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FEEDBACK SYSTEMS: ABSOLUTE STABILITY. controllable. Circle criterion : quadratic common Lyapunov function. is strictly positive real (SPR):. For this reduces to SPR ( passivity ). Popov criterion not suitable: depends on.
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FEEDBACK SYSTEMS: ABSOLUTE STABILITY controllable Circle criterion: quadratic common Lyapunov function is strictly positive real (SPR): For this reduces to SPR (passivity) Popov criterion not suitable: depends on
FEEDBACK SYSTEMS: SMALL-GAIN THEOREM Small-gain theorem: quadratic common Lyapunov function controllable
TWO-DIMENSIONAL SYSTEMS Necessary and sufficient conditions for GUES known since 1970s worst-case switching quadratic common Lyap fcn <=> convex combinations of Hurwitz