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25 June 2009, Volume 29 Issue 03 Previous Issue    Next Issue

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Design of Federated Filtering Based Satellite Attitude Determination System Wang Zhisheng~1 Zhen Ziyang~1 Fan Dapeng~2 (1 College of Automation Engineering, Nanjing University of Aeronautics and Astronautics,Nanjing 210016) (2 College of Mechatronics Engineering and Automation, National University of Defense Technology,Changsha 410073) 2009, 29 (03):  1-9.  Abstract ( 1998 )   Save A sun synchronous polar satellite attitude determination system composed of gyros, GPS sensors,sun sensors and infrared horizon sensors was designed.Federated filter structure and algorithm of the attitude determination system are proposed,and then the measurement equations of all sensors and the error state equation of attitude determination system were deduced.To avoid the noncorrelation processing,the attitude filtering value which decreases the GPS sensor output was utilized as the frequency of the system measurement.Simulation results show that federated filtering based information fusion method for the multi-sensor satellite system is characterized by small computation cost,high precision and good reliability. Related Articles | Metrics

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Blind Separation of Space Radio Reconnaissance Signals with Same Frequency Zhou Zhiyu Chen Hao (China Academy of Space Technology,Xi'an 710100) 2009, 29 (03):  10-15+22.  Abstract ( 2026 )   Save The problem of separating several signals with same frequency is very common in space radio reconnaissance,but it is difficult to deal with it by traditional signal processing.A new blind signal separation method of parallel FastICA to solve the problem was proposed,which didn't need any information of the source signals and could correctly separate the signals mixed in the frequency-domain.The method is fit for radio reconnaissance and can be used widely.The simulations demonstrate that the FastICA can separate the signals mixed in the frequency-domain whose power has 10000 times difference.The FastICA not only has a good performance under gauss white noise condition,but also has a fast convergence.The proposed method will have a good application prospect. Related Articles | Metrics

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Traversability Based Path Planning Algorithm for Lunar Rovers Liu Jianjun~(1,2) Chen Jianxin~(1,2) (1 Beijing Institute of Control Engineering,Beijing 100190) (2 National Laboratory of Space Intelligent Control,Beijing 100190) 2009, 29 (03):  16-22.  Abstract ( 2001 )   Save It is very necessary for a path planning algorithm of a planetary rover to utilize the rover's mobility and terrain characteristics better.A path planning algorithm,which is based on the traversability of a lunar rover and terrain information,was proposed.The grid based world model was subdivided and four statistical parameters were analyzed which implyed the security as the rover holding still or moveing along predetermined arcs,and the path search algorithms were based on A* and D* algorithms.The flow charts were presented and simulation results demonstrate the effectiveness of the proposed algorithms. Related Articles | Metrics

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Research on GPS/GLONASS/GALILEO Multi-constellation Integrated Navigation System Wu Ling Sun Yongrong Yu Xiaolei Li Rongbing (College of Automation,Nanjing University of Aeronautics & Astronautics,Nanjing 210016) 2009, 29 (03):  23-28.  Abstract ( 2449 )   Save The position algorithm of multi-constellation integrated navigation system was researched.Due to the different reference coordinate and time systems used in GPS,GLONASS and GALILEO system,coordinate conversion and increased elements method were adopted to realize the space-time unification.Aiming at the increasing number of visible satellite,the least square method was used in the position calculation to improve the precision.Simulation validation was carried out on GPS,GLONASS and GALILEO multi-constellation integrated navigation system and the results indicate that in contrast with the GPS single system,the GPS/GLONASS/GALILEO multiconstellation integrated navigation system has perfect orientation ability and reliability,and can simultaneously gain more visible satellites,diminish PDOP value and improve the position precision effectively. Related Articles | Metrics

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Thermal Control Design and Analysis of Remote Sensor Onboard Geostationary Satellite Liu Zhenyu~1 Cheng Huier~1 Sun Jingliang~2 (1 School of Mechanical Engineering,Shanghai Jiaotong University,Shanghai 200240) (2 Shanghai Academy of Spaceflight Technology,Shanghai 200235) 2009, 29 (03):  29-35.  Abstract ( 1950 )   Save A thermal model of a remote sensor onboard the geostationary satellite was established to meet the high quality requirements in thermal analysis of the space remote sensor and dispose heat radiation and heat conduction in orbit.The temperature distribution of the remote sensor instrument was calculated based on the advanced finite difference method with control volume approach,which can deal with the radiation boundary condition efficiently.The Oppenheim' s method was used to calculate the radiation heat transfer inside the remote sensor and the calculation of radiation view factor of boundary surface was based on a blockage criterion.The thermal control design for the remote sensor was presented,which contributed to its channel registration and focus stability.The steady and transient analyses were performed to obtain the temperature response of the remote sensor scan mirror. Related Articles | Metrics

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Research on Characteristics of Microstrip Yagi Array Antenna Hou Banghuan Wan Guobin Zhang Xuesong (School of electronics and information,Northwestern Polytechnical University,Xi'an 710072) 2009, 29 (03):  36-41+49.  Abstract ( 1934 )   Save The frequency response and radiation characteristics of a microstrip Yagi Array antenna were studied.The phase and amplitude of the coupled field on parasitic patches were observed with the EM software HFSS and their variation characteristics with respect to the patch sizes and gaps between the patches were investigated.The study revealed the nature of the variation of the frequency response and radiation pattern with the antenna parameters.Based on the study,a design methodology of the microstrip Yagi array antenna was given.An antenna was designed and optimized using the proposed design methodology to satisfy the desired gain and radiation pattern. The test results of the fabricated antenna are consistent with the simulation,which prove the validity of the proposed design methodology. Related Articles | Metrics

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Analysis of Orbit Dynamics for Spacecraft Octahedron Formation Configuration in the Circular Orbit Lin Laixing Che Rucai (Beijing Institute of Control Engineering,Beijing 100190) 2009, 29 (03):  42-49.  Abstract ( 1835 )   Save A novel octahedron configuration of satellite formation flying was proposed.The characters of many formation flying configurations in recent years can be represented in this octahedron configuration.It is also suitble to the formation flying mode of the space demonstration project.The design method of octahedron formation configuration was based on the CW equation, and the along-track formation configuration in the orbit plane can be maintained using orbit dynamics.The above or below hanging formation configuration can be achieved using contorl in the orbit plane,and the formation configuration perpendicular to the orbit plane can be achieved using cross-track control.The precision of hanging dynamic model based on CW equation was analyzed in detail,and a low earth orbit satellite octahedron configuration was simulated for validation. Related Articles | Metrics

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Autonomous Relative Orbit Determination for Satellite Formation Flying Wang Hui Gu Xuemai (Harbin Institute of Technology,Harbin 150001) 2009, 29 (03):  50-56+63.  Abstract ( 1844 )   Save In order to study the approach for autonomous determination of relative orbit for satellite formation flying,the relative motion equations of formation satellites were established based on orbit element differences.The inter-satellite distance and orientation measurements were chosen as the observation information.Instead of using the Extended Kalman Filter,the relative orbit state estimation was achieved through an Unscented Kalman Filter.The simulation results show that the relative orbit can be precisely determined by this method and it is validity for autonomous determination of relative orbit for formation satellite flying. Related Articles | Metrics

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Study on FPGA Fault Models in Evolutionary Fault Tolerance Gong Jian~(1,3) Yang Mengfei~(2,3) Wen Liang~1 (1 Beijing Institute of Control Engineering,Beijing 100190) (2 China Academy of Space Technology,Beijing 100094) (3 National Laboratory of Space Intelligent Control,Beijing 100190) 2009, 29 (03):  57-63.  Abstract ( 1992 )   Save Different fault models are required according to the corresponding fault tolerance methods.The features of evolutionary fault tolerance method was analyzed,considering that compatible FPGA fault model should be studied.First,the concept of fault model partition was presented based on the definition of fault model,so that FPGA fault models can be studied from different perspectives.Second,according to the architecture features of SRAM based FPGA,two FPGA fault model partitions classified by the function and the configuration of FPGA were proposed.Finally,the corresponding fault tolerance methods fitting for the two fault model partitions were analyzed.The test results show that the fault model partition classified by the configuration of FPGA can simplify the fault detection in evolutionary fault tolerance method. Related Articles | Metrics

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Heuristic Algorithm for Aerospace Multi-project Scheduling with Multi-resource Constraints Su Qing~1 Yang Haicheng~(1,2) Jing Shikai~3 Wang Yanbing~4 (1 School of Mechatronics,Northwestern Polytechnical University,Xi'an 710072) (2 China Aerospace Science and Technology Corporation,Beijing 100048) (3 Beijing University of Aeronautics and Astronautics,Beijing 100083) (4 China Aerospace Engineering Consultation Center,Beijing 100048) 2009, 29 (03):  64-70+77.  Abstract ( 2205 )   Save To solve the multi-project scheduling problem with multi-resource constraints in aerospace industry,a mathematical model was built and a heuristic algorithm was introduced based on the model.The model is proposed with the target of minimizing the weighted sum of multiproject total duration and single project duration.Considering a single activity requires multiresource and resource can be deprived,the algorithm can optimize the resource allocation among project activities and achieve the goal of the model.The case study shows that the model and algorithm have practical value for engineering application. Related Articles | Metrics

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Application of Neural Network-expert System for Fault Diagnosis of Satellite Attitude Control System An Ruoming Qin Zhenhan Jiang Xingwei (School of Astronautics,Harbin Institute of Technology,Harbin 150001) 2009, 29 (03):  71-77.  Abstract ( 1832 )   Save In order to resolve the problems of acquiring knowledge and reasoning in traditional expert system,a new diagnosis system based on the combination of the neural network and expert system was proposed.The principal component analysis method was adopted to simplify the training pattern of neural network,and optimize the structure of the network.The technique of neural network ensemble was used to resolve the difficulties of choosing the number of network middle layer and the threshold of judgement.The reasoning process and the interpreting methods for diagnosis results were given.The technology was applied to fault diagnosis of a satellite position control system,and the result proved that the diagnosis efficiency and accuracy was increased. Related Articles | Metrics

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Priority Design Method Analysis for TT&C Resource Ran Chengxin Wang Huilin Xiong Gangyao (College of Information System and Management, National University of Defense Technology,Changsha 410073) 2009, 29 (03):  78-83.  Abstract ( 1946 )   Save It is an important and key problem to set priority on TT&C resource during the satellite TT&C scheduling process.Based on the engineering analysis of resource requirements, nine priority factors were studied,and the factor's quantificational description model was also presented.The reformative TOPSIS model for priority calculation was carried out and its calculation steps were given.An example was given to show the validation of this model.The result is expected to be useful in scheduling algorithm research. Related Articles | Metrics