Abstract
The necessity of rejecting the external disturbance and model uncertainty is vital for control design to achieve high performance and robustness of the system. Disturbance cancelation techniques are, therefore, of interest for both academic and industrial research and development. Among them, disturbance observer based control (DOBC) and active disturbance rejection control (ADRC) are widely applied, thanks to their high performance and effectiveness in synthesis and realization. However, two knowledge gapsvis-à-visthe dynamical delay and the unification of these techniques exist in literature. This article proposes a study on the unification of DOBC and ADRC for the application of speed control of permanent magnet synchronous motor. The explicit formulas of the estimated disturbance are carried out and the dynamical delays of the observations are, therefore, straightforwardly deduced. By addressing these transparent delay formulas, the unification of DOBC and ADRC is verified. The identical performance of two methods in rejecting both external disturbance and model uncertainty is demonstrated by simulation and experimental validations.