Robust controller design methodology for multivariable chemical processes: Structured perturbations

Abstract In this work, a methodology for the design of robust multivariable linear time invariant control systems with structured perturbations is presented. Useful properties of the μ-function are used to develop an algorithm that extends previous results on unstructured uncertainties. The complet methodology allows the specification of the dominant time constant for each control loop. The frequency response of an ideal controller is first computed allowing the synthesis of different controller structures (PI, PID, etc.). The specified time constants are then de-tuned in order to meet a desired upper bound over the multivariable stability margin. Some implementation aspects are discussed and the control design of a triple effect evaporator is considered to illustrate the feasibility of the methodology.