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    25 June 2012, Volume 32 Issue 3 Previous Issue    Next Issue
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    Pointing Control of Large Deployable Antenna Based on Beacon 
    XING Zhi-Gang, LIU Li-Kun, ZHENG Gang-Tie, ZHOU Zhi-Cheng
    2012, 32 (3):  1-6.  doi: 10.3780/j.issn.1000-758X.2012.03.001
    Abstract ( 2175 )   PDF (415KB) ( 1626 )   Save
    In order to increase pointing accuracy of the large deployable antenna and adapt to on-orbit conditions such as jet dumping, the Craig-Bampton modal synthesis was used in antenna pointing dynamic modeling,  and a pointing control method based on beacon was proposed. By using Kalman filter, the flexible antenna vibration status was estimated. If the antennas do not vibrate obviously, the antenna pointing was adjusted by beacon sensors, and the stability was ensured by collocated attitude sensors. While the  antenna vibration exceeds the threshold,  only the collocated attitude sensors were induced to attenuate oscillation until vibration was attenuated. By using the in orbit thermal deformation testing data of the Thuraya satellite, the simulation results show that the antenna pointing accuracy without jet is superior to ±0.02°, and the vibration could be estimated correctly with the switch of tracking input after jet dumping. The results indicate that the antenna pointing error is adjusted with the guarantee of stability, and the influences of jet dumping and station-keeping are limited with the proposed vibration estimation method. 
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    Vision-based IMM-UKF Spacecraft Relative Position and Attitude Determination Algorithm
    YUE Xiao-Kui, LI Bin, ZHAO Kai
    2012, 32 (3):  7-14.  doi: 10.3780/j.issn.1000-758X.2012.03.002
    Abstract ( 1763 )   PDF (395KB) ( 1638 )   Save
    In the  process of spacecraft relative navigation, the relative distance measurement information is susceptible to disturbances, which results in greatuncertainty of measurement error. In general, filtering algorithm based on a single model cannot identify the noise and it is difficult to obtain accurate navigation results. As for the limitation of circle orbit  assumption, close relative motion equation (Lawden equation) was studied in the inertial coordinate system using Clohessy-Wiltshire (C-W) equation, and the two equations were established based on the model set. Considering the characteristics of the navigation sensors, a vision based dynamical algorithm of relative position and attitudes estimation using interacting multiple model (IMM-UKF) algorithm was designed based on the Rodrigues parameters and UKF filtering algorithm. The stability and precision of the relative orbit and attitudes determination are certified by using this algorithm under the condition of computation efficiency guarantee.
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    Positioning Algorithm for Airborne Pseudolites Based on Electro-optical Navigation
    WANG Wei, GUAN Yu-Wei, HU Sheng-Jun, LIU Zong-Yu
    2012, 32 (3):  15-19.  doi: 10.3780/j.issn.1000-758X.2012.03.003
    Abstract ( 1986 )   PDF (254KB) ( 1264 )   Save
    Due to the stronger anti-jamming capability and flexibility compared with orbiting satellites, pseudolite based positioning systems provide more precisenavigation information. To position precisely for airborne pseudolites is one of the key technique to construct the pseudolite based regional positioning system. The positioning algorithm based on electro-optical navigation was studied. The error model was established according to the characteristics of airborne pseudolites and the least-squares method was employed to estimate the position errors using the information from images and inertial navigation system. The simulation results indicate that the algorithm proposed is feasible and has great practical value.
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    Algorithm for Relative Position and Attitude of Formation Flying Satellites Based on Dual Quaternion
    JIANG Feng, WANG Hui-nan, HUANG Chao-Song
    2012, 32 (3):  20-26.  doi: 10.3780/j.issn.1000-758X.2012.03.004
    Abstract ( 2018 )   PDF (401KB) ( 1524 )   Save
    To unify the description of relative position and attitude of the formation flying satellites, a boating algorithm based on dual quaternion was proposed. Using the dual quaternion method, the kinematics model of formation flying satellites was established and its physical meanings were analyzed. This algorithm combined the solutions for relative position and attitude calculating. Simulation results indicate that the algorithm can effectively describe the relative position and attitude of formation flying satellites in a scientific and rational way.
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    Algorithm for Ground-base Orbit Determination of Navigation Satellites
    CHEN Zhi-Guo, CHEN Pei, HAN Chao
    2012, 32 (3):  27-34.  doi: 10.3780/j.issn.1000-758X.2012.03.005
    Abstract ( 2473 )   PDF (438KB) ( 1615 )   Save
    Precision of navigation satellite orbit determination is an important factor for the operation of the constellation navigation system. However, there are many problems in the field of navigation satellite ground-base orbit determination, such as low accuracy and high computational complexity. To find potential solutions of these problems, the ground-base orbit determination algorithm of navigation satellites was studied by one-way and passive measuring mode. The state process and the observation model were derived to establish the filter model, with pseudo-range between a monitor station and a satellite as the measurement, and parameters of the satellite clock as elements of the filtering state vector. Based on four GPS satellites in different orbital planes, a two-day simulation was designed to verify the algorithm. Considering the visibility of the satellite, an interruption of measurement between measuring process was introduced, a strategy for restarting the filter was proposed. The simulation results show that the position estimation error is less than 10 meters and the clock bias estimation error is less than 10 ns for all the four satellites. Furthermore, it could keep the previous filtering performance after the filter restarting. All these results indicate that this algorithm is convergent and stable.
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    Uniform Design Method of Optimal Sensor Deployment for Satellite Antenna
    LI Wen-Bo, WANG You-Yi, ZHAO Zhi-Gang, ZHAO Yang
    2012, 32 (3):  35-42.  doi: 10.3780/j.issn.1000-758X.2012.03.006
    Abstract ( 2146 )   PDF (480KB) ( 1570 )   Save
    In order to improve the precision of modal parameter identification for large close mode satellite antenna reflector, the genetic algorithm based on uniform design method was proposed to optimize the numbers and locations of sensors. The order of observed modal shape was selected by the energy criterion based on H2 norm in modal space. According to the largest orthogonality and the highest energy of measured information as the optimal objectives respectively, the uniform design method was introduced to optimize the four compounding parameters in genetic algorithm, including: sensor number, population size, probability of crossover and mutation. The eigensystem realization algorithm (ERA) was utilized in on-orbit modal identification. The numerical simulation results show that the proposed method can solve the problem of optimizing the numbers and locations of the sensors effectively, and avoid the blindness in parameters selection.
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     Planar Search Algorithm for GPS Ambiguity Resolution with Short Baseline Length Constraint
    PANG Chun-Lei, ZHAO Xiu-Bin, LU Yan-E, YAN Yu-Guo, YU Yong-Lin
    2012, 32 (3):  43-48.  doi: 10.3780/j.issn.1000-758X.2012.03.007
    Abstract ( 2001 )   PDF (391KB) ( 1574 )   Save
    A new planar search method for GPS ambiguity resolution with short baseline length constraints was proposed. The integer ambiguity was fixed in the condition of least square error by searching the baseline elevation and azimuth angle. The model was established, the search principle and application process of the new algorithm were discussed, and the step of extensive search and intensive search was induced. Through the experiments and comparing with LAMBDA algorithm, the new method with simple algorithm and high efficiency was proved. The error is no more than 1cm in baseline precision, no more than 0.6° in elevation precision and no more than 0.4° in azimuth precision. This method is also adaptive to attitude measurement.
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    Collision-free Motion Planning Algorithm for Redundant Space Manipulators during Coarse Target Capturing
    WANG Yue, JIA Ying-Hong, XU Shi-Jie
    2012, 32 (3):  49-56.  doi: 10.3780/j.issn.1000-758X.2012.03.008
    Abstract ( 1836 )   PDF (634KB) ( 1675 )   Save
    The existing collision-freemotion planning algorithms based on configuration space (C-Space) need to find the boundaries of C-space obstacles by solving C-space, which will cost much computation and memories for redundant manipulators with larger degrees of freedom (DOF). A novel algorithm was proposed to find the collision-free path in C-space by testing motion directions without solving C-space. This algorithm contained four sub-algorithms: the collision detection algorithm, the collision free target configuration solver, the collision-free path-searching algorithm and the path smoothing algorithm. Given the desired position and attitude of the end-effector, the target configuration solver calculated a collision-free target onfiguration. then the path-searching algorithm found a collision-free path with C-space  obstacle boundaries unknown. Finally, the path smoothing algorithm smoothed the obtained path. To verify the effectiveness of the algorithm, two numerical examples were carried out. And the results indicatethat the algorithm is efficient and can be used in fast motion planning for redundant manipulators in space applications.
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    Reliability Test and Evaluating Methods of Port Quick Leak Detector for Manned Spacecraft
    CUI Zhi-He, CAO Jun, YANG Xiao-Lin, ZHANG Xiao-Yi, QUAN Xin, DONG Yi-Peng
    2012, 32 (3):  57-63.  doi: 10.3780/j.issn.1000-758X.2012.03.009
    Abstract ( 1870 )   PDF (422KB) ( 1562 )   Save
    As the port and its docking system testing instrument, manned spacecraft port quick leak detector (PQLD) is used for checking the sealing quality of the docking surface after the door is closed and the docking surface is linked. By analyzing the function, the work principle and main failure mode of PQLD for manned spacecraft was presented, and the PQLD′s reliability characteristic was determined. According to the basic considerations of life type and computation type reliability test method, the methods of the PQLD reliability test was proposed, including the choice of the method, statement of the test piece, determination of the test condition, test program, failure criterion, and means of the reliability evaluating. 
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    Research on Aeroassisted Orbital Transfer between Elliptical Orbits
    FU Jun, CAI Hong, ZHANG Shi-Feng
    2012, 32 (3):  64-71.  doi: 10.3780/j.issn.1000-758X.2012.03.010
    Abstract ( 1757 )   PDF (444KB) ( 1540 )   Save
    Two kinds of coplanar elliptic orbital transfer methods were studied: two-impulse symmetric transfer using pure rocket propulsion and synergetic maneuver using aeroassisted orbital  transfer technology. For the problem of two impulse symmetric transfer, the formula for solving elliptical transfer orbit was derived. Then the optimal position of orbit changing was obtained by genetic algorithm, and the characteristic velocity was given. The process of aeroassisted symmetric transfer was divided into three parts, including vacuum flight portion, atmospheric flight portion, and vacuum flight portion. Assuming the minimum fuel as performance index, trajectory optimization during atmospheric flight was transformed into standard optimal control model and was solved by Gauss pseudospectral method. The optimal atmospheric flight trajectory was “aerocruise+aeroglide+aerocruise+aeroglide”. Finally, detailed comparisons were carried out for the two methods. The results show that when the perigee of initial elliptic orbit is more close to atmospheric boundary, aeroassisted symmetric transfer is more predominant than the two-impulse symmetric transfer.
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    Effect Analysis of Plasma Density on Ion Beam Extracted by Grid System
    JIA Yan-Hui, LI Zhong-Ming, ZHANG Tian-Ping, LI Juan
    2012, 32 (3):  72-77.  doi: 10.3780/j.issn.1000-758X.2012.03.011
    Abstract ( 1844 )   PDF (390KB) ( 1090 )   Save
    Presentanalysesontheionbeamofthegridsystemdonottakeaccounttheplasmadensityindischargerchamber.Ionbeamextractionwassimulatedbytheparticleincell(PIC)method.Theelectricfieldwascalculatedbythefinitedifferentialmethod(FDM),andtheionparticleswereacceleratedbytheleapfrogmethod.WithChinese20-centimeterXeionthruster,theelectricpotentialandionbeamdistributionsinthecenterandbrimapertureofgridsystemwereobtained.Theresultsshowthattheionbeamextractedbythecenteraperturehasbetterfocuspropertyandsmallerdivergenceanglethanthatofthebrimionbeam.However,thesaddlepointpotentialofthecenterapertureis24.8V,higherthanthatofthebrim.Hence,theplasmadensityindischargerchamberhasanimportanteffectontheionbeamextraction,andelectronbackstreamingphenomenatakeplaceonthecenterpositionofgridsystemfirstly.
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    Compression Mass Gauge Method for Liquid Propellant Residue
    FU Juan, CHEN Xiao-Qian, HUANG Yi-Yong
    2012, 32 (3):  78-83.  doi: 10.3780/j.issn.1000-758X.2012.03.012
    Abstract ( 1603 )   PDF (356KB) ( 1530 )   Save
    The measurement methods for liquid propellant residue was mainly discussed and the theory of compression mass gauge (CMG) was introduced. Firstly, thermodynamic models were established based on the gas in tank. According to the real thermodynamic process of the gas, the process exponential could be calculated, and the gas and liquid volume could be computed respectively. Then, the thermodynamic models for isothermal, adiabatic and normal conditions were deduced based on the tank system. Heat and mass transfer between gas and tank/liquid were considered. The compression adiabatic model was selected. Secondly, measurement errors were analyzed and the relevant modifications were put forward. Finally,  the accuracy for liquid propellant residue volume reached 1% of the total tank volume. The problems were studied, such as the selection of the compression frequency, volume change and measurement equipment.  With proper design, CMG is an available method for liquid propellant residue with high accuracy.
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