Absolute stability conditions in a fuzzy phase-lead compensation and their extension to MIMO systems

This paper presents absolute stability conditions in a fuzzy phase-lead compensation and their extension to multi-input-multi-output (MIMO) systems. A theorem which realizes an effective phase-lead compensation is recalled. A so-called "transformation matrix" is derived in the theorem. A fuzzy phase-lead compensator (FPLC) is constructed by using the transformation matrix. The circle condition is employed to derive absolute stability conditions of feedback systems in a fuzzy phase-lead compensation. Next, a generalized class of FPLCs is defined, and its stability conditions are derived from the viewpoints of H/sub /spl infin// norm and quadratic stability. It is found that the stability conditions realize stability analysis not only for single-input-single-output (SISO) systems, but also for MIMO systems.