研究基于PI滤波估计加速度漂移的X射线脉冲星敏感器与加表组合导航算法。因长时间惯导误差积累导致发散,X射线脉冲星敏感器不能实时定位,且不能确定速度,提出利用X射线脉冲星敏感器脉冲到达时间(Time of arrival,TOA)作为观测量,与惯导...研究基于PI滤波估计加速度漂移的X射线脉冲星敏感器与加表组合导航算法。因长时间惯导误差积累导致发散,X射线脉冲星敏感器不能实时定位,且不能确定速度,提出利用X射线脉冲星敏感器脉冲到达时间(Time of arrival,TOA)作为观测量,与惯导推算的航天器位置在脉冲星指向上的投影估计位置误差,基于PI滤波估计加速度漂移,修正惯导误差,通过组合导航连续确定位置/速度。仿真表明,基于X射线脉冲星敏感器相位ϕ与加表组合天文导航算法能有效估计加速度漂移,并给出较高精度的位置/速度。展开更多
连线干涉测量(Connected Element Interferometry,CEI)是一种全天时全天候的被动测角技术,已用于空间目标的跟踪监视.地球静止轨道(Geostationary Earth Orbit,GEO)卫星需要频繁机动以保持轨位或完成其他任务,其机动后的快速轨道恢复能...连线干涉测量(Connected Element Interferometry,CEI)是一种全天时全天候的被动测角技术,已用于空间目标的跟踪监视.地球静止轨道(Geostationary Earth Orbit,GEO)卫星需要频繁机动以保持轨位或完成其他任务,其机动后的快速轨道恢复能力对于监视预警极为重要.针对基于CEI的GEO短弧定轨和预报,分析了定轨算法的形亏和数亏,在附加先验轨道约束的短弧定轨基础上,提出了轨道半长轴初值的自适应优化方法.利用亚太七号卫星的CEI仿真和实测数据进行了短弧定轨和预报,实验结果表明,采用优化后的半长轴初值,30min短弧定轨和10min预报的卫星位置分量精度均优于4km,能够满足非合作GEO目标机动后快速轨道恢复的需求.展开更多
Optical survey is an important means for observing resident space objects and space situational awareness.With the application of astronomical techniques and reduction method,wide field of view telescopes have made si...Optical survey is an important means for observing resident space objects and space situational awareness.With the application of astronomical techniques and reduction method,wide field of view telescopes have made significant contributions in discovering and identifying resident space objects.However,with the development of modern optical and electronic technology,the detection limit of instruments and infrastructure has been greatly extended,leading to an extensive number of raw images and many more sources in these images.Challenges arise when reducing these data in terms of traditional measurement and calibration.Based on the amount of data,it is particularly feasible and reliable to apply machine learning algorithms.Here an end-to-end deep learning framework is developed,it is trained with a priori information on raw detections and the automatic detection task is performed on the new data acquired.The closed-loop is evaluated based on consecutive CCD images obtained with a dedicated space debris survey telescope.It is demonstrated that our framework can achieve high performance compared with the traditional method,and with data fusion,the efficiency of the system can be improved without changing hardware or deploying new devices.The technique deserves a wider application in many fields of observational astronomy.展开更多
接收机系统间偏差(Inter-System Bias,ISB)稳定性分析对于了解ISB误差特性和建模预报具有重要意义.为了分析ISB的长期稳定性,选择MGEX(Multiple Global Navigation Satellite System Experiment)网2014—2016年每年各1周的数据,分别采...接收机系统间偏差(Inter-System Bias,ISB)稳定性分析对于了解ISB误差特性和建模预报具有重要意义.为了分析ISB的长期稳定性,选择MGEX(Multiple Global Navigation Satellite System Experiment)网2014—2016年每年各1周的数据,分别采用武汉大学和德国地学研究中心提供的精密钟差和轨道产品,利用BDS(Bei Dou Navigation Satellite System)/GPS(Global Positioning System)组合精密单点定位(Precise Point Positioning,PPP)计算测站的ISB值,并对ISB的日稳定性和周稳定性进行了深入分析.实验结果表明:ISB的日变化比较稳定,日标准差平均值约为0.5 ns.不同年份数据的ISB周平均值和周标准差的差异较大,并且ISB周平均值与测站的接收机类型有关.采用不同精密产品计算得到的ISB之间存在系统性偏差,对于同一周不同测站的ISB周平均值,该系统性偏差一致性较好.展开更多
根据高精度卫星导航定位的实际需要,介绍了利用中国GPS区域网双频相位平滑伪距实测数据,准实时监测区域网电离层电子总含量(TEC)变化和GPS卫星硬件延迟(DCB)的方法和结果.着重研究了区域网独立测定DCB的可靠性,利用中国境内的GPS站点分...根据高精度卫星导航定位的实际需要,介绍了利用中国GPS区域网双频相位平滑伪距实测数据,准实时监测区域网电离层电子总含量(TEC)变化和GPS卫星硬件延迟(DCB)的方法和结果.着重研究了区域网独立测定DCB的可靠性,利用中国境内的GPS站点分别构造了3个大小不同的区域网,通过实测DCB和垂直电子总含量(VTEC)与CODE(Center for Orbit Determination in Europe)结果的比对表明:为了获得区域网准实时测定DCB的可靠结果,对区域网的大小有一定的要求;利用中国GPS区域网,准实时测定的VTEC和DCB的比较精度可达2.0 TECu和0.25 ns.展开更多
文摘极移参数(polar motion,PM)是地球定向参数(earth orientation parameter,EOP)的重要组成部分,在天文大地测量、卫星的导航定位以及卫星的自主定轨等领域有重要的应用。本文首先利用国际地球自转服务(international earth rotation and reference systems service,IERS)提供的极移观测值进行极移时间序列频谱分析及周期项的提取。结果表明,快速傅里叶变换与离散傅里叶变换周期项提取到的周期项基本无差异,但极移X、Y分量时变分析结果存在差异。此外,本文将正弦逼近应用到极移参数的预报,对于长时间尺度的极移参数预报最小二乘外推模型效果最佳,但预报模型精度易受到周期项提取结果的影响;最小二乘外推模型在极移正向预报和反推拟合效果相近,借助正弦逼近方法可以一定程度上增强模型拟合效果。上述研究结果可为地球自转参数的预报研究提供参考。
文摘研究基于PI滤波估计加速度漂移的X射线脉冲星敏感器与加表组合导航算法。因长时间惯导误差积累导致发散,X射线脉冲星敏感器不能实时定位,且不能确定速度,提出利用X射线脉冲星敏感器脉冲到达时间(Time of arrival,TOA)作为观测量,与惯导推算的航天器位置在脉冲星指向上的投影估计位置误差,基于PI滤波估计加速度漂移,修正惯导误差,通过组合导航连续确定位置/速度。仿真表明,基于X射线脉冲星敏感器相位ϕ与加表组合天文导航算法能有效估计加速度漂移,并给出较高精度的位置/速度。
文摘连线干涉测量(Connected Element Interferometry,CEI)是一种全天时全天候的被动测角技术,已用于空间目标的跟踪监视.地球静止轨道(Geostationary Earth Orbit,GEO)卫星需要频繁机动以保持轨位或完成其他任务,其机动后的快速轨道恢复能力对于监视预警极为重要.针对基于CEI的GEO短弧定轨和预报,分析了定轨算法的形亏和数亏,在附加先验轨道约束的短弧定轨基础上,提出了轨道半长轴初值的自适应优化方法.利用亚太七号卫星的CEI仿真和实测数据进行了短弧定轨和预报,实验结果表明,采用优化后的半长轴初值,30min短弧定轨和10min预报的卫星位置分量精度均优于4km,能够满足非合作GEO目标机动后快速轨道恢复的需求.
基金funded by the National Natural Science Foundation of China(NSFC,grant Nos.12473079 and 12073082)the National Key R&D Program of China(No.2023YFF0725300)。
文摘Optical survey is an important means for observing resident space objects and space situational awareness.With the application of astronomical techniques and reduction method,wide field of view telescopes have made significant contributions in discovering and identifying resident space objects.However,with the development of modern optical and electronic technology,the detection limit of instruments and infrastructure has been greatly extended,leading to an extensive number of raw images and many more sources in these images.Challenges arise when reducing these data in terms of traditional measurement and calibration.Based on the amount of data,it is particularly feasible and reliable to apply machine learning algorithms.Here an end-to-end deep learning framework is developed,it is trained with a priori information on raw detections and the automatic detection task is performed on the new data acquired.The closed-loop is evaluated based on consecutive CCD images obtained with a dedicated space debris survey telescope.It is demonstrated that our framework can achieve high performance compared with the traditional method,and with data fusion,the efficiency of the system can be improved without changing hardware or deploying new devices.The technique deserves a wider application in many fields of observational astronomy.
文摘根据高精度卫星导航定位的实际需要,介绍了利用中国GPS区域网双频相位平滑伪距实测数据,准实时监测区域网电离层电子总含量(TEC)变化和GPS卫星硬件延迟(DCB)的方法和结果.着重研究了区域网独立测定DCB的可靠性,利用中国境内的GPS站点分别构造了3个大小不同的区域网,通过实测DCB和垂直电子总含量(VTEC)与CODE(Center for Orbit Determination in Europe)结果的比对表明:为了获得区域网准实时测定DCB的可靠结果,对区域网的大小有一定的要求;利用中国GPS区域网,准实时测定的VTEC和DCB的比较精度可达2.0 TECu和0.25 ns.
