Abstract
An adaptive observer to estimate deterministic periodic disturbances in servo systems is proposed. The observer in this paper uses a sinusoidal wave model as a disturbance model, which includes frequencies as unknown parameters. The adaptive observer identifies frequencies of the disturbance model, then estimates the disturbance. This paper gives a simple condition of the observability of the disturbance. It also gives a simple scheme to calculate the linear model for the frequency identification. The proposed method to estimate the disturbance is straightforward and it does not require to calculate a transfer matrix for the observable canonical form. This scheme and the method are obtained by taking account of the restricted structure of disturbance models. The results of disturbance estimation in two examples are shown. These estimations are obtained from simulated data and experimental data of the repeated movement of the 5th axis of a manipulator.
