A novel 2-DOF fractional-order PIλ-Dμ controller with inherent anti-windup capability for a magnetic levitation system

The facility of an extra degree-of-freedom (DOF) to reshape the transient response of unstable systems arises to the concept of 2-DOF controller. Integration of fractional calculus strengthens the performance of it. In this paper, a novel methodology for the design of a 2-DOF PIλ-Dμ controller for a class of open-loop unstable systems is proposed and is applied in a magnetic levitation system (MLS). The restructuring of PIλ controller dematerializes the requirement of a dedicated anti-wind scheme for removing the actuator saturation problem. A new graphical tuning approach is suggested to tune the fractional order parameters of the controller and the integer order gain parameters are decided by employing the pole-placement technique. Stability of the proposed controller scheme employed to MLS is analyzed on the basis of Riemann sheets concept in w-plane. Experimental demonstration of proposed scheme on MLS confirms the ability of the controller to reject the external random perturbations as well as actuator saturation.