762 Works

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

Pierre Vuillemin, Fabrice Demourant & Charles Poussot-Vassal
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. Secondly, the stability of the aforementioned model, represented as a Linear Fractional Representation (LFR) and subject to actuator saturation and dynamical uncertainties, is addressed through the use of an irrational multiplier-based Integral Quadratic Constraint (IQC) approach. The...

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

Atul Kamath, Prathyush P Menon, Martine Ganet-Schoeller, Guillaume Maurice & Samir Bennani
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...

Structured Control for Future European Launchers

Martine Ganet-Schoeller, Jean Desmariaux & Clement Combier
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. This paper focuses on co-funded AG/CNES research activities on the development of an advanced modular control strategy using recent advances...

Anti-Windup Algorithms for Pilot-Induced-Oscillation Alleviation

Isabelle Queinnec, Sophie Tarbouriech, Jean-Marc Biannic & Christophe Prieur
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. A complete methodology including theoretical conditions and associated toolbox is then proposed and compared to solutions based on anti-PIO...

Robustness Margins for Linear Parameter Varying Systems

Ann-Kathrin Schug, Peter Seiler & Harald Pfifer
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. Specifically, a norm bounded linear time invariant...

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

Fabrice Demourant
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). Usually, the Kalman-...

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

Mohammadreza Chamanbaz, Fabrizio Dabbene, Dimitri Peaucelle & Christelle Pittet
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 randomization-based approaches, which guarantee performance for all values of the uncertainties except for a subset with arbitrary small probability measure. The paper is devoted to the description of these two approaches for analysis and control...

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

Florian Seve, Spilios Theodoulis, Philippe Wernert, Michel Zasadzinski & Mohamed Boutayeb
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. The itch/yaw-channel dynamics linearized system is useful for highlighting important properties specific to these dynamics, in particular in relation with the...

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

Jean-Marc Biannic, Clement Roos & Jeremy Lesprier
Anew 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. Our approach is successfully tested on a realistic...

The H Control Problem is Solved

Pierre Apkarian & Dominikus Noll
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...

Design and Validation of Aerospace Control Systems An overview on methods tools

Jean-Marc Biannic & Clement Roos
Since their early development in the 1970s with the introduction of fly-by-wire technology, control systems have considerably evolved. Thanks to powerful on-board computers whose capacities have undergone an exponential growth over the past thirty years, together with the development of enhanced sensors and actuators, the complexity of aerospace control systems is almost no longer bounded today. This is true at least from a technological viewpoint. Control engineers should, however, keep in mind that there are...

Design and Validation of Aerospace Control Systems: New methods and tools with illustrations

Biannic Et Al.
Since their early development in the 1970s with the introduction of fly-by-wire technology, control systems have considerably evolved. Thanks to powerful on-board computers whose capacities have undergone an exponential growth over the past thirty years, together with the development of enhanced sensors and actuators, the complexity of aerospace control systems is almost no longer bounded today. This is true at least from a technological viewpoint. Control engineers should, however, keep in mind that there are...

Modelling Powder Bed Additive Manufacturing Defects

H.W. MINDT, O. DESMAISON & M. MEGAHED
The qualification of powder bed fusion processes is based on lengthy and expensive experimental trial and error. If models can be applied to predict process details and determine the probability of manufacturing defects, the qualification process could be accelerated and cost can be reduced significantly. This paper describes numerical results resolving powder bed fusion processes and defects that could potentially happen during manufacturing. A multi-physics and multiscale modelling platform is first introduced in section 1...

Turning model-based FDIR theory into practice for aerospace and flight-critical systems

Ali ZOLGHADRI
Modern control theory offers a huge number of various designs, techniques and methods related to advanced FDIR and fault tolerant Control Guidance. On the other hand, aerospace and flight-critical applications provide numerous grounds where such techniques are needed to support conventional industrial practices. However, today, we have to recognize that the assessment is not overly enthusiastic in terms of real-world applications. The main focus of this talk is on a number of practical design considerations...

High speed flow control with nanosecond discharge

Irina ZNAMENSKAYA, Irina MURSENKOVA, Igor IVANOV & Dmitry NAUMOV
The paper deals with the problem of pulse discharge localization in a supersonic and transonic non-homogeneous flow and its use for flow control. Discharge plasma was shown to be localized in zones of low density - in front of shock wave and in vortex separation zones - at rear side of the wedge and at shock interaction with boundary layer. The amplitude of electric current localized in vortex may be twice higher than in homogeneous...

Large-eddy simulation of multi-element LOx/H2 combustion at transcritical conditions

Julian ZIPS, Hagen MULLER & Michael PFITZNER
This study presents a numerical method for the efficient large-eddy simulation (LES) of non-premixed combustion at supercritical pressures. A flamelet-based approach is extended to incorporate real-gas thermodynamics at moderate computational cost. Real-gas effects are taken into account using the cubic Peng-Robinson equation of state. The resulting model with its assumptions is assessed and the respective errors are quantified. Its computational cost are comparable to ideal gas simulations. The method is consequently applied to the multi-element...

Skeletal Kinetic Mechanism of Methane Oxidation for High Pressures and Temperatures

Victor ZHUKOV & Alan KONG
A skeletal methane kinetic mechanism is developed for conditions which are the combustion of undiluted methane-oxygen mixtures at high pressures. The new skeletal mechanism is based on the detailed mechanism of alkanes oxidation by Zhukov. The skeletal model has been created by cutting unimportant species and reactions from the detailed mechanism. The reduction technique is based on the reaction path and sensitivity analyses. They allow to determine the reactions and species that play important role...

Evaluation of the Grid Convergence for a Rocket Combustion Chamber with a Porous Injector

Victor ZHUKOV & Klaus HEINRICH
The purpose of the present study is to quantify the grid convergence in simulations of rocket combustion chambers performed with the averaged Navier-Stokes equations. The present work is a continuation of the previous studies on simulations of rocket combustion chambers with porous injector head API-68. Turbulence is modelled by the SST turbulence model; turbulent combustion is modelled using the extended eddy-dissipation model developed earlier. The grid convergence study is carried out for two injector configurations...

Numerical Research of A Propeller Plane Based on Actuator Disc Model

Yifei ZHANG, Haixin CHEN & Yufei ZHANG
The flow of a propeller is complex and has obvious influence on the aircraft. Though computer is becoming powerful, numerical simulation on propeller slipstream is still difficult. When doing optimization, actuator disc model could be used to save computation costs and computation time. This paper studies a propeller, then use the actuator disc model to study the slipstream of a propeller plane.

A Novel Design Technique of Hypersonic Gliding Vehicle

Tian-Tian ZHANG, Wei HUANG, Shi-Bin LI & Zhen-Guo WANG
Hypersonic gliding vehicle is attracting an increasing attention because of its high lift-to-drag ratio and high cruising speed. Based on the design theory of cone-derived waverider, this paper proposes a novel design approach of hypersonic gliding vehicle, which is accommodated in a wide speed range. The parametric method employed in ascender line makes it possible to control the overall configuration. Numerical analysis demonstrates that this kind of aircrafts own good wave-ride properties in the designed...

Modeling and validation of propulsion system for small battery powered electric aircraft

Maoquan ZHANG & Haixin CHEN
Many rules and disciplines need to be taken into account for the preliminary design of the small battery powered electric aircraft, such as mass and power characteristics of the motor, aerodynamic characteristics of the propeller and parameters of the aircraft itself. In this paper, the model of propulsion system for battery powered aircraft is developed. Comparison with the experimental data has proved the model to be reliable. Then the propulsion model is used for range...

A Valid Joint Detection and Tracking Method for Weak Space Debris

Lefeng ZHANG & Xiaoyong DU
There are lots of space debris and microsatellites flying on the low earth orbit, which could bring forever damage to the spacecraft and more space debris give birth if collision happening. As for ubiquitous space surveillance radar, both of them are characteristic of small physical size, weak radar cross section, fluctuating cluster, so they are come down to the multiple weak target detection and tracking problem. The paper puts forward an joint detection and tracking...

Helicopter noise simulation and experimental technique for its validation

Mikhail ZAYTSEV, Victor KOPIEV, Vladimir VORONTSOV & Sergey KARABASOV
The paper presents a method of prediction the helicopter main rotor noise and the results of comparison of predictions and experimental data for hovering rotor. The noise prediction method is based on an integral representation theorem which follows from the Lighthill acoustic analogy. The nonlinear sources in the penetrable Ffowcs Williams - Hawkings (FW-H) formulation are supplied by the acoustically targeted near-field CFD computation. The near-field flow (including transonic blade tip Mach numbers) is found...

Microwave resonator method for measuring transient mass gasification rate of condensed systems

Vladimir ZARKO, Victor PEROV, Alexander KISKIN & Denis NALIVAICHENKO
The paper deals with developing a new contactless method for measuring transient mass gasification rate of condensed systems based on recording attenuation signal induced by the mass of tested material in a microwave sensor of resonator type. According estimations the temporal resolution of the sensor is better than 10^-3 s and apparent space resolution is about few microns. The sensor design provides measurements of the gasification rate in conditions of intense gas blowing through a...

Dynamic layer formation in the reattachment zone for a supersonic laminar separation flow

Valeriy ZAPRYAGAEV, Ivan KAVUN & Lukeriya TRUBITZYNA
Results of an experimental study of the flow structure in the region of reattachment of a supersonic laminar separated flow are reported. The separated flow is generated by a model shaped as a compression corner consisting of a horizontal flat plate followed by a ramp. The model with is equal to the plate length from the leading edge to the plate/ramp junction line. The ramp angle is varied in the interval phi = 20deg -...

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