抄録
In the present paper, we propose a discrete-time nonlinear observer (DNO) design method and an unknown disturbance estimation based on DNO. The proof of the boundedness of the estimated error is derived based on the Lyapunov stability theorem. The proposed unknown disturbance estimation method is applied to a rotational machine system. The effectiveness of the proposed method is verified through numerical simulations and experiments. The obtained results indicate that the proposed discrete-time unknown disturbance observer provides sufficient estimation performance for relatively low sampling frequencies.