A Robust Internal Model-Based Fractional Order Controller for Fractional Order Plus Time Delay Processes
Pushkar Prakash Arya, Sohom Chakrabarty
Abstract
This letter proposes a fractional order internal model controller (FO-IMC) for a fractional order plus time delay (FrOPTD) process model to satisfy desired gain margin (A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> ) and phase margin (φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> ) specifications. A method is proposed to solve four equations arising from the Am and φm specifications, which also generates solution of the system gain-cross-over frequency (ω <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> ) and phasecross-over frequency (ω <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> ) as intermediate variables. The designed FO-IMC is implemented on laboratory DC servosystem and compared with other integer order controller and fractional order controller.