Linear Fractional Transformation Modeling of Multibody Dynamics Around Parameter-Dependent Equilibrium

This brief proposes a new linear fractional transformation (LFT) modeling approach for uncertain linear parameter-varying (LPV) multibody systems with parameter-dependent equilibrium. Traditional multibody approaches, which consist of building the nonlinear model of the whole structure and linearizing it around equilibrium after a numerical trimming, do not allow to isolate parametric variations with the LFT form. Although additional techniques, such as polynomial fitting or symbolic linearization, can provide an LFT model, they may be time-consuming or miss worst case configurations. The proposed approach relies on the trimming and linearization of the equations at the substructure level, before assembly of the multibody structure, which allows to only perform operations that preserve the LFT form throughout the linearization process. Since the physical origin of the parameters is retained, the linearized LFT-LPV model of the structure exactly covers all the plants, in a single parametric model, without introducing conservatism or fitting errors. An application to the LFT-LPV modeling of a robotic arm is proposed; in its nominal configuration, the model obtained with the proposed approach matches the model provided by the software Simscape Multibody, but it is enhanced with parametric variations with the LFT form; a robust LPV synthesis is performed using MATLAB robust control toolbox to illustrate the capacity of the proposed approach for control design

FIREBall-2: flight preparation of a proven balloon payload to image the intermediate redshift circumgalactic medium

FIREBall-2 is a stratospheric balloon-borne 1-m telescope coupled to a UV multi-object slit spectrograph designed to map the faint UV emission surrounding z~0.7 galaxies and quasars through their Lyman-alpha line emission. This spectro-imager had its first launch on September 22nd 2018 out of Ft. Sumner, NM, USA. Because the balloon was punctured, the flight was abruptly interrupted. Instead of the nominal 8 hours above 32 km altitude, the instrument could only perform science acquisition for 45 minutes at this altitude. In addition, the shape of the deflated balloon, combined with a full Moon, revealed a severe off-axis scattered light path, directly into the UV science detector and about 100 times larger than expected. In preparation for the next flight, and in addition to describing FIREBall-2's upgrade, this paper discusses the exposure time calculator (ETC) that has been designed to analyze the instrument's optimal performance (explore the instrument's limitations and subtle trade-offs)

Linear Fractional Transformation modeling of multibody dynamics around parameter-dependent equilibrium

This paper proposes a new Linear Fractional Transformation (LFT) modeling approach for uncertain Linear Parameter Varying (LPV) multibody systems with parameter-dependent equilibrium. Traditional multibody approaches, which consist in building the nonlinear model of the whole structure and linearizing it around equilibrium after a numerical trimming, do not allow to isolate parametric variations with the LFT form. Although additional techniques, such as polynomial fitting or symbolic linearization, can provide an LFT model, they may be time-consuming or miss worst-case configurations. The proposed approach relies on the trimming and linearization of the equations at the substructure level, before assembly of the multibody structure, which allows to only perform operations that preserve the LFT form throughout the linearization process. Since the physical origin of the parameters is retained, the linearized LFT-LPV model of the structure exactly covers all plants, in a single parametric model, without introducing conservatism or fitting errors. An application to the LFT-LPV modeling of a robotic arm is proposed; in its nominal configuration, the model obtained with the proposed approach matches the model provided by the software Simscape Multibody, but it is enhanced with parametric variations with the LFT form; a robust LPV synthesis is performed using Matlab robust control toolbox to illustrate the capacity of the proposed approach for control design

Robust integrated control/structure co-design for stratospheric balloons

Stratospheric balloons offer cost-effective platforms for optical payloads in the context of astronomy missions. During the 2018 flight of the Faint Intergalactic medium Redshifted Emission Balloon (FIREBall) experiment, the moon light was scattered from the surface of the balloon and re-directed into the telescope which resulted in degraded optical performance. To reduce this parasite effect, it is sought to increase the length of the fight train. However, this change in the mechanical design significantly modifies the dynamics of the system and the pointing performance must not be altered. In this purpose, a robust integrated control/structure co-design method is proposed. After deriving a Linear Fractional Transformation (LFT) model of the system, the co-design is tackled as a multi-objective, structured, robust H2/H∞ problem that is solved with a non-smooth optimization algorithm to maximize the train's length under constraints of pointing performance. By optimizing in a single iteration the controllers along with the structural parameter with regard to the worst-case configurations of the uncertain parameters, time-consuming procedures requiring not only to iterate between control and mechanical design, but also to analyze the robustness based on Monte-Carlo simulations, are avoided

Robust line-of-sight pointing control on-board a stratospheric balloon-borne platform

This paper addresses the lack of a general methodology for the controller synthesis of an optical instrument on-board a stratospheric balloon-borne platform, such as a telescope or siderostat, to meet pointing requirements that are becoming more and more stringent in the context of astron- omy missions. Most often in the literature, a simple control structure is chosen, and the control gains are tuned empirically based on ground testings. However, due to the large dimensions of the balloon and the flight chain, experimental set-ups only involve the pointing system and the platform, whereas flight experience shows that the pointing performance is essentially limited by the rejection of the natural pendulum-like oscillations of the fully deployed system. This obser- vation justifies the need for a model that predicts such flight conditions that cannot be replicated in laboratory, and for an adequate methodology addressing the line-of-sight controller design. In particular, it is necessary to ensure robust stability and performance to the parametric uncertain- ties inherent to balloon-borne systems, such as complex balloon’s properties or release of ballast throughout the flight, especially since experimental validation is limited. In this paper, a dynam- ical model of the complete system is proposed, based on a multibody approach and accounting for parametric uncertainties with Linear Fractional Transformations. The comparison with flight data shows that the frequency content of the platform’s motion is accurately predicted. Then, the robust control of the line-of-sight is tackled as a H∞ problem that allows to reach the performance objectives in terms of disturbance rejection, control bandwidth and actuators limitations

Intestinal Akkermansia muciniphila predicts clinical response to PD-1 blockade in patients with advanced non-small-cell lung cancer

43siAside from PD-L1 expression, biomarkers of response to immune checkpoint inhibitors (ICIs) in non-small-cell lung cancer (NSCLC) are needed. In a previous retrospective analysis, we documented that fecal Akkermansia muciniphila (Akk) was associated with clinical benefit of ICI in patients with NSCLC or kidney cancer. In the current study, we performed shotgun-metagenomics-based microbiome profiling in a large cohort of patients with advanced NSCLC (n = 338) treated with first- or second-line ICIs to prospectively validate the predictive value of fecal Akk. Baseline stool Akk was associated with increased objective response rates and overall survival in multivariate analyses, independent of PD-L1 expression, antibiotics, and performance status. Intestinal Akk was accompanied by a richer commensalism, including Eubacterium hallii and Bifidobacterium adolescentis, and a more inflamed tumor microenvironment in a subset of patients. However, antibiotic use (20% of cases) coincided with a relative dominance of Akk above 4.8% accompanied with the genus Clostridium, both associated with resistance to ICI. Our study shows significant differences in relative abundance of Akk that may represent potential biomarkers to refine patient stratification in future studies.reservedopenDerosa, Lisa; Routy, Bertrand; Thomas, Andrew Maltez; Iebba, Valerio; Zalcman, Gerard; Friard, Sylvie; Mazieres, Julien; Audigier-Valette, Clarisse; Moro-Sibilot, Denis; Goldwasser, François; Silva, Carolina Alves Costa; Terrisse, Safae; Bonvalet, Melodie; Scherpereel, Arnaud; Pegliasco, Hervé; Richard, Corentin; Ghiringhelli, François; Elkrief, Arielle; Desilets, Antoine; Blanc-Durand, Felix; Cumbo, Fabio; Blanco, Aitor; Boidot, Romain; Chevrier, Sandy; Daillère, Romain; Kroemer, Guido; Alla, Laurie; Pons, Nicolas; Le Chatelier, Emmanuelle; Galleron, Nathalie; Roume, Hugo; Dubuisson, Agathe; Bouchard, Nicole; Messaoudene, Meriem; Drubay, Damien; Deutsch, Eric; Barlesi, Fabrice; Planchard, David; Segata, Nicola; Martinez, Stéphanie; Zitvogel, Laurence; Soria, Jean-Charles; Besse, BenjaminDerosa, Lisa; Routy, Bertrand; Thomas, Andrew Maltez; Iebba, Valerio; Zalcman, Gerard; Friard, Sylvie; Mazieres, Julien; Audigier-Valette, Clarisse; Moro-Sibilot, Denis; Goldwasser, François; Silva, Carolina Alves Costa; Terrisse, Safae; Bonvalet, Melodie; Scherpereel, Arnaud; Pegliasco, Hervé; Richard, Corentin; Ghiringhelli, François; Elkrief, Arielle; Desilets, Antoine; Blanc-Durand, Felix; Cumbo, Fabio; Blanco, Aitor; Boidot, Romain; Chevrier, Sandy; Daillère, Romain; Kroemer, Guido; Alla, Laurie; Pons, Nicolas; Le Chatelier, Emmanuelle; Galleron, Nathalie; Roume, Hugo; Dubuisson, Agathe; Bouchard, Nicole; Messaoudene, Meriem; Drubay, Damien; Deutsch, Eric; Barlesi, Fabrice; Planchard, David; Segata, Nicola; Martinez, Stéphanie; Zitvogel, Laurence; Soria, Jean-Charles; Besse, Benjami

FIREBall-2: flight preparation of a proven balloon payload to image the intermediate redshift circumgalactic medium

ESA Rocket and Balloon Symposium. Biarritz, May 2022.FIREBall-2 is a stratospheric balloon-borne 1-m telescope coupled to a UV multi-object slit spectrograph designed to map the faint UV emission surrounding z~0.7 galaxies and quasars through their Lyman-alpha line emission. This spectro-imager had its first launch on September 22nd 2018 out of Ft. Sumner, NM, USA. Because the balloon was punctured, the flight was abruptly interrupted. Instead of the nominal 8 hours above 32 km altitude, the instrument could only perform science acquisition for 45 minutes at this altitude. In addition, the shape of the deflated balloon, combined with a full Moon, revealed a severe off-axis scattered light path, directly into the UV science detector and about 100 times larger than expected. In preparation for the next flight, and in addition to describing FIREBall-2's upgrade, this paper discusses the exposure time calculator (ETC) that has been designed to analyze the instrument's optimal performance (explore the instrument's limitations and subtle trade-offs)

FIREBall-2: flight preparation of a proven balloon payload to image the intermediate redshift circumgalactic medium

ESA Rocket and Balloon Symposium. Biarritz, May 2022.FIREBall-2 is a stratospheric balloon-borne 1-m telescope coupled to a UV multi-object slit spectrograph designed to map the faint UV emission surrounding z~0.7 galaxies and quasars through their Lyman-alpha line emission. This spectro-imager had its first launch on September 22nd 2018 out of Ft. Sumner, NM, USA. Because the balloon was punctured, the flight was abruptly interrupted. Instead of the nominal 8 hours above 32 km altitude, the instrument could only perform science acquisition for 45 minutes at this altitude. In addition, the shape of the deflated balloon, combined with a full Moon, revealed a severe off-axis scattered light path, directly into the UV science detector and about 100 times larger than expected. In preparation for the next flight, and in addition to describing FIREBall-2's upgrade, this paper discusses the exposure time calculator (ETC) that has been designed to analyze the instrument's optimal performance (explore the instrument's limitations and subtle trade-offs)

Balloon-borne FIREBall-2 ultraviolet spectrograph stray light control based on nonsequential reverse modeling of on-sky data

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