Discrete time robust load disturbance torque estimator for a DC motor drive system

This paper introduces a method to achieve robust disturbance torque estimation in discrete time. H_-/ℋ_∞ theory is applied in this design to realize both accurate estimation and robustness to model uncertainty. This robust estimator is designed to estimate constant disturbance torques and disturbance torques that vary with low frequency. Since the estimation scheme is designed to be robust to model uncertainties, the system model is assumed to contain inherent process and measurement uncertainties. Thus various cases for the estimator design are considered to realize different robustness requirements. Varying degrees of model uncertainty are used to test the cases in order to confirm the robustness of the design.