Realization of 3-degree-of-freedom control using fine-grain parallel processing

The article reports a sprout of 3-degree-of-freedom (DOF) control. The limitation of feedback control, including 2-DOF control, has been raised for a long time; however, a suitable control theory for overcoming those limitations has still not been formulated. An underlying reason is that the disturbance-suppression performance and noise sensitivity cannot be decoupled. Several researches have tried to tackle this problem using a hardware approach, as a noise level depends on a hardware configuration. It should be noted that the hardware design expands spatiotemporal resolution of a system. This approach helps in reducing noise, namely, it works as the 3rd-DOF for a control system. Therefore, an improvement in the hardware design could be a new angle for solving a mixed-sensitivity problem. This article quantitatively presents the relation between noise-reduction performance and the spatiotemporal resolution, and provides a foothold for the 3-DOF control.