Direct reduced order discretization of continuous-time controller

Journal article

In this paper, we investigate the problem of closed-loop approximation of a continuous-time controller by a low-order discrete-time controller with sample and hold devices and an anti-aliasing filter. The problem is first reduced to an open-loop problem of sampled-data controller reduction with continuous-time weights. The operator representing the error in approximation can be approximated (arbitrarily closely) by a time-invariant discrete-time system resulting from applying fast sampling and lifting. We propose a method for obtaining a low-order discrete-time controller which makes small the approximation error based on recasting the approximation problem as a four-block H∞ problem. The latter can be solved efficiently by the method proposed by Glover et al. We also give a numerical example to verify the effectiveness of the method.

Authors: Anderson, B; Chongsrid, K; Limebeer, D; Hara, S

• Publication status: Published
• Publisher: John Wiley and Sons Ltd
• Journal: INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL
• Volume: 9
• Issue: 3
• Pages: 143-155
• Publication date: 1999-03-01
• DOI: 10.1002/(SICI)1099-1239(199903)9:3<143::AID-RNC397>3.0.CO;2-O
• ISSN: 1049-8923
• Language: English
• Keywords: discretization; sampled-data system; four-block problem; controller reduction