Approximate identification with closed-loop performance criterion and application to LQG feedback design

Alam, act-A model-based controller generally works better w3th the model than vath the modelled plant due to the modelhng error This dtfference between the performances can be made small by selecting a model that ts accurate at the closed-loop relevant frequenoes In thts paper tt ts shown that an tteraUve approach of tdenttficatmn and control design can lead to a model that ts much better stated for feedback design than a model resulting from an unwetghted open-loop tdenttficatton In this iteration each ldenUficatlon is performed such that a certam closed-loop cntenon funcUon is nummtzed This ts accomphshed by closed-loop identification wtth persistent set-point excttatmn and a proper stgnal filtering Each control de,ugh step employs the latest tdenttfied model to construct an I X ~ compensator The performance requn'ements are gradually mcreased during the i t e r a t i o n