The Outlier Interval Detection Algorithms on Astronautical Time Series Data.

The Outlier Interval Detection is a crucial technique to analyze spacecraft fault, locate exception, and implement intelligent fault diagnosis system. The paper proposes two OID algorithms on astronautical Time Series Data, that is, variance based OID (VOID) and FFT and κ nearest Neighbour based OID (FKOID). The VOID algorithm divides TSD into many intervals and measures each interval's outlier score according to its variance. This algorithm can detect the outlier intervals with great fluctuation in the time domain. It is a simple and fast algorithm with less time complexity, but it ignores the frequency information. The FKOID algorithm extracts the frequency information of each interval by means of Fast Fourier Transform, so as to calculate the distances between frequency features, and adopts the KNN method tomeasure the outlier score according to the sum of distances between the interval's frequency vector and the κ nearest frequency vectors. It detects the outlier intervals in a refined way at an appropriate expense of the time and is valid to detect the outlier intervals in both frequency and time domains. [ABSTRACT FROM AUTHOR]