IEEE Control Systems SocietyActa Medica Okayama001892865142006Operator-based nonlinear feedback control design using robust right coprime factorization645648ENMingcongDengAkiraInoueKazushiIshikawaIn this note, robust stabilization and tracking performance of operator based nonlinear feedback control systems are studied by using robust right coprime factorization. Specifically, a new condition of robust right coprime factorization of nonlinear systems with unknown bounded perturbations is derived. Using the new condition, a broader class of nonlinear plants can be controlled robustly. When the spaces of the nonlinear plant output and the reference input are different, a space change filter is designed, and in this case this note considers tracking controller design using the exponential iteration theorem.No potential conflict of interest relevant to this article was reported.IEEE Control Systems SocietyActa Medica Okayama0018-92863881993A direct computation of state deadbeat feedback gains12831284ENKenjiSugimotoAkiraInoueShiroMasudaA method for computing a feedback gain that achieves state deadbeat control is given. From systems given in the staircase form, this method derives the deadbeat gain in a numerically reliable way. It is shown that the gain turns out to be LQ optimal for some weightings.No potential conflict of interest relevant to this article was reported.