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<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Publishing DTD v1.0 20120330//EN" "JATS-journalpublishing1.dtd"><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" article-type="research-article"><front><journal-meta><journal-id journal-id-type="publisher-id">INFORMATICA</journal-id><journal-title-group><journal-title>Informatica</journal-title></journal-title-group><issn pub-type="epub">0868-4952</issn><issn pub-type="ppub">0868-4952</issn><publisher><publisher-name>VU</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="publisher-id">INF11307</article-id><article-id pub-id-type="doi">10.3233/INF-2000-11307</article-id><article-categories><subj-group subj-group-type="heading"><subject>Research article</subject></subj-group></article-categories><title-group><article-title>Closed-loop Robust Identification Using the Indirect Approach</article-title></title-group><contrib-group><contrib contrib-type="Author"><name><surname>Pupeikis</surname><given-names>Rimantas</given-names></name><email xlink:href="mailto:pupeikis@ktl.mii.lt">pupeikis@ktl.mii.lt</email><xref ref-type="aff" rid="j_INFORMATICA_aff_000"/></contrib><aff id="j_INFORMATICA_aff_000">Institute of Mathematics and Informatics, Vilnius Gediminas Technical University, Akademijos 4, 2000 Vilnius, Lithuania</aff></contrib-group><pub-date pub-type="epub"><day>01</day><month>01</month><year>2000</year></pub-date><volume>11</volume><issue>3</issue><fpage>297</fpage><lpage>310</lpage><history><date date-type="received"><day>01</day><month>06</month><year>2000</year></date></history><abstract><p>In the previous paper (Pupeikis, 2000) the problem of closed-loop robust identification using the direct approach in the presence of outliers in observations have been considered. The aim of the given paper is a development of the indirect approach used for the estimation of parameters of a closed-loop discrete-time dynamic system in the case of additive correlated noise with outliers contaminated uniformly in it. To calculate current M-estimates of unknown parameters of such a system by means of processing input and noisy output observations, obtained from closed-loop experiments, the recursive robust technique based on an ordinary recursive least square (RLS) algorithm is applied here. The results of numerical simulation of closed-loop system (Fig. 3) by computer (Figs. 4–7) are given.</p></abstract><kwd-group><label>Keywords</label><kwd>adaptive system</kwd><kwd>closed-loop</kwd><kwd>direct approach</kwd><kwd>identification</kwd><kwd>observations</kwd><kwd>outliers</kwd></kwd-group></article-meta></front></article>