Data reduction in the mixed-sensitivity H∞ design problem

This paper addresses the generalized mixed sensitivity H^∞ design problem for linear time-invariant systems. The state space approach is used to investigate the internal structure of this design problem which inherits many pole-zero cancellations. The Toeplitz plus Hankel operator, essential to the computation of the achievable performance, is embedded in this approach. Not only the McMillan degree but also the structure of the H^∞ controller can be visualized. Mathematical software can be implemented efficiently.