An LMI approach to fixed order LTR controller

In this paper the problem of optimal /spl Hscr//sub /spl infin// norm approximation of an LTR controller with specified poles is considered. A structurally predefined fixed order LTR controller is introduced which has the same dimension as the number of transmission zeros. It is shown that the design problem can be reduced into an equivalent convex optimization problem involving LMI which can be solved efficiently. We demonstrate the performance of this LTR controller by comparing it to a functional observer-based LTR controller of the same dimension.