The Inverse Nyquist Array for Non-Square Systems

The Inverse Nyquist Array (INA) is a frequency domain technique introduced by Rosenbrock. It aims at designing compensators for multivariable systems so that they become sufficiently decoupled to be treated using univariable techniques. Requiring the calculation of the inverse transfer function, it is only applicable in its original form to square, controllable (f) systems. Its extension to non-square systems with a given feedback structure, which includes an inner-loop, is proposed. The graphical interpretation and the new form of the elementary operations are presented.