Improved H∞ pole placement constraint controller design with application to a flexible transmission system

A robust control scheme of a flexible transmission system in the presence of load variations is presented. In this approach, the loading variations are considered as multiplicative perturbation of the nominal plant and desired specifications are enforced by closed-loop pole clustering in an LMI region and several H_∞ constraints on different closed-loop transfer functions. A well known change of control variable is used to turn the resulting constraint to a system of LMIs, which can easily be solved using efficient interior-point algorithms. At the end, weight functions are tuned using genetic algorithm. The resulting controller provides satisfactory performance for large range of load variations.