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Beijing, China

Xu M.,Beihang University | Liang Y.,Beihang University | Tan T.,DFH Satellite Co. | Wei L.,Chengdu Aircraft Design and Research Institute
Celestial Mechanics and Dynamical Astronomy | Year: 2016

This paper deals with the stabilization of cluster flight on an elliptic reference orbit by the Hamiltonian structure-preserving control using the relative position measurement only. The linearized Melton’s relative equation is utilized to derive the controller and then the full nonlinear relative dynamics are employed to numerically evaluate the controller’s performance. In this paper, the hyperbolic and elliptic eigenvalues and their manifolds are treated without distinction notations. This new treatment not only contributes to solving the difficulty in feedback of the unfixed-dimensional manifolds, but also allows more opportunities to set the controlled frequencies of foundational motions or to optimize control gains. Any initial condition can be stabilized on a Kolmogorov–Arnold–Moser torus near a controlled elliptic equilibrium. The motions are stabilized around the natural relative trajectories rather than track a reference relative configuration. In addition, the bounded quasi-periodic trajectories generated by the controller have advantages in rapid reconfiguration and unpredictable evolution. © 2016 Springer Science+Business Media Dordrecht Source

Han X.,DFH Satellite Co.
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2014

Agile satellite can point to any interested place very deftly and fast, improving observe range and time efficiency of mission greatly. Most agile satellite take pictures either along satellite track or parallel with satellite track. Imaging parameter and imaging quality of change time delay and integration charge coupled devices (TDICCD) during dynamic imaging process are analysed, error effects on image quality are given, and simulation result of main parameters change is acquired, in the end satellite control method is proposed. Source

Wang X.,DFH Satellite Co.
19th International Congress on Sound and Vibration 2012, ICSV 2012 | Year: 2012

A new approach for updating the finite element model of a satellite structure using frequency response obtained in the vibration test is presented in this paper. The algorithm uses a mathematical optimization strategy to minimize deviations between measured and analytical frequency response. The destination of optimization is the frequency and amplitude of the peaks on the spectrum in three vibrating direction. The variables are Young's Modulus of composite plate and viscous damping of all model frequency in analysis frequency rang. The strategy was successfully implemented using LMS Virtual lab software. The results demonstrate the precision of the updating model is enough for satellite dynamic simulation. Source

Xu M.,Beihang University | Zhu J.,Beihang University | Tan T.,DFH Satellite Co. | Xu S.,Beihang University
Celestial Mechanics and Dynamical Astronomy | Year: 2012

The bounded quasi-periodic relative trajectories are investigated in this paper for on-orbit surveillance, inspection or repair, which requires rapid changes in formation configuration for full three-dimensional imaging and unpredictable evolutions of relative trajectories for non-allied spacecraft. A linearized differential equation for modeling J 2 perturbed relative dynamics is derived without any simplified treatment of full short-period effects. The equation serves as a nominal reference model for stationkeeping controller to generate the quasi-periodic trajectories near the equilibrium, i. e., the location of the chief. The developed model exhibits good numerical accuracy and is applicable to an elliptic orbit with small eccentricity inheriting from the osculating conversion of orbital elements. A Hamiltonian structure-preserving controller is derived for the three-dimensional time-periodic system that models the J 2-perturbed relative dynamics on a mean circular orbit. The equilibrium of the system has time-varying topological types and no fixed-dimensional unstable/stable/center manifolds, which are quite different from the two-dimensional time-independent system with a permanent pair of hyperbolic eigenvalues and fixed-dimensions of unstable/stable/ center manifolds. The unstable and stable manifolds are employed to change the hyperbolic equilibrium to elliptic one with the poles assigned on the imaginary axis. The detailed investigations are conducted on the critical controller gain for Floquet stability and the optimal gain for the fuel cost, respectively. Any initial relative position and velocity leads to a bounded trajectory around the controlled elliptic equilibrium. The numerical simulation indicates that the controller effectively stabilizes motions relative to the perturbed elliptic orbit with small eccentricity and unperturbed elliptic orbit with arbitrary eccentricity. The developed controller stabilizes the quasi-periodic relative trajectories involved in six foundational motions with different frequencies generated by the eigenvectors of the Floquet multipliers, rather than to track a reference relative configuration. Only the relative positions are employed for the feedback without the information from the direct measurement or the filter estimation of relative velocity. So the current controller has potential applications in formation flying for its less computation overload for on-board computer, less constraint on the measurements, and easily-achievable quasi-periodic relative trajectories. © 2012 Springer Science+Business Media B.V. Source

Fan D.,DFH Satellite Co.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

The B3M-FTS instrument, inherited from ACE-FTS and PARIS, is built by Canadian ABB and Beijing Vision Sky Aerospace Co., Ltd. The B3M is a complete stand-alone spectrometer designed to operate from the ground in moderate environment. It can acquire atmospheric spectra with the Sun as back illumination. This instrument is an adapted version of the classical Michelson interferometer using an optimized optical layout, and it is a high-resolution infrared Fourier transform spectrometer operating in the 750 to 4100cm -1 spectral range. In this paper, the instrument concept of a compact, portable, high-resolution Fourier transform spectrometer is introduced. Some test results of the instrument such as ILS and SNR are presented, and the spectral resolution of 0.028cm-1 @ 750cm-1 and SNR over 100:1 are achieved. Sample atmospheric absorption spectra and corresponding retrieval results measured by the FTS are given. The B3M-FTS, with its high performance, provides the capability to monitor the atmospheric composition changes by measuring the atmospheric absorption spectra of solar radiance. Lots of measurements have been acquired at the Olympics atmospheric observation super-station. Up to now, the VMRs of near 10 trace gases have been retrieved. The success of atmospheric composition profile retrieval using the FTS measurements makes the further application of FTS type payload possible in China. Source

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