AN ALTERNATIVE SMALL GAIN APPROACH

A classical method is first presented for computing a MIMO phase or delay margin, in the case of a closed loop without any other model uncertainty than the uncertain time delays: a conservative value of the MIMO phase or delay margin is computed with the small gain theorem (first subsection), possibly with D scaling matrices (second subsection). The method is extended to the case of a closed loop subject to uncertain time delays and to classical model uncertainties (third subsection).