This paper advocates disturbance observer based control (DOBC) for uncertain nonlinear systems. Within this framework, a nonlinear controller is designed based on the nominal model in the absence of disturbance and uncertainty where the main design specifications are to stabilize the system and achieve good tracking performance. Then a nonlinear disturbance observer is designed to not only esti...

Disturbance attenuation for a class of nonlinear systems under unknown disturbances is considered in this paper. Based on the Disturbance-Observer-Based Control (DOBC) concept, two design schemes are proposed for external disturbances generated by exogenous systems where the disturbances could be unbounded. One design scheme is obtained by augmenting the estimation of the disturbance into a sta...

In this paper, we consider the output regulation problem for a one dimensional wave equation with harmonic disturbance anti-collocatedwith control. We first design an adaptive observer by themeasured output to estimate unknown parameters of the disturbance and recover the system state. Then by using the observer system and estimator of unknown harmonic disturbance, we construct an auxiliary sys...

A disturbance observer based tracking control algorithm is presented in this paper. The key idea of the proposed method is that the plant nonlinearities and parameter variations can be lumped into a disturbance term. The lumped disturbance signal is estimated based on a plant dynamic observer. A state observer then corrects the disturbance estimation in a two-step design. First, a Lyapunov-base...

A novel digital implementation of speed controller for a Permanent Magnet Synchronous Motor (PMSM) with disturbance rejection using conventional observer combined with Extended Kalman Filter (EKF) is proposed. First, the EKF is constructed to achieve a precise estimation of the speed and current from the noisy measurement. Second, a proportional integral derivative (PID) controller is developed...