Quantitative feedback design for a benchmark quadruple-tank process

In this paper level control for a quadruple-tank process with variable nonlinear zero dynamics is considered. This provides a nice benchmark problem that illustrates some of the challenges posed by complex interconnected systems for linear design paradigms. A Quantitative Feedback Theory (QFT) methodology is used to provide robust control of the water level in the lower two tanks. The linear design is validated on the nonlinear system model.