Control-Relevant Input Signal Design for Multivariable System Identification: Application to High-Purity Distillation

Abstract

Input signal design issues associated with a discrete-time MIMO control-relevant identification methodology are the focus of this paper. Using a priori information such as the open-loop dominant time constants and desired closed loop speed-of-response, guidelines are presented for the design variables in two periodic, deterministic inputs: the PRBS and Schroeder-phased signals. The guidelines are illustrated on the Weischedel-McAvoy high purity distillation column, which represents an ill-conditioned, highly interactive system. The case study clearly demonstrates that the sensible use of open-loop experimental design and nonparametric estimation, followed by control-relevant parameter estimation, naturally results in a low-order model description capturing the directionality information important for control.