A discussion on discrete implementation of disturbance-observer-based control

One of the main requirements for motion control systems is their robustness. There are several previously introduced control methods possessing the aforementioned requirement. The algorithms designed in acceleration control framework based on disturbance observer (DOB) belong to that group. The DOB introduced in eighties by Ohnishi and his group has been discussed considerably in the literature and applied in numerous applications. However, in majority of them, the control algorithms have been designed in continuous time domain, even though today they are almost always implemented on digital platforms. In addition, a discussion about discrete implementation of the designed algorithms, and influence of the parameters of discrete systems on the control performance, appeared only in several previous works. This paper aims to fill part of that gap, by discussing discrete implementation of the control algorithms which are well developed in continuous domain. The given results will provide an opportunity to give recommendations for engineers employing DOB-based control in practice.