Title: Two-degree-of-freedom control with tuning of both prefilter and feedforward controller

Authors: Lorlynn Asuncion Mateo; Kenji Sugimoto

Addresses: Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan ' Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan

Abstract: Using a two-degree-of-freedom structure allows us to independently design the feedforward controller and the feedback controller to improve system response and achieve plant stabilisation, respectively. Feedforward control with online tuning is particularly promising for achieving good response, which is why various schemes have been proposed in literature. This paper proposes yet another scheme, which focuses on tuning both the prefilter and feedforward controller with a fixed feedback controller synthesised via H∞-optimisation. The scheme thereby avoids pole/zero cancellation and tunes parameter in those blocks linearly. Furthermore, the presence of bounded parametric model uncertainty can be addressed by mixed sensitivity controller synthesis that will focus on stabilising the plant, allowing robustness. Numerical simulation with a couple of examples is carried out to illustrate the proposed design procedure.

Keywords: 2DOF structures; feedforward control; learning control; feedback error learning; FEL; h-infinity optimisation; h-infinity norm; mixed sensitivity; model uncertainty; 2DOF control; controller tuning; prefilter control; controller design; numerical simulation.

DOI: 10.1504/IJAMECHS.2015.074789

International Journal of Advanced Mechatronic Systems, 2015 Vol.6 No.6, pp.277 - 288

Received: 22 Dec 2014
Accepted: 06 Oct 2015

Published online: 16 Feb 2016 *

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