Robust active noise control in a car cabin: evaluation of achievable performances with a feedback control scheme

International audienceThe application dealt with in this paper is the active attenuation of broadband noise (produced by the tire/road contact) in a car cabin, using only a feedback control scheme (1-DOF (one degree of freedom)). The objective of the proposed control methodology is to evaluate achievable performances according to the frequency bandwidth in which attenuation is desired. This is investigated numerically, by seeking a multi-input multi-output (MIMO) active noise control solution that reaches the best attenuation level, under explicit robustness constraints. The paper aims to i) formalize the underlyingoptimization problem including performance and robustness indicators as well as industrial constraints, ii) perform an effective MIMO identification, and iii) provide an a priori control structure and then proceed to direct optimization of some meaningful parameters using a well-suited nonsmooth optimization solver. Finally, the simulation and experimental results obtained following the proposed methodology are shown and discussed

Système actif d’atténuation du bruit dans un habitacle

Présentation au Groupe de Travail Automatique et Automobile (GTAA

Hinf Multi-objective and Multi-model MIMO control design for Broadband noise attenuation in an enclosure

International audienceThe Active Noise Control (ANC) problem considered throughout this paper consists of attenuating the noise in one point of an enclosure, over a broadband frequency range, using a feedback control scheme. This paper proposes a general framework and a benchmark which allow a fair and quantitative comparison of achievable performances according to the number of actuator(s) and sensor(s) used for the control. At first, the experimental set up is described, then the identification of a low order MIMO acoustic model is presented. A multi-objective and multi-model control approach, is then proposed. The multi-objective synthesis allows to cope with design trade-off without conservatism, while the multimodel design enhances the robustness of the control. Finally some simulation and experimentation results are given which illustrate how the proposed methodology makes possible to compare achievable performances depending on the number of sensors and actuators used

Robust active noise control in a car cabin: evaluation of achievable performances with a feedback control scheme

International audienceThe application dealt with in this paper is the active attenuation of broadband noise (produced by the tire/road contact) in a car cabin, using only a feedback control scheme (1-DOF (one degree of freedom)). The objective of the proposed control methodology is to evaluate achievable performances according to the frequency bandwidth in which attenuation is desired. This is investigated numerically, by seeking a multi-input multi-output (MIMO) active noise control solution that reaches the best attenuation level, under explicit robustness constraints. The paper aims to i) formalize the underlyingoptimization problem including performance and robustness indicators as well as industrial constraints, ii) perform an effective MIMO identification, and iii) provide an a priori control structure and then proceed to direct optimization of some meaningful parameters using a well-suited nonsmooth optimization solver. Finally, the simulation and experimental results obtained following the proposed methodology are shown and discussed

Investigating achievable performances for robust broadband active noise control in an enclosure

International audienceThis brief presents a complete methodology for evaluating achievable performances in applications of activenoise control aiming robust broadband attenuation. A comparison between different control architectures, the influence ofthe number of available actuators and sensors on attainable performances, and the impact of considering the perturbation asmeasured or not are all discussed. First, a generic experimental device, specifically designed to study active noise attenuation,is identified as a multi-input multi-output system. Then, robust multiobjective control is considered, using a Hinfty criterion,and recasts as Hinfty optimization under constraints. Appropriate indicators are proposed for comparison purposes. Finally,quantified results are presented and validated experimentally. Intrinsic limitations introduced by non minimum phase zeros areillustrated and discussed

Broadband Active Noise Control Design through Nonsmooth Hinf Synthesis

Présentation aux JDOC - Ecole Doctorale S.T.I.M

Broadband Active Noise Control Design through Nonsmooth Hinfinity Synthesis

International audienceThis paper deals with active control of a broadband noise in a car cabine. It aims to study the achievable performance of such control in the SISO feedback case. The main limitations involved, known as waterbed effect, are critical for such problem due to the presence of non-minimum phase zeros. To evaluate the intrinsic limitations due to these non-minimum phase zeros, a multi-objective control synthesis is proposed, allowing to cope with classical specifications (performance and robustness), without pessimism. The control synthesis is based on a H1 criterion to be minimized under some decoupled constraints. It consists in a non-convex and non-smooth optimization problem, for which a local optimum may be efficiently obtained. A particular control structure is considered in order to reduce the number of decision variables, to set relevant bounds on these parameters and to choose appropriateinitial conditions. Then the optimization problem is solved using recent results on non-smooth optimization. The whole design process is detailed, including the identification of the synthesis model. The control strategy is then applied to an instrumented cavity, which shares most of the acoustic characteristics of a car cabin. Finally, the analysis of the results gives clear conclusions on SISO feedback possibilities, and paves the way for an efficient multivariable design case

A Robust feedback control design for broadband noise attenuation in a car cabin

International audienc

Differences in cytochrome P450 enzyme activities between fish and crustacea: Relationship with the bioaccumulation patterns of polychlorobiphenyls (PCBs)

7 pages, 3 figures, 4 tables.Variations in cytochrome P450 enzyme (CYPs) distribution and function between animal groups could result in differential metabolism and elimination kinetics for certain contaminants. Although a number of studies have suggested that differences in polychlorobiphenyl (PCB) accumulation profiles between crustacea and fish might result from differential CYP patterns, the relationship between PCB bioaccumulation and CYP capacities has not been demonstrated in these organisms. In the present study we investigated the hepatic microsomal catalytic activities in three deep-sea fish species, Alepocephalus rostratus (Alepocephalidae), Coelorinchus mediterraneus (Macrouridae), and Lepidion lepidion (Moridae), and the decapod crustacean Aristeus antennatus (Decapoda), using six fluorescent CYP-mediated substrates, namely ER (7-ethoxyresorufin), PR (7-pentoxyresorufin), BR (7-benzyloxyresorufin), CEC (3-cyano-7-ethoxycoumarin), DBF (dibenzylfluorescein) and BFC (7-benzyloxy-4-trifluoromethylcoumarin). Furthermore, we related the metabolic activities to the accumulation patterns of 41 PCB congeners in the muscle of these organisms. The results indicated a marked difference in the presence and activities of CYP isoforms between fish and the crustacean A. antennatus. Liver microsomes of the three selected fish species were capable of metabolizing all six CYP-mediated substrates and enzymes were identified as primarily belonging to CYP1A and CYP3A subfamilies. In contrast, hepatopancreas microsomes from A. antennatus only showed activity for PR and DBF substrates, generally related to mammalian CYP2-like enzymes. Furthermore, a direct relationship between metabolic activities and PCB accumulation profiles could be established. Results revealed that A. antennatus accumulated significantly higher proportions of PCBs 28, 52, 118, 138, 158 and 169 than fish, which is in accordance with the previously observed lack of CYP1A-like biotransformation capacities. Moreover, A. antennatus exhibited lower levels of PCBs 87, 149, 153, 170, 180, 183, 194 and 206 indicating that this crustacean is able to metabolize congeners considered mammalian CYP2B inducers. Hence, the present findings highlight the role of CYP-mediated metabolism in the congener-specific accumulation of PCBs in aquatic organisms and stress the need to further investigate quantitative and qualitative differences in xenobiotic metabolism among animal groups.The present work was funded by the Spanish Science and Technology Ministry projects PROMETEO (CTM2007-66316-C02-02/MAR) and BIOFUN (CTM2007-28739-E/MAR). Samuel Koenig holds a PhD grant (AFR 08/067) from the Fonds National de la Recherche (FNR), Luxembourg. The authors also wish to thank David Huertas (IDAEA-CSIC), the “Deep-Sea Group” (ICM-CSIC) and the R/V Garcia del Cid (CSIC) crew for helping with field sampling.Peer reviewe