Showing papers by "Juan I. Yuz published in 2008"
TL;DR: It is argued that, in some circumstances, it is essential that special precautions, including discarding some part of the data, be taken to ensure that robustness is preserved, and presented several practical case studies to illustrate the results.
38 citations
TL;DR: This analysis reveals that the inclusion of appropriate zero dynamics is essential to ensure that the relative error converges to zero as the sampling period is reduced.
17 citations
01 Jan 2008
TL;DR: In this paper, the authors argue that the sampling process is reversible provided one has detailed knowledge of the relationship between the low-frequency and folded components so that they can be untangled from the sampled model.
Abstract: Whilst most physical systems occur naturally in continuous time, it is necessary to deal with sampled data for identification purposes. In principle, one can derive an exact sampled data model for any given linear system by integration. However, conversion to sampled data form implicitly involves folding of high-frequency system characteristics back into the lower-frequency range. This means that there is an inherent loss of information. The sampling process is reversible provided one has detailed knowledge of the relationship between the low-frequency and folded components so that they can be untangled from the sampled model. However, it is clear from the above argument that one has an inherent sensitivity to the assumptions that one makes about the folded components. The factors that contribute to the folded components include
the sampling rate
the nature of the input between samples (i.e., is it generated by a firstorder hold or not, or is it continuous-time white noise or not)
the nature of the sampling process (i.e., has an anti-aliasing filter been used and, if so, what are its frequency domain characteristics)
the system relative degree (i.e., the high-frequency roll-off characteristics of the system beyond the base band)
high-frequency poles and or zeros that lie outside the base band interval.
13 citations
TL;DR: In this paper, a closed form expression for the squared H⊥2norm of a partial fraction expansion with repeated unstable poles was obtained. But the closed form result was not applicable to the case of repeated stable poles in the plant model.
7 citations
11 Jun 2008
TL;DR: This paper shows that there is a specific relation between the characterization of these sampling zeros and the order of the B-splines used to generate the continuous-time input to the system.
Abstract: Real systems are usually modelled in continuous-time by differential equations but, in practice, we have to deal with them through digital devices using sampled data. For linear systems, exact sampled-data models can be obtained. These models, however, will generally have more zeros than the continuous-time model. In this paper we show that there is a specific relation between the characterization of these sampling zeros and the order of the B-splines used to generate the continuous-time input to the system. Moreover, we show that this connection can also be established if the smoothness of the B-spline is taken into account in the integration strategy used to discretize the continuous-time model.
5 citations