Guide lines for the tuning and the evaluation of decentralized and decoupling controllers for processes with recirculation

This paper gives guidelines for the pairing, the time response specificatio n, and the tuning for processes with recirculation when decentralized contr ollers are used. This selection is based on the condition number, which is an indicator of the process directionality, and on the generalized dynamic relative gain (GDRG), which is a measure of the interaction. Simple tuning rules are developed and results are compared to algebraic controllers with decouplers. Performances are evaluated for set-point changes as well as dis turbance rejection using the generalized step response (GSR). The GSR gives a 3D graphic of the system response as a function of the input direction. (C) 2001 Published by Elsevier Science Ltd. All rights reserved.