基于机器学习的低轨卫星高精度轨道预报

High-Accuracy Orbit Prediction of Low Earth Orbit Satellites Using Machine Learning Algorithms

  • 摘要: 高精度低轨卫星预报轨道是全球低轨导航增强应用的基础。目前应用较为广泛的动力学外推方法存在着受动力学模型精度影响大、预报误差累积快的问题。为弥补这一缺陷,将机器学习方法与动力学外推法结合以提升低轨卫星轨道预报精度,并对支持向量机(support vector machine,SVM)、反向传播(back propagation,BP)神经网络和长短期记忆(long short term memory,LSTM)神经网络3种机器学习方法在低轨卫星轨道预报中的适用性进行了深入分析。利用Sentinel-3A卫星2019-01-01—2019-07-14的数据集进行了预报时长为180 min的短期轨道预报实验,对模型最优参数进行了探究,基于各模型最优参数配置进行轨道预报实验。结果表明,三种机器学习方法均能有效提升低轨卫星轨道预报精度,提升效果在不同预报时长下存在明显差异。当轨道预报时间为20 min,LSTM神经网络模型对预报轨道的精度提升效果(38.1%)显著优于SVM(-0.1%)与BP(-1.2%),预报轨道精度可达1.07 cm(3D)。当预报时长大于40 min,SVM和BP模型效果优于LSTM模型。在预报时长达到180 min时SVM和BP模型仍可以实现6-7 cm的轨道预报精度,相比于传统动力学法提升了约50%。

     

    Abstract: Objectives: Precise orbit prediction of low earth orbit (LEO) satellites is the foundation of LEO augmentation navigation. Due to the impact of non-conservative perturbation forces, conventional dynamic extrapolation method relies on high-accuracy dynamic models and suffer from rapid error accumulation. Methods: We combine machine learning algorithms and dynamic integration method to improve the accuracy of LEO orbit prediction. Three machine learning models are analyzed, including support vector machine (SVM), back propagation (BP) and long short term memory (LSTM) neural networks. To compare the performance of different machine learning algorithms in the high-accuracy orbit prediction, we process the orbit error time series of Sentinel-3A from January 1, 2019 to July 14, with the dynamic features selected by extreme gradient boosting (XGBoost). The optimal input configuration parameters for each machine learning models are further investigated to exploit the potential of the models in the orbit prediction. Results: The result shows that the performance of three machine learning models in the prediction varies from prediction time. When the prediction time is limited to 20 min, LSTM model presents the best performance with an accuracy improvement of 38.1%, which is evidently superior to SVM (-0.1%) and BP (-1.2%), and the corresponding orbit accuracy is 1.07 cm (3D). For the prediction exceeding 40 min, SVM and BP models outperform LSTM. When the prediction time reaches 180 min, the predicted orbit can still achieve the accuracy around 6-7 cm with the employment of SVM/BP models. Conclusion: Three models can effectively improve the orbit prediction accuracy of LEO satellites. LSTM model can achieve the best performance in ultra-short prediction (20 min), while SVM and BP models are more suited to the prediction exceeding 40 min. Compared with the traditional orbit prediction method, the improvement of machine learning models is about 40-50% overall.

     

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