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    25 April 2008, Volume 28 Issue 02 Previous Issue    Next Issue
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    Autonomous Navigation for Navigation Satellites Based on X-ray Pulsars
    Shuai Ping Li Ming Chen Shaolong Wu Yifan Zhang Chunqing(China Academy of Space Technology,Beijing 100094)
    2008, 28 (02):  1-7. 
    Abstract ( 1828 )   Save
    Constellation rotation errors accumulating with time is a problem for the autonomous navigation constellation based on the cross-links.It is very difficult to keep the constellation autonomously operating for a long time.A new approach to solve the constellation rotation issue is using the X-ray pulsar navigation(XPNAV).When the X-ray photons from the pulsars are detected with the on-board detector,the pulse profile of the pulsar is folded and the image also obtained.And then pulse arrival time is recorded with the on-board atomic clocks.Moreover,the navigation parameters for the satellites,including the position,velocity,attitude and time,can be determined accurately by the data processing with the on-board computer.Since the X-ray signal from the pulsar provides an absolute space-time reference for the navigation satellites,consequently there is not the constellation rotation issue.The basic concept,system composing and geometric principle of XPNAV were described briefly.Especially,the adaptive Kalman filtering algorithms of the orbit determination and time synchronization for the navigation satellites were studied in detail.According to the numerical analysis results,the feasibility and rationality to solve the issue of the autonomous navigation constellation rotation using the X-ray pulsar is demonstrated.
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    Selection of Reference Systems for Optimal Impulsive Rendezvous Between Two Near Circular Orbits
    Xie Yongchun Chen Changqing Zhang Hao Hu Jun(National Laboratory of Space Intelligent Control,Beijing Institute of Control Engineering,Beijing 100190)
    2008, 28 (02):  8-14+27. 
    Abstract ( 1945 )   Save
    First,the dimensionless linear equations were introduced.Then it was proved that the selection of reference systems had no influence on the categories of optimal impulsive rendezvous.By using three examples including two-impulse optimal rendezvous,two-impulse with coast optimal rendezvous and Hohmann optimal rendezvous,it was demonstrated that the choice of reference systems had no effect on the process of solving the corresponding optimal rendezvous model.Finally,analysis and simulation show that the selection of reference systems does affect the final results of the optimal rendezvous.
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    Research on Method of Spacecraft Orbit Determination Based on Penalized Least Squares Estimation
    Pan Xiaogang Zhou Haiyin(Department of Mathematic and System Science,National University of Defense Technology,Changsha 410073)
    2008, 28 (02):  15-20+50. 
    Abstract ( 2115 )   Save
    The partial linear observation model was established by transforming the spacecraft dynamic model error into system error of observation model,and the parameter estimation method of partial linear observation model based on Penalized Least Squares Estimation was deduced,and correlative character of the method was proven.Estimation experiment results prove that partial linear model is close to the true characteristic of the measurement data,and the parameter estimation method approaches to the real state of spacecraft,the precision of orbit determination based on penalized least squares estimation is obviously better than the traditional least squares estimation.
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    Analysis of Locking Stiffness of Primary Mirror Deployment Mechanism for Space Optical Remote Sensors
    Sun Guopeng Liu Zhiquan(China Academy of Space Technology,Beijing 100094)
    2008, 28 (02):  21-27. 
    Abstract ( 1727 )   Save
    The locking stiffness between the petal and the central part was simplified by the equivalent spring model.Using this model,the effects of the locking force and the ball diameter on the modal frequencies of the structure were analyzed.The analytical results show that the fundamental frequency of the structure connected by the kinematic couplings declines from 33.592 Hz of the fixed structure to 10~20 Hz,and it is more effective to increase the modal frequencies of the structure connected by the kinematic couplings by increasing the diameters of the location balls than by increasing the locking force.
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    Micro-spacecraft Attitude Matrix Determination Algorithm Based on Unscented Particle Filter
    Wang Chen Fang Jiancheng(School of Instrumentation Science and Optoelectronics Engineering,Beijing University of Aeronautics and Astronautics,Beijing 100083)
    2008, 28 (02):  28-34. 
    Abstract ( 1850 )   Save
    In view of the problem that the noise of the inertial-stellar attitude determination system is non-Gaussian distribution,selected unscented particle filter(UPF)for the attitude determination system.UPF uses the unscented Kalman Filter(UKF)to generate sophisticated proposal distributions.It can avoid the limitation of the Extended Kalman Filter(EKF)and the UKF which only apply to Gaussian distributions.This paper takes the Micro Electro Mechanical System(MEMS) gyros and CMOS APS(Complementary Mental Oxide Semiconductor,Active Pixel Sensor)star sensor as attitude sensors,the method of attitude determination uses minimal-parameter attitude matrix estimation as the attitude parameter,presents a UPF attitude estimator.The attitude determination filter was constructed and semiphysical simulation was adopted from the MEMS gyro,and the unscented particle filter's characters are analyzed and compared with the EKF and the UKF.The simulation results show the system performance is improved by the suggested method.The convergence rate and the determination accuracy are higher than the EKF and the UKF.
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    Satellite Attitude Fault-tolerant Control Based on Robust Adaptive Inverse Optimal Control
    Chen Xueqin Geng Yunhai Wang Feng Zhang Yingchun(Research Center of Satellite Technology,Harbin Institute of Technology,Harbin 150080)
    2008, 28 (02):  35-41. 
    Abstract ( 2184 )   Save
    The robust adaptive inverse optimal fault-tolerant control problem of satellite attitude control system was studied.Considering the faults of actuators and sensors and uncertainty in fault detection and diagnosis(FDD),the adaptive inverse optimal fault-tolerant controller was designed by using the uncertainty parameter as the on-line estimated adaptive parameter.The design of the adaptive inverse optimal fault-tolerant controller was based on the inverse optimal principle to solve the adaptive control Lyapunov function(ACLF) of auxiliary system.The robustness of system under fault conditions was proved.The simulations validate that this solution is effective and more suitable for on-board real-time computation.
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    Research and Simulation on Precise SINS/CCD/GPS Integrated Navigation System
    Yang Bo1 Qin Yongyuan2 Chai Yan3 Peng Huihuang4(1 The Second Artillery Engineering College,Xi'an 710025)(2 College of Automation,Northwestern Polytechnical University,Xi'an 710072)(3 School of Materials,Northwestern Polytechnical University,Xi'an 710072)(4 The Military Deputy Office of the Second Artillery in Factory of Hong Yang,Xiaogan 432100)
    2008, 28 (02):  42-50. 
    Abstract ( 2116 )   Save
    The errors of strapdown inertial navigation system(SINS) were chosen as states of the integrated system.The attitude matrix outputs from SINS and charge coupled device(CCD) starsensor were used to construct the observation,and the algorithm of SINS/CCD integrated navigation was designed.The velocity outputs and position outputs from SINS and global positioning system(GPS) were used to construct the observation,and the algorithm of SINS/GPS integrated navigation was designed.Then by the federated Kalman filtering,local optimal estimations of system states from the local filters were passed to the master filter,and the master filter can give the global optimal estimates of states through the global optimal fusion algorithm.Simulation results show that SINS/CCD/GPS integrated navigation system had high navigation accuracy,with the positioning accuracy up to 3.5 meters,and the azimuth accuracy up to 9 angle seconds,which was very fit for the precise navigation for aerocrafts.
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    Research on Orbit Determination of Micro-satellite Using GPS Pseudo-range
    Zhang Limin1 Xiong Zhi1 Yu Feng1 He Liang2 Liu Jianye1(1 Navigation Research Center,Nanjing University ofAeronautics and Astronautics,Nanjing 210016)(2 Shanghai Aerospace Control Engineering Institute,Shanghai 200233)
    2008, 28 (02):  51-55+65. 
    Abstract ( 2153 )   Save
    The trends of developing micro-satellites are high reliable,high accuracy,completely autonomous and low cost.GPS has been applied in low earth orbit spacecraft,because it has the advantages of low cost,high accuracy and low power consumption.The GPS pseudo-range was used as measurement values,and the measurement still could be obtained even when the GPS visible stars were few.The orbit accuracy was improved and the cost was reduced.The memory attenuated extended Kalman filter(MAEKF) was presented.Through adjusting covariance matrix,the application of historic data in the new data was reduced,so the influence of orbit perturbation on orbit accuracy was reduced.The simulation reslts show that the MAEKF is better than extended Kalman filter(EKF) in accuracy.When visible GPS stars are few,it still can realize information fusion.
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    Influence of Outgas Effect and Radiometer Effect on Sensitivity of Electrostatic Accelerometer
    Wang Zuolei(Lanzhou Institute of Physics,Lanzhou 730000)
    2008, 28 (02):  56-59+71. 
    Abstract ( 2154 )   Save
    Radiometer effect and outgas effect will occur in the vacuum chamber of the electrostatic accelerometer if temperature gradient noise exist.Based on kinetic theory of gases and statistical theory,the analysis and calculation show that the acceleration noise incluced by outgas effect is dozens of times larger than what radiometer effect incluced under the same condition,and the outgas effect also has greater influence on the sensitivity of the electrostatic accelerometer.Thus outgas effect should be an important reference factor for the design of the electrostatic acceler-ometer.
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    Arithmetic and Analysis of Phased Array Scanning
    Gao Zhaozhao Yang Hui(China Academy of Space Technology,Beijing 100094)
    2008, 28 (02):  60-65. 
    Abstract ( 1890 )   Save
    The arithmetic of satellite phased array scanning was deduced and a simplified model for on board phased array scanning was presented.The arithmetic in this paper gave out the formula of computing the planar angle of satellite phased array scanning based on the satellite orbit and attitude,and during the flight the phased array kept pointing to targeted point.According to the simulation,the relationship between pointing precision and attitude precision is achieved,a simplified model of autonomous control is provided,and meanwhile,the validity of the arithmetic is proved.The arithmetic can act as a basis for on-board autonomous computation.
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    Flow Simulation and Performance Prediction of Free Molecule Micro-resistojet
    Chen Maolin Mao Genwang Yang Juan Xia Guangqing(College of Astronautics,Northwestern Polytechnical University,Xi'an 710072)
    2008, 28 (02):  66-71. 
    Abstract ( 3734 )   Save
    To accurately predict the performance of FMMR,under different propellant and working conditions,Direct simulation Monte Carlo method was used to simulate the gas flow in FMMR.The thrust and specific impulse of FMMR were calculated,and the influence of propellant types,working pressure as well as heating temperature on the performance of FMMR was studied.Results of calculation and analysis show that the propellant kind has no effect on thrust,while specific impulse rapidly increases with the decreasing of propellant molecule weight;the specific impulse of FMMR increases with the height of working pressure and heating temperature,and thrust increases with the increasing of the working pressure but decreases with the increasing of the heating temperature.
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