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25 June 2008, Volume 28 Issue 03 Previous Issue    Next Issue

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Self-adaptive Selecting Method for Scaling Factor of Scaled Unscented Transformation Jiang Weinan Zhou Haiyin Duan Xiaojun Pan Xiaogang(Science College,National University of Defense Technology,Changsha 410073) 2008, 28 (03):  1-6+28.  Abstract ( 2810 )   Save By applying the scaled UT(Unscented Transform) to a general sampling strategy,the problem of non-local effects of sampling can be resolved,and the estimating precision of UKF(Unscented Kalman Filter) can be improved as well.The scaling factor is one of the most important parameters,so a self-adaptive selecting method for the scaling factor was proposed.The self-adaptive scaled UT was applied to the scaled minimal skew simplex sampling,and the relevant UKF was applied to the real-time orbit determination of Low-Earth satellites.Simulation results indicate that the method is of high stability,and the relevant precision of the orbit determination approaches to the precision of the UKF with an optimal fixed scaling factor. Related Articles | Metrics

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Research on Fusion Method for Satellite Orbit Determination Based on Bayes Statistics Model Wang Jiongqi1 Zhou Haiyin1 Zhao Deyong2 Wu Yi1 (1 Department of Mathematics and System Science,National University of Defense Technology,Changsha 410073) (2 School of Information System and Management,National University of Defense Technology,Changsha 410073) 2008, 28 (03):  7-14.  Abstract ( 1962 )   Save According to the existing conditions of space-based navigating and positioning system and the precision orbit requirements of our country for LEO and MEO,the orbit determination principle based on information fusion was addressed. By introducing the prior information of satellite state parameters to be estimated,a method of information fusion for satellite orbit determination based on Bayes statistics model was presented,which added the observation noises into the linearized fusion model of observation equations,and then used the probability estimation fusion model to obtain the MAP(maximum aposteriori probability) of satellite states by Bayes theory,moreover,the orbit determination precision was analyzed.In addition,the fusion coefficients of multi-information were given based on the minimization of variance of desired fusion satellite states.Finally,through the simulation calculations and analysis for the distance data and velocity data integrative fusion strategy used for orbit determination based on combined measurement and control system,it indicates that this fusion method is more feasible and efficient. Related Articles | Metrics

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Federal Filter Method of Autonomous Orbit Determination for Low-Earth-Orbit Satellite Wang Peng Zhang Yingchun (Research Center of Satellite Technology,Harbin Institute of Technology, Harbin 150080) 2008, 28 (03):  15-21+71.  Abstract ( 1669 )   Save The Earth's magnetic field is well modeled and is a function of the satellite's position,therefore,autonomous Low-Earth-Orbit(LEO) satellite navigation can be achieved based on the measurement data of the onboard three axis magnetometer(TAM).High precision satellite motion model was presented firstly,then autonomous navigation algorithm by using measurement information of star sensor and TAM was presented.The observation equation was established by using two observation models and integrating measurement vectors of star sensor and TAM based on Federal Kalman Filter.The algorithm convergence and numerical simulation precision were analyzed in detail.The results of computer simulation show that the proposed system can improve the navigation precision,robustness and reliability. Related Articles | Metrics

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Analyses and Applications of Continuous Constant Thrust Maneuver Zhu Renzhang Wang Xiaoguang (Beijing University of Aeronautics and Astronautics,Beijing 100083) 2008, 28 (03):  22-28.  Abstract ( 2070 )   Save Continuous constant thrust is very important in orbital maneuver and escape flight.Small thrust maneuvers are fit for spacecraft rendezvous,and the tangential(or transverse) thrust and radial high-thrust can be applied in escaping from the earth's gravitational field.By using the motion equations of constant thrust maneuver,there is no limit on the thrust-level and no restraints on the relative distance when used in spacecraft rendezvous.Radius and orbital velocities can be directly expressed as functions of time or polar angle,which is helpful for designing flight mission and motion trajectory.Especially,when the initial orbit is circular,for small thrust and short flight time,approximate analytic solutions can be derived from non-dimension form of the motion equations. Related Articles | Metrics

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Application of SINS/GPS/Landmark Integrated Navigation in Stratospheric Airship Liu Tong Li Zhibin (Beijing Institute of Control Engineering,Beijing 100080) 2008, 28 (03):  29-36+44.  Abstract ( 1821 )   Save SINS/GPS/Landmark integrated navigation system was proposed according to the flight characteristic of the stratospheric airship.The observation equation of SINS /Landmark integrated navigation system was deduced and the improved SageHusa adaptive filtering method combined with federated filter was applied to SINS/GPS/Landmark integrated navigation system.Simulation results show that this new integrated navigation system can improve the attitude precision effectively relative to SINS/GPS integrated system and the improved adaptive federated filter can enhance the global estimation accuracy. Related Articles | Metrics

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Polynomial Interpolation Filtering for Relative Navigation of Spacecraft on Elliptical Orbit Liu Yong Xu Shijie (School of Astronautics,Beijing University of Aeronautics and Astronautics,Beijing 100083) 2008, 28 (03):  37-44.  Abstract ( 1833 )   Save According to Kepler orbit motion,the short distance relative dynamics equations of spacecrafts were obtained in the inertial frame.Compared with Clohessy-Wiltshire(C-W) equations,these equations were adaptable to the spacecrafts on the elliptical orbit because of no restriction for eccentricity.To avoid the Taylor linearization,the divided difference 2(DD2) filtering used polynomial interpolation to parameterize the first two moments of a probability distribution.For the determination of the spacecrafts relative position and relative velocity,the DD2 filtering was more accurate and easier to implement than the extended Kalman filtering(EKF).The simulation results validate the availability of the relative navigation algorithm based on DD2 filtering. Related Articles | Metrics

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Stiffness Optimization of Space Manipulator Based on Mass Allocation Jia Hongliang1 Yao Qiong2 Huang Qiang1 (1 School of Aerospace Science and Engineering,Beijing Institute of Technology,Beijing 100081) (2 Xichang Satellite Launch Center,Xichang 615000) 2008, 28 (03):  45-52.  Abstract ( 1745 )   Save The stiffness is a crucial problem for a space manipulator.It is very difficult to construct a high stiffness space manipulator with limited mass since high stiffness manipulator usually requires high expenditure on mass and volume.A method of stiffness optimization was presented to improve the stiffness of a space manipulator with limited mass.First,the stiffness model was established.Then,an optimization algorithm based on mass allocation was proposed.Finally,the optimum proportion between component mass and dimension was calculated. Related Articles | Metrics

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Feedback Coefficients Optimization Design Based on Ant Colony Algorithm for Magnetic Controller of Momentum Bias Satellite Chen Shiming Dong Yunfeng (Beijing University of Aeronautics and Astronautics,Beijing 100083) 2008, 28 (03):  53-58.  Abstract ( 1939 )   Save When designing feedback coefficients of satellite attitude determination and control system,the precision of the system mathematics model can be significant improved by applying uncertain component model.However,traditional optimization algorithm is insufficient in solving problems with uncertain factors.A robust feedback coefficients optimization approach based on Ant Colony Algorithm (ACA) was proposed.The method was applied to feedback coefficient design for magnetic rods of a momentum bias micro-satellite.Comparing with the traditional Powell algorithms,the new method has clear convergence tendency,which means the algorithm based on ACA has better capability in dealing with random factors,therefore,it can be used in coefficient design for a system considering random factors. Related Articles | Metrics

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Atomic Oxygen Erosion Resistance of Hybrid Silica Coatings on Kapton Zhang Xin Wu Yiyong Zhao Huijie He Shiyu (School of Materials Science and Engineering,Harbin Institute of Technology,Harbin 150001) 2008, 28 (03):  59-64.  Abstract ( 1912 )   Save The organic/inorganic hybrid silica coatings were prepared on Kapton substrate by sol-gel process,using tetraethoxysilane(TEOS) and 3-(methacryloxypropyl)-trimethoxy silane(MEMO) as precursors.The experiment results of atomic oxygen with ground simulation device show that the erosion yield of the silica-coated Kapton is one order less than that of the pristine Kapton.Comparatively,the silica coating with 0.2 MEMO presents better AO-ersion resistance.After AO exposure,the coated Kapton can keep optically stable.The analysis results of SEM,FTIR-ATR and XPS indicate that after AO exposure,the characteristic peak of Si-O-Si bonds shifts to that of Si-O bonds of SiO2,and the intensity of Si 2p state peak from MEMO decreases.Therefore,the coating structure tends to transfer to stabile SiO2. Related Articles | Metrics

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Application of Single-phase Fluid Loop System on Thermal Control of Satellite Zhang Li Jiang Jun Zhao Qiwei (China Academy of Space Technology,Beijing 100094) 2008, 28 (03):  65-71.  Abstract ( 1986 )   Save Single-phase fluid loop system is one of the most important method of active thermal control technique on spacecraft.The fundamental and process of designing single-phase fluid loop were summarized.One scheme of fluid loop was designed, and its performance was evaluated by numerical simulating in SINDA/FLUINT.The results proved that single-phase fluid loop is effective on thermal control of satellite. Related Articles | Metrics