A Note on Diagonal Dominance and the Stability of Multi-variable Feedback Systems

Diagonal dominance plays a fundamental role in the design of multi-variable feedback control systems by the method of dyadic expansion and the Inverse Nyquist array by providing a systematic procedure for the structural simplification of the return-difference determinent. It is shown that, by the use of equivalent transformations and origin shift methods, sufficient conditions for closed-loop stability using diagonal dominance methods can be obtained which remove many of the difficulties arising in previous formulations.