Boundary feedback stabilization of a flexible wing model under unsteady aerodynamic loads

This paper addresses the boundary stabilization of a flexible wing model, both in bending and twisting displacements, under unsteady aerodynamic loads, and in presence of a store. The wing dynamics is captured by a distributed parameter system as a coupled Euler-Bernoulli and Timoshenko beam model. The problem is tackled in the framework of semigroup theory, and a Lyapunov-based stability analysis is carried out to assess that the system energy, as well as the bending and twisting displacements, decay exponentially to zero. The effectiveness of the proposed boundary control scheme is evaluated based on simulations.Comment: Published in Automatica as a brief pape

Boundary Control of a Nonhomogeneous Flexible Wing with Bounded Input Disturbances

This note deals with the boundary control problem of a nonhomogeneous flexible wing evolving under unsteady aerodynamic loads. The wing is actuated at its tip by flaps and is modeled by a distributed parameter system consisting of two coupled partial differential equations. Based on the proposed boundary control law, the well-posedness of the underlying Cauchy problem is first investigated by resorting to the semigroup theory. Then, a Lyapunov-based approach is employed to assess the stability of the closed-loop system in the presence of bounded input disturbances.Comment: Published in IEEE Transactions on Automatic Control as a Technical Not

Robust scheduled control of longitudinal flight with handling quality satisfaction

Classic flight control systems are still widely used in the industry because of acquired experience and good understanding of their structure. Nevertheless, with more stringent constraints, it becomes difficult to easily fulfil all the criteria with these classic control laws. On the other hand, modern methods can handle many constraints but fail to produce low order controllers. The following methodology proposed in this paper addresses both classic and modern flight control issues, to offer a solution that leverages the strengths of both approaches. First, an H∞ synthesis is performed in order to get controllers which satisfy handling qualities and are robust withrespect to mass and centre of gravity variations. These controllers are then reduced and structured by using robust modal control techniques. In conclusion, a self-scheduling technique is described that will schedule these controllers over the entire flight envelope

Robust control of longitudinal flight with handling qualities constraints

Classical flight control systems are still widely used in industry because of acquired experience and good understanding of their structure. Nevertheless, with more stringent constraints, it becomes difficult to easily fulfill all the criteria with this classical control laws. This article aims at showing that this problem can be solved by first designing a high order controller satisfying all the constraints, then by reducing and structuring it in order to make it look like a classical controller. Firstly, an H∞ synthesis is performed in order to get a robust controller versus mass and center of gravity variations, which will satisfy the handling qualities; then it will be reduced by using robust modal control techniques

Control of a launcher in atmospheric ascent with guardian maps

This paper describes the synthesis of a SISO scheduled controller for a launcher vehicle. The problem consists in designing a control law which will be valid on the atmospheric ascent trajectory from time 25 s to time 60 s, while ensuring robustness and performance requirements. Moreover a flexible model with two bending modes is considered, making the problem more challenging. An algorithm based upon guardian maps has been retained in order to find an a priori fixed architecture controller. The algorithm yields a sequence of controllers that ensures that pole confinement constraints are fulfilled for any time between 25 s and 60 s. The user can then interpolate those controllers to find a scheduled controller with respect to time

Real-Time Distributed Aircraft Simulation through HLA

This paper presents some ongoing researches carried out in the context of the PRISE (Research Platform for Embedded Systems Engineering) Project. This platform has been designed to evaluate and validate new embedded system concepts and techniques through a special hardware and software environment. Since many actual embedded equipments are not available, their corresponding behavior is simulated using the HLA architecture, an IEEE standard for distributed simulation, and a Run-time infrastructure called CERTI and developed at ONERA. HLA is currently largely used in many simulation applications, but the limited performances of the RTIs raises doubts over the feasibility of HLA federations with real-time requirements. This paper addresses the problem of achieving real-time performances with HLA. Several experiments are discussed using well-known aircraft simulators such as the Microsoft Flight Simulator, FlightGear, and X-plane connected with the CERTI Run-time Infrastructure. The added value of these activities is to demonstrate that according to a set of innovative solutions, HLA is well suited to achieve hard real time constraints

Contrôle du vol longitudinal d'un avion civil avec satisfaction de qualités de manoeuvrabilité

RÉSUMÉ Satisfaire les qualités de manœuvrabilité demeure toujours une contrainte essentielle lors de la conception des commandes de vol. Ces critères de différentes natures sont le fruit d'une longue expérience d'essais en vol et d'analyse de données et il convient de les considérer pour espérer un bon comportement de l'appareil en vol. Dans ce cadre, l'enjeu de cette thèse est d'élaborer des méthodes de synthèse capables de satisfaire au mieux ces critères en respectant d'une part des architectures classiques imposées par le constructeur et, d'autre part, en adoptant une nouvelle architecture de contrôle. Le travail est effectué sur le vol longitudinal d'un avion d'affaire de Bombardier Inc., le Challenger 604. Une première étape consiste à rassembler les qualités de manœuvrabilité les plus souvent utilisées et de les confronter. Nous étudions plus particulièrement le critère du dropback pour lequel une analyse théorique permet d'établir une formulation pratique utilisable lors d'une synthèse. De plus, la confrontation de ces critères sur un modèle standard met en évidence des critères dominants, qui, une fois satisfaits, impliquent que d'autres critères le sont aussi. Nous pouvons dès lors considérer le problème de satisfaction de ces critères dominants dans le cadre d'une loi de contrôle dont l'architecture est imposée. Nous nous tournons alors du côté des applications gardiennes (Saydy et al., 1990). Initialement destinées à l'étude de la robustesse, elles sont intégrées dans différents algorithmes pour la synthèse de correcteur. Ce problème s'inscrit dans le cadre plus général de stabilisation par retour de sortie et de synthèse de correcteurs d'ordre réduit. Il en ressort des algorithmes permettant la stabilisation de système et le placement de pôles dans une région du plan complexe. Ceux-ci sont étendus dans le cadre du séquencement du contrôleur sur toute l'enveloppe de vol en fonction de certains paramètres. Nous faisons ensuite fi de la structure du correcteur en conservant seulement les mêmes sorties. L'idée est à présent d'utiliser une synthèse H pour obtenir un correcteur satisfaisant les qualités de manœuvrabilité grâce à l'appariement avec un modèle de référence et robuste à des variations de masse et de centrage de l'avion. Grâce aux travaux sur la commande modale robuste (Magni, 2002), nous pouvons réduire substantiellement l'ordre de ce correcteur ainsi que le structurer afin de nous rapprocher d'une architecture classique. Une méthode d'auto-séquencement de correcteurs, nous permet finalement de séquencer ce correcteur à travers toute l'enveloppe de vol. Deux voies différentes sont donc empruntées pour la résolution du même problème; chacune montre ses avantages et ses inconvénients.----------ABSTRACT Fulfilling handling qualities still remains a challenging problem during flight control design. These criteria of different nature are derived from a wide experience based upon flight tests and data analysis, and they have to be considered if one expects a good behavior of the aircraft. The goal of this thesis is to develop synthesis methods able to satisfy these criteria with fixed classical architectures imposed by the manufacturer or with a new flight control architecture. This is applied to the longitudinal flight model of a Bombardier Inc. business jet aircraft, namely the Challenger 604. A first step of our work consists in compiling the most commonly used handling qualities in order to compare them. A special attention is devoted to the dropback criterion for which theoretical analysis leads us to establish a practical formulation for synthesis purpose. Moreover, the comparison of the criteria through a reference model highlighted dominant criteria that, once satisfied, ensure that other ones are satisfied too.Consequently, we are able to consider the fulfillment of these criteria in the fixed control architecture framework. Guardian maps (Saydy et al., 1990) are then considered to handle the problem. Initially for robustness study, they are integrated in various algorithms for controller synthesis. Incidently, this fixed architecture problem is similar to the static output feedback stabilization problem and reduced-order controller synthesis. Algorithms performing stabilization and pole assignment in a specific region of the complex plane are then proposed. Afterwards, they are extended to handle the gain-scheduling problem. The controller is then scheduled through the entire flight envelope with respect to scheduling parameters. Thereafter, the fixed architecture is put aside while only conserving the same output signals. The main idea is to use H synthesis to obtain an initial controller satisfying handling qualities thanks to reference model pairing and robust versus mass and center of gravity variations. Using robust modal control (Magni, 2002), we are able to reduce substantially the controller order and to structure it in order to come close to a classical architecture. An auto-scheduling method finally allows us to schedule the controller with respect to scheduling parameters. Two different paths are used to solve the same problem; each one exhibits its own advantages and disadvantages

Real-time distributed simulations in an HLA framework: Application to aircraft simulation

This paper presents some ongoing research carried out in the context of the PRISE Project (Research Platform for Embedded Systems Engineering). This platform has been designed to evaluate and validate new embedded system concepts and techniques through a special hardware and software environment. Since much actual embedded equipment is not available, corresponding behavior is simulated within a high-level architecture (HLA) federation implemented with a run-time infrastructure (RTI) called CERTI and developed at ONERA. HLA is currently largely used in many simulation applications, but the limited performances of the RTIs raise doubts over the feasibility of HLA federations with real-time requirements. This paper addresses the problem of achieving real-time performances with the HLA standard. Several experiments are discussed using well-known aircraft simulators such as Microsoft Flight Simulator, FlightGear, and X-plane connected with the CERTI RTI. The added value of these activities is to demonstrate that according to a set of innovative solutions, HLA architecture is well suited to achieve hard real-time constraints. Finally, a formal model guaranteeing the schedulability of concurrent processes is also proposed

The ROSACE Case Study: From Simulink Specification to Multi/Many-Core Execution

This paper presents a complete case study - named ROSACE for Research Open-Source Avionics and Control Engineering - that goes from a baseline flight controller, developed in MATLAB/SIMULINK, to a multi-periodic controller executing on a multi/many-core target. The interactions between control and computer engineers are highlighted during the development steps, in particular by investigating several multi-periodic configurations. We deduced ways to improve the discussion between engineers in order to ease the integration on the target. The whole case study is made available to the community under an open-source license

Towards the design of a distributed aircraft flight control system connected to simulation components

The design and the implementation of Flight Control Systems (FCS) still remains a key element of modern avionic systems. During the development process and before flight tests, aeronautical standards require performing piloted simulations. Based on our background in distributed real-time aircraft simulation, we developed a distributed flight control system connected to a simulation environment. This complex distributed architecture is composed of several avionic entities (e.g., primary flight control systems, autopilot) interconnected to simulated components (e.g., aircraft flight dynamics, primary and secondary control surfaces, sensors). Based on a detailed bibliography, we present in this paper the building bricks of this special architecture and the design characteristics of its implementation. In particular, we are introducing architectural fault tolerance aspects and present results to assess the global behaviour of the system