On the optimal two block H∞ compensators for distributed unstable plants

In this paper we discuss how the optimal compensator can be calculated in H^∞ mixed sensitivity minimization problems for a class of unstable distributed systems. An operator theoretic (skew Toeplitz) approach is taken which builds on a framework developed in the previous papers [12] [13], [14] for calculating the optimal performance. We point out that such an optimal controller, which be infinite dimensional in general can be approximated using the techniques of [11] to find a corresponding suboptimal finite dimensional compensator.