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. ► We propose frequency domain approach to accurately compute gain and phase margins for TITO. ► The stability boundaries are shown to be the intersection points of constructed curves. ► Geometry analysis method is used to calculate the stability boundaries without any iteration. ► The proposed method is suitable for time delay and high-order processes.