MULTIVARIABLE PI CONTROL OF UNSTABLE SYSTEMS

Decentralized and centralized multivariable PI controllers are designe d for unstable systems described by a transfer function matrix. Decent ralized PI controllers are designed by using a constant detuning facto r and centralized PI controllers are designed by the Tanttu and Liesle hto method [J.T. Tanttu, J. Lieslehto, A comparative study of some mul tivariable PI controller tuning methods, in: R. Devanathan (Ed.), Inte lligent Tuning and Adaptive Control Methods, Pergamon, 1991, pp. 357-3 62]. For systems with one-way unstable interaction, both the decentral ized and centralized PI controllers stabilize the systems. For systems with two-way unstable interactions, decentralized controllers do not stabilize the systems, whereas the centralized PI controllers do stabi lize the systems. The Tanntu and Lieslehto method is extended for desi gning centralized PID controllers also. (C) 1997 Elsevier Science B.V.