INVERTING AND NONINVERTING H-INFINITY CONTROLLERS

摘要

It is well known that two-block S/KS/T H-infinity problems in which the plant is weighted at the output tend to invert the plant in the controller. This paper shows that even four-block S/KS/T problems in which the plant is weighted at the input result in controllers which invert the plant. However, if a GS/T weighting scheme is used where the weight for the sensitivity includes the plant, the inversion is avoided. This GS/T scheme therefore is especially suited for ill-conditioned plants. An example confirms these results. (C) 1997 Elsevier Science B.V. [References: 5]