Cryogenic Liquid Rocket Engine Test Bench Fault-Tolerant Control System: Cooling System Application

International audienceA nonlinear fault-tolerant control strategy relying on quantitative physics-based models for a cryogenic combustion bench operation is proposed in this paper. The aim is to improve the reliability of a cryogenic bench operation in the transients and to allow to converge to a wider range of operating points. The fault detection is performed with residual-based methods. The residual is generated by an unknown input observer with an unscented transformed which also allows to reconstruct the unknown input. Then the goal is to provide a fault-tolerant system reconfiguration mechanism with a control law which compensates for the estimated actuator additive faults to maintain the overall system stability. For that purpose we use a model predictive control method on an equivalent system with the reconstructed unknown input. An error feedback and a fault compensation control law is designed in order to minimize an infinite horizon cost function within the framework of linear matrix inequalities. The model and the estimation part were validated on real data from Mascotte test bench (ONERA/CNES), and the reconfiguration control law was validated in realistic simulations

Hardware-in-the-loop performance analysis of a railway traction system under sensor faults

Fault mode and effects analysis (FMEA) has been used during decades for analysing the effects of faults in different applications. Initially, FMEA based on risk priority numbers provided information about the effects in the system, but during the last years different approaches have been developed to obtain a more robust risk evaluation. The proposed enhanced FMEA can provide the quantitative effects of sensor faults in a railway traction drive, in variables such as torque, current and voltages. In addition to the previous work, quantitative effects on overall performance indicators, such as energy efficiency and comfort, are obtained too. Hardware-in-the-loop (HIL)-based fault injection approach has been used to generate fault scenarios. The test platform is composed of a real-time simulator and a commercial traction control unit for a railway application

Robust minimax design from costly simulations.

Design of complex physical systems most often relies on numerical simulations that may be extremely costly. In this paper, design is formalized as the optimization of a performance index with respect to control variables. Uncertainty is modeled via a vector of environmental variables that can take any value in a known compact set and may have an adverse effect on performance. In this context, the determination of a robust design requires the continuous minimax optimization of black-box functions. An algorithm combining Kriging-based optimization with relaxation is presented, which makes it possible to find approximate solutions to such problems on a limited computational budget. The design of a vibration absorber is presented as an illustrative example

Réalisation d'un réflecto-interféromètre dans la bande des 70 GHz destiné à la mesure de la permittivité complexe de liquides à fortes pertes. Application a l'étude de l'eau, de l'éthylène-glycol et du formamide en fonction de la température

Description and realisation of an interferometric apparatus in the 4 mm band for the determination of the complex permittivity from reflection coefficients for high-loss liquids as a function of temperature. Application to the determination of ε' and ε" of water, ethylene-glycol and formamide at 69.2 GHz.Description et mise en oeuvre d'un banc interférométrique dans la bande des 4 mm permettant de déterminer, à partir de la mesure du coefficient de réflexion, la permittivité complexe de liquides à fortes pertes en fonction de la température. Application à la mesure de ε' et ε" de l'eau, de l'éthylène glycol et du formamide en fonction de la température à 69,2 GHz