Table of Content

    25 August 2008, Volume 28 Issue 04 Previous Issue    Next Issue
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    Feed Forward PID Control of Satellite Single-phase Fluid Loop Thermal Control System
    Ning Xianwen Zhang Jiaxun Zhao Xin (China Academy of Space Technology,Beijing 100094)
    2008, 28 (04):  1-6. 
    Abstract ( 1975 )   Save
    The transfer mechanism of satellite single-phase fluid loop thermal control system was analyzed and simplified.A transient thermal model including thermal modules model, controlled-object model,and control system model was developed.Aiming at the reduction of the temperature dynamic deviation caused by the larger inertia of satellite single-phase fluid loop,the heat load was taken as a feed forward control disturbance signal of satellite single-phase fluid loop on the basis of current PID control.Simulation results indicate that the feed forward PID control strategy has less disadvantage and better performance.The results can also instruct the engineering design.
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    Study on the Problem of Broadcast Ephemeris for Hybrid-constellation Navigation Satellite
    Xi Bo Wang Wei Xi Xiaoning (National University of Defence Technology,Changsha 410073)
    2008, 28 (04):  7-12. 
    Abstract ( 1955 )   Save
    The broadcast ephemeris parameters for GPS have the characters of less parameters, unambiguous physical significance and high precision.It may be used in hybrid-constellation satellite navigation system which includes different kinds of satellites,for example,MEO satellites, IGSO satellites and GEO satellites.The accuracy of broadcast ephemeris for above different kinds of satellite orbits using the broadcast ephemeris parameters for GPS was analyzed.The variety law of the fitting result for broadcast ephemeris parameters within an orbit period of satellite was com- pared too.The simulation result shows that the fitting errors of broadcast ephemeris for MEO, IGSO and GEO are less than decimeters.It also shows that the variety laws of the fitting result of broadcast ephemeris for MEO and IGSO satellites are similar to each other and are different to GEO satellites.
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    Information Fusion Algorithm of Satellite Multi-sensor Autonomous Navigation System
    Li Dan Liu Jianye Xiong Zhi Zhang Limin (Navigation Research Center,Nanjing University of Aeronautics and Astronautics,Nanjing 210016)
    2008, 28 (04):  13-18. 
    Abstract ( 2231 )   Save
    There are many navigation sensors onboard a satellite.The main question is how to manage and use the information they supplied.Combining two or more navigation systems with information fusion technology and optimal estimation theory becomes the trend of the navigation techniques.It takes full advantage of the system complementarily.A satellite autonomous orbit determination system which composed of star tracker,infrared horizon sensor,radar altimeter and ultraviolet sensor was put forword.Base on that system,a federated kalman filter and a new information fusion algorithm were presented.The simulation results verify that this method can obtain high accuracy and reliability.The divergence of filter can be controlled.The calculation speed and convergence speed to the whole system also can be improved.
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    Lunar Soft Landing Rapid Trajectory Optimization Using Direct Collocation Method
    Tu Lianghui Yuan Jianping Luo Jianjun Fang Qun (College of Astronautics,Northwestern Polytechnical University,Xi'an 710072)
    2008, 28 (04):  19-24+39. 
    Abstract ( 2490 )   Save
    The application of direct optimization method (direct collocation method & nonlinear programming (NLP)) to lunar probe soft landing trajectory optimization was introduced.Firstly, the model of trajectory optimization control problem to lunar probe soft landing trajectory was established and the equations of motion were simplified respectively based on some reasonable hypotheses.Performance was selected to minimize the fuel consumption.The control variables were thrust attack angle and thrust of engine.Terminal state variable constraints were velocity and altitude constraints.Then,the optimal control problem was transformed into nonlinear programming problem using direct collocation method.The state variables and control variables were selected as optimal parameters at all nodes and collocation nodes.Parameter optimization problem was solved using the SNOPT software package.The simulation results demonstrate that the direct collocation method is not sensitive to lunar soft landing initial conditions;they also show that the optimal solutions of trajectory optimization problem are fairly good in real-time.Therefore, the direct collocation method is a viable approach to lunar probe soft landing trajectory optimization problem.
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    Application of Euler-Poincare Equation in Lost of Attitude Control Mechanism of Russian Space Station Mir
    Liu Yunping Wu Hongtao Fang Xifeng (College of Mechanical Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210016)
    2008, 28 (04):  25-31. 
    Abstract ( 1923 )   Save
    The Russian space station Mir suffered an unexpected collision when airship M-34 docked with it in1997.The kinematics equations established by methods of Euler and quaternion and the dynamics equations by Euler-poincare equations were applied to demonstrate the attitude maneuvers of Mir.An useful method by using thrust of Soyuz to make solar arrays illuminated by the sun obtained.Simulation results show that the method is effective and feasible.
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    Dynamic Modeling and Modal Analysis of Smart Solar Array
    Jiang Jianping Li Dongxu (College of Aerospace and Material Engineering,National University of Defense Technology,Changsha 410073)
    2008, 28 (04):  32-39. 
    Abstract ( 1867 )   Save
    Researches on the dynamic and control for the flexible spacecraft usually use the modal of the flexible appendages.In order to achieve precision attitude of the spacecraft,the vibration of the flexible appendages need to be suppressed.This problem can be solved effectively with piezoelectric sensor/actuator.The finite element modeling of the solar array with piezoelectric sensor/actuator was presented.The mathematical model was based on the first order shear deformation (FSDT).The dynamic models included the mechanical-electrical coupling effect and axial load in the 3-D beam elements.The shear locking problem was solved by assuming a shear strain field.The results of the modal analysis show that the dynamic characteristics changes with the different distribution of piezoelectric sensor/actuator.The axial load in the tripod of the solar array can increase the swaying frequency largely.The piezoelectric actuators applied voltages can enhance the structural damp of the solar array.
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    Implementation and Application Study of CCSDS Lossless Data Compression Algorithm
    Zhu Yunhua Wang Fengyang Liu Yong Dong Yong (Shandong Aerospace Electro-technology Institute,Yantai 264000)
    2008, 28 (04):  40-46. 
    Abstract ( 2273 )   Save
    Lossless data compression is one of the major services in space flight missions and remote-sensing systems.Based on the preliminary study of CCSDS (Consultative Committee for Space Data System) recommended standard for lossless data compression,the fundamental principles and coding methods for the Rice algorithm recommended by CCSDS were discussed.Then its DSP (Digital Signal Processor) implementation and optimization version were addressed with the input data rate 11Mbit/s.The results in terms of performances show that it can be integrated into on-board data processing module for missions that don't require high throughout rate.Finally,how the lossless data compression was integrated into the CCSDS-based on-board data systems was studied.
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    Effect Analysis of Work of Thruster to Satellite Orbit
    Yang Hui Yuan Lifang (China Academy of Space Technology,Beijing 100094)
    2008, 28 (04):  47-52. 
    Abstract ( 1818 )   Save
    The analytical model of the thrusts was built based on its assembly and the operation information in geosynchronous orbit.The impact of the thrust to the operating orbit in various conditions was analyzed.The impact effect of the thrust on the orbit was evaluated and the analytical results were compared.In addition,the thrust extrapolate modeling modification was also presented,which improved the orbital extrapolate precision.
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    Life Prediction for Circulation Pump of Manned Spacecraft Based on Wiener Process
    Feng Jing Zhou Jinglun (College of Information System and Management,National University of Defense Technology,Changsha 410073)
    2008, 28 (04):  53-58. 
    Abstract ( 1809 )   Save
    Reliability of eccentric pump of manned spacecraft is very high,life data is rare.It's difficult for traditional reliability analysis methods based on life data to meet the engineering re- quirements.Firstly,lift and power were proved to be two critical performance parameters for circu- lation pump.The Wiener process with drift was proposed to fit the degradation process of the two performance parameters.The random weighted method was proposed to solve the small sample problem confronted in estimating parameters for degradation paths.The life distribution model was obtained by random process theory.In the end,the life of circulation pump is predicted to illustrate the effectiveness of the model.
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    Research on Rough Set Applied to Satellite Power System Fault Diagnosis
    An Ruoming~1 Gu Jihai~2 He Chuanyan~1 Jiang Xingwei~1 (1 School of Astronautics,Harbin Institute of Technology,Harbin 150001) (2 College of Mechanical-electronic Engineering,Harbin University of Commerce,Harbin 150028)
    2008, 28 (04):  59-64. 
    Abstract ( 2167 )   Save
    Rough Set technique is introduced for increasing the diagnosis capability of multi- fault diagnosis algorithm when diagnosis knowledge is not mature.The reduction problem of decision table,which is one of Rough Set techniques,is researched.The reduced algorithm was given.The step and disadvantages of the diagnosis algorithm was discussed in detail.The Rough Set technique and the diagnosis algorithm were combined.The modified diagnosis algorithm was put forward.The technology was applied to fault diagnosis of a satellite power system.Real time diag- nosis can be proceed successfully while lack of symptom information is lack.It proved that the diag- nosis capability and efficiency was increased.
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    Methods of Accelerated Life Tests for Long-life Spacecraft Mechanisms
    Liu Zhiquan Li Xinli Yu Jin (China Academy of Space Technology,Beijing 100094)
    2008, 28 (04):  65-71. 
    Abstract ( 2170 )   Save
    The basic concept,types and features of accelerated life tests were introduced.The methods of accelerated life tests for long-life spacecraft mechanisms,both in China and abroad, were reviewed.The characteristics of methods of accelerated life tests for both solid-lubricated and oil-lubricated long-life spacecraft mechanisms were analyzed.Solutions to some problems existed in quasi-accelerated life tests for long-life spacecraft mechanisms were put forward.
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