Design of fractional order QFT controller for nonlinear systems

This paper presents the design of a robust fractional order controller for the nonlinear RC circuit based on quantitative feedback theory (QFT). In this work, a fractional-order compensator, with a flexible controller structure, is introduced into the QFT design to give a better approximation of optimum open loop in Nichols. It has been demonstrated that the fractional order controller can provide smaller high frequency gain than the integer order controller due to its extra tunable parameters.