Comment on 'Comments on A new kind of nonlinear disturbance observer for nonlinear systems with applications to cruise control of air-breathing hypersonic vehicles'

In the comment by Kaldmae and Kotta [2018. Comments on 'a new kind of nonlinear disturbance observer for nonlinear systems with applications to cruise control of air-breathing hypersonic vehicles'.International Journal of Control, 1-2 (just-accepted)], it is shown that the result in Yang, Meng, and Sun [2017. A new kind of nonlinear disturbance observer for nonlinear systems with applications to cruise control of air-breathing hypersonic vehicles.International Journal of Control,90(9), 1935-1950] is not practically usable and it cannot be corrected easily. In this note, it is shown how the result can be corrected. Previous work that enables such estimation is mentioned.