Aerospace Contrd and Application

Select A Survey of GNC Critical Techniques for Development of China Spacecrafts in the Future

LI Guo

2009, 35(6): 1-5.

Abstract ( 25 )

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This paper shows needs for spacecraft development in the future, based on comparing the gap between advanced techniques of spacecraft control system abroad and existing techniques in China, presents development goals and direction of the spacecraft control field. Finally, some critical techniques for developing spacecraft guidance, navigation and control of China are proposed.

Select Dynamics Modeling and Simulation Verification for Space Robot

ZHANG Jun, , HU Haixia,

2009, 35(6): 6-12.

Abstract ( 52 )

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The dynamics model of a free-flying space robot with arbitrary joints connected manipulator is established, and verified by numerical simulation. Firstly, the model of a space multi-body system with three degrees of freedom in adjacent bodies is established using Kane equation. Then, projective operators are used to transform general equations into the dynamics model of a space robot with one degree of freedom between the bodies of its manipulator. Three fundamental dynamical theorems, i.e. momentum theorem, momentum moment theorem, kinetic energy theorem are used to design the algorithm to verify the dynamics model. Finally, numerical simulation verifies the dynamics model of the space robot.

Select Deep Space Exploration Mission-Oriented Flight Control Simulation and Support System#br#

YUAN Li, CHENG Ming

2009, 35(6): 13-18.

Abstract ( 31 )

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To ensure accurate and flawless flight and timely actuation of failure-safety measures for deep space exploration spacecrafts, a flight control simulation and support system is proposed. Based on the requirement analysis, a frame scheme diagram and a work flow chart are depicted. Five technical features including high accuracy attitude and orbit simulation, failure simulation and injection etc. are described. The effectiveness of the system is verified by comparing the simulation result and the result of in-orbit flying. Finally the prospect of further development is presented.

Select An Attempt at Improving Dynamic Performance of Star Tracker by Motion Compensation

GONG Dezhu, WU Yanpeng, LU Xin

2009, 35(6): 19-23.

Abstract ( 27 )

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A motion compensation (MC) method is introduced to improve dynamic capability of star tracker. Then the MC principle is explained in detail, including charge-transfer in hardware and SNR-improving in software, with the emphasis on implementation means and conditions. The charge-transfer in hardware include special disposal in X and Y directions of charge couple device (CCD)，and SNR-improving in software is realized in digital signal processing (DSP) .Finally, in order to improve the dynamic capability, primary design and calculation based on STS star tracker made in China are presented. The results show the MC takes effect on dynamic capability improvement of star sensors.

Select A LIDAR-Based Autonomous Landing Site Selection Method for Pinpoint Lunar Soft Landing

LIANG Dong, , WANG Pengji, , LIU Liangdong

2009, 35(6): 24-29.

Abstract ( 35 )

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This paper studies an autonomous landing site selection method for lunar pinpoint soft landing during lander’s motion. The method includes 4 steps: motion compensation, digital elevation map generation, obstacle detection and optimal safe-site search. According to the compensated data provided by light detection and ranging, the digital elevation map is generated, then the definitions of the lunar surface roughness and slope are given, and a safely landing criterion is presented to detect the obstacle. Based on this concept, a central-helix searching method is designed to select the optimal safe landing site for lunar landers. The simulation results show validity and superiority of the autonomous landing site selection method.

Select Design of Space Rendezvous and Docking Transverse Linear Movement Simulator Control System Based on H∞ Theory

LI Gming, YAO Yu

2009, 35(6): 30-35.

Abstract ( 16 )

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The paper investigates the design of simulator transverse linear movement control system for space rendezvous and docking, and discusses the unstructured uncertainty model. The robust H∞ control strategy is designed according to performance indexes and main uncertainties, and the principle and method for choosing weighting functions of the mixed sensitivity optimal design are studied. The robust H∞ controller is provided and obtained through solving three LMIs. The physical test results meet the requestments, and show the effectiveness of the proposed method.

Select CCD Chip’s Temperature Effect on Position Accuracy of Star Sensor

SHEN BenjianLIU HaiboJIA HuiYANG JIankun

2009, 35(6): 36-40.

Abstract ( 44 )

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CCD noise is an error source of guide star position of star sensor. The DV437-BU2 CCD chip’s dark current, dark current shot noise and dark current non-uniform noise characteristics of temperature have been measured in this paper. The effect of CCD chip’s temperature on star position accuracy has been researched. The results show that decreasing CCD chip’s temperature could improve the star position accuracy effectively when the temperature is higher than 300K, but could not remarkably when the temperature is lower than 300K. The star position accuracy level is improved from 0.12 pixel to 0.078 pixel when the temperature reduces from 330K to 300K.

Select Sun Sensor-Based Orbit Position Estimating Method for GEO Satellites

XU Jingyu, GAO Yijun

2009, 35(6): 41-44.

Abstract ( 20 )

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In order to estimate orbit position of GEO satellites using existing on-board equipments, this paper describes the system composed of sun sensors and earth sensors. According to nature of orbit of GEO satellites combined with Hill equation, state equations and measurement equations of this system are established by using measurement information from sun sensors and earth sensors, as well as orbit perturbation characteristics. Simulation results show that longitude’s excursion of the satellite can be accurately estimated by this method, and it is a feasible autonomous navigation method for GEO satellites.

Select Quadratic-Based Computation of Four-Impulse Optimal Rendezvous between Near Circular Orbits

CHEN Changqing, XIE Yonghcun

2009, 35(6): 45-49.

Abstract ( 26 )

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In this paper, a method of solving quadratic equations-based four-impulse optimal rendezvous between near circular orbits is investigated. Dimensionless dynamics equations for rendezvous between near circular orbits and their corresponding primer vector equations are introduced. And the method of quadratic equations-based four-impulse optimal rendezvous presented by Carter is explained. Then four concepts including original solution, reciprocal solution, dual solution and dual reciprocal solution of rendezvous between near circular orbits are given. By using these concepts the problems of solving quadratic equations-based four-impulse optimal rendezvous are analyzed, and a modifying method is given. The simulation results show that the modifying method is a good supplement for the method of quadratic equations-based four-impulse optimal rendezvous.

Select Monocular Vision-Based Relative Position and Attitude Measurement Algorithm for Non-Cooperative Spacecrafts

ZHANG Jinfeng, SUN Chengqi, CAI Wei

2009, 35(6): 50-53.

Abstract ( 28 )

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A novel monocular vision-based relative position and attitude measurement algorithm named as the Similar Iteration algorithm is presented for non-cooperative spacecrafts in this paper. The algorithm derives a new depth iteration mechanism from principle of triangular similitude and involves two steps, i.e. the depth estimation and solving the absolute orientation problem. Numerical simulations have demonstrated the effectiveness of the proposed algorithm.

Select Numerical Simulation for Reorientation of Propellant in a Vane Tank under Microgravity

HU Qi, CHEN Jian, LI Yong

2009, 35(6): 54-57.

Abstract ( 33 )

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Reorientation of propellant in a vane surface tension tank is of great significance for the ascertainment of propellant distribution, and research on liquid shaking mechanism, and improvement of control accuracy and so on. In order to investigate a law of propellant reorientation, propellant reorientation processes in vane type tank under different microgravity conditions are numerically simulated. The paper introduces a two-phase flow model of three-dimensional unsteady VOF (volume of fluid) , and based on the model numerically simulates all kinds of reorientation processes in a vane type tank during near depletion phase under different microgravity acceleration conditions, then all processes of propellant reorientation under different working conditions and propellant distributions after reorientation are obtained. The simulation results provide advantageous foundation for design of the vane tank.