A novel computational method for loop gain and phase margins of TITO systems

This paper addresses the problem of loop gain and phase margins of two-input two-output (TITO) systems. A new frequency domain approach is proposed to accurately compute the loop gain and phase margins for TITO systems. With the help of geometry analysis method, the stability boundaries are shown to be the intersection points of some constructed curves. The computational burden is reduced by restricting the frequency range estimated by the norm analysis. The gain and phase margins are determined in the stable region. The method is demonstrated by two examples.