FULL AND REDUCED-ORDER OBSERVER-BASED CONTROLLER-DESIGN FOR H-2-OPTIMIZATION

In this paper the most general H-2 control problem is considered. We d erive necessary and sufficient conditions when the infimum is attained by state feedback. We do the same for the measurement feedback case w here we derive necessary and sufficient conditions when the infimum is attained by proper dynamic compensators. We also investigate reduced- order compensators if some states are observable without noise. We dis cuss, for all of these cases, the freedom that the non-uniqueness of o ptimal compensators gives us in assigning the closed-loop eigenvalues. The second half of this paper investigates the case when the infimum cannot be attained. We give a constructive algorithm to find a minimiz ing sequence of stabilizing controllers and discuss the freedom in the asymptotic locations of the closed-loop eigenvalues. Again we do the above for three different cases: static-state feedback, full-order mea surement feedback and reduced-order measurement feedback.