturbation matri x on either the given initial controller or the nominal plant model. T he applicability of the method to the case of structured perturbations is discussed. The block sensitivity of the M-Delta structure is explo ited, yielding bounds on the structured singular value. These bounds a llow us to construct an interactive design strategy for various contro ller modifications to shape the blocks of the M matrix that have the s trongest impact on mu.