ABSTRACT
This chapter analyses the main characteristics of Multi-Input Multi-Output (MIMO) plants, and introduces two methodologies to design non-diagonal QFT controllers for MIMO systems with model uncertainty. It analyzes the special properties that define MIMO systems and propose some tools to understand their dynamics and design appropriate control systems. It presents the non-diagonal MIMO QFT Method 1 and 2, including both theory and a detailed example. The Method 1 analyses the role played by the non-diagonal compensator elements by means of three coupling matrices and a quality function. The Method 2 is a formal reformulation of Method 1. It avoids former hypotheses of diagonal dominance and simplifies the calculations for the off-diagonal elements and the method itself. It also reformulates the classical matrix definition of MIMO specifications by designing a new set of loop-by-loop QFT bounds on the Nichols chart with necessary and sufficient conditions.
