Extending PI tuning rules to 2-dof regulator structures

This manuscript addresses the problem of tuning two-degree-of-freedom (2-dof) industrial controllers. Peculiar of the work is the idea of tuning the feedforward path of the regulator after the feedback path is synthesised, so as to allow the presented method to be used for complementing existing and well assessed tuning rules for 1-dof controllers. Also, no additional process information (nor stimulation) is required with respect to that used to tune the feedback regulator path-an important characteristic for the acceptance of the proposed method. Finally, the structure of the feedforward path has here some degrees of freedom, that prove to yield better results than the traditional “set point weighing” technique. Reference is made here to the PI regulator for simplicity, although the proposed ideas are general.