Robust Geometric Control of a Distillation Column

A frequency domain method, which makes it possible to adjust multivariable controllers with respect to both nominal performance and robustness, is presented. The basic idea in the approach is that the designer assigns objectives such as steady-state tracking, maximum resonance peaks, bandwidth, minimum stability margin, steady-state sensitivity and maximum sensitivity to modelling errors. For a given control structure the parameters are found which minimize an objective function consisting of the weighted sum of deviations between desired and obtained values of these objectives. This method is used to examine and improve geometric control of a binary distillation column.