Fractional-order QFT Controllers for unstable plants based on Automatic Loop Shaping

This paper presents the design of a robust fractional order controller for unstable plants with only one unstable pole based on quantitative feedback theory (QFT) using Particle Swarm Optimization (PSO). In this work, a fractionalorder compensator, with a flexible controller structure, is introduced into the QFT design to give a better approximation of optimum open loop in Nichols. The fractional order controller is designed for not only minimum phase system but also uncertain non-minimum phase and unstable plants in QFT. It has been demonstrated that the