The critical issues of uncertainty estimation and robust feedback controller design for nonlinear systems are addressed in this paper. Using a high-purity distillation column as an example, a set of linear models representing the dynamics of the column at different operating conditions around the initial steady state are identified and utilized to assess the nonlinearity-induced uncertainty. A robust controller design using singular values and eigenvalues of the closed-loop system based on the estimated uncertainty is also presented. Effectiveness of the designed linear control systems in controlling both end products of the column is also analyzed.
