High-performance conversions between continuous- and discrete-time systems

In this paper, a new algorithm for converting an S-domain model to a Z-doma in model is proposed. The resultant Z-domain model is much closer to the or iginal S-domain model than that obtained from conventional conversion schem es such as Tustin approximation with or without frequency pre-warping, zero -pole mapping equivalent, and Triangle hold equivalent. The proposed algori thm adopts the standard recursive least squares approach, and it has the fo llowing advantages. First, the computation is trivial and can be easily imp lemented online. Second, it can handle both parametric and non-parametric m odels, while conventional conversion methods can only handle parametric mod els. Third, it is very flexible and applicable to Z- to S-domain model conv ersion, sampling rate selection. re-sampling, time delay system conversion. and model order selection. The superior performance of the method is demon strated with several simulation examples in this paper. (C) 2001 Elsevier S cience B.V. All rights reserved.