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25 August 2004, Volume 24 Issue 04 Previous Issue    Next Issue

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A Control Method for Large Angle Rapid Maneuvering of Spacecraft Appendages Guan Yifeng Li Tieshou Wang Dianjun(Beijing Institute of Control Engineering, Beijing 100080) 2004, 24 (04):  .  Abstract ( 1583 )   Save Spacecraft appendages maneuver with large angle, the whole system is a nonlinear, coupled one. For the appendage control loops, it is required that appendages maneuver to the anticipated position and stabilize as soon as possible. Based on feedback linearization nonlinear differentiation control method is presented in this paper. The dynamic performance of appendage loops is improved and the stability of the closed-loop system is proved. At last, the result of simulation shows that this method is effective. Related Articles | Metrics

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Advances and Trends on Non-linear Dynamics ofSpacecraft Joint-Dominated Structure Wang Wei Yu Dengyun(Chinese Academy of Space Technology, Beijing 100081)Ma Xingrui(China Aerospace Science and Technology Corporation, Beijing 100830) 2004, 24 (04):  .  Abstract ( 1506 )   Save Non-linear dynamic behaviors of spacecraft joint-dominated structure affect spacecraft modeling, attitude control and pointing precision. This paper introduces advancement in local non-linearity, non-linear vibration of structure, normal non-linear modal and model reduction. Finally, some advices about future development in this field are given. Related Articles | Metrics

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Fault-tolerant Twice Median Smoother Algorithmfor Non-stationary Signals Hu Shaolin Huang Liusheng(University of Science & Technology of China, Hefei 230027)Wang Min Zhang Junhong(Xi'an Satellite Control Center, Xi'an 710043) 2004, 24 (04):  .  Abstract ( 2060 )   Save Smoother is one of the widely used approaches to eliminate or to weaken the stochastic error from sampling data. A new kind of fault-tolerant smoothing algorithm is presented in this paper. This so-called fault-tolerant twice-median smoother is constructed with doubly sliding median smoothers and sliding mean smoothers, and can be used to smooth noise and to extract signals without removing any outliers before. Some theoretical results and simulation show that this new smoothing algorithm has the abilities to avoid bad influence from outliers and patchy in sampling time series and to extract signals unfailingly. Related Articles | Metrics

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Integrated Analysis of Thermal ManagementSystem in Large Spacecraft Xu Xiaoping Li Jindong Fan Hanlin(Chinese Academy of Space Technology, Beijing 100086) 2004, 24 (04):  .  Abstract ( 1621 )   Save The temperature of thermal management system in hypothetic space lab is illustrated. The model of the system is consisted of external and internal thermal control sub-system, avionics air cooling sub-system in racks, cabin air cooling system and two sub-modules of heat transfer. The one of sub-modules modeled heat transfer by radiation and conduction among equipment, racks, gas cylinders and inner cabin wall. The other modeled heat transfer by radiation among outer cabin wall, radiatior, solar panel and external radiation environment. The results of temperature's modeling of the system will not only support design of thermal management system of large spacecraft, but also provide system analysis, which included sensible analysis, test data correlation, optimizing design, reliability analysis and robust design. The thermal management system can be extended to energy system by adding power sub-system and then the modeling of thermal system will benefit to analyse energy balance and power/thermal system matching of the energy system. Related Articles | Metrics

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Improved Scheme and Simulation ofDouble-star Positioning System Zhao Li Liu Jianye Lin Xueyuan Xiong Zhi(Nanjing University of Aeronautics & Astronautics, Nanjing 210016) 2004, 24 (04):  .  Abstract ( 1505 )   Save Double-star positioning system has its disadvantages because the mode of the system is active two-way ranging, such as user's position is easily exposed to enemies, the time delay, and so on. So passive ranging mode is considered to improve the double-star positioning system. Two improved schemes with adding pseudo-satellite based on the actuality to get more observed quantities are presented in this paper and optimum layout of the pseudo-satellites is also pointed out. When the position of pseudo-satellites is in optimum condition, it can be proved that the way that adding pseudo-satellites in the double-star positioning system can really improve the precision of position by comparison and analysis. Related Articles | Metrics

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Research on the Orbit Keeping of theSun-synchronous Repeating Orbit Zhao Jian(National Universit of Defense Technology, Changsha 410073) 2004, 24 (04):  .  Abstract ( 2288 )   Save This paper discusses some subjects about the orbit keeping of the sun-synchronous repeating orbit by the analytical point of view. The factors that affect the action of the sun-synchronous repeating orbit are put forward,which include non-sphere perturbation, air-drag and sun-gravity resonance. These analysis lay the foundation for the research of orbit keeping of the sun-synchronous repeating orbit. The result of quantitative analysis shows that the method is feasible, and be helpful for the research of orbit design and control. Related Articles | Metrics

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Study for Gimbal Magnetic Suspension Momentum Wheel Wu Gang * Zhang Yulin ** Liu Kun * Cheng Moushen * Xiao Kai *(* National University of Defense Technology, Changsha 410073)(** Academy of Equipment Command & Technology, Beijing 101416) 2004, 24 (04):  .  Abstract ( 2039 )   Save Fly wheel system is widely used in majority of spacecrafts to control three axes attitude recently. Its precision is higher than that of small thruster system. But the magnetic suspension momentum wheel has better performance than the conventional ball bearing momentum wheel in spacecraft attitude control. The gimbal magnetic suspension momentum wheel developed from the ordinary one can adjust the angular orientation of its spin axis and complete three axes attitude control in high precision separately, which has great value in practice. Simultaneously, the study for gimbal magnetic suspension momentum wheel can benefit the integrated power and attitude control system technologically. This paper describes the research status and development of the gimbal magnetic suspension momentum wheel in detail. Then the key technologies are analyzed. Finally the example of structure design is introduced. Related Articles | Metrics

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Bilevel Decomposition Based Global Optimization Approachfor Launch Trajectories of GTO Launchers Luo Yazhong Tang Guojin Liang Yangang Zhou Lini(National University of Defense Technology, Changsha 410073) 2004, 24 (04):  .  Abstract ( 2550 )   Save An approach for GTO launch trajectory optimization design is proposed, which is consisted of bilevel programming method,trajectory decomposition optimization design and hybrid Genetic Algorithm. In order to overcome the poor convergence problems caused by the couple of system variables and optimal control variables, the bilevel programming model is set up, in which the master problem only deals with the system variables, and the junior problem only deals with the trajectory optimal control variables. The all-up launch trajectory optimization design problem is divided into two segment trajectory optimization design problems. The pipeline hybrid Genetic Algorithm is applied to solve the junior problem. As an example, maximal payload optimization design of a two-stage GTO launcher is completed, several problems such as how to choose pitch angle and how to choose parameters of launch trajectory are discussed, and several constructive conclusions are gained. This approach for GTO launch trajectory optimization has been testified with predominant performance index, and has great engineering value in launch vehicle system design. Related Articles | Metrics

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Integrative Analysis on Thermal and FlowPerformance of Single-phase Fluid Loop System Zhang Li Fan Hanlin(Chinese Academy of Space Technology, Beijing 100086) 2004, 24 (04):  .  Abstract ( 1508 )   Save Three methods of studying the fluid loop system are outlined. The procedure for calculating and analyzing the thermal and flow performance of single-phase fluid loop is introduced. And then , take a single-phase fluid dual-loop system for instance, it is calculated using MATLAB and modeled with SINDA/FLUINT. The applicability of SINDA/FLUINT in this area is proved by comparing the results acquired in the above two ways . Related Articles | Metrics

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Modal Analysis of Reflector of Deployable Parabolic Antennawith Truss Structure Xiong Yonghu(Institute of Electronic, Chinese Academy of Science, Beijing 100080)Kou Xiaodong Liu Xiaoning(ANSYS, Inc. Beijing Office, Beijing 100007) 2004, 24 (04):  .  Abstract ( 1833 )   Save Modal analysis is described about the reflector of deployable parabolic antenna with truss structure by using ANSYS soft with its many element types and its powerful programming language APDL. The results show that the connection type of poles in reflector doesn't play an important role in oscillation of reflector, different rigidness of the torsion spring within a certain range will result in same numbers of mode and similar mode shapes. Related Articles | Metrics

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Precision Analysis of SGP4/SDP4 Implemented in Space Debris Orbit Prediction Han Lei Chen Lei Zhou Bozhao(National University of Defense Technology, Changsha 410073) 2004, 24 (04):  .  Abstract ( 3103 )   Save To insure the security of space mission, the dangerous big debris must be tracked and predicted. Firstly, the computing model of standard orbit is given in this paper. Secondly the coordinate transformation from True Equator and Mean Equinox of Date to Earth Mean Equator and Equinox of Date which two-line mean element (TLE)used is provided. And Simplified General Perturbations Version 4 and Simplified Deep-space Perturbation (SGP4/SDP4)which developed from analytic orbital theory are introduced. Then according to the typical orbits, the precision of SGP4/SDP4 is analyzed. The result shows that SGP4/SDP4 are efficient and valid to the initial prediction of danger. Related Articles | Metrics