Ali Zolghadri

Ali Zolghadri
University of Bordeaux -CNRS

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269
Publications
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4,498
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Introduction

Publications

Publications (269)
Article
The problem addressed in this paper is that of fault-tolerant multi-sensor data-fusion for flight navigation during approach and landing of a civil jetliner. The work falls within the scope of a large collaborative project on future single pilot operations issues. The proposed methodology is based on a multi-layer hierarchical architecture which ca...
Article
What is the Achilles’ heel of academic Fault Detection and Isolation (FDI) methods when it comes to application to real aircraft systems? This paper discusses some major and decisive issues that stand in the way of their transition from lab developments and simulations to real life applications in aeronautics. Often underestimated by academics, the...
Article
This paper proposes a resilient and robust model predictive control (MPC) scheme for a class of Cyber-Physical Systems (CPS) subject to state and input constraints, unknown but bounded disturbances and Denial of Service (DoS) attacks. The attacker blocks the controller to actuator communication and the attacks are assumed to be time-limited. The co...
Article
The problem studied in this paper is that of distributed controller design for interconnected systems using abstraction-based techniques. Controller synthesis for each subsystem uses local distributed sensor information from other subsystems. Such partial information in an abstraction will be characterized in terms of ranking functions which can be...
Conference Paper
Symbolic control is an approach to the control of continuous or hybrid systems with specifications expressed in a logic form. This approach is based on the use of symbolic models describing the dynamical system behavior with a finite description of the transition relation between its states. In the literature, many results using this approach assum...
Article
Symbolic control is an approach to the control of continuous or hybrid systems with specifications expressed in a logic form. This approach is based on the use of symbolic models describing the dynamical system behavior with a finite description of the transition relation between its states. In the literature, many results using this approach assum...
Article
The problem addressed in this paper is that of robust state estimation in Linear Time-Varying (LTV) systems in a noisy environment and within a distributed and networked architecture. Both bounded disturbances and random noises are considered. A Distributed Zonotopic and Gaussian Kalman Filter (DZG-KF) is proposed where each network node implements...
Article
This paper provides a brief perspective of academic model-based Fault Detection, Identification and Recovery (FDIR) developments for aerospace and flight systems, and discusses a future paradigm shift in civil aviation operations.
Article
The problem addressed is that of robust Fault Detection and Isolation (FDI) in Cyber Physical Systems (CPS) modeled by interconnected linear time-varying (LTV) dynamics in a noisy environment with both bounded disturbances and random noises. A Distributed Zonotopic and Gaussian Kalman Filter (DZG-KF) framework is proposed where each network node im...
Article
The aim of this paper is to sketch a model-based crew aided-decision system for anticipatory operational flight issues management. The system, termed Virtual co-Pilot (VcP), is intended to anticipate off-normal flight conditions and to support aircrew for better planning of upcoming flight phases and recovery from critical flight regimes. The core...
Article
This paper aims at providing a brief perspective of advanced model-based Fault Detection, Identification and Recovery (FDIR) for aerospace and flight-critical systems. A number of practical key factors for designing credible technological options are emphasized. Such considerations are decisive for the survivability of the design during ground/flig...
Article
Full-text available
The problem addressed in this paper is that of quadrotor roll and pitch estimation without any assumption about the knowledge of perturbation bounds when Inertial Measurement Units (IMU) data or position measurements are available. A Smooth Sliding Mode (SSM) algorithm is first designed to provide reliable estimation under a smooth disturbance assu...
Article
This paper presents a parametric model-based monitoring technique for detection and confirmation of faults in control surface servo-loops related to the Electrical Flight Control System. It is shown that there exists a direction in the parameter space which is sensitive to the occurrence of the faults on interest. On-line system parameter estimatio...
Article
The general problem addressed in this paper is that of the estimation and prediction of the aircraft flight maneuvering envelope. This work is intended to be further used as the basis of a new approach for predictive safe flight envelope monitoring and early notification of developing off-nominal flight situations. The proposed method combines: i)...
Article
Full-text available
In this brief, an approach is presented to design a robust quadrotor attitude estimator when only inertial measurement units (IMUs) sensor data can be available. A two-step procedure is proposed to improve attitude estimation in the presence of IMU biases and measurement noise. In the first step, a smooth sliding mode observer is designed to estima...
Conference Paper
In this paper, three different differentiation schemes are studied for the development of a generic fault detection scheme. The case of runaway fault is investigated. A runaway is an uncontrolled deflection of a control surface which can go until its physical limitation if it remains undetected. The proposed technique is a signal-based one that rel...
Article
The problem studied in this paper is one of improving the performance of a class of adaptive observer in the presence of exogenous disturbances. The H∞ gains of both a conventional and the newly proposed sliding-mode adaptive observer are evaluated, to assess the effect of disturbances on the estimation errors. It is shown that if the disturbance i...
Article
This paper discusses some key factors which may arise for successful application of model-based Fault Detection (FD) techniques to aircraft systems. The paper reports on the results and the lessons learned during flight V&V (Validation & Verification) activities, implementation in the A380 Flight Control Computer (FCC) and A380 flight tests at Airb...
Conference Paper
In this paper, a fault tolerant control strategy based on a combination of a standard state feedback linearization and quasi-continuous high-order sliding mode controller is proposed within a backstepping setting for a class of nonlinear systems. The proposed controller is based on a hierarchical application of the control methodology ensuring the...
Conference Paper
Full-text available
The problem studied in this paper is that of quadrotor attitude estimation using an adaptive second-order sliding mode (SM) observer. The gains are dynamically adapted to the sliding motion to ensure the convergence of observer error to the sliding manifold in the finite time. Position measurements of quadrotor are used in this adaptive SM observer...
Conference Paper
Full-text available
This paper addresses the problem of quadrotor attitude estimation when only IMU sensor data are available. First, a Smooth Sliding Mode (SSM) algorithm is considered to provide an estimation of roll/pitch angles. In a second step, the estimates provided by SSM algorithm are used to reformulate the innovation term of the complementary filter in orde...
Article
THE required technological advances identified by the aeronautics sector to achieve the long-term goals of greener aviation are multiple and challenging. New technological options will be needed to produce incrementally more efficient and environmentally friendlier aircraft. The early and robust detection of faults that have an influence on structu...
Conference Paper
Full-text available
This paper presents a robust parametric test dedicated to control surface runaway (a.k.a. hard-over) detection, jointly developed by the University of Bordeaux and Airbus Operations S.A.S. A robust Recursive Least-Square (RLS) algorithm allows for estimating the parameters of an appropriate parametric model structure of the control surface servo-lo...
Conference Paper
Full-text available
This paper addresses the problem of quadrotor pitch/roll estimation when only IMU sensors are available. A Smooth Sliding Mode (SSM) algorithm is firstly considered to provide reliable estimation of pitch/roll angles under a smoothness disturbance assumption. The performance is compared to use a recently developed high-order sliding mode (HOSM) dif...
Article
Full-text available
In this paper a fault tolerant control strategy that combines the backstepping procedure and the quasi-continuous high-order sliding mode controller is proposed. The fault tolerance principle is based on a hierarchical application of the backstepping methodology ensuring the finite time convergence of the desired system states, in spite of the cons...
Article
Full-text available
This paper deals with the output tracking problem of a MIMO system subjected to a class of actuator faults and unmatched perturbations. The proposed methodology is based on high order sliding mode observation and identification techniques. A dynamic sliding surface is proposed using a backstepping-like design strategy in order to counteract the eff...
Conference Paper
The paper presents several examples on model and signal based fault detection in aircraft Electrical Flight Control System (EFCS). The examples are taken from past and on -going research projects and actions between Airbus Group and the University of Bordeaux (France). The techniques presented have been tested on highly representative aircraft b...
Article
An approach to interval observer design for Linear Parameter-Varying (LPV) systems is proposed. It is assumed that the vector of scheduling parameters in LPV models is not available for measurement. Two different interval observers are constructed for nonnegative systems and for a generic case. Stability conditions are expressed in terms of matrix...
Article
This work is devoted to interval observers design for discrete-time linear parameter-varying systems under the assumption that the vector of scheduling parameters is not available for measurements. Two problems are considered: a pure estimation problem and an output stabilizing feedback design problem where the stability conditions are expressed in...
Article
This paper addresses the problem of interval observer design for unknown input estimation in Linear Time-Invariant (LTI) systems. Although the problem of unknown input estimation has been widely studied in the literature, the design of joint state and unknown input observers has not been considered within a set-membership context. While conventiona...
Article
The paper develops a set membership detection methodology which is applied to the detection of abnormal positions of aircraft control surfaces. Robust and early detection of such abnormal positions is an important issue for early system reconfiguration and overall optimization of aircraft design. In order to improve fault sensitivity while ensuring...
Chapter
Full-text available
This paper tackles the output tracking problem of a MIMO system subjected to actuator faults and unmatched perturbations. The proposed methodology is based on high order sliding mode observation and identification techniques. A dynamic sliding surface is proposed using a nested-backward design strategy in order to counteract the effects of the unma...
Chapter
Full-text available
The paper addresses the problem of sensor fault estimation in avionics multisensor systems. Under the assumption of system strong observability, sliding mode observers are designed to estimate the faults in finite time and in the presence of bounded disturbances. It is shown that the fault estimation error is bounded in the L ∞ -norm sense, and an...
Article
Full-text available
This work addresses the problem of oscillatory failure case detection in the electrical flight control system of a generic commercial airplane. A non-homogeneous differentiator is first used to provide accurate derivatives in noisy environment and fast convergence time. In this study case, fault detection is addressed in the unknown input estimatio...
Article
Full-text available
In avionics and aerospace multisensor systems, reliable and early detection of individual sensor faults present substantial challenges to health monitoring designers of such systems. This study addresses the problem of sensor fault diagnosis. The proposed solution is based on a non-homogeneous high-order sliding mode observer used to estimate the f...
Article
SUMMARY In this paper, the problem of continuous and discrete state estimation for a class of linear switched systems with additive faults is studied. The class of systems under study can contain non-minimum phase zeroes in some of their ‘operating modes’. The conditions for exact reconstruction of the discrete state are given using structural prop...
Article
The presented work is undertaken within the FP7-ADDSAFE (Advanced Fault Diagnosis for Sustainable Flight Guidance and Control) project, a European collaborative project that aims to propose new fault diagnosis techniques for AIRBUS aircraft that could significantly advance the aircraft performance, e.g. by optimizing the aircraft structural design...
Article
An interval observer for Linear Time-Varying (LTV) systems is proposed in this paper. Usually, the design of such observers is based on monotone systems theory. Monotone properties are hard to satisfy in many situations. To overcome this issue, in a recent work, it has been shown that under some restrictive conditions, the cooperativity of an LTV s...
Article
In this paper a continuous fault tolerant control allocation is proposed. This approach is based on a uniform High-Order Sliding-Mode Observer where only measurable outputs are used. The fault tolerant control scheme is developed using, for the first time, a continuous integral sliding-mode and a fixed control allocation technique which provides an...
Patent
Le dispositif de détection (1) comporte des premiers moyens (22) pour estimer la valeur d'au moins un paramètre d'une équation modélisant la dynamique de la boucle d'asservissement de la gouverne (3), conformément à une méthode récursive autorégressive à variable exogène de type RARX au sens des moindres carrés récursifs, et des deuxièmes moyens (2...
Patent
Full-text available
A detection device determines whether an uncontrolled movement of a control surface of an aircraft is occurring. The device includes means for calculating the difference between a theoretical command and an actual command in order to form a residual value, and means for detecting an uncontrolled movement of the control surface, if a comparison valu...
Article
This paper deals with a model-based prognosis approach for assessing the remaining useful life (RUL) of a printed circuit board (PCB) subjected to impact or vibration loads applied to its support contour. The approach deals with the interaction (coupling) of the "fast" Ball-Grid-Array (BGA) vibration model and the "slow" low cycle fatigue damage mo...
Article
Based on a consistent interface between a data-driven and a model-driven approach within an interval framework, the paper deals with the detection of two important electrical flight control system failure cases of aircraft control surfaces, namely runaway and jamming. Robust and early detection of such abnormal positions is an important issue for e...
Article
Full-text available
In this paper the problem of adaptive observer design in the presence of disturbances is studied, and an augmented adaptive observer is proposed. First, the H∞ gain of a conventional adaptive observer is estimated, which characterizes the effect of disturbances on output errors. Next, it is shown that if the disturbance is "matched" in the plant eq...
Patent
A system for detecting jamming and/or uncontrolled movement of an aircraft control surface includes first means for estimating the value of at least one parameter of an equation simulating the feedback loop dynamic of the control surface, according to a recursive autoregressive method with exogenous variable of RARX type in a recursive least square...
Conference Paper
Full-text available
This paper deals with a signal-based method for robust and early detection of lock-in-place failures (a.k.a. jamming) in aircraft control surface servo-loops. Early and robust detection of such failures is an important issue since they may cause additional structural load and affect the sustainability of civil transport airplane. The proposed signa...
Conference Paper
Full-text available
This paper deals with the design of an estimator-based supervisory Fault Tolerant Control (FTC) scheme for Linear Time Invariant (LTI) systems. A formal stability proof based on dwell-time conditions is presented when the state of the detection filter does not correspond to the plant state, as in classical (Luenberger) observer-based approaches. In...
Patent
Full-text available
The detection device includes, but is not limited to a device that is configured to determine a control error corresponding to the difference between a first control instruction and a control surface position, a second device that is configured to calculate the difference between this control error and a second control instruction in such a way as...
Conference Paper
In this paper, a method for computing reachable sets of uncertain nonlinear continuous-time systems is proposed. The approach, based on Linear Parameter-Varying (LPV) inclusions of nonlinear systems, relies on a time-varying change of coordinates which ensures some monotony properties in the new base. A sufficient condition ensuring the non diverge...
Chapter
This chapter starts with some basic definitions and concepts as well as a quick literature review on FDIR academic methods. The main concepts of the industrial state-of-practice for space and avionics systems will also be briefly presented. An attempt will be made to analyze major reasons for the slow-progress in applying advanced model-based techn...
Chapter
This chapter is dedicated to final remarks and suggestions on future challenges and opportunities. We focus on what useful and realistic contributions the research community can make in order to develop successful solutions for future space and avionics systems. In this chapter, we would like to discuss briefly some future challenges and opportunit...
Chapter
This chapter is dedicated to two other important EFCS-failure cases in aviation: runaway and jamming. A runaway is an untended (or uncontrolled) deflection of a control surface which can go until its stops if it remains undetected. A jamming is a scenario where a control surface is physically stuck at its current position. It will be shown that by...
Chapter
This chapter is dedicated to techniques for ensuring fault tolerance in redundant aircraft sensors involved in computation of flight control laws. The objective is to switch off the faulty sensor and to compute a reliable (a.k.a. as “consolidated”) parameter using data from valid sensors, in order to eliminate any anomaly before propagation in the...
Chapter
This chapter presents briefly the motivations and the book outline. This book presents a number of advanced fault detection and diagnosis and reconfiguration technologies for aerospace vehicles. An attempt is made to develop useful solutions that can be relevant and viable candidates for future space and aeronautical systems. The presented techniqu...
Article
The work presented in this paper is undertaken within the European FP7 funded Advanced Fault Diagnosis for Sustainable Flight Guidance and Control (ADDSAFE) project. The goal is to propose new fault detection and fault diagnosis techniques that could significantly help developing environmentally-friendlier aircraft. In this paper, LPV model-based f...
Conference Paper
In this paper, a printed circuit board (PCB) carrying surface mounted devices (SMD) subjected to impact or vibration loads applied to its support contour is considered. A model-based prognosis approach is employed to assess the remaining useful life (RUL) of the ball-grid-array (BGA) solder joint interconnections. The approach deals with the intera...
Chapter
This chapter is dedicated to space applications. Three application cases will be presented: an Earth observation satellite, a deep space mission and an atmospheric re-entry vehicle. The design method is based on H ∞ /H − tools and is associated with a suitable post-analysis process, the so-called generalized μ-analysis. It is shown that the resulti...
Chapter
This chapter deals with model-based Fault Detection and Diagnosis (FDD) methods which have been recently applied to Oscillatory Failure Case (OFC) in aircraft control surface servo-loops. This failure case, related to the Electrical Flight Control System (EFCS), could have an influence on structural loads and aircraft controllability. Two methods w...
Chapter
This chapter deals with the next step following the design of an FDD system, i.e. appropriate recovery strategies, based on all available actuator/sensor/communication resources. An active fault tolerant flight control strategy based on H∞ design tools is presented. The Fault Tolerant Control (FTC) strategy operates in such a way that once a fault...
Article
This paper deals with the problem of joint state and parameter estimation based on a set adaptive observer design. The problem is formulated and solved for an LPV (linear parameter-varying) system. The resolution methodology avoids the exponential complexity obstruction usually encountered in the set-membership parameter estimation. A simulation ex...
Article
Full-text available
This paper deals with interval state observer design for time-varying discrete-time systems. The problem of a similarity transformation computation which connects a (time-varying) matrix and its nonnegative representation is studied. Three solutions are proposed: for a generic time-varying system, a system with positive state, and for a particular...
Article
Full-text available
Robust estimation of the amplitude, frequency and bias of unknown noisy sinusoidal signals is considered. It is only assumed that the measurements noise is bounded without any additional information such as stationarity, uncorrelation or type of distribution. The estimation problem is formulated as a Constraint Satisfaction Problem (CSP) where the...
Article
Full-text available
For aerospace systems, advanced model-based Fault Detection, Identification, and Recovery (FDIR) challenges range from predesign and design stages for upcoming and new programs up to the improvement of the performance of in-service flying systems. However, today, their application to real aerospace world has remained extremely limited. The paper un...
Article
Full-text available
The problem of observer design for fault detection in a class of nonlinear systems subject to parametric and signal uncertainties is studied. The design procedure includes formalized optimization of observer free parameters in terms of trade-offs for fault detection performance and robustness to external disturbances or model uncertainties. The tec...
Article
Full-text available
The problem of model-based fault detection is studied with application of the Kalman filter for residual generation. The filter has two important incoming parameters, the state noise and the output noise covariance matrices, which tuning is analyzed in order to optimize the fault detection performance. The problem is formulated through an appropria...
Conference Paper
Full-text available
This work is devoted to interval observers design for discrete-time Linear Parameter-Varying (LPV) systems under assumption that the vector of scheduling parameters is not available for measurements. Two scenarios are considered: a pure estimation and an output stabilizing feedback design. Stability conditions are expressed in terms of linear matri...
Conference Paper
Full-text available
The industrial state-of-practice to diagnose Electrical Flight Control System (EFCS) faults and obtain full flight envelope protection at all times is to provide high levels of hardware redundancy to perform built-in-tests of various sophistication. Although not obvious at the first sight, there is a strong link between advanced Fault Detection and...