Tuning PI^ν Fractional Order Controllers for Position Control of DC-Servomotors

This paper introduces a loop shaping approach for easily tuning PIν fractional order controllers of position DC-servomotor drives. The design requirements are stated in terms of band-width and stability robustness. The synthesis procedure consists in shaping the open loop frequency response so as to achieve the flatness of its Bode's phase plot ensuring a good phase margin, which remains constant in a wide range around the crossover frequency. In this way, high stability robustness to gain variations in the loop is achieved. The fractional order integration also leads to limited overshoot and short settling time. Simulation results are confirmed by laboratory experiments.