Data-Based Iterative Dynamic Decoupling Control for Precision MIMO Motion Systems

Decoupling control is still an important research topic for precision multiple-input–multiple-output (MIMO) motion systems involved in computer numerically controlled (CNC) machine tools, wafer scanners, etc. In this paper, to minimize internal coupling and improve servo performance, a data-based iterative dynamic decoupling control (IDDC) approach is synthesized. Specifically, a MIMO dynamic decoupling controller structured with finite impulse response filter is used as an add-on to a static decoupling part. Then, a data-based parameter optimization algorithm is developed such that the optimal parameters can be iteratively solved based entirely on the input/output data by minimizing the coupling-induced error. Unlike pre-existing IDDC approaches, the proposed approach can achieve an unbiased estimate of the optimal parameters combined with a small estimate variance that is illustrated through numerical simulation. Finally, application to an ultraprecision wafer stage confirms that the proposed approach significantly decreases the coupling-induced error and achieves enhanced performance compared to pre-existing approaches.