Design and Validation of Fractional-Order Control Scheme for DC Servomotor via Internal Model Control Approach

This paper proposes a robust fractional-order controller for DC servomotor using internal model control and CRONE (Commande Robuste d'Ordre Non Entier) principle. The controller acquires a PID (proportional-integral-derivative) form followed by a fractional-order integrator. Unlike the conventional fractional-order PID controller which demands five tuning parameters, the proposed scheme has only two tuning parameters which can be obtained on the basis of desired gain crossover frequency and phase margin. For speed control problem, the performance of the proposed controller is studied on hardware set up called precision modular servo system. The proposed controller outperforms in terms of robustness and optimality when compared with controllers designed by integer-order technique. Furthermore, the proposed scheme is applied for position control problem and validated on QUBE-Servo 2 set up.