“…Therefore, let the polynomial KCmC1 C 1 KCm C C KCm C KCmC1 be Hurwitz, and let 0 < % 1 be a sufficiently small parameter. An 'over-sized' high-gain 'practical' observer for the time derivatives of the control input u can be obtained by using (14), with y replaced by u, " replaced by %, N replaced by K, l replaced by m, Á i replaced by i , for i D 0; : : : ; K CmC1, and O y e;N replaced by O u e;K , respectively, obtaining, in this way, an estimate O u e;K of u e;K .…”