Linear control of nonlinear processes: recent developments and future directions

Virtually all chemical processes are nonlinear, but for several of them linear feedback control is adequate. Therefore, before nonlinear controller design is attempted, it is natural to ask 'when is linear control adequate for a nonlinear process?' to ensure favorable cost/benefit ratio. Consequently, methods are needed that quantify the nonlinearity of a process within the context of assessing whether linear control is adequate or nonlinear control is warranted. In this work we summarize efforts towards this end and elaborate on our latest research in this area. Specifically, we present a rigorous and general theoretical framework as well as an associated, heuristically refined computational methodology that allow not only analysis but also synthesis of a linear control system for a nonlinear process. Application to the multivariable case is presented. Potential future developments within this framework are discussed. (C) 2003 Elsevier Science Ltd. All rights reserved.