Selection of pairing and constrained robust decentralized PI controllers

This paper describes tuning methods for robust decentralized PI controllers. Four of these methods involve minimizing a μ-synthesis criterion. For two of them, a constraint on the variations of the controller outputs is added to the performance criterion. The above methods and a fifth one, which is not based on the robust performance, are applied and compared for a two input-two output grinding circuit model. The paring is selected with the linearized generalized relative dynamic gains plotted on 3D graphics. For the desired closed-loop bandwidths, this method can be used to select the pairing that minimizes the interaction between the loops. Results of the simulations are presented using the generalized step response (GSR). The GSR gives a 3D graphic representing the system response as function of the input direction