System and Control Letters, Vol. 54, pp. 607-612, 2005.
On validating closed-Loop behaviour from noisy frequency-response measurements
It is shown how noisy closed-loop frequency response measurements can be used to obtain pointwise in frequency bounds on the possible difference between the actual closed-loop system and the closed-loop comprising a nominal model of the plant and the stabilising controller. To this end, Vinnicombe's gap metric framework for robustness analysis plays a central role. Indeed, an optimisation problem and corresponding algorithm are proposed for estimating the chordal distance between the frequency responses of the nominal plant model and a plant that is consistent with the closed-loop data and a priori information, when projected onto the Riemann sphere. Key Words: nu-gap metric, robust performance, controller validation
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