Geomagnetic orbit determination fits for nanosatellites which pursue low cost and high-density ratio,but one of its disadvantages is the poor position accuracy introduced by magnetic bias.Here,a new method,named the f...Geomagnetic orbit determination fits for nanosatellites which pursue low cost and high-density ratio,but one of its disadvantages is the poor position accuracy introduced by magnetic bias.Here,a new method,named the fuzzy regulating unscented Kalman filter(FRUKF),is proposed.The magnetic bias is regarded as a random walk model,and a fuzzy regulator is designed to estimate the magnetic bias more accurately.The input of the regulator is the derivative of magnetic bias estimated from unscented Kalman filter(UKF).According to the fuzzy rule,the process noise covariance is adaptively determined.The FRUKF is evaluated using the real-flight data of the SWARMA.The experimental results show that the root-mean-square(RMS)position error is 3.1 km and the convergence time is shorter than the traditional way.展开更多
IGRF（International Geomagnetic Reference Field）即全球地磁参考模型，是由国际地磁和高空物理学联合会（International Association of Geomagnetism and Aeronomy）发布的一系列关于地球主磁场及其年变率的数学模型。作为科学研...IGRF（International Geomagnetic Reference Field）即全球地磁参考模型，是由国际地磁和高空物理学联合会（International Association of Geomagnetism and Aeronomy）发布的一系列关于地球主磁场及其年变率的数学模型。作为科学研究和工程应用的背景场、参考场广泛用于地球深部、地壳、电离层和磁层的研究。本文以最新的一代至第10代IGRF模型为基础，以Google公司开发的虚拟三维地球软件Google Earth为载体，进行了国际地磁参考场可视化研究。生成了一系列地磁要素的KML文件。并发布在世界数据中心中国地球物理学科中心的网站上，用户通过下载并打开这些文件就可以在Google Earth上查看到中国地区地磁场7个分量的可视化结果。本文所使用的方法也同样适用于第一代至第九代IGRF模型以及今后将要建立的IGRF模型。展开更多
The latitudinal dependence of the westward drift in the main geomagnetic field is examined by using the correlation analysis of moving random pattern. The study reveals the characteristics in the differential rotation...The latitudinal dependence of the westward drift in the main geomagnetic field is examined by using the correlation analysis of moving random pattern. The study reveals the characteristics in the differential rotation of the main field. The results show that the global geomagnetic field drifts westward with an average speed of 0.18/a during 1900—2000. The westward drift rate is not symmetrical with re-spect to the equator. The maximum westward drift rate, 0.31/a, occurs at the latitude j = -15? forming a Rapid Westward Drift Belt (RDB) around this latitude. Going northward and southward from this belt, the drift rate de-creases and reaches the minimum (0.12/a) at j = 50?and the minimum (0.14/a) at j = -56? forming a Northern Hemi-sphere Slow Westward Drift Belt (N-SDB) and a Southern Hemisphere Slow Westward Drift Belt (S-SDB). Three phases can be detected in the evolution of the westward drift. In the first phase (1900—1940), the RDB dominates the global drift pattern. The westward drifts in this belt are much faster than those in other areas. In the second phase (1940—1960), the drift rates in the RDB are less than those in the first phase, while the drifts in the N-SDB and S-SDB are relatively large. In this phase, the differential rotation becomes less obvious. In the third phase (1960—2000), the westward drift in the RDB increases again and the differen-tial rotation gradually becomes apparent.展开更多
基金supported by the National Natural Science Foundation of China(No.61673212).
文摘Geomagnetic orbit determination fits for nanosatellites which pursue low cost and high-density ratio,but one of its disadvantages is the poor position accuracy introduced by magnetic bias.Here,a new method,named the fuzzy regulating unscented Kalman filter(FRUKF),is proposed.The magnetic bias is regarded as a random walk model,and a fuzzy regulator is designed to estimate the magnetic bias more accurately.The input of the regulator is the derivative of magnetic bias estimated from unscented Kalman filter(UKF).According to the fuzzy rule,the process noise covariance is adaptively determined.The FRUKF is evaluated using the real-flight data of the SWARMA.The experimental results show that the root-mean-square(RMS)position error is 3.1 km and the convergence time is shorter than the traditional way.
文摘IGRF（International Geomagnetic Reference Field）即全球地磁参考模型，是由国际地磁和高空物理学联合会（International Association of Geomagnetism and Aeronomy）发布的一系列关于地球主磁场及其年变率的数学模型。作为科学研究和工程应用的背景场、参考场广泛用于地球深部、地壳、电离层和磁层的研究。本文以最新的一代至第10代IGRF模型为基础，以Google公司开发的虚拟三维地球软件Google Earth为载体，进行了国际地磁参考场可视化研究。生成了一系列地磁要素的KML文件。并发布在世界数据中心中国地球物理学科中心的网站上，用户通过下载并打开这些文件就可以在Google Earth上查看到中国地区地磁场7个分量的可视化结果。本文所使用的方法也同样适用于第一代至第九代IGRF模型以及今后将要建立的IGRF模型。
基金support of K.C.Wong Education Foundation,Hong Kongsupported by the National Natural Science Foundation of China(Grant Nos.40204003 and 40074015).
文摘The latitudinal dependence of the westward drift in the main geomagnetic field is examined by using the correlation analysis of moving random pattern. The study reveals the characteristics in the differential rotation of the main field. The results show that the global geomagnetic field drifts westward with an average speed of 0.18/a during 1900—2000. The westward drift rate is not symmetrical with re-spect to the equator. The maximum westward drift rate, 0.31/a, occurs at the latitude j = -15? forming a Rapid Westward Drift Belt (RDB) around this latitude. Going northward and southward from this belt, the drift rate de-creases and reaches the minimum (0.12/a) at j = 50?and the minimum (0.14/a) at j = -56? forming a Northern Hemi-sphere Slow Westward Drift Belt (N-SDB) and a Southern Hemisphere Slow Westward Drift Belt (S-SDB). Three phases can be detected in the evolution of the westward drift. In the first phase (1900—1940), the RDB dominates the global drift pattern. The westward drifts in this belt are much faster than those in other areas. In the second phase (1940—1960), the drift rates in the RDB are less than those in the first phase, while the drifts in the N-SDB and S-SDB are relatively large. In this phase, the differential rotation becomes less obvious. In the third phase (1960—2000), the westward drift in the RDB increases again and the differen-tial rotation gradually becomes apparent.
