Comparison between Robustness of Two Fractional–Order PI Controllers for Irrigation Canals

This paper deals with the design of robust controllers for irrigation canals that undergo large changes in their model parameters: gain, dominant time constant, and time delay. Three controllers are compared: the standard PI controller and two fractional-order PI controllers designed using different methodologies. In order to carry out such study, the experimentally identified model of a pool of our laboratory canal has been used. This model included a nominal dynamics and the ranges of variation of the model parameters. The three controllers were designed for this particular process and simulated results were obtained, which show the robustness features of each controller.