Showing papers by "Cédric Join published in 2008"
TL;DR: Non-linear state estimation and some related topics like parametric estimation, fault diagnosis and perturbation attenuation are tackled here via a new methodology in numerical differentiation within the framework of differential algebra.
Abstract: Non-linear state estimation and some related topics like parametric estimation, fault diagnosis and perturbation attenuation are tackled here via a new methodology in numerical differentiation. The corresponding basic system theoretic definitions and properties are presented within the framework of differential algebra, which permits to handle system variables and their derivatives of any order. Several academic examples and their computer simulations, with online estimations, illustrate our viewpoint.
363 citations
25 Jun 2008
TL;DR: The main tool is an online numerical differentiator, which is based on easily implementable fast estimation and identification techniques, which demonstrates the efficiency of the method when compared to more classic PID regulators.
Abstract: Intelligent PID controllers, or i-PID controllers, are PID controllers where the unknown parts of the plant, which might be highly nonlinear and/or time-varying, are taken into account without any modeling procedure. Our main tool is an online numerical differentiator, which is based on easily implementable fast estimation and identification techniques. Several numerical experiments demonstrate the efficiency of our method when compared to more classic PID regulators.
166 citations
01 Apr 2008
TL;DR: In this paper, a model-free control and a control with a restricted model for finite-dimensional complex systems are introduced, which can be viewed as a contribution to intelligent PID controllers, the tuning of which becomes quite easy, even with highly nonlinear and/or time-varying systems.
Abstract: We are introducing a model-free control and a control with a restricted model for finite-dimensional complex systems. This control design may be viewed as a contribution to ``intelligent'' PID controllers, the tuning of which becomes quite easy, even with highly nonlinear and/or time-varying systems. Our main tool is a newly developed numerical differentiator. Differential algebra provides the theoretical framework. Our approach is validated by several numerical experiments.
89 citations
TL;DR: A new approach to enhance the performance of an active fault tolerant control system based on a modified recovery/trajectory control system in which a reconfigurable reference input is considered when performance degradation occurs in the system due to faults in actuator dynamics.
Abstract: The prospective work reported in this paper explores a new approach to enhance the performance of an active fault tolerant control system. The proposed technique is based on a modified recovery/trajectory control system in which a reconfigurable reference input is considered when performance degradation occurs in the system due to faults in actuator dynamics. An added value of this work is to reduce the energy spent to achieve the desired closed-loop performance. This work is justified by the need of maintaining a reliable system in a dynamical way in order to achieve a mission by an autonomous system, e.g., a launcher, a satellite, a submarine, etc. The effectiveness is illustrated using a three-tank system for slowly varying reference inputs corrupted by actuators faults.
88 citations
09 Dec 2008
TL;DR: Previous works on real-time estimation through algebraic techniques are extended to the recovering of the switching signal and of the state for switching linear systems, and singular inputs for which the switched systems become undistinguishable.
Abstract: We extend previous works on real-time estimation, via algebraic techniques, to the recovering of the switching signal and of the state for switching linear systems. We characterize also singular inputs for which the switched systems become undistinguishable. Several convincing numerical experiments are illustrating our techniques which are easily implementable.
48 citations
TL;DR: In this paper, the authors deal with the first application of the new framework of model-free control to the promising technology of shape memory alloys actuators, in particular antagonistic shape memory actuators.
29 citations
TL;DR: The approach, which is of algebraic flavor and avoids asymptotic and statistical techniques, yields fast implementable formulae in closed form for critical density and free flow speed of a motorway segments.
16 citations
20 Oct 2008
TL;DR: This paper proposes an original adaptation of an approach used into nonlinear control for fault-diagnosis and fault-tolerant control based on algebraic derivation and which is robust to noise.
Abstract: Extrema of curvature are useful key points for different image analysis tasks. Indeed, polygonal approximation or arc decomposition methods used often these points to initialize or to improve their algorithms. Several shape-based image retrieval methods focus also their descriptors on key points. This paper is focused on the detection of extrema of curvature points for a raster-to-vector-conversion framework. We propose an original adaptation of an approach used into nonlinear control for fault-diagnosis and fault-tolerant control based on algebraic derivation and which is robust to noise. The experimental results are promising and show the robustness of the approach when the contours are bathed into a high level speckled noise.
12 citations
01 Nov 2008
TL;DR: In this article, a model-free approach to the forecast of foreign exchange rates via repeated identifications of low-order linear difference equations on sliding short time windows is presented, and several convincing computer simulations, including the prediction of the position and the volatility with respect to a forecasted trendline, are provided.
Abstract: New fast estimation methods stemming from control theory lead to a fresh look at time series, which bears some resemblance to "technical analysis". The results are applied to a typical object of financial engineering, namely the forecast of foreign exchange rates, via a "model-free" setting, i.e., via repeated identifications of low order linear difference equations on sliding short time windows. Several convincing computer simulations, including the prediction of the position and of the volatility with respect to the forecasted trendline, are provided. $\mathcal{Z}$-transform and differential algebra are the main mathematical tools.
9 citations
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TL;DR: In this article, a model-free approach to the forecast of foreign exchange rates via repeated identifications of low-order linear difference equations on sliding short time windows is presented, and several convincing computer simulations, including the prediction of the position and the volatility with respect to a forecasted trendline, are provided.
Abstract: New fast estimation methods stemming from control theory lead to a fresh look at time series, which bears some resemblance to "technical analysis". The results are applied to a typical object of financial engineering, namely the forecast of foreign exchange rates, via a "model-free" setting, i.e., via repeated identifications of low order linear difference equations on sliding short time windows. Several convincing computer simulations, including the prediction of the position and of the volatility with respect to the forecasted trendline, are provided. $\mathcal{Z}$-transform and differential algebra are the main mathematical tools.
8 citations
01 Jan 2008
TL;DR: This paper considers the problem of change-point detection for noisy data and applies the approach to the study of changes that may be observed in EEG signal dynamics during epileptic seizure and in ECG signal during the occurrence of a QRS complex.
Abstract: This paper considers the problem of change-point detection for noisy data. Estimation of signal frequency content relies on differential algebra and non-commutative algebra together with operational calculus. We adapt this approach to the study of changes that may be observed in EEG signal dynamics during epileptic seizure and in ECG signal during the occurrence of a QRS complex. The correlation with frequency change is what this idea is based on. The interest of our estimator is firstly il lustrated according to several academic examples. Then, the method is applied on real physiological signals to detect abrupt frequency changes.
25 Jun 2008
TL;DR: In this paper, a change-point detection method based on direct online estimation of the signalpsilas singularity points is presented, which casts the problem into a delay estimation.
Abstract: We are presenting a change-point detection method based on a direct online estimation of the signalpsilas singularity points. Using a piecewise local polynomial representation of the signal, we cast the problem into a delay estimation. A change-point instant is characterized as a solution of a polynomial equation, the coefficients of which are composed by short time window iterated integrals of the noisy signal. The so designed change-point detector shows good robustness to various type of noises.
Posted Content•
TL;DR: New fast estimation methods stemming from control theory lead to a fresh look at time series, which bears some resemblance to "technical analysis" in a typical object of financial engineering, namely the forecast of foreign exchange rates, via a "model-free" setting.
Abstract: New fast estimation methods stemming from control theory lead to a fresh look at time series, which bears some resemblance to "technical analysis". The results are applied to a typical object of financial engineering, namely the forecast of foreign exchange rates, via a "model-free" setting, i.e., via repeated identifications of low order linear difference equations on sliding short time windows. Several convincing computer simulations, including the prediction of the position and of the volatility with respect to the forecasted trendline, are provided. $\mathcal{Z}$-transform and differential algebra are the main mathematical tools.