GPC Control of a Fractional–Order Plant: Improving Stability and Robustness

This work deals with the use of Generalized Predictive Control (GPC) with fractional order plants. Low integer–order discrete approximations will be used as models to design the controllers. The stability and robustness of the closed loop system will be studied with the Nyquist criterion. Three techniques will be proposed to enhance robustness: the improvement of the model response at low frequencies, the use of the prefilter T(z), and a new recommendation to choose two of the parameters (the control horizon Nu and the error weighting sequence λ) of the GPC controller.