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25 February 2019, Volume 39 Issue 1 Previous Issue    Next Issue

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SLAM method of failure spacecraft based on prior submap detecting KANG Guo-Hua, MA Yun, QIAO Si-Yuan, GUO Yu-Jie, JIN Chen-Di 2019, 39 (1):  1.  doi: 10.16708/j.cnki.1000-758X.2019.0001 Abstract ( 653 )   PDF (9002KB) ( 369 )   Save The technology of estimating position and pose of spacecraft based on laser lidar is a research hotspot of onorbit services. For the position and pose estimation of failure spacecraft, the technology of general graphbased optimization SLAM was applied to the research of noncooperative target in space. In order to solve the problem of accumulative error generated in the dynamic scene, an improved SLAM algorithm based on detection of prior submap according to the characteristics of failure spacecraft was proposed. In this algorithm, laser lidar and inertia measurement unit were used to sample the point cloud data of failure spacecraft as well as the environment and the movement information of service spacecraft, to construct a relative pose graph of service scenario. Then the method of detecting prior submap was used to generate the constraints of discontinuous poses. At last, the constraints information was used to optimize the result of pose graph. The simulation result shows that the method decreases the cumulative deviation and improves precision of relative position and pose estimation compared to general SLAM algorithm, providing information for onorbit tasks such as navigation and controlling. Related Articles | Metrics

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A method of SpaceWireD schedule generation JIANG Hong, YANG Meng-Fei, LIU Bo, LIU Hong-Jin, GONG Jian 2019, 39 (1):  11.  doi: 10.16708/j.cnki.1000-758X.2018.0065 Abstract ( 614 )   PDF (2330KB) ( 364 )   Save Being aimed at highspeed SpaceWireD, a method of schedule generation was put forward, implemented with greedy algorithm combined with SMTSolver. The greedy algorithm was designed to generate a set of constraint for SMTSolver and to make the frames and frame chips distribute more uniformly in the generated schedule. The SMTSolver is an important tool and its function is to determine the satisfiability of input parameters. If it is satisfiable, the output module is the schedule wanted. In addition, new policies were proposed about setting the length of frame chips, the size of timeslots, and collision area division. The method was verified with experiments. The results show that the generation algorithm can acquire a schedule featured by approximate uniform distribution in hundreds of milliseconds. Related Articles | Metrics

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Error source analysis and compensation in test chain for dualaxial analog sun sensor XU Xiaodan, WANG Jianfu, CHONG Huixuan, GAO Changshan, LIANG He, HONG Shuai, 2019, 39 (1):  19.  doi: 10.16708/j.cnki.1000-758X.2018.0072 Abstract ( 553 )   PDF (8157KB) ( 155 )   Save Based on 4quadrant silicon cell, a dualaxial analog sun sensor can get the sun incident angle about two axes simultaneously. The acquisition accuracy of the four quadrant photocurrents determines the sensor performance directly. But the inconformity arisen from the test chain brings measurement deviation to the sensor. Therefore, based on numerical simulation, the influence model of the inconformity in the responsivity of each cell quadrant and then the C/V transformer, amplifier, A/D conversion and dark current for each quadrant photocurrent was established and analyzed. Then the calibration and compensation of such error sources were proposed. As a result, the requirement for the uniformity in the test chain can be lowered with the precondition of the sensor measurement accuracy. Test result shows that without changing the test chain parameters, the measuring accuracy of the sun sensor is improved from 2.05° (αaxis, 3σ) and 1.94° (βaxis, 3σ) to 0.28° (αaxis, 3σ) and 0.26° (βaxis, 3σ). Related Articles | Metrics

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Regional improved Klobuchar model for BeiDou and its correction accuracy analysis LIU Ruihua, XUE Kaimin, WANG Jian 2019, 39 (1):  25.  doi: 10.16708/j.cnki.1000-758X.2018.0066 Abstract ( 675 )   PDF (4652KB) ( 437 )   Save The BeiDou satellite navigation system uses the Klobuchar model to correct the ionospheric delay error for single frequency receiver users. However, due to the application of this model from the perspective of the Asian region, the correction accuracy in a specific region is even less than 50%.In order to further improve the accuracy of regional ionospheric delay correction, an improved Klobuchar model that adds five key parameters on the basis of eight correction parameters of the original model was proposed, and then the values of these additional parameters were obtained through the algorithm combining relax iterative and the golden section of the linear search.Taking Tianjin and its vicinity as an example, the measured data collected by the GPStation6 receiver was used to calculate the improved model and the original model.The global ionospheric grid data published by the International GNSS Service (IGS) was used as a reference value to compare and analyze the accuracy of the improved model and the original model.The results show that the average correction accuracy of ionospheric delay of the improved model in Tianjin and its vicinity is 10.46% higher than that of the original model, and the average accuracy reaches 77.51%. Related Articles | Metrics

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Research on spatial target structure recognition based on deep neural network ZHOU Chi，LI Zhi，XU Can 2019, 39 (1):  32.  doi: 10.16708/j.cnki.1000-758X.2018.0064 Abstract ( 657 )   PDF (10928KB) ( 383 )   Save The use of Radar Cross Section (RCS) sequences for spatial target structure recognition is an important part of space situational awareness. RCS sequence is easily affected by the target physical characteristics and attitude characteristics,and the nonstationary characteristics of the sequence signal are obvious. In this paper, deep neural network (DNN) algorithm was used to solve the problem of spatial target structural feature recognition. For the problem of feature extraction without distinguishing degree, fractal features were used to extract the fractal features of RCS sequences, and the Fisher′s decision rate was used for selecting traditional features. What′s more, the DNN algorithm and data processing process were introduced. Finally, a set of simulation test data were used to verify the algorithm. The analysis results show that the DNN algorithm is robust and accurate in solving the problem of using RCS sequence to identify the target structure. Related Articles | Metrics

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Highprecision visual navigation for space debris based on satellite formation YANG Bo，WANG Haofan，MIAO Jun，ZHAO Xiaotao 2019, 39 (1):  40.  doi: 10.16708/j.cnki.1000-758X.2018.0073 Abstract ( 381 )   PDF (9660KB) ( 205 )   Save Visual methods are widely used for noncooperative targets navigation because there is no communication among satellites and noncooperative targets like space debris. To solve the uncertainty positions caused by aberrations of visual sensors, a stereoscopic visual navigation strategy based on satellite formation was formulated. Firstly, a longbaseline visual sensor was constructed by satellite formation. The observability of the system was analyzed and verified by Fisher matrix. Secondly, the error analysis of the stereo sensor was performed, and by arranging the optimal parallax angle, the measurement information fusion of multiple satellites was optimized. Finally, the proposed method is applied in the navigation of space debris. The simulation results demonstrate that the satellite navigation based visual navigation can significantly reduce the observation errors, the accuracy can reach the order of 0.1m, and the formation configuration is simple and easy to implement. Related Articles | Metrics

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Design and test of a sampler for lunar surface regolith JIANG Shuiqing, LIU Rongkai, LIN Yuncheng, MA Ruqi, LIU Bin, LIU Tianxi 2019, 39 (1):  49.  doi: 10.16708/j.cnki.1000-758X.2018.0067 Abstract ( 668 )   PDF (13262KB) ( 559 )   Save A sampler carried on the end of the manipulator was designed in view of the sampling task of the lunar surface regolith. Based on the discrete element method, the parameters matching of the simulation particle characteristics was completed by using the data of the miniature three axis compression test data of Scott real lunar regolith. The simulation analysis of the sampling process of the sampler was carried out and the dynamic characteristics of sampler during the working process were obtained. In addition, the performance test system of sampler was set up. The sampling test was carried out for different simulated lunar soil. The test acquired the sampling capacity of the sampler changing with the depth and the lunar soil hardness. And the feasible region of the sampling device's operating parameters was obtained by testing. The sampler can achieve the multiple tasks of transferring encapsulated containers, shoving and excavating. The research work will provide reference and technical support for future lunar sampling missions in China. Related Articles | Metrics

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Research and development of simulation platform for orbital debris removal with spacebased laser system YANG Wulin, CHEN Chuan, YU Qian, LI Ming, GONG Zizheng 2019, 39 (1):  59.  doi: 10.16708/j.cnki.1000-758X.2019.0002 Abstract ( 407 )   PDF (6312KB) ( 694 )   Save In order to analyze the procedures from both debris and removal system perspectives during debris deorbiting to improve the removal planning and schemes, a three dimensional simulation platform for orbital debris removal with spacebased laser system was constructed based on the trackable debris data. First of all, requirements, overall structures and modules of the simulation platform were fully described. Then laserdriven orbital transfer model was analyzed to realize the modules. Finally, the simulation platform was developed using C++/Qt and validated by simulations. This simulation platform can be used to removal planning for various spacebased lasers and debris, removal system design for hotspot debris removal and spacecraft defense as well as scheme optimization for clean space. Related Articles | Metrics

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A study on matrix error correction code for memory hardening SHI Yugen, LI Shaofu,QI Yike 2019, 39 (1):  67.  doi: 10.16708/j.cnki.1000-758X.2018.0070 Abstract ( 318 )   PDF (4941KB) ( 420 )   Save In order to correct the multiple bit upsets (MBU) of high energy particles in the radiation environment, a matrix error correcting code circuit was proposed to strengthen the memory effectively. A method of rectangular cyclic parity was proposed to construct the parity bit, and the decode algorithm and the corresponding decoding circuit of correct code against MBU was proposed. The detection bit was constructed by parity bit. The order of the input of the data was arranged to ensure the error correcting code circuit worked normally when redundant bits flipped. In the 16bit data,the proposed matrix error correct code can correct MBU with 5 bit data. Compared with the current known error correction codes in the same conditions, the matrix error correction codes are obtained with higher mean time to failure (MTTF). Related Articles | Metrics

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Satellite attitude control method and physical test with load disturbance suppression LI Mingqun，LEI Yongjun，MU Xiaogang 2019, 39 (1):  73.  doi: 10.16708/j.cnki.1000-758X.2018.0074 Abstract ( 417 )   PDF (4350KB) ( 684 )   Save The interference suppression method was studied for the periodic change of the satellite generated by the rotation of the load. Using the theory of Lyapunov stability, an adaptive control algorithm based on parameter identification for periodic signal was proposed. And then physical experiment verification using real onorbit computer and control components was carried out．The results show that the method proposed is in effect, improving satellite stability by fifty percent, and is easy to realize. Related Articles | Metrics

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A ROSbased solution to the space plugandplay architecture LI Changchun，QIAO Bing，WANG Hebin 2019, 39 (1):  78.  doi: 10.16708/j.cnki.1000-758X.2018.0068 Abstract ( 665 )   PDF (6377KB) ( 551 )   Save To enable the plugandplay of the spacecraft systems, a middleware software system should be equipped beforehand to automatically deal with the selfdiscovering, selfconfiguration and communication between the components. A SPA software solution based on the Robot Operating System (ROS), or RSPA in short, was proposed. The RSPA software architecture that can handle the heterogeneous nature of SPA network was presented after the analysis and comparison between the software architectures of ROS and SPA. Then the problem of the implementation of SPA protocol through ROS environment was addressed. Finally, an emulation system which was used to verify the effectiveness of RSPA was demonstrated. Compared with the previous space plugandplay architecture software implementation, RSPA has a clear network model, is easier to expand, and can effectively utilize ROS′s stable infrastructure and rich tools to accelerate software development. Related Articles | Metrics