# Stéphane VictorUniversity of Bordeaux · College of Science and Technology

Stéphane Victor

## About

73

Publications

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751

Citations

Citations since 2017

## Publications

Publications (73)

This paper proposes a method to design a wind turbulence model based on real wind spectral characteristics. It uses models based on Cole-Cole fractional functions to approximate the wind turbulence power spectral density. Von Kármán model is the most commonly used model but originally designed for aircraft in high altitude. Therefore, it is not sui...

Fractional derivatives are non local operators that has compacity property in terms of parameter number for modeling diffusive phenomenon with very few parameters. One of its main properties is its non-local behavior, as it can be exploited to model long-memory phenomena such as heat transfers. However, such non-locality implies a constant knowledg...

This paper deals with continuous-time system identification of multiple-input single-output (MISO) fractional differentiation models. When differentiation orders are assumed to be known, coefficients are estimated using the simplified refined instrumental variable method for continuous-time fractional models extended to the MISO case. For unknown d...

This paper deals with recursive continuous-time system identification using fractional-order models. Long-memory recursive prediction error method is proposed for recursive estimation of all parameters of fractional-order models. When differentiation orders are assumed known, least squares and prediction error methods, being direct extensions to fr...

Unmanned Aerial Vehicle applications have highly increased in the last years, from surveillance, exploration, rescue to transport applications. UAVs are more and more autonomous, therefore real-time trajectory planning is necessary and can be achieved thanks to artificial potential fields. The classic Ge & Cui repulsive force solely allows taking i...

System thermal modeling allows heat and temperature simulations for many applications, such as refrigeration design, heat dissipation in power electronics, melting processes and bio-heat transfers. Sufficiently accurate models are especially needed in open-heart surgery where lung thermal modeling will prevent pulmonary cell dying. For simplicity p...

Experiment design is an important topic in system identification. It enables choosing the best input signal that allows computing parameters with minimum variance. Experiment design for system identification with fractional models is treated in this paper. Elementary fractional models of the second kind are considered, extending the previous result...

This paper deals with recursive continuoustime system identification using fractional differentiation models. Long-memory recursive prediction error method is proposed for recursive estimation of all parameters of fractional order models. When differentiation orders are assumed known, least-squares and prediction error methods, being direct extensi...

Thermal models often consider low-frequency approximations and are largely based upon RC circuits. If temperature fluctuations are non-negligible, a more accurate model is needed and is proposed through thermal two-port network which is direct extension of the heat equation into matrix formalism. As blood flow plays a major role for heat transfers...

Thermal models often consider low-frequency approximations and are largely based upon RC circuits. If temperature fluctuations are non-negligible, a more accurate model is needed and is proposed through thermal two-port network which is direct extension of the heat equation into matrix formalism. As blood flow plays a major role for heat transfers...

This article proposes a very simple deterministic mathematical model, which, by using a power-law, is a non-integer power model (or fractional power model (FPM)). Such a model, in non-integer power of time, namely tm up to constants, enables representing the totality of the contaminated individuals at each day, with a good precision, thus expressin...

This paper deals with system identification for continuous-time multiple-input single-output (MISO) fractional differentiation models. An output error optimization algorithm is proposed for estimating all parameters, namely the coefficients and the differentiation orders. Given the high number of parameters to be estimated, the output error method...

Sufficiently accurate thermal modeling is necessary for many applications such as heat dissipation, melting processes, building design or even bio-heat transfers in surgery. Circuit models help modeling heat transfer dynamics: this method is simple and is often used to model thermal phenomena. However, such models well approximates low and high fre...

Thermal modeling of systems allows heat and temperature simulations for many applications, such as refrigeration design, heat dissipation in power electronics, melting processes and bio-heat transfers. Sufficiently accurate models are especially needed in open-heart surgery where lung thermal modeling will prevent pulmonary cell dying. For simplici...

Obstacle avoidance is one of the main interests regarding path planning. In many situations (mostly those regarding applications in urban environments), the obstacles to be avoided are dynamical and unpredictable. This lack of certainty regarding the environment introduces the need to use local path planning techniques rather than global ones. A we...

This paper proposes a very simple deterministic mathematical model, which, by using a power-law, is a \emph{non-integer power model} (or \emph{fractional power model (FPM)}). Such a model, in non-integer power of time, namely $t^m$ up to constants, enables representing at each day, with a good precision, the totality of the contaminated individuals...

This article deals with the issue of tracking a reference optimal trajectory for an autonomous nonlinear vehicle model by designing both lateral and longitudinal robust feedback control and a suited feedforward control. In previous works, a strategy based on a human-driver field of view was used to plan an optimal trajectory reference. The optimiza...

Fractional-order calculus has already proven to be effective in order to model diffusive phenomena, such as heat transfer or anomalous mass transfer. This has led to developments of fractional-order transfer function models and, as a consequence, system identification algorithms have been developed to identify the parameters for this type of struct...

In open-heart surgery, temperature changes may severely damage organ tissues, therefore a better knowledge of thermal transient effects is required to improve temperature control. Heat transfer in a biological context is usually treated by means of empirical relationships or simple resistance models. In some cases, fairly simplified models only inv...

This article deals with the issue of trajectory optimization of autonomous terrestrial vehicles on a specific range handled by the human driver. The main contributions of this paper are a genetic algorithm-potential field combined method for optimized trajectory planning, the definition of the multi-criteria optimization problem by including a time...

One of the main problems related to path planning is to find a method which will effectively allow the robot or vehicle to avoid obstacles, provided that these obstacles can be static or dynamic. One of the most interesting methods for path planning is the use of the artificial potential fields in order to create a representation of the environment...

In recent years, applications for drones have increased, from surveillance, exploration, rescue to transport applications. UAVs are more and more autonomous, therefore real-time trajectory planning is necessary and can be achieved with potential fields. A study is proposed to better scale attractive and repulsive forces which has always been proble...

This paper proposes an instrumental variable approach for continuous-time system identification using fractional models with multiple input single output context. This work is an extension of the simplified refined instrumental variable approach (srivcf ) developed for single input-single output fractional model identification (Malti et al. (2008a)...

Many experiments and measures have been carried out on skeletal muscles of different species, such as frog, salamander, rabbit, and rat. Exploiting these measures for system identification through non-integer models has led to many promising results. These models are useful in medicine as they help understanding their organ working or dysfunction....

In this chapter, we investigate the dynamics of fractional order models in bio-medical. First, we examine the fractional order model of HIV Infection and analyze the stability results for non-infected and infected equilibrium points. Then, we concentrate on the fractional order tumor growth model and establish a sufficient condition for existence a...

Trajectory planning for autonomous vehicles is a research topical subject. In previous studies, optimal intermediate targets have been used in the Potential Fields (PFs). PFs are only a path planning method, or a reactive obstacle avoidance method and not a trajectory tracking method. In this article, the PFs are interpreted as an on-line control m...

Trajectory planning for autonomous vehicles has significantly increased as more and more ADAS are included in modern cars. It A vehicle definitely needs to globally plan a trajectory, taking all the driving factors into account. For an autonomous terrestrial vehicle, this article proposes using an optimal trajectory on a specific range as a referen...

Path planning is an essential stage for mobile robot control. It is more newsworthy than ever in the automotive context and especially for autonomous vehicle. Also, path planning methods need to be reactive and adaptive regarding life situations, traffic and obstacle crossing. In this paper, a Bézier curve optimization method is proposed to cope wi...

System identification through fractional models is proposed for modeling thermal transfers in the lungs. In general, during open-heart surgery, an extracorporeal circulation is carried out on the patient. First, the lungs are disconnected from the circulatory system so that an artificial heart/lung machine can be plugged on the bloodstream. Pulmona...

La planification de trajectoire est une partie essentielle pour le contrôle des robots mobiles. Ceci est plus vrai
que jamais dans le contexte automobile et tout particulièrement pour le véhicule autonome. Dans ce papier, la méthode
des champs de potentiel est proposée afin de respecter ces contraintes. De plus, les véhicules autonomes sont considé...

This paper deals with the problem of experiment design in system identification using elementary fractional models of the second type. It is based on a frequency domain approach and answers the question what is the best sine input signal maximizing D-optimality criterion of the Fisher Information Matrix. A single parameter is assumed to be unknown:...

In this paper, system identification is proposed for closed-loop systems in input/output noisy context. Although instrumental variable techniques exist in the literature, the proposed filtering in input/ouput noisy context is not optimal. Also, three algorithms are proposed, and the closed-loop simplified refined instrumental variable for continuou...

Path planning is an essential stage for mobile robot control. It is more newsworthy than ever in the automotive context and especially for autonomous vehicle. Also, path planning methods need to be adaptive regarding life situations, traffic and obstacle crossing. In this paper, potential field methods are proposed to cope with these constraints an...

In the last few years much effort has been made towards more autonomous vehicles and fuel consumption reduction. This article deals with the issue trajectory optimization of unmanned terrestrial vehicles so as to reduce consumption, travel time or to improve comfort. Main focuses are set on testing different criteria and the possibility of using a...

First, heat rod models linking temperature to heat flux density are obtained from system identification using fractional order systems. Then, motion planning of the nominal system is obtained through an open-loop control stemming from flatness principles. Usually, each model should have its own control reference in order to follow a desired output...

This paper is devoted to the study of the flatness property of linear
time-invariant differential systems of fractional systems. We give two
characterizations of fractionally flat outputs and algorithms to compute them.
We then present an application to a two dimensional thermal system that we
approximate by a fractional model of order $\frac{1}{2}...

In trajectory planning, flatness is used to compute inputs generating suitable trajectories, without using any integration. The flatness property of linear controllable time-invariant fractional systems is studied. The formalism of polynomial matrix of the fractional differential operator is used leading to the characterization of fractionally flat...

Automatic control has a long history in engineering. At the end of the seventeenth century, Hooke introduced a system of balls rotating around an axis in which the velocity was proportional to the velocity of the windmill: the greater the ball velocity, the larger the gap from the axis activating the windmill sails in order to reduce the velocity....

This paper presents the latest developments for the continuous-time system identification toolbox with fractional models (or fractional order systems): the CRONE toolbox. This toolbox is to be run with Matlab which includes time-domain identification algorithms for estimating continuous-time models directly from sampled data. The originality of the...

The flatness property is studied for linear time-invariant fractional systems. In the framework of polynomial matrices of the fractional derivative operator, we give a characterization of fractionally flat outputs and a simple algorithm to compute them. These results are applied to a bidimensional thermal system approximated by a fractional transfe...

The flatness property is studied for linear time-invariant fractional systems. In the framework of polynomial matrices of the fractional derivative operator, we give a characterization of fractionally flat outputs and a simple algorithm to compute them. These results are applied to a bidimensional thermal system approximated by a fractional transfe...

This paper deals with continuous-time system identification using fractional differentiation models. So far, no algorithm exists concerning model order identification of fractional models. The “simplified” refined instrumental variable method is proposed to estimate parameters of fractional differential equation models when all the fractional order...

This paper deals with continuous-time system identification using fractional differentiation models. An adapted version of the simplified refined instrumental variable method is first proposed to estimate the parameters of the fractional model when all the differentiation orders are assumed known. Then, an optimization approach based on the use of...

In trajectory planning, flatness is used to compute inputs generating suitable trajectories, without using any integration. The extension of linear flat outputs to linear controllable time-invariant fractional systems is put forward by means of polynomial matrix formalism, leading to the notion of fractional flatness. The so-called defining matrice...

Flatness principles using polynomial matrices, well-suited for trajectory planning, are studied for fractional systems. Once a path has been defined by flatness for a real fractional system, a robust path tracking based on CRONE control is presented. Flatness in path planning is used to determine the controls to apply without integrating any differ...

this paper deals with continuous-time system identification using fractional differentiation models in a colored noisy output context. An optimal instrumental variable method for identifying fractional models in a hybrid Box-Jenkins form is described. The relationship between the measured input and the output is a fractional continuous-time transfe...

Flatness principles using polynomial matrices, well-suited for trajectory planning, are studied for fractional systems. Once a path has been defined by flatness for a real fractional system, a robust path tracking based on CRONE control is presented. Flatness in path planning is used to determine the controls to apply without integrating any differ...

Les études menées permettent de prendre en main un système depuis l'identification jusqu'à la commande robuste des systèmes non entiers. Les principes de la platitude permettent de parvenir à la planification de trajectoire à condition de connaître le modèle du système, d'où l'intérêt de l'identification des paramètres du système.Les principaux tra...

This paper deals with robust path tracking using flatness principles extended to fractional linear MIMO systems. As soon as the path has been obtained by means of the fractional flatness, a robust path tracking based on CRONE control is presented. Flatness in path planning is used to determine the controls to apply without integrating any different...

A generalization of exterior calculus is considered by allowing the partial derivatives in the exterior derivative to assume fractional orders: a fractional exterior derivative is defined [1]. This definition is found to generate new vector spaces of finite and infinite dimension, fractional differential form spaces. The transformation rules are di...

This paper deals with continuous-time system identification using fractional differentiation models in a noisy output context. The simplified refined instrumental variable for continuous-time fractional systems (srivcf) is extended to optimize the commensurate order with a gradient-based method as the coosrivcf algorithm. Simulation analysis is use...

This paper deals with continuous-time system identification using fractional differentiation models in a noisy output context. The simplified refined instrumental variable for continuous-time fractional systems (srivcf ) is extended to optimize the commensurate order with a gradient-based method as the coosrivcf algorithm. Simulation analysis is us...

This paper deals with continuous-time system identification using fractional differentiation models in a noisy output context. The simplified refined instrumental variable for continuous-time systems (srivc) is extended to fractional models. Monte Carlo simulation analysis are used to demonstrate the performance of the proposed optimal instrumental...

This paper concerns the application of flatness principle to fractional MIMO systems in the pseudo-state-space representation. The aim here is to compute linear flat outputs for linear controllable time-invariant systems in polynomial matrix form. The defining matrices expressed with the system variables in terms of a linear flat output and its der...

This paper presents an up to date advances in time-domain system identification using fractional models. Both equation-error- and output-error-based models are detailed. In the former models, prior knowledge is generally used to fix differentiation orders; model coefficients are estimated using least squares. The latter models allow simultaneous es...

This paper presents a state of the art of actual achievements in time-domain system identification using fractional models. It starts with some general aspects on time and frequency-domain representations, time-domain simulation, and stability of fractional models. Then, an overview on system identification methods using fractional models is presen...

Deux méthodes d'identification non entière, basées sur la définition de Grünwald de la dérivée non entière, sont comparées dans cet article. La première, minimisant l'erreur de prédiction à un pas, est plus délicate à mettre en œuvre. La seconde est plus facile à mettre en œuvre, car elle est basée sur la différenciation directe des signaux d'entré...