Stabilizing constant controllers for two-input, two-output systems with reducible and irreducible characteristic equations

This paper proposes a theoretical and practical approach for determining the stabilizing gain intervals for two-input, two-output (TITO) systems with a constant diagonal controller. Our main contribution is to present an algorithm which is more practical than the stabilizing methods that depend on the Nyquist stability criterion. Numerical examples illustrate the effectiveness of the proposed algorithm for TITO systems with reducible or irreducible characteristic equations.