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    25 June 2004, Volume 24 Issue 03 Previous Issue    Next Issue
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    Federated Filter Design for Multi-sensors Satellite Attitude Determination
    Gu Dongqing Wang Yan Zhou Wenjun Qin Yongyuan(Northwestern Polytechnical University, Xi'an 710072)
    2004, 24 (03):  . 
    Abstract ( 1736 )   Save
    A federated filter is designed to fuse information from the inertial measurement unit, the star sensor, the digital sun sensor and the digital earth sensor which compose the satellite attitude determination system. The algorithm and structure of the federated filter are proposed. The error propagation equations and the each subsystem measurement equations of the satellite attitude determination system are derived. Simulation results show that the federated filter realizes the optimal estimation at the cost of low computational complexity. And when parts of attitude sensors fail, the federated filter could still give satisfied estimation uninfluenced by the information of failed attitude sensors.
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    Dynamics Modeling and Analysis of Lunar Rover Steering System
    Wang Zuowei Wu Hongxin(Beijing Institute of Control Engineering, Beijing 100080)
    2004, 24 (03):  . 
    Abstract ( 1615 )   Save
    The dynamic characteristics of lunar rover are very complex when the rover steers on soft soil. The paper analyzes dynamics modeling of lunar rover steers on soft soil based on the known work. A kinematic expression of 4 wheel steering for 6 wheel lunar rovers is presented, a dynamic model of 4 wheel steering for rovers driving on soft soil is expounded, and some simplified methods are presented. At last, the steady characteristics is analyzed. The results provide a foundation for designing of steering system of rovers.
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    Analysis of Constant Continuous Radial Thrust and N-thrusts in Space Rendezvous
    Zhu Renzhang Lin Yan(Beijing University of Aeronautics and Astronautics, Beijing 100083) Li Yili(China Academy of Space Technology, Beijing 100081)
    2004, 24 (03):  . 
    Abstract ( 1565 )   Save
    The absolute motion(orbital motion)and relative motion of space rendezvous V bar approach using constant continuous radial thrust and N thrusts are investigated, calculated and compared with impulsive thrust transfer. The results show that the N thrusts transfer has a better performance.
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    Development and Modification of Thermal Network Correction Techniques for Satellites
    Li Jindong(Chinese Academy of Space Technology, Beijing 100086)
    2004, 24 (03):  . 
    Abstract ( 1690 )   Save
    The recent progress of thermal network model correction methods for satellites is summarized and reviewed in this paper. In order to overcome the difficulties such as the insufficient testing data, many constraints and engineering applications, some improvements of the thermal network correction methods based on least square approximation are presented, including parameter correction, graded correction and transient correction methods, and providing some technical references for further research.
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    Research of Stratosphere Balloon Platform Inverse Positioning System
    Duan Fang Liu Jianye Lai Jizhou Xiong Zhi(Nanjing University of Aeronautics and Astronautics,Nanjing 210016)
    2004, 24 (03):  . 
    Abstract ( 1817 )   Save
    Inverse positioning system(IPS)is a new type of positioning system for the resident stratosphere balloon platform. The basic principle of IPS is to calculate the position of the radiator with known positions of receivers. In this paper, the calculating model is built based on Kalman Filter method, and the algorithm is given. Since the locations of ground stations have a great influence on positioning accuracy, the selection principle of ground station location is given, and a set of locations with good performance are given after plenty of calculating and simulation. Besides, the asynchronism of clocks is a main source of error, the positioning error caused by it is analyzed, and a way of estimating is given. The transmitting error and the equipment error are also analyzed. In the end, a simulation model is built and the simulation is proceeded, the result shows that the system has higher positioning accuracy.
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    Study on Synthetic Orbit Maneuver of Spacecraft During Space Rendezvous
    Guo Hailin Qu Guangji(Institute of Spacecraft System Engineering of CAST, Beijing 100086)
    2004, 24 (03):  . 
    Abstract ( 1764 )   Save
    This paper presents the approaches and practical theoretical models on synthetic orbit maneuver during long distance guidance stage of space rendezvous. Firstly, it briefly describes technical conditions and methods of synthetic orbit maneuver. Secondly, it deduces the model of orbit dynamics on synthetic orbit maneuver under multi impulse. Finally, it gives the example simulation of synthetic orbit maneuver under multi impulse during long distance guidance using the self developed simulation software. The simulation results show that the theoretical models and algorithms presented in this paper are of practical engineering value.
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    The Fusion Method for Prior Distribution Based on Expert's Information
    Liu Qi Feng Jing Zhou Jinglun(National University of Defense Technology, Changsha 410073)
    2004, 24 (03):  . 
    Abstract ( 1640 )   Save
    How to acquire proper prior distribution is a key problem in complex system Bayesian reliability evaluation. In this paper, the application of expert's information in prior distribution fusion is studied. Based on AHP and synthesis factor methods, the weight factor calculation method is presented. Finally with the fused prior distribution, the posterior distribution is analyzed.
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    Summary for the Research Methods of Parachute Inflation Process
    Peng Yong Cheng Wenke Song Xumin Zhang Qingbin(National University of Defense Technology, Changsha 410073)
    2004, 24 (03):  . 
    Abstract ( 1671 )   Save
    This paper presents the research methods about the parachute inflation course. These methods include fully experimental method , semi experimental method and theoretical method. Then the development status of the semi experimintal method and the fully theoretical method are emphasized presented, it also presents the complex physical phenomena, difficulties and key to these problems during the inflation process. In the end, the currently research hotspot and development trend are presented
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    Study of the Current Satellite Navigation System Techniques
    Shuai Ping Qu Guangji Xiang Kaiheng(China Academy of Space Technology, Beijing 100086)
    2004, 24 (03):  . 
    Abstract ( 2266 )   Save
    Firstly, the technical features and modemization process of American GPS are analyzed in detail in this paper. Secondly, the current status and shortcoming of Russian GLONASS system are described and the differences between GLONASS and GPS are also discussed. Meanwhile, the development and associated techniques of European Galileo system are introduced. Finally, it expounds that the Beidou satellite navigation system is not able to better meet many users' requirements in China yet. Thereby, the system frameworks and key techniques for developing the second generation satellite navigation system of China are presented preliminarily.
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    Estimation Method of Relative Position and Attitude for Spacecraft Rendezvous and Docking
    Fei Weichun(Beijing Institute of Targets and Environment, Beijing 100854)
    2004, 24 (03):  . 
    Abstract ( 1923 )   Save
    In spacecraft rendezvous and docking, a computer vision system is used as an accurate sensing device for estimating the three dimensional position and orientation of the spacecraft relative to a coordinate system fixed on a space station, providing feedback information needed for guidance and control loops. In this paper, the methods of the two dimensional image information sampled by computer vision system are studied for estimating the position and attitude of the spacecraft relative to the space station. Algorithm of fitting measured light line with light point is proposed in this paper, and the digital simulation results are also presented.
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