Automatic control

FFTG

FFTG crew members focus their research activities on fault tolerant guidance applied to  aerospace systems by flatness approach.

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Scientific presentation

For a Flat system there is a set of outputs named flat outputs, such that all states variables and inputs can be expressed in terms of the flat outputs and a finite number of her derivatives. This property is very useful for both path planning and controller synthesis for nonlinear dynamical systems and members of FFTG team have used it, for previous research activities. Today, the team explore the possibility to use different sets of flat outputs for diagnosis which is required to realise a fault tolerant guidance controller. 
 
FFTG research crew is composed of Franck CAZAURANG and Loïc LAVIGNE, both members of the Automatic Group of IMS Laboratory.

Teams details

obtained the B.S and M.S degrees in Electrical Engineering from ENS Cachan in 1988 and 1990, respectively, the Ph. D. degree in Automatic control from University Bordeaux 1 in 1997 and the research degree for leading research and PhD students in 2009. From september 1992 to August 1998 he worked as lecturer (agrégé) at Bordeaux University. From september 1998 to August 2010 he worked as Associate Professor of Control engineering in Bordeaux University. Since 2010 he has been Professor of Control engineering in Bordeaux University.His main research interests include path planning, fault tolerant guidance dynamic inversion and robust control dedicated to aeronautics and space domains. Pr. Cazaurang is also the head of IMSAT, the aeronautical department of University Bordeaux.

obtained his Ph.D. degree in Automatic Control from the University of Bordeaux in 2003. Since September 2005 he has been Associate Professor at Bordeaux University. His main research interests include fault detection and diagnosis, path planning, flat systems and robust control dedicated to aeronautics and space domains. Dr. Lavigne has been involved in two different European projects (GARTEUR, SIRASAS) which deals respectively on robust control and Fault Detection and Diagnosis in the Flight Control System. Dr. Lavigne is also responsible of IMA cursus in the Master GSAT of Bordeaux University.

obtained his Ph.D degree in Automatic control jointly from the University of Grenoble anf University Politechnica of Bucarest, Romania in 2012. He spent 16 months as Post doctoral position in INRIA Rennes, and since september 2014 he has been Associate professor at Bordeaux University. His main reseach interests include robust and adaptative control dedicated to active control vibrations and fluid flow control. Currently he start a new joint research topic between Crone and FFTG teams. This topic is focused on the use of formal calculus to determine the sets of flat outputs in the case of non linear systems and noninteger systems.

ARIA research team
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FFTG FOR UAV PROJECT

The objective of this stuy is to provide a flatness based active fault tolerant control technique. The fault detection and isolation block has to provide a fast and accurate fault isolation. This action is carried out by exploiting the non-uniqueness property of the flat outputs. In fact, if a second set of flat outputs which are coupled by a differential equation of the first is calculated, the number of residues augments. Differentially coupled means that it exists an equation with time derivatives inside, that couple one element of the first set with one of the second.

As a consequence of augmenting the number of residual signal more faults than in the one set case may be isolated. Regarding reconfiguration, if the flat system complies with the properties listed above, we will obtain versions of states and control inputs as much of flat output vectors, are found, because each control input and state is a function of the flat output. The proposed approach provides in this manner one measure related to a faulty flat output vector and one or more computed by using an unfaulty one. The redundant state signals could be used as reference of the controller in order to hide the fault effects. This will be helpful to provide an entirely flatness based fault-tolerant control strategy. The works presented are under the following hypothesis: The flat outputs are functions of the state of the system, however in this work the flat outputs are constrained to be states of the system or a linear combination of them. The control loop is closed with a state feedback controller. For purposes of this work flat outputs need to be measured. Faults affecting the actuators are considered rejected by the controller; by consequence reconfiguration is only carried out after a sensor fault occurs. Feasibility of the proposed approach is analyzed in two nonlinear plants, an unmanned quadrotor and a three tank system.

First, he earned his M.S degree in aerospace engineering from Bordeaux University, France in 2010 and also received the Engineer diploma with honours in electronics and telecommunications at FIME (Facultad de ingeniería Mecánica y Eléctrica), since september 2011 until march 2014, he is a PhD student in automatic control at IMS laboratory, University of Bordeaux working under a CONACYT (Consejo Nacional de Ciencia y Tecnología) grant and an international joint doctorate supervision signed by the university of Bordeaux and the UANL (Universidad Autónoma de Nuevo León). He is co-supervised by Efrain ALCORTA and David DIAZ from the department of electrical engineering at FIME. He is co-supervised by Loïc LAVIGNE and Franck CAZAURANG from IMS.

SYRENA PROJECT

The SYRENA project inclued two main work packages. The first one is focused on diagnosis methods for fuel system on a Turbo machinery. The second one is focused on critical system command and diagnosis applied to actuators for airborne system.

The fist workpackage is based on the alliance of automatic control skills of the IMS laboratory LAPS department and the expertise of David REUNGOAT from TREFLE laboratory in hydraulic systems modeling. Indeed this project requires on one hand the realization of models in the field of mechanics fluids (TREFLE) and on the other hand the development of model-based diagnosis algorithm which constitutes one of the automatic group thematic fields. 

This study focuses on the development and evaluation of a diagnostic algorithm for the fuel system of a gas turbine based on nonlinear multi-physics models. This algorithm allows detection of internal leakage faults of the gear pump in the fuel metering system from pressure measurements. The 1D multi physics approach combines hydraulic, kinematic and dynamic equations of all components of the fuel metering system. The parameters of the simulation bench test meet the technical specifications of each component while the associated tolerance intervals are used for setting the detection threshold of the algorithm in order to ensure a certain degree of robustness to the risk of false alarm. This approach is compared with the results obtained by conventional linear methods and contributions are specified. This diagnostic tool allows maintenance costs reduction of the gas engine fuel system by proposing a new architecture consisting of modular units and line replaceable units. This new architecture is defined from failure characteristics of the components and provides a level of security comparable to the previous architecture.

This study is presented in the PhD manuscript of Mohcine SIFI. He earned the B.S. and M.S. degrees with honors in aerospace engineering from Bordeaux University, France, in 2008 and 2010, respectively. Since October 2010 until January 2015, he is a PhD student in automatic control at IMS laboratory, University of Bordeaux. He is co-supervised by David Reungoat from TREFLE Laboratory. His current research interests include modeling of fuel flow control and nonlinear dynamic inversion applied to the diagnosis of a turbomachine. The work falls within the scope of the SYRENA project piloted by Turbomeca. This work is granted by “la région d’Aquitaine”.

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CRITICAL SYSTEM COMMAND AND DIAGNOSIS WORKPACKAGE

The second workpackage is focused on Flight-Critical Systems (FCS) such as Electromechanical Actuators (EMA) controlled by Engine Control Units (ECU) or Flight Control Units (FCU) which are designed and developed regarding drastic safety requirements. 

In this study, a flight critical redundant architecture is proposed regarding designed to be airborne must be compliant with ARP4754 and ARP4761 standard. In case of fault occurrences, material redundancies in avionic equipment allow the critical system to reconfigure or to switching into a safe mode. However, duplex or triplex rows of sensors and actuators used for material redundancies increase equipment volume, weight and then cost in aircrafts. Analytical redundancies, based on dynamical models is an interesting way to further enhance safety and availability without increasing the number of redundant items . Model-based fault detection and isolation (FDI) methods such as observers, parity space and parameter estimation are often used for robust fault analysis but mostly using linear models. Indeed, a FDI method based on a complex nonlinear model needs usually more output sensors to be able to process estimated outputs than in a linear case.

He obtained the MSc. in digital Signal and Image Processing at Cranfield University (UK) in 2011 and also received the Engineer Diploma in automatic processes at ESTIA (Ecole Supérieure des Technologies Industrielles Avancées) in Bidart in 2010. From June 2011 to January 2015 he is a PhD. Student at the IMS Laboratory, University of Bordeaux working under a CIFRE Grant in partnership with Thales Airborne system, Pessac. He is co-supervised by Bruno BLITEAU from ESTIA Recherche Laboratory.  His current research interests include critical system command and diagnosis applied to actuators for airborne system. The work falls within the scope of the SYRENA project driven by Turbomeca.He start in January 2015 a new career as an design engineer in an high-tech company, holds world or European leadership positions in optronics, avionics, electronics and critical software for both civil and military market.

PATH PLANNING BY FLATNESS APPROACH FOR SATELLITE

 In this cooperative research work with CNES Toulouse center, we have proposed an innovative attitude estimation filter based on differential flatness of the satellite dynamics with Rodriguez Modified Parameters for star tracker only Attitude and Orbit Control System (AOCS) architectures. The main characteristic of this estimator is to be able to maintain the satellite Absolute Pointing Error (APE) within safe limits, avoiding safe hold mode recovery in case of long duration loss of measurements (attitude control with no measurements for 1000s). This filter has been selected for in flight testing on PARASOL CNES microsatellite, and was experimented in May 2013.  The experimentation proved the efficiency of the proposed approach.

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Members

Staff

Meet the members of the research team

Loïc LAVIGNE
Franck CAZAURANG
Guillaume COTTIN
Tudor-Bogdan AIRIMITOAIE
Résumé en français

Les membres de l’équipe du FFTG concentrent leurs activités de recherche sur le guidage tolérant aux fautes appliqué aux systèmes aérospatiaux par l’approche de la planéité.

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