qAssume D(s)=diag[d1Ir1, …, dsIrs, D1, …, DF] Î RH¥ with ||di||¥<1 and ||Dj||¥<1.
• Robust Stability Û The interconnection is stable.
•
qStability Conditions:
• (1) (sufficient
condition) ||M11||¥ £1
• Conservative: ignoring
structure of D(s).
• (2)
(necessary conditions ) Test for each di (Dj) individually (assuming no uncertainty in other
channels): ||(M11 )ii ||¥ £1
• Optimistic: ignoring
interaction between the di (Dj).