Cédric Lorand

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This paper models and analyzes the effect of multiple sub-systems that are driven by the same clock signal with active clock edges reaching subsystems at different time instants. This type of problem appears in high speed circuits and systems where the clock signal propagation delays differ significantly and the global system properties of the ideally(More)
In the rst part of this paper it is shown that long access delays are not necessarily detrimental to the stability of local area network embedded control systems. In the second part we show that (under some mild conditions on the control system) scheduling in the return path is not needed. This is a consequence of the fact that for local area networks the(More)
This paper addresses the problem of synchronization errors and their effects on feedback loops that are closed over communication networks. It is assumed that the feedback loop consists of two discrete-time systems, the clock frequency ratio of which has a special rational form, and is close to one. A Toeplitz matrix approach is taken to model the(More)
The problem addressed in this brief originates from the use of nonidentical clocks in distributed systems, i.e., clocks with slightly different frequencies. At first, we introduce an event driven state space model for asynchronous system equations. Then, we derive necessary and sufficient conditions for stability and show that unlike in the case of(More)
This paper studies stabilizing data rates for unstable plants with limited data rates in the state feedback path. The effects of limited data rates and time-variant delays are modeled for the case of floating point number representation. Bounds for stabilizing mantissa rates are obtained and some interesting special cases are highlighted. The first order(More)
This work presents a model for distributed feedback systems that operate at almost identical sampling rates. A Toeplitz model approach is used in order to capture the effect of small synchronization errors. In previous works, a similar model was used to formulate necessary and sufficient stability conditions, under the simplifying assumption that the(More)
This paper proposes a model that recurrently determines the switching patterns of two interconnected discrete-time systems with small differences in the clock frequencies. It is based on a time-variant or switched state-space representation of both systems. The method uses a continued fraction representation of the sampling period ratio of the two systems.(More)
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