May 2022, Volume 4 Issue 4
    

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  • Research Progress of Small Body Surface Motion Technologies
    YU Zhengshi, ZHU Shengying, CUI Pingyuan, LIU Yanjie
    2017, 4(4): 301-309. https://doi.org/10.15982/j.issn.2095-7777.2017.04.001
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    Based on small body surface exploration missions carried out so far and future development trends of small body surface exploration technology, the necessity and key technologies of small body surface motion are elaborated. Firstly, the difficulties and challenges encountered in small body surface explorations are summarized. Then, thekey technologies related to the small body surface motion are outlined, and the research progress of these technnologies are surveyed. Finally, future research focuses and development trends of small body landing technologies are discussed.
  • The Status of NASA Mars 2020 Rover Landing Site Selection and Some Thoughts on the Landing Part of China 2020 Mars Mission
    YE Binlong, ZHAO Jiannan, HUANG Jun
    2017, 4(4): 310-324. https://doi.org/10.15982/j.issn.2095-7777.2017.04.002
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    The important discoveries of Mars exploration in the past 20 years and the major unsolved questions on Martian life, climate and geology were reviewed. The scientific goals, payloads information and engineering constrains of the National Aeronautics and Space Administration (NASA) 2020 Mars mission were presented. In addition, the geologic characteristics of the top 8 candidate landing sites selected by hundreds of planetary scientists in three landing site selection workshops were described. Three candidate landing zones for China’s 2020 Mars mission were proposed based on the different mission goals: 1) addressing key life, climate and geology questions; 2) resource reconnaissance for future human missions; 3) engineering demonstration.
  • Research on Form-Finding and Deployment Dynamics for Modular Cable-Truss Antenna
    CHANG Hanjing, WANG Bi, LUO Kai, TIAN Qiang, HU Haiyan
    2017, 4(4): 325-332. https://doi.org/10.15982/j.issn.2095-7777.2017.04.003
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    In recent years，large deployable space structures such as modular space deployable antenna has great development potential to meet the nation’s requirements in future space technology. The modular space deployable antenna is a rigid-flexible coupling multi-body system mainly composed of flexible supported truss，cable-net structure，metal mesh reflector and rigid joints. In order to indicate the dynamic response of the space deployable antenna，an asymptotic iterative form-finding method is proposed based on the force density method，and the rigid-flexible truss is modeling in the frame of the absolute nodal coordinate formulation. Besides，the cable-net structure is modeling with NURBS （Non-Uniform Rational B-Splines） cable element. Further more，，the dynamic differential algebraic equations of the rigid-flexible system are established based on the first Lagrangian’s equation，and the generalized -α method is used for the high-performance numerical integration. Finally，the dynamic deployable response of the modular cable-truss antenna is studied.
  • Mobility and Kinematic Analyses of a Novel Deployable Composite Element
    XU Yundou, LIU Wenlan, CHEN Liangliang, YAO Jiantao, ZHAO Yongsheng, ZHU Jialong
    2017, 4(4): 333-339. https://doi.org/10.15982/j.issn.2095-7777.2017.04.004
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    A novel deployable mechanism9RR-12URU with multiple degrees of freedom（DoFs）is proposed，which can be used as the minimum composite element of the supporting mechanism of large-diameter truss antennas. This deployable mechanism consists of three 3RR-3URU tetrahedral units. The DoF of a tetrahedral unit is analyzed based on the screw theory，and then the DoF of the 9RR-12URU mechanism is obtained by using the method of splitting rod groups. According to the geometric positions and coordinate transformation matrices of the nodes，the analytic expressions of the position and velocity of each node in the folding/deploying process of the mechanism are derived. Furthermore，the RPY angle is adopted to describe the orientation of each node with respect to the fixed node. The theoretical analyses on the DoF and kinematics of the9RR-12URU mechanism are verified by Adams software. The results show that the mechanism has two kinds of DoFs：translational and rotational DoFs，which contribute to achieving the maximum folding ratio of the mechanism. The9RR-12URU deployable mechanism has a simple structure and a large folding ratio，that can be applied to truss deployable reflectors with a bent surface.
  • Design and Analysis of Approximate Cylindrical Deployable Mechanism with Bennett Linkages
    YANG Jiaxin, LV Shengnan, DING Xilun
    2017, 4(4): 340-345. https://doi.org/10.15982/j.issn.2095-7777.2017.04.005
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    Deployable mechanisms can be deployed to the designated configuration for work，and can also be folded for facilitating transportation. It has broad application prospects in space，architecture，and other fields. A deployable mechanism is presented, which uses the Bennett over-constraint mechanism as a basic element. Working surface of the mechanism can be fitted to cylindrical surface. Meanwhile，all bars of the mechanism can be compactly folded into a bundle configuration. Firstly，geometric description of the Bennett mechanism is analyzed，and its kinematic characteristics are discussed. Secondly，combination of unit mechanism is realized by using the scissors linkage，ensuring that the design key points are accurately located on the target surface. Finally，kinematics and dynamic performances of the mechanism are simulated, validating the proposed design and providing theoretical fundamental for the follow-up prototype development.The Bennett over-constraint mechanism in this paper is simple and have high precision and rigidity，which can be well applied to the cylindrical surface of the antenna design. This study is of great value to the design and analysis of aerospace deployable mechanism.
  • Experimental Study on the Bending Creep Behavior of CFRP Tube
    MA Yu, WANG Hui, SHAO Zhenwei, YANG Zengqin, SHANG Fulin, HOU Demen, GENG Hongbin, LV Gang
    2017, 4(4): 346-354. https://doi.org/10.15982/j.issn.2095-7777.2017.04.006
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    To evaluate the service reliability of Carbon Fiber Reinforced Plastic （CFRP） composite tubes used in spacecraft structure，static three-point-bending and creep tests of the CFRP tube are performed. At first，experimental tests of bending modulus and bending rupture strength，500-hour-long constant temperature creep，–60 ℃～100 ℃ and –160 ℃～80 ℃ thermal cyclic creep are conducted for the tube respectively. Based on the testing results，long-term creep deformation of the tube is predicted，using the time-temperature-stress superposition principle，the derived creep master curves as well as a phenomenal Findley model. Then，assessment on the mechanical strength and load-carrying capacity of the CFRP tube is made according to a maximum strain criterion. Results show that the CFRP tube can meet the creep deformation and strength requirements under the long-term service lifetime.
  • Rigid-Flexible-Attitude Control Integrated In-Orbit Vibration Analysis Method for Large Satellite Reflector Antennas
    LIU Cuicui, GE Dongming, DENG Runran, ZOU Yuanjie, SHI Jixin
    2017, 4(4): 355-360. https://doi.org/10.15982/j.issn.2095-7777.2017.04.007
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    Large deployable mesh antennas will be used increasingly in the spacecraft. Not only the size of the antenna increases more and more，but also the technical requirement becomes even tighter. The mechanical motions coming from attitude control，orbit control，solar array rotating inevitably result in vibrations of large reflector structure and lead to reducing the electrical performance of the antenna and the quality of the mission. A rigid-flexible-attitude control integrated analysis method is presented. The integrated simulation model consists of disturbance，rigid-flexible coupling dynamic model，attitude control，and antenna vibration effect analysis. Under the typical operating disturbance modes of the satellite，the computations of the vibration responses，the whole antenna pointing and the distortion level of the antenna structure are carried out. The analysis results will support the antenna in-orbit vibration effect analysis，performance index prediction，and vibration transfer mechanism analysis and vibration control measures.
  • Coverage of Lunar Farside Surface of the Earth-Moon L2 Periodic Orbits
    LIU Lei, CAO Jianfeng, HU Songjie, TANG Geshi
    2017, 4(4): 361-366. https://doi.org/10.15982/j.issn.2095-7777.2017.04.008
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    Orbits nearby the Earth-Moon libration points have the specific dynamic characteristicsand are the preferred position of relay satellites for the lunar farside exploration. For relay requirements of the future lunar farside exploration, the surface coverage of the Earth-Moon L2 periodic orbits is studied. Firstly, the continuation method calculating the halo orbit family is proposed with the circular restricted three-body problem. The south and north halo families with a large scope are calculated in the Earth-Moon system. Secondly, the coverage model of the lunar farside surface is presented for the relay satellites. The coverage factors are consequently defined. Finally, the coverage is numerically simulated. The results show that the coverage capacity is decided by the amplitude and style of L2 orbits. A halo orbit with small amplitude has an excellent entire coverage capacity, while a large one has a better coverage capacity for the south or north poles. Furthermore, the research can provide a beneficial reference for the orbit design of the future CHANG’E-4 mission.
  • Same-Beam VLBI in Lunar Orbiter Rendezvous and Docking
    REN Tianpeng, TANG Geshi, XU Bai, LU Weitao, CHEN Lue, HAN Songtao, WANG Mei
    2017, 4(4): 367-372. https://doi.org/10.15982/j.issn.2095-7777.2017.04.009
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    To obtain a high precision relative measurement between the orbiter and the ascender of the CE-5 lunar probe, a same-beam VLBI algorithm is propsed in the framework of the deep-space interferometry processing center. The conditions and results of getting a right cycle ambiguity are discussed. After introducing the group-delay-aided phase interferometry，the random errors of interferometrical delay are suppressed greatly. It provides a priori condition for a right cycle ambiguity. Finally，the proposed algorithm is verified by using the CE-5 data，laying the foundation for the X-band same-beam VLBI in the CE-5 task.
  • Study on Deep Space Time Registration Method of Integrated Navigation System Based on Celestial Angle and Velocity Mesurement
    ZHANG Heng, ZHANG Wei, CHEN Xiao
    2017, 4(4): 373-378. https://doi.org/10.15982/j.issn.2095-7777.2017.04.010
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    Combining the celestial angle measurement with the velocity measurement, the deep space integrated navigation system is derived to determine the position and velocity information of deep space probe. The integrated navigation system has the advantages of continuous, autonomous, real-time and high precision measurement. In the multi-sources information fusion process of the integrated navigation system, an unified time standard of multi-sensor data is required. The basic principle of celestial angle and velocity measurement integrated navigation system is clarified. However, there are many factors will cause time asynchrony in the actual system, such as time standard error, sampling period inconsistent, data transmission delay of angle measurement sensors and velocity measurement sensors, which have great influence on the position and the velocity of measurement information. The mechanism of time error in position and velocity estimation of deep space integrated navigation system is analyzed. The time registration method based on interpolation and extrapolation methods is studied, achieving the measurement information synchronization between the angle measurement sensor and the velocity measurement sensor. The simulation results show that the interpolation and extrapolation time registration algorithm can effectively suppress the time error, improve the accuracy of the deep space integrated navigation system.
  • Application of Fuzzy Grey Clustering Evaluation Method in Navigation Filter
    XU Zhaoqian, ZHAO Fangfang, CHEN Cuiqiao
    2017, 4(4): 379-384. https://doi.org/10.15982/j.issn.2095-7777.2017.04.0011
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    At present, there are many kinds of methods for the comprehensive evaluation of filtering algorithms in deep space exploration, but most of them have problems more or less because of their singleness. In this case, a set of index system that reflects the degree of the filtering algorithm was put forward，and the corresponding mathematical model for the algorithm was established. The data of deep space probe sampling points were calculated by the model, and then synthetically evaluated by the fuzzy grey clustering method. The proposed evaluation model combines the grey system theory with the fuzzy comprehensive evaluation method . The model overcomes the shortcomings when the two methods are used seperately, and improves the accuracy of the evaluation results. The evaluation results show that the evaluation model is more accurate, and reasonable, which can evaluate the filtering algorithm comprehensively.
  • Performance Analysis and Simulation of BCH（63，56）
    ZHAN Yafeng, XIE Dezhun
    2017, 4(4): 385-389. https://doi.org/10.15982/j.issn.2095-7777.2017.04.012
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    BCH（63，56）is widely used in uplink channel of deep space communication for low-complexity implementing，which can check 2 bits error and correct 1 bit error. The performance of BCH（63，56）is studied by theoretical analysis and computer simulation in this paper. On the basis of introducing the basic principle of BCH（63，56），the performance of bits error rate is calculated and the Monte Carlo simulation is carried out. The results show that the coding gain of BCH（63，56）can be up to 2.1 dB when the bit error rate is 1e–5.
  • Distributed Finite-Time Control Method for Formation Flying
    KANG Shen, SHAN Jiayuan
    2017, 4(4): 390-394. https://doi.org/10.15982/j.issn.2095-777.2017.04.0013
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    In this paper，a dynamic model of single spacecraft is simulated by a double integrator and the communication topology is assumed fixed. Based on the information exchanges among neighbors，the distributed finite-time control protocol is designed and mathematically verified. Adopt the presented control protocol and combined with virtual structure and hierarchical protocol，the formation algorithm is designed，where in a group spacecraft on a lower level takes orders from spacecraft on a higher level. The numerical simulation is conducted，verifying the effectiveness of the proposed method.