Synthèse et validation d'une lois de contrôle de charge a deux degrés de liberté

International audienceThe design and assessment of a two degree of freedom gust load allevi-ation control system for a business jet aircraft is presented in this paper. The two degrees of freedom are a disturbance estimator to compute the incoming gusts as well as a feedback control law to mitigate the estimated disturbance to reduce the aircraft loads. To facilitate the estimator design, high order, infinite models of the structural and aerodynamic aircraft dynamics are approximated by low order models using advanced model reduction techniques. For the robust disturbance estimator design an innovative approach relying on nullspace based techniques together with non-linear optimizations is proposed. Time delays, originating from the aerodynamics modeling, the discrete control loop, and the sensor and actuator dynamics, play a key role in the stability and performance assessment of a gust load alleviation controller. Thus, a novel analytical analysis method is presented to explicitly evaluate the influence of these time delays on the closed loop. Finally, the developed tool-chain is applied to a fly-by-wire business jet aircraft. The resulting two degree of freedom gust load alleviation system is verified in a simulation campaign using a closed loop, non-linear simulator of the aircraft

A Frequency-Limited H2 Model Approximation Method with Application to a Medium-Scale Flexible Aircraft

In this paper, the problem of approximating a medium-scale MIMO LTI dynamical system over a bounded frequency range is addressed. A new method based on the SVD-Tangential model order reduction framework is proposed. Grounded on the frequency-limited gramians defined in [5], the contribution of this paper is to propose a frequency-limited iterative SVD-Tangential interpolation algorithm (FL-ISTIA) to achieve frequency-limited model approximation without involving weighting filters. The efficiency of the approach is addressed both on standard benchmark and on an industrial flexible aircraft model

The design of a chassis system based on multi-objective qLPV control

In this paper we compare LTI and qLPV H_infty H_2 controllers. The Pareto limit is used to show the compromise that has to be done when a mixed synthesis is achieved. Simulations on a nonlinear half vehicle model, with multiple objectives, are performed to show the efficiency of the method

Optimal Modal Truncation

This paper revisits the modal truncation from an optimisation point of view. In particular, the concept of dominant poles is formulated with respect to different systems norms as the solution of the associated optimal modal truncation problem. The latter is reformulated as an equivalent convex integer or mixed-integer program. Numerical examples highlight the concept and optimisation approach

Identification of parametric models in the frequency-domain through the subspace framework under LMI constraints

International audienceIn this paper, an algorithm to identify parametric systems with an affine (or polynomial) parameter dependence through the subspace framework is proposed. It stands as an extension of the standard subspace-based algorithm which is well established in the Linear Time Invariant (LTI) case. The formulation is close to the LTI identification scheme and simply involves frequency-domain data obtained at different operating points (the parameters are frozen during each experiment). The proposed algorithm allows to identify directly a parameter-dependent model instead of interpolating multiple local models as in traditional local approaches. Another contribution is that it is possible to impose the poles location through Linear Matrix Inequalities (LMI) constraints, extending what has been done in the LTI case. This technique is applied to a numerical example and to real industrial frequency-domain data originating from an open-channel flow simulation for hydroelectricity production

Data-driven approximation of a high fidelity gust-oriented flexible aircraft dynamical model

International audienceComputing responses to discrete gusts are sizing steps when designing and optimizing a new aircraft structure and geometry. Indeed, this is part of the imposed clearance certifications requested by the flight authorities. During the aircraft preliminary design phase, this clearance is done by intensive simulations, however, due to the involved models complexity, these latter are time consuming and imply an important computational burden. Especially as these simulations are involved at different steps of the aircraft optimisation process e.g. by aeroelastic, flight and control engineers. In this paper we propose a systematic way to fasten the gust simulation step and simplify the analysis by mean of data-driven model approximation in the Loewner framework. The proposed approach gathers recent advances in aeroelastic modelling and model approximation techniques. As illustrated on a high fidelity long range aircraft model, the drastic reduction of the simulation time does not induce any significant loss of accuracy

Structured linear fractional parametric controller H ∞ design and its applications

International audienceThis paper proposes a simple but yet effective approach to structured parametric controller design in a linear fractional form. The main contribution consists in using structured H1 oriented optimization tools in an original manner to either construct a parametric controller or a family of controllers with varying performances. Practical and numerical issues are also discussed to provide practitioners a simple way to deploy the proposed process. The overall approach is illustrated through two numerical examples: first, a controller parametrized by the model characteristics applied on a clamped beam model and second, a parametric performance controller applied on a very complex fluid flow control setup