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    25 February 2018, Volume 38 Issue 1 Previous Issue    Next Issue
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    TOA estimation methods for the observation data based on the X-ray pulsar-based navigation-1 (XPNAV-1) satellite
    Lin Qingqing, SHUAI Ping, HUANG Liangwei, ZHANG Xinyuan, CHEN Shaolong, WU Yaojun, BEI Xiaomin, MENG Jing, CHEN Qiang, ZHANG Qian, ZHANG Hengbin
    2018, 38 (1):  1-7.  doi: 10.16708/j.cnki.1000-758X.2018.0001
    Abstract ( 96 )   PDF (1088KB) ( 136 )   Save
    The first X-ray Pulsar-based Navigation-1 (XPNAV-1) satellite of China operates two X-ray instruments. The purpose of the XPNAV-1 mission is to detect the X-ray pulsars′ radiation photons and validate the pulsar navigation method. To acquire high precision pulse time of arrival (TOA) estimation, a novel method based on the multiple signal classification (MUSIC) algorithm was proposed, then numerical simulation was done for the novel method. The data from coordinate universaltime (UTC) 57727.0 MJD (modified Julian day) to UTC 57812.0 MJD of Crab pulsar observed by XPNAV-1 satellite was analyzed. Firstly, 121 pieces of the observations in the 0.5~10keV energy band were refined using epoch folding method. Secondly, the TOA of the epoch folding profiles was estimated by cross correlation method and MUSIC method. Finally, the estimations of the two methods were analyzed.
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    Adaptive control of coupled position and attitude for tracking characteristic point of disabled satellite
    WANG Xiao, SHI Peng, WEN Changxuan, ZHAO Yushan
    2018, 38 (1):  8-17.  doi: 10.16708/j.cnki.1000-758X.2018.0015
    Abstract ( 87 )   PDF (5683KB) ( 50 )   Save

    In order to realize the hovering and the attitude directing to characteristic point on disabled satellite at the same time, the relative dynamics and control between the characteristic point and the chaser were researched. The coupled position and attitude dynamic model was built under the chaser’s body frame. Combined with the kinematics of characteristic point, specific point, the expected position and attitude of the chaser were derived. considering the chaser’s mass, moment of inertia uncertainty, system’s disturbing force and disturbing moment uncertainty, and the moment of inertia uncertainty of the disabled satellite, an adaptive control law was designed, and the closed-loop system was proved to be stable through Lyapunov method. If there were constraints for the output, the process for adjusting the control parameters was designed and the output values were limited. The numerical simulation shows that the system can complete the tracking mission with position error1cm and attitude error 0.01° under the designed control law With the increasing of uncertain parameter’s deviations, the position error is raised to 7cm while the attitude error is raised to 0.1°. To adjust the control parameter and limit the output’s value, the control force and control moment can be restrained in the expected range while the tracking accuracy does not change, and the control required impulse can be reduced 9% while the required impulse moment can be reduced 30%.

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    Fast and stable tracking method for space manipulator capturing dynamictarget#br#
    WANG Xiaoxue, LIU Chuankai, WANG Baofeng, TANG Geshi, WANG Jia, GUO Xiangyan
    2018, 38 (1):  18-28.  doi: 10.16708/j.cnki.1000-758X.2018.0014
    Abstract ( 68 )   PDF (8243KB) ( 14 )   Save

    According to the application requirements of space manipulator capturing of flying targets, the problem of tracking the cooperative targets in the close range rendezvous and docking was investigated, and a novel method including three main steps was proposed. Firstly, according to the target’s luminescent property the feature selection algorithm was designed to eliminate the influence of invalid information. Secondly, using these features a method of similarity comparison between different frames and the strategy of template updating were investigated to solve the problem of invalidation of original features due to the variation of targets’ orientation and illumination. Thirdly, aiming at the problem of accessing and coming out of the view field, a method of abandoning and retrieving targets was designed. Finally, simulation results show that the proposed approach is fast and robust, and it can realize tracking speed of 10 frame/s.

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    Research ontime domain evaluation method ofBDS B1 band signal quality#br#
    ZHAO Yanan, LIU Ruihua, WANG Jian
    2018, 38 (1):  29-35.  doi: 10.16708/j.cnki.1000-758X.2018.0006
    Abstract ( 35 )   PDF (4137KB) ( 40 )   Save

    According to the modulation characteristics of BeiDou signal, the time do main quality of Beidou B1 frequency band signal was assessed from the time-domain waveforms, eye diagrams of Beidou B1 frequency signal and other aspects by using offline data analysis method, and theoretical analysis combined with real signal test. The feasibility of the evaluation method was verified and a relatively perfect time domain evaluation method was obtained to provide a basis for checking the signal time domain distortion. Besides, in order to measure the degree of signal distortion, three parameters were calculated, namely, lead/lag parameters in TMA, resonance frequency and attenuation factor in TMB, derived from the 2OS model adopted in Annex 10 of the Convention on International Civil Aviation issued by ICAO. The relationship between ranging bias and these parameters was analyzed to provide criteria for evaluating the single-satellite signal quality in time-domain.

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    Design ofreentry neuralnetwork adaptive attitude controller for reusable launch vehicle
    YU Guangxue, CHENG Xing, YANG Yunfei
    2018, 38 (1):  36-43.  doi: 10.16708/j.cnki.1000-758X.2018.0003
    Abstract ( 79 )   PDF (6136KB) ( 34 )   Save

    The control of reusable launch vehicle (RLV) is challenging due to the changes in the dynamics as the vehicle flies through large flight envelopes. There are uncertainties and disturbances in the reentry phase of RLV, influencing attitude control performance. Based on radical basis function neural network (RBFNN), an adaptive attitude controller design scheme was presented. Firstly, an RLV control model was developed. The fast and slow loops control system was designed based on time-scale separate theory. Then an RBFNN was implemented to generate the estimation of model uncertainty and disturbance. The adaptive controller based on RBFNN was used to compensate for the effect of the modeling error and disturbance torque. Results show that the control scheme meets the attitude tracking performance requirements. Simulation demonstrates that the RBFNN can estimate the modeling uncertainty and disturbance torque effectively.

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    Kinetic analysis on nano-pico satellite formation keeping
    YANG Bo, TIAN Miao, WEI Yanming
    2018, 38 (1):  44-53.  doi: 10.16708/j.cnki.1000-758X.2018.0016
    Abstract ( 34 )   PDF (6404KB) ( 35 )   Save

    To solve the control precision problem of the nano-pico satellite formation keeping, which had been the bottleneck of the nano-pico satellite applications, such as the earth-orienting technology, the high precision control theory was proposed based on low thrusters and the bang-bang control. A hybrid control principle and the finite-state machine were used to designtheprecisionoptimizationoftheformationkeeping.Anenergyoptimizationcontrol theory was developed based on the precision optimization. Simulation results show that the validity of the proposed strategy makes the system quickly converge to the equilibrium point and improves there liability and precision of the nano-pico satellite formation keeping on the low thrusters. The formation keeping precision can reach 1 μm, which means the precision 103 times better than the sliding mode method.

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    Contact dynamics analysis and control of space capture considering friction#br#
    DOU Bo, YUE Xiaokui
    2018, 38 (1):  54-62.  doi: 10.16708/j.cnki.1000-758X.2018.0018
    Abstract ( 75 )   PDF (5950KB) ( 35 )   Save

    Recently, there are a lot of researches for the contact of space capture, but the effect of friction is rarely considered. However, as an inevitable phenomenon in capture the friction has huge influence on the contact dynamics and the space capture missions. Combined with the advantages of the Coulomb dry friction theory and the Lagrange multiplier method, a new friction model considering both sliding and viscous states was established, and then the solution to the friction and contact force vector was combined to correct the contact model. In addition, regarding the influence of contact on the base of the space robot with the method of feedback linearization, a feedback decoupling controller was designed to control the base. A planar 2-DOF space robot was simulated to demonstrate the effectiveness of the proposed model and the control method. The results verify the dynamic model by linear and angular momentum theory, and the attitude of the base showed the effectiveness of the controller.

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    Research oncontrolstrategy ofterritory-hovering aerostatin nearspace#br#
    WANG Yiping, ZHOU Fei, XU Ming
    2018, 38 (1):  63-69.  doi: 10.16708/j.cnki.1000-758X.2018.0005
    Abstract ( 50 )   PDF (2696KB) ( 37 )   Save

    In order to achieve the aim of near space aerostat in territory-hovering, based on the analysis of the thermodynamic environment condition, the coupled aerodynamic and thermodynamic model of high altitude balloon containing the ballonet was established. Based on the special wind field of quasi-zero wind layer, a flight control strategy was designed to achieve the aim of territory-hovering by aerostat. The adjustment of flight altitude was controlled by changing volume of ballonet that succeeded in the balloon zonal direction movement through reverse airflow in quasi-zero wind layer of zonal wind, with utilizing propeller to generate a control force to achieve meridional direction control, and numerical simulation was carried out with ECMWF wind field data. The simulation results show that aerostat can fly within the territory at latitude 41°(N) to 43°(N), longitude 86.5°(E) to 87.1°(E) as long as 7 days, which proves the possibility of using quasi zero wind to achieve the aim of near space aerostat in territory-hovering.

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    Spacecraft autonomous navigation with cubature Kalman filter based on sun-earth-moon information#br#
    DENG Guanghui, LIAO Zhuofan, ZHU Rong, WANG Jiongqi
    2018, 38 (1):  70-76.  doi: 10.16708/j.cnki.1000-758X.2018.0012
    Abstract ( 59 )   PDF (2005KB) ( 38 )   Save

    High-precision and all-time spacecraft autonomous navigation is the development direction in the space technology application, and is also the foundation for the actual on-orbit application for the spacecraft. An autonomous navigation algorithm for spacecraft base on the astronomical information of the sun, the earth and the moon was researched. Firstly, by using the dynamics equations and the angles between the spacecraft, the earth, the sun and the moon, as well as the distance between the spacecraft and the earth as the state model and observation model respectively, the navigation system was established. Then, the autonomous navigation algorithm was presented. When the sun and the moon were observable, the autonomous navigation through the nonlinear cubature Kalman filter (CKF) was adopted; and the high-precise orbit prediction algorithm was used to predict the orbit by using the track dynamics directly during the eclipse. Finally, the numerical simulation was provided. Results show that the positioning accuracy of this method is lower than 2km, which is enough to satisfy the autonomous navigation.

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    A rapid three-dimensional measurement method for non-cooperative target#br#
    SUN Xiuqing, ZHANG Duzhou, WANG Li, WU Fenzhi
    2018, 38 (1):  77-83.  doi: 10.16708/j.cnki.1000-758X.2018.0019
    Abstract ( 72 )   PDF (4031KB) ( 35 )   Save

    When the servicing spacecraft is tracking, approaching and capturing target satellites, it is necessary to quickly and precisely obtain 3-D profile of target satellites’ local modules. A monocular camera measurement system based on structured-light was discussed. The system was designed to meet the needs of high speed and high accuracy. A coding method of De Bruijn sequence using white and black was proposed, and the reconstruction could be finished by a single picture. Besides, black and white stripes were still adopted, which has strong ant-interference in space. Compared with the method based on binocular vision, the projector’s physical model was the same as the camera, so the projector was served as a camera model according to this method. Without the matching of detected points in cameras and projectors in binocular stereo vision, the computing time was reduced. Three-dimensional points by iterative approach were reconstructed, with no need for advance distortion correction for pictures to use. Taking the satellite model as the target, reconstruction experiment was carried out using a high-speed camera. The experiment results indicate that the image acquisition time could reduce, and the depth information error is 0.0583 mm in reconstruction by this method. It can be used to measure the three-dimensional structure of non-cooperative spacecraft rapidly.

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