【作者】 郁丰；

【导师】 刘建业；

【作者基本信息】 南京航空航天大学 ， 导航、制导与控制， 2008， 博士

【摘要】 微小卫星是当前空间技术领域的热点之一,提高微小卫星姿态确定技术的水平对提升微小卫星平台的性能具有重要意义;同时,随着微小卫星的增多与空间安全的需要,由微小卫星组网构成微小卫星星座的轨道自主确定也引起了人们的重视。本文就微小卫星姿态确定与基于星间测距信息的微小卫星组网自主定轨技术开展了研究,主要内容如下:微小卫星姿态确定系统受成本、质量和功耗的严格限制,姿态敏感器的选择范围小,所以开展了基于微型低功耗新型姿态敏感器的姿态确定技术研究:提出利用CMOS相机对地球边缘成像,克服由安装和控制系统指向误差带来的图像畸变,并利用非线性最小二乘算法提取地心矢量,仿真表明效果较理想;GNSS(Global Navigation Satellite System)接收机可将部分功能集成在星载计算机中实现,所以基于GNSS的卫星姿态确定技术可使姿态确定系统进一步微型化,针对GPS研究了基于单频短基线的整周模糊度快速搜索方法,设计了姿态确定的解算流程,并搭建了地面验证系统,结果表明方法可行;针对建设中的伽利略卫星导航系统,研究了采用三个载波频率的整周模糊度快速求解算法,在分析三载波模糊度搜索成功率的基础上,提出建立小模糊度搜索空间与相应的寻优搜索方法,提高了模糊度搜索的成功率,缩短了初始化时间。采用新型的信息融合技术是提高微小卫星姿态确定精度和可靠性的有效措施。为提高无陀螺微小卫星姿态确定的精度,将预测滤波算法引入到姿态确定中,从而克服无法建模的非高斯误差的影响,并提出模型误差加权阵偏小设计准则,简化了滤波器设计并克服了滤波的初始振荡;采用改进联邦滤波实现多个低精度姿态敏感器的信息融合,该算法在主滤波器中实现信息预测与分配,子滤波器仅完成量测更新,降低运算量的同时仍具有较高容错能力。在轨实时标定是提高微型低精度姿态敏感器测量精度的又一途径。开展了基于磁强计的剩磁在轨标定方法的研究,基于常值偏置的磁强计测量模型建立了考虑星体剩磁干扰的姿态动力学模型,仿真表明该标定模型效果良好;建立了不依赖其余测量信息的MEMS陀螺偏置标定模型,并分析了适用条件,仿真表明标定方法可行并具有一定精度,适合微小卫星入轨初期使用。利用星间测距信息进行了微小卫星组网自主定轨技术的研究。针对由数目众多的微小卫星组网构成的微小卫星星座,首先分析了基于星间测距的可观测性,提出了星间测距模型与关键的仿真方法,并进行了测距定位精度的影响分析,仿真表明了方法的有效性;在此基础上引入星地链路来固定星座整体基准,仿真验证了该方案的可行性,为微小卫星组网并实现轨道长期自主确定提供了一种解决思路。利用STK(Satellite Tool Kit)与Matlab构建了一套姿态确定与控制系统的仿真验证平台,该平台能实现姿态确定算法与控制律的快速验证,减轻了研制人员的负担;根据某型微小卫星姿态确定与控制系统的任务,在确定系统配置、布局、任务流程和基本算法的基础上,利用PC104嵌入式计算机与VxWorks实时多任务操作系统开发了某型微小卫星的软件研制与半物理仿真平台,验证了方案、任务规划与算法设计的准确性。本文的研究工作有助于微小卫星姿态确定与组网轨道自主确定技术的进步,具有理论与工程参考价值。更多还原

【Abstract】 Micro-Satellite is one of hotspots in space technology domain currently. It’s significative to enhance micro-satellite attitude determination technology to improve performance of micro-satellite platform, and autonomous orbit determination of constellation composed of micro-satellites is attractive while the increasing number of micro-satellites and space safety stress. In this dissertation, micro-satellite attitude determination and constellation autonomous orbit determination based on inter-satellite ranges is researched, which mainly consist of following parts:Because micro-satellite attitude determination system(ADS) is strictly restricted by cost, mass and power, so available attitude sensors are less, then attitude determination technology based on new subminiature attitude sensors with low power consumption is researched. COMS camera is adopted to image the earth rim, and correction method is derived to conquer earth rim image deformation which is produced by angle mounting and control error, consequently, the geocentric vector observation is achieved using nonlinear least squares estimation, the effect of the method is verified by simulation. Some functions of GNSS receiver can be realized in onboard computer, so ADS will be more subminiature if GNSS attitude determination technology is adopted. GPS ambiguity quick search algorithm based on short baseline and single carrier is presented and attitude resolution flow is designed. A GPS attitude determination system is established on ground and the results indicate the method is available. Ambiguity quick resolution method based on Three-Carrier Ambiguity Resolution(TCAR) Technique using Galileo system is researched, and a method based on a small ambiguity space and optimized ambiguity search algorithm is presented by analysis of probability distribution of integer ambiguity resolution by TCAR. It wins a higher success probability of integer ambiguity determination and save the initialization time.Adopting new information fusing method is effective to enhance precision and reliability for micro-satellite attitude determination. Predictive filtering is introduced into satellite attitude determination to conquer influence of non-gauss error which can’t be modeled to improve attitude determination performance for satellite without gyros. Lower design criterion of model error weight matrix is presented, so filter design is simplified and the oscillation at initial time is conquered. A improved federal filtering is presented to fuse multi-information from low precision attitude sensors. Prediction and distribution information are done in main filter, and only measurement renovating is processed by local filters. The method is with low computing cost and high tolerance.On-orbit calibration is an effective approach to improve attitude determination accuracy using micro attitude sensors of low precision. The satellite attitude dynamics including satellite remanence disturbing torques and magnetometer bias observing model are established. Simulation results indicate that calibration algorithm works well. A MEMS gyro bias real-time on-orbit calibration model independent of any other sensors is presented, and applicable conditions of the algorithm are derived. Simulation results show that the calibration algorithm is accurate, and is suitable for satellite orbit injection phase.Autonomous orbit determination of micro-satellite constellation relying on inter-satellite range is researched. According to constellation composed of numerious micro-satellites, observability of inter-satellite range is analyzed and inter-satellite range model and key simulation methods are given, then precision analysis for inter-satellite range is processed, and simulation proves the method is effective. Furthermore, satellite-ground range is introduced to fix the whole constellation, and the simulation validates the blue print is feasible and presents a solution for micro-satellite constellation long time autonomous orbit determination.A simulation platform for attitude determination and control system(ADCS) is constructed by STK and Matlab. Quick design and validating for attitude determination algorithm and control law is available using the platform, so designer’s burden is lightened. According to the ADCS tasks of a certain micro-satellite, the system configuration, components arrangement, task flow and essential algorithm are introduced, then ADCS software developing and semi-physics simulation platform is made based on PC104 embeded computer and VxWorks RTOS, and the scheme, task design and algorithm are proved to be correct.The research work in the dissertation is useful for further developing of micro-satellite attitude and orbit autonomous determination technology, and is valuable in theory and engineering.更多还原