Stability Analysis of a Set of Uncertain Large-Scale Dynamical Models with Saturations


P. Vuillemin, F. Demourant, C. Poussot-Vassal (ONERA)

From a sparse set of large-scale Linear Time Invariant (LTI) dynamical models, a methodology to generate a low-order parameter-dependent and uncertain model, with guaranteed bounds on the approximation error is firstly obtained using advanced approximation and interpolation techniques.

Surrogate Assisted Computation of the Parametric Safety Margin for a Flexible Launcher


A. Kamath (GE Global Research Centre)
P. P. Menon (College of Engineering, Mathematics and Physical Sciences, University of Exeter)
M. Ganet-Schoeller, G. Maurice (Ariane Group)
S. Bennani (Guidance, Navigation and Control Section, ESA/ESTEC)

In order to assess the robustness of dynamical systems, an approach is to demarcate the uncertain parameter space as safe set and unsafe set. Unsafe set represents the region within which the system lacks the required level of performance, or even loses its stability. However, determining the minimum distance metric for the unsafe set from the nominal operating point, the so-called parametric safety margin, for a higher dimensional dynamical system is not trivial and is often computationally demanding.

Structured Control for Future European Launchers


M. Ganet-Schoeller (Ariane Group)
J. Desmariaux (CNES)
C. Combier (ISAE)

Control of a flexible launcher during the atmospheric flight phase is a highly challenging control problem involving multiple and concurrent design requirements: stability (stabilization of unstable rigid dynamics, sloshing modes and flexible structural modes), performance (guidance tracking, structural load minimization) and robustness (physical parameter uncertainties and accommodation to multiple vehicle configurations) on a non-stationary system.

Anti-Windup Algorithms for Pilot-Induced-Oscillation Alleviation


I. Queinnec, S. Tarbouriech (LAAS-CNRS, Université de Toulouse, CNRS)
J.-M. Biannic (ONERA)
C. Prieur (Univ. Grenoble Alpes, CNRS, Gipsa-lab)

The paper deals with the development of anti-windup schemes and related numerical oriented tools. The objective is then to design anti-windup compensators to guarantee stability and performance for some particular classes of nonlinear actuators presenting both magnitude and rate saturations. The lateral flying case for a civil aircraft undergoing aggressive maneuvering by the pilot is addressed.

Robustness Margins for Linear Parameter Varying Systems


A-K. Schug (Hamburg University of Technology)
P. Seiler (University of Minnesota)
H. Pfifer (University of Nottingham)

An approach for extending classical robustness margins to linear parameter varying (LPV) systems is presented. LPV systems are often used to model aircraft dynamics that are highly dependent on the operating conditions such as altitude and airspeed. Classical gain and phase margins are evaluated in the frequency domain and therefore cannot be applied to LPV systems. The proposed approach is based on a time-domain interpretation for disk margins.

Stability Analysis by a New Algorithmic Approach Based on Integral Quadratic Constraints: Application to an Aircraft Benchmark


F. Demourant (ONERA)

To analyze a non-linear, uncertain and time-varying closed loop representing a fighter aircraft model interconnected with a control law, an Integral Quadratic Constraint (IQC) approach has been used. This approach is particularly interesting for two reasons. The first one is that it is possible with the same stability criterion to analyze a large class of stability problems. The second reason is that the stability criterion is based on frequency dependent inequalities (FDI).

Randomized and Robust Methods for Uncertain Systems using R-RoMulOC, with Applications to DEMETER Satellite Benchmark


M. Chamanbaz (Arak University of Technology, Arak, Iran)
F. Dabbene, R. Tempo (CNR-IEIIT Politecnico di Torino, Italy)
D. Peaucelle (LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, France)
C. Pittet (CNES, Toulouse, France)

R-RoMulOC is a freely distributed toolbox aimed at making easily available to the users various optimization-based methods for dealing with uncertain systems. It implements both deterministic LMI-based results, which provide guaranteed performance for all values of the uncertainties, and probabilistic randomizationbased approaches, which guarantee performance for all values of the uncertainties except for a subset with arbitrary small probability measure.

Gain-Scheduled H∞ Loop-Shaping Autopilot Design for Spin-Stabilized Canard-Guided Projectiles


F. Sève, S. Theodoulis, P. Wernert (French-German Research Institute
of Saint-Louis (ISL), Department of Guidance Navigation and Control, Saint-Louis (FR))

M. Zasadzinski, M. Boutayeb (Research Center for Automatic Control of Nancy (CRAN), University of Lorraine, UMR 7039, CNRS, Cosnes-et-Romain (FR))

This article is dedicated to the design of a complete guidance & control system for the roll/pitch/yaw-channels of a 155 mm dual-spin projectile equipped with nosemounted trajectory correction canards. The projectile airframe parameter-dependent nonlinear model including aerodynamic and actuator/sensor uncertainty descriptions is given and the subsequently computed linearized models necessary for autopilot design are presented.

Nonlinear Structured H∞ Controllers for Parameter-Dependent Uncertain Systems with Application to Aircraft Landing


J.-M. Biannic, C. Roos, J. Lesprier (ONERA)

A new design methodology inspired by dynamic inversion techniques is proposed in this paper. It combines partially linearizing inner-loops with structured and robust outer-loops, which are designed using a non-smooth multi-model H∞ optimization approach. The proposed methodology also includes a robustness analysis scheme providing worst-case configurations, which are then used to enrich the bank of design models and thus iteratively improve the robustness properties of the designed outerloops.

The H∞ Control Problem is Solved


P. Apkarian (ONERA)
D. Noll (Institut de Mathématiques de Toulouse, Université Paul Sabatier)

The H control problem was posed by G. Zames in 1981 [1], and various attempts to address it had been made over the years. Ultimately, in 2006, the authors presented their solution, which is based on a tailored non-smooth optimization technique [2]. In this treatise we present the rationale of H control, give a brief history, and recall the milestones reached before our 2006 solution. We clarify why our novel approach is welcomed in the high-tech and aerospace industry.