NEW MULTIVARIABLE FREQUENCY-DOMAIN DESIGN TECHNIQUES.

An efficient design procedure for the control of multivariable feedback systems must be evaluated against the following criteria: ease of design procedure, computational burden in design procedure, complexity of compensator, and quality of closed loop performance. Although the most direct design approach is perhaps to reduce the multivariable design problem to independent scalar design problems, the existing design techniques tend to use trial-and-error procedures to achieve this aim. Two new techniques are presented that have been developed to solve this problem systematically, the difference between the two techniques being in the structure of the compensated system: the complete decomposed diagonal form or the partly decomposed triangular form with a special property-namely triangular-diagonal-dominance. The new techniques are illustrated by two practical examples: an unstable chemical reactor and a pressurized flow-box.