Multivariate Engineering Parameter Anomaly Detection of the Satellite Based on Similarity Metric of the Symbolic Representation
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摘要: 随着卫星系统复杂程度的日益增加,综合分析卫星多元参数之间的相关性异常对于卫星安全运行和空间任务的正确执行具有重要意义。利用某卫星工程参数数据,基于符号聚合近似算法(SAX),研究卫星多元工程参数的异常检测问题,解决了当前异常检测方法中多元参数融合时不考虑上下文信息造成信息丢失的问题,实现多元参数有效融合,形成一种优化的基于快速动态时间规整算法(Fast-DTW)的异常检测算法。研究结果表明,模型在某卫星电源子系统的异常检测过程中,recall,precision和F1 score分别为0.947,0.9和0.923,能够实际应用于卫星异常检测,提高卫星在轨运行的安全性。
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关键词:
- 异常检测 /
- 卫星工程参数 /
- 符号聚合近似 /
- 快速动态时间规整(Fast-DTW)
Abstract: The complexity of the satellite system is increasing, and the comprehensive analysis of the abnormal correlation between the satellite with multiple parameters is important for the safe operation of the satellite and the correct execution of space tasks. Aiming at the characteristics of large amount of engineering parameter data, high parameter correlation and pseudo-period, a satellite multivariate engineering parameter anomaly detection method based on symbolized representation similarity measurement is proposed. Using real satellite engineering parameter data, based on Symbol Aggregation Algorithm (SAX), this paper studies the anomaly detection problem of satellite multiple engineering parameters, solves the problem of the context information, realizes effective fusion, and forms an optimized anomaly detection algorithm based on similarity measurement Fast-DTW algorithm. Results show that during the abnormality detection process, the recall, precision and F1 score are 0.947, 0.9 and 0.923 respectively in the real satellite power subsystem, and the algorithm can be actually used in satellite anomaly detection to improve the safety of satellite in-orbit operation. -
表 1 字母数为3~7的断点查找表
Table 1. Breakpoint lookup table with alphabetically numbered 3~7
3 4 5 6 7 $ {\mathrm{\beta }}_{1} $ –0.43 –0.67 –0.84 –0.97 –1.07 $ {\mathrm{\beta }}_{2} $ 0.43 0 –0.25 –0.43 –0.57 $ {\mathrm{\beta }}_{3} $ - 0.67 0.25 0 –0.18 $ {\mathrm{\beta }}_{4} $ - - 0.84 0.43 0.18 $ {\mathrm{\beta }}_{5} $ - - - 0.97 0.57 $ {\mathrm{\beta }}_{6} $ - - - - 1.07 表 2 极值点获取(EPA)算法流程
Table 2. Extremum point acquisition algorithm process
Input: Time series $ T=\left({t}_{1},{t}_{2},\cdots .{t}_{n}\right) $, $ {\rm{threshold}} $ Initialize: The sliding window $ \omega ={T}_{{\rm{cycle}}}+{T}_{\mathrm{f}\mathrm{i}\mathrm{t}\mathrm{t}\mathrm{e}\mathrm{d}}, $ $ {t}_{i}={t}_{1} $ 1. while i<=n do 2. $ {t}_{i} $= maximum/mininum ($ \left[{t}_{i},{t}_{i+\omega }\right] $) 3. $ {t}_{j} $= maximum/mininum ($ \left[{t}_{i+\omega -threshold},{t}_{i+\omega +threshold}\right] $) 4. Add $ i $ and $ j $ to the extreme point set $ {\rm{EPS}} $ 5. Set $ i=j $ 6. end while 7. return $ {\rm{EPS}} $ 表 3 分段(Segment)算法流程
Table 3. Segment algorithm process
Input: The extrepoint set sequence $ {\rm{EPS}}=({e}_{1},{e}_{2}, \cdots ,{e}_{m}) $, Time series $ T=\left({t}_{1},{t}_{2},\cdots .{t}_{n}\right) $ Initialize: The sliding window size $ len $,$ {e}_{i}={e}_{1} $ 1. while i<=m do 2. $ {t}_{{e}_{i}} $= maximum/mininum ($ \left[{t}_{{e}_{i}},{t}_{{l}_{en}+{e}_{i}}\right] $) 3. $ {t}_{{e}_{j}} $= maximum/mininum ($ \left[{t}_{{e}_{i}},{t}_{{l}_{en}+{e}_{i}}\right] $) 4. If $ {e}_{j}={e}_{i} $ 5. Add $ {e}_{i} $ to the set of segmentation time points $ {\rm{STP}} $ 6. set $ {e}_{i}={e}_{j} $; 7. end while 8. ${\rm{STP}}=({s}_{1},{s}_{2},\cdots ,{s}_{k})$ 9. while i<k do 10. Add $ \left[{t}_{{s}_{i}},{t}_{{s}_{i+1}}\right] $ to the set of pseudo-periodic subsequences $ {\rm{PPS}} $ 11. end while 12. return $ {\rm{PPS}} $ 表 4 EPA_Segment算法调参优化结果
Table 4. Results of EPA_Segment tuning optimization algorithm
$ {l}_{\mathrm{e}\mathrm{n}} $ EPA_Segment
(max)/ cycleEPA_Segment
(min) / cycleActual/
cycle2 43 35 12 3 22 20 12 4 18 16 12 5 13 12 12 6 12 12 12 7 12 11 12 8 11 10 12 表 5 电源分系统特征选择的最优结果
Table 5. Optimal result of the feature selection of the power supply subsystem
卫星参数 相关性百分比/(%) 测控应答机A机配电状态 83.5 测控应答机B机配电状态 83.3 GNSS接收机A机配电状态 83.0 备相位计配电状态 82.9 备载荷电控箱配电状态 82.8 相位计配电状态 82.8 表 6 不同算法的异常检测结果
Table 6. Anomaly detection results for different algorithms
评价指标 EMF 1-NN ED KMeans ED Recall 0.947 0.871 0.833 Precision 0.9 0.9 0.714 F1 score 0.923 0.885 0.769 -
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