W. Yan, C. Du and C. K. Pang, "Direct closed-loop identification of mechanical resonances above the nyquist frequency without any external persistently exciting signals," IECON 2014 - 40th Annual Conference of the IEEE Industrial Electronics Society, Dallas, TX, 2014, pp. 2750-2755.
In this paper, a general multirate approach is proposed for direct closed-loop identification of mechanical
resonances above the Nyquist frequency without injecting any external persistently exciting (PE) signals. Based on the polynomial transformation technique, an extended least-squares (ELS) algorithm is designed to estimate parameters of the mixed-rate model, from which parameters of the fast-rate model is extracted.
Convergence properties of the ELS algorithm are analyzed, and the parameter identifiability is ensured if the plant output sampling rate is non-integer multiples of the controller sampling rate. The performance of the proposed approach is evaluated by simulation results on the head-positioning servo control system
of a hard disk drive (HDD) during track-following mode, where no external PE signal is added on.
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