- 著者
- Paul ACQUATELLA B.
- 出版者
- THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES
- 雑誌
- TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)
- 巻号頁・発行日
- vol.61, no.2, pp.79-86, 2018 (Released:2018-03-04)
- 参考文献数
- 34
- 被引用文献数
- 4
The satellite platform BIROS is the second technology demonstrator of DLR’s ‘FireBIRD’ space mission aiming to provide infrared remote sensing for early fire detection. Among several mission goals and scientific experiments, to demonstrate a high-agility attitude control system, the platform is actuated with an extra array of three orthogonal ‘High-Torque-Wheels.’ However, to enable agile reorientation, a challenge arises from the fact that time-optimal slew maneuvers are, in general, not of the Euler-axis rotation type; especially whenever the actuators are constrained independently. Moreover, BIROS’ on-board computer can only accommodate rotational acceleration commands twice per second. The objective is therefore to find a methodology to design fast slew maneuvers while considering a highly dynamic plant commanded by piecewise-constant sampled-time control inputs. This is achieved by considering a comprehensive analytical nonlinear model for spacecraft equipped with reaction wheels and transcribing a time-optimal control problem formulation into a multi-criteria optimization problem. Solutions are found with a direct approach using the trajectory optimization package ‘trajOpt’ of DLR-SR’s optimization tool, Multi-Objective Parameter Synthesis (MOPS). Results based on numerical simulations are presented to illustrate this method.
- 著者
- Tomoya FUJIMOTO Hirotaka OTSU Ikkoh FUNAKI Yoshiki YAMAGIWA
- 出版者
- THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES
- 雑誌
- TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)
- 巻号頁・発行日
- vol.53, no.180, pp.84-90, 2010 (Released:2010-08-06)
- 参考文献数
- 14
- 被引用文献数
- 2
To propel a spacecraft away from the Sun, a magneto plasma sail (MPS) spacecraft produces an artificial magnetic cavity to block the hypersonic solar wind. To make a large magnetic cavity sufficient to obtain significant thrust, the MPS spacecraft increases the magnetic cavity size using an onboard coil with assistance from a plasma jet. This process is called magnetic field inflation. In this study, we performed ideal and resistive magnetohydrodynamic (MHD) analyses to investigate the magnetic diffusion effect on the magnetic field inflation process. Our results indicate that a dipole-like magnetic field is drastically deformed by a plasma jet; when the magnetic Reynolds number Rm was 10 or more, the magnetic field lines were nearly identical to the streamlines of the plasma jet. Hence, no magnetic diffusion effect appeared for Rm>10. Meanwhile, when Rm is an order of unity, the magnetic diffusion effect was remarkable in the current sheet formed around equatorial region. For example, when the divergence angle of a plasma jet in the polar direction was 30°, the magnetic field strength at 40 m from the spacecraft (calculated by resistive MHD model) was 19% smaller than the ideal MHD model (Rm=∞).
- 著者
- Yuichi TSUDA Daniel J. SCHEERES
- 出版者
- THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES
- 雑誌
- TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)
- 巻号頁・発行日
- vol.53, no.180, pp.105-113, 2010 (Released:2010-08-06)
- 参考文献数
- 17
- 被引用文献数
- 1
This paper presents a numerical method for deriving a symplectic state transition matrix for high-fidelity Earth orbits subject to non-dissipative perturbation forces. By taking advantage of properties of Hamiltonian systems, this method provides an exact solution space mapping of linearized orbital dynamics, preserving the symplectic structure that all Hamiltonian systems should possess by nature. This method can be applied to accurate, yet computationally efficient dynamic filters, long-term propagations of the motions of formation flying spacecraft and the eigenstructure analysis of N-body dynamics, etc., when the exact structure-preserving property is crucial. We show the derivation of the numerical method of symplectic state transition matrix, and apply it to Earth orbits with perturbation forces based on real ephemerides. These numerical examples reveal that this method shows improvements in preserving the structural properties of the state transition matrix, and in the computational efficiency compared to the conventional linear state transition matrix with Euler or Runge-Kutta integration.