The balloon-borne telescope system for optical observation of planets

Nakano, Toshihiko; Sakamoto, Yuji; Yoshida, Kazuya; Kuwahara, Toshinori; Shoji, Yasuhiro; Taguchi, Makoto; Yamamoto, Mutumi; Takahashi, Yukihiro

doi:10.1109/sii.2010.5708331

Cited by 5 publications

(2 citation statements)

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“…However, in the literature, dynamical models of the balloon-borne system are rarely integrated in the control design. Instead, the control gains are generally tuned empirically based on ground testings [3,30,[35][36][37][38][39], with simple control structures such as Proportional-Integral-Derivative (PID) gains [18,32,33,[40][41][42] possibly with some dynamic filters [2,43,44]. To the authors knowledge, there exists no general model-based methodology for controller synthesis in the literature, and, more critically, experimental ground-based setups are not representative of the dynamics of the fully deployed system in flight (which cannot be obtained in laboratory due to the dimensions of the system), whereas flight experience proves that the lineof-sight control is essentially limited by the rejection of the natural pendulum-like modes of the flight chain [2], excited by wind disturbance.…”

Section: Introductionmentioning

confidence: 99%

Modeling of stratospheric balloons and robust line-of-sight pointing control

Kassarian¹,

Sanfedino

Alazard

et al. 2023

CEAS Space J

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This paper investigates state-of-the-art modeling and control techniques for the robust line-of-sight pointing control of an optical payload on-board a stratospheric balloon, to meet stringent pointing requirements in the context of astronomy missions. Previous experience shows that the pointing performance of such systems is essentially limited by the rejection of the natural pendulum-like oscillations of the flight chain. This observation justifies the need for a model that accurately predicts such flight conditions that cannot be replicated in laboratory, and for a systematic methodology addressing the line-of-sight controller design to reject these flexible dynamics excited by wind disturbances. Moreover, it is sought to ensure robust stability and performance to the parametric uncertainties 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 first dynamical model of the complete system is proposed, based on Lagrangian mechanics; the comparison with flight data show that the frequency content of the platform's motion is accurately predicted. Then, a multibody approach is applied to derive a second model taking into account the parametric uncertainties with the Linear Fractional Transformation representation. Finally, the control of the line-of-sight is tackled as a robust, structured H 2 ∕H ∞ problem that improves the performance with regard to traditional PID controller. A -sensitivity analysis is also proposed to identify the most sensitive parameters and verify the performance.

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Section: Introductionmentioning

confidence: 99%

Modeling of stratospheric balloons and robust line-of-sight pointing control

Kassarian¹,

Sanfedino

Alazard

et al. 2023

CEAS Space J

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“…Once an accurate dynamical model is obtained, it is possible to address the pointing control of the optical instrument on-board the gondola, generally a telescope [3,5,[19][20][21] or siderostat [7,22,23]. Most often, simple control structures such as Proportional-Integral-Derivative (PID) gains are chosen [13,21,22,[24][25][26] and the control gains are tuned empirically based on ground testings [3,19,[27][28][29][30][31]. There exists no general model-based methodology for controller synthesis, and, more critically, experimental ground-based set-ups are not representative of the dynamics of the fully deployed system in flight, whereas flight experience proves that the line-of-sight control is essentially limited by the rejection of the natural modes of the flight chain excited by wind disturbances [2].…”

Section: Introductionmentioning

confidence: 99%

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

Kassarian¹,

Sanfedino²,

Alazard³

et al. 2021

Preprint

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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 astronomy 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 observation 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 uncertainties 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 dynamical 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.

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