ABSTRACT
In this chapter, the authors focus on the analysis of the control system for multivariable processes. They discuss aspects related to the quantification of the degree of interaction in a multiloop system through the concept of relative gain array. The authors introduce the singular value decomposition as a means to gain further insight towards the structural properties of multivariable systems. They also introduce Singular Value Analysis (SVA) to be used in analysis of the steady-state properties (structural) of the multivariable system. Specifically, SVA plays a key role in determining the suitability of control structures (i.e., pairing of manipulated and measured variables) from the standpoint of robustness, or, loop sensitivity to uncertainties. The presence of interactions among loops is a unique feature that distinguishes Multiple-Input Multiple-Output (MIMO) systems from SISO systems. The authors provide additional insight into the structural aspects present in MIMO processes and are a valuable tool in designing the controllers to minimize the effect of interactions.
