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-lea d 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-le ad compensation. Next, a generalized class of FPLC's is defined, and i ts stability conditions are derived from the viewpoints of H-infinity norm and quadratic stability. It is found that the stability condition s realize stability analysis not only for single-input-single-output ( SISO) systems, but also for MIMO systems.