Table of Content

    25 April 2010, Volume 30 Issue 02 Previous Issue    Next Issue
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    Method of Designing Embedded Computer System Architecture in Distributed Satellite
    Li Xinming1,2 Li Xiaojiang1 Li Yi1 Liu Dong1(1 Academy of Equipment Command & Technology,Beijing 101416)(2 School of Computer,Nanjing University of Science & Technology,Nanjing 210094)
    2010, 30 (02):  1-8. 
    Abstract ( 2042 )   Save
    Being an advanced technique of spacecraft system,the distributed satellite has become one of the research hotpots.According to the running environment and the tasks of distributed satellite,and considering its reliability,security,and real-time requirements,a design method of master-assistant dual-system architecture based on three-level fault-tolerance was presented.The properties and design requirements of distributed satellite were discussed.And the designs of three-level fault-tolerance,security mechanism of master-assistant dual-system,and assistant system based on trusted platform module (TPM) were introduced.The design method has been tested in a prototype system.It showed that the system effectively resolved the reliability,security,and real-time problems of the distributed satellite.
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    Fractal Characterization of Lunar Surface Roughness
    Cheng Jing 1 Yang Ruiyan 1,2 Huang Dinghua 2 Yu Bing1 Hu Haiyan 1 Xiang Shimin 2(1 Institute of Mathematics and Physics,China University of Geosciences,Wuhan 430074)(2 Research Center for Space Science & Technology,China University of Geosciences,Wuhan 430074)
    2010, 30 (02):  9-14. 
    Abstract ( 3030 )   Save
    Researching the relativity between the lunar surface's dimension and roughness may contribute significantly to the stratigraphic study of the moon.The laser detector's data from Chang'E1 satellite.The selected Mare Humorum region of the lunar,and the SPSS statistical software were used to determind the best fitting model about the lunar surface's dimension and roughness parameters.The results show that the fractal dimension can be characterized as an independent parameter to represent the degree of rough surface.For the Mare Humorum region,it exists increasing relationship between the fractal dimension and surface roughness,and the Mare Humorum's hypsography has great disparity.Through the relationship between the fractal dimension and roughness,we can calculate any contour's roughness when we know the fractal dimension of the contour,vice versa.For the other regions of the moon,this method also can be used to study the relativity between the lunar surface's dimension and roughness so as to study the lunar's evolution process.
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    Bus-based Reconfigurable Drive Techniques of Satellite Retroaction Flywheel
    Zhou Zhaoyong1 Qi Yamei1 Kong Xiang1 Li Tiecai2(1 Institute of Advanced Digital Equipment,Shenzhen Academy of Aerospace Technology,Shenzhen 518057)(2 School of Electrical Engineering and Automation,Harbin Institute of Technology,Harbin 150001)
    2010, 30 (02):  15-23. 
    Abstract ( 2835 )   Save
    A design scheme of bus-based servo drive controller and system reconfiguration for the satellite retroaction flywheel was investigated.In this scheme,a reliable power inverter as well as a pumped voltage suppresser was constructed,and a magnetic induction sensor was developed to monitor the three-phase motor currents.Besides,only six Hall-effect latches,half of which were backups,were used to control commutation and measure the speed with improved M/T algorithm.IP cores and system level ASIC of the full-digital servo controller were completed based on field bus protocol,integrated with a redundant reconfiguration manager as well as multiple reconstruction techniques.This system-on-chip of flywheel controller was implemented on an FPGA platform.Experimental results indicate that the designed system can provide satisfactory dynamic and static performances throughout the whole four quadrants.
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    Design of General-purpose Electric Simulator for Satellite Attitude and Orbit Control System Based on SOC
    Hu Di Dong Yunfeng(Beihang University,Beijing 100191)
    2010, 30 (02):  24-30. 
    Abstract ( 1785 )   Save
    The interfaces of Attitude and Orbit Control System (AOCS) were analyzed during the process of some satellite desktop electric integration tests.A design method of general-purpose electric simulator based on SOC (System-On-a-Chip) was proposed to solve the complex interfaces and multi-type signals.The satellite general-purpose electric simulator was designed and how to adapt it to configure the gyro electric simulator,wheel electric simulator was presented and a general control module was illustrated.According to the requirements of the AOCS desktop electric integration testing system,On-Board-Computer simulator,general interfaces box,sensor simulator and actuator simulator were configured.The simulators,communicating with other parts by CAN (Controller Area Network) bus,were used in the desktop electric integration testing system to simulate sun capture,earth capture and normal control modes.The results show that the general-purpose electric simulator meets the requirements and has reference value to the development of other electric simulators of satellite desktop electric integration testing system.
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    Thermal Radiation Equivalent Test Method of Complex or Large Structures
    Zhong Qi Liu Zijun Fan Qingmei(China Academy of Space Technology,Beijing 100094)
    2010, 30 (02):  31-36. 
    Abstract ( 1923 )   Save
    In the incomplete thermal balance test,which some complex or large structures can't be involved,to make the test equivalent to the real status,difference of radiation heating between the two statuses should be compensated.The proposed method was proved to be necessary and partly sufficient by two independent numerical tests on a simple satellite.
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    Determination Method of Capture Parameters in Antenna Pointing Control of Relay-satellite
    Wang Xiang Yang Hui (China Academy of Space Technology,Beijing 100094)
    2010, 30 (02):  37-41+67. 
    Abstract ( 1752 )   Save
    In order to obtain the design parameters required during the antenna capturing process in the satellite pointing control of the relay satellite,the movement relation between relay satellite and user satellite was analyzed.The result proves that the time to capture of antenna is a function of the velocity of the user satellite relatively to the relay satellite.The relation curves and formulas between the antenna capture time,the capture rate and the velocity of user satellite were deduced after analyzing and calculating the velocity of the user satellite relatively to the relay satellite.
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    Coplanar Hovering Method over Space Target on Non-circular Orbit
    Yan Ye Zhu Yawen(College of Aerospace and Material Engineering,National University of Defense Technology,Changsha 410073)
    2010, 30 (02):  42-48. 
    Abstract ( 1847 )   Save
    The mission satellite is always forced to fly in the orbital plane of the target satellite by using vector control technique.At the same time,the angle of mission satellite to target satellite to geocenter,and the objective distance between two satellites will keep constant.So the coplanar hovering orbit was achieved.The dynamic theoretical analysis of the hovering orbit was conducted.Then the radial and tangential acceleration requirements during the hovering process were deduced,and the open loop orbit control strategy was proposed.After that the energy requirements of different hovering tasks were analyzed.The dynamic simulation of the hovering process was conducted to validate the theoretic results.
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    Formation Mechanism of Anti-deep-charged Modification for Space Dielectric
    Wu Jiang Bai Jingjing Shen Bin Zheng Xiaoquan(National Key Lab of Power Equipment and Electrical Insulation,Xi'an Jiaotong University,Xi'an 710049)
    2010, 30 (02):  49-54. 
    Abstract ( 1718 )   Save
    In order to decrease the level of deep charged in the spacecraft organic dielectric and improve the stability and life span of the spacecraft.The effects of grounding modes and conductance property on the space dielectric were analyzed.It shows that the non-linear conductance modification can decrease the level of deep charged.The modification to the commonly used spacecraft dielectric was tested,and the preconceived non-linear conductance property was gained.The non-linear conductance modification was considered to be one of the most effective protection methods in deep charged for the dielectric material.
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    Optimal Multi-impulse Close-range Rendezvous
    Tu Lianghui1,2 Yuan Jianping1 Luo Jianjun1 Fang Qun1(1 College of Astronautics,Northwestern Polytechnical University,Xi'an 710072)(2 Hongdu Aircraft Design & Research Institude,Aviation Industry Corporation,Nanchang 330024)
    2010, 30 (02):  55-60. 
    Abstract ( 1927 )   Save
    The application of hybrid genetic algorithm to space vehicle close-range orbital rendezvous optimization problem was studied based on Lawden's equations,while target vehicle was on an arbitrary elliptical orbit.Firstly,the Lawden's motion model of close-range orbital rendezvous was established,which was simplified based on some reasonable hypotheses.Then,theory of multi-impulse rendezvous was developed and optimal multi-impulse rendezvous control problem was established.The multi-ocjective optimization performance was selected to minimize the total fuel consumqtion and total time.The optimal variables included magnitude of impulse components and imposed time of impulse.Terminal state variable constraints included relative position and velocity constraints.Finally,hybrid genetic algorithm was put forward which has high convergence both in global and local optimization problem,and optimization problem was solved using hybrid genetic algorithm,no matter whether the influence of the first impulse's position was taken into consideration.A numerical example was presented to demonstrate the effectiveness of hybrid genetic algorithm.Simulation results show that the total fuel consumption in both conditions is nearly the same.
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    Control on the Spacecraft Hovering Based on Hybrid Systems
    Xue Bai She Zhikun Yu Jing Liu Tiegang Zheng Zhiming(School of Mathematics and Systems Science,Beihang University,Beijing 100191)
    2010, 30 (02):  61-67. 
    Abstract ( 2778 )   Save
    Based on the dynamical principle of spacecraft orbits,the hybrid system model was used to study the hovering problems and a hybrid system model of hovering orbits was established.Based on this model,in the case that the target satellite orbit is elliptic,an equidistant hovering orbit control scheme and an elliptical hovering orbit control scheme were proposed,and the corresponding forces exerted on the hovering satellite for these two schemes were derived respectively.Numerical simulation results showed that hovering movement can be realized by exerting the corresponding forces on the hovering satellite.
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    Autonomous Determination of Range and Attitude Based on an Asteroid Terrain Feature Database
    Li Xiao1 Hu Weiduo2(1 China Academy of Space Technology,Beijing 100094)(2 School of Astronautics,Beihang University,Beijing 100191)
    2010, 30 (02):  68-75+82. 
    Abstract ( 1653 )   Save
    A scheme of range and attitude measuring for soft landing on the asteroids based ona terrain feature database was presented.First,the terrain feature database about a landing target was established which contained the longitude and latitude data of the feature points,image texture information and position-correlation of the feature points.Then,after terrain feature extraction was performed during the descent,image matching was processed in the database.The spill problem of feature points out of a camera was solved,and the applicability of the optical measurement was improved.Finally,the relative positions and attitudes between the asteroid and the explorer were obtained by computer vision principle associated with the position of the matching points.The feasibility of this scheme was validated by mathematical simulation.
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    In-orbit Estimation of Satellite Mass and Center of Mass Using STLS
    Lin Jiawei1,2 Wang Ping1(1 Beijing Institute of Control Engineering,Beijing 100190)(2 National Laboratory of Space Intelligent Control,Beijing 100190)
    2010, 30 (02):  76-82. 
    Abstract ( 1924 )   Save
    The structured total least norm (STLN) algorithm was used to estimate the mass and center of mass parameters.This method has three advantages comparing with the existing methods:the dynamic equations of satellites were not simplified;practically inaccurate thrust force and torque were not used in the equations,sensor noise was considered.Theoretical analysis shows that the STLS solution is maximum likelihood estimate when the sensor noise is Gaussian.Simulation confirms the usefulness of the method.
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