Abstract
The mission execution process of a fixed-wing UAV has multiple phases and multiple operation conditions. Its parameters are nonlinear and dynamic. These characteristics make its online fault detection rather complicated. To carry out the fault detection, this paper selects nine key parameters of the transverse, longitudinal and velocity control loops of the UAV to characterize its real-time conditions. The core parameters are dynamically preprocessed to construct an augmented matrix so as to describe the dynamic characteristics of the UAV. Then, the improved k-mediods* algorithm is used to cluster the operation conditions of the UAVs by means of augmented dimensions. Neural networks are used to achieve the online matching of operation conditions. To overcome the nonlinearity of the UAV, the fault detection is performed by using the DKPCA algorithm; the fault monitoring is conducted through constructing the compound indexes of SPE and T2, notated as FAI. Furthermore, the fault separation algorithm is proposed to specify the variables of fault from the augmented high-dimensional data set. In order to deal with the erroneous reporting of faults due to measurement errors, the paper conducts the wavelet denoising of FAI, the compound indexes of the DKPCA algorithm. Finally, the data set collected from a real UAV flight is used to verify the effectiveness of the DKPCA algorithm for operation condition clustering and matching, fault detection and wavelet denoising.
Highlights
使用 k⁃mediods∗ 算法对动态扩维后矩阵 D 进 行聚类分析,最终获得 4 种工况,如图 3 所示。 图 3 中横轴为变量数目( 扩维后为 45 维) ,纵轴为采样 数,竖轴为归一化后的变量幅值。 对比图 3 各子图 可以发现各工况内数据高度相似且工况间数据差异 较大,表明 k⁃mediods∗算法在 UAV 动态数据工况划 分中获得了满意结果。
Neural networks are used to achieve the online matching of operation conditions
To overcome the nonlin⁃ earity of the UAV, the fault detection is performed by using the DKPCA algorithm; the fault monitoring is conduc⁃ ted through constructing the compound indexes of SPE and T2, notated as FAI
Summary
使用 k⁃mediods∗ 算法对动态扩维后矩阵 D 进 行聚类分析,最终获得 4 种工况,如图 3 所示。 图 3 中横轴为变量数目( 扩维后为 45 维) ,纵轴为采样 数,竖轴为归一化后的变量幅值。 对比图 3 各子图 可以发现各工况内数据高度相似且工况间数据差异 较大,表明 k⁃mediods∗算法在 UAV 动态数据工况划 分中获得了满意结果。 线有一定波 动 成 分, 这些波动会造成故障的误报。 例如,在图 7b) 1 517 采样点,UAV 无故障但 FAI 曲 线也越过了控制限。 为了应对此故障误报问题,本 文采用小波阈值去噪算法对 FAI 进行处理,如图 7 所示。 [1] ABBASPOUR A, ABOUTALEBI P, YEN K K, et al Neural Adaptive Observer⁃Based Sensor and Actuator Fault Detection in Nonlinear Systems: Application in UAV[ J] .
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More From: Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University
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