Fault Detection and Isolation in Inertial Measurement Units Based on -CUSUM and Wavelet Packet

Élcio Jeronimo de Oliveira,Hélio Koiti Kuga,Ijar Milagre da Fonseca

doi:10.1155/2013/869293

Abstract

The aim of this paper is to present a fault detection algorithm (FDI) based on signal processing techniques developed for an inertial measurement unit (IMU) with minimal redundancy of fiber optic gyros. In this work the recursive median filter is applied in order to remove impulses (outliers) arising from data acquisition process and parity vector operations, improving the fault detection and isolation performance. The FDI algorithm is divided into two blocks: fault detection (FD) and fault isolation (FI). The FD part of the algorithm is used to guarantee the reliability of the isolation part and is based on parity vector analysis using -CUSUM algorithm. The FI part is performed using parity space projection of the energy subbands obtained from wavelet packet decomposition. This projection is an extension of clustering analysis based on singular value decomposition (SVD) and principal component analysis (PCA). The results of the FD and FI algorithms have shown the effectiveness of the proposed method, in which the FD algorithm is capable of indicating the low-level step bias fault with short delay and a high index of correct decisions of the FI algorithm also with low-level step bias fault.

Highlights

The main goal of fault detection, isolation, and recovery (FDIR) is to effectively detect faults and accurately isolate them to a failed component in the shortest time possible
The respective projection matrices (P) to be applied in validation tests are given by (A.5)–(A.8). Using these parameters in another data set obtained with different movements of the inertial measurement unit (IMU), it was found the results summarized in Table 2, where the low performance of gyro #4 is explained as a result of its higher noise level with respect to the others sensors. It was developed a fault detection algorithm (FDI) algorithm based on signal processing techniques applied to IMU with minimal redundancy of fiber optic gyros
This unity was built with low-quality fiber optic gyros (FOG) and a prototype of acquisition system that generates a high quantity of impulsive noise, justifying the use of recursive median filter

Summary

Introduction

The main goal of fault detection, isolation, and recovery (FDIR) is to effectively detect faults and accurately isolate them to a failed component in the shortest time possible. This capability leads to reduction in diagnostic time or downtime in general, increasing the system availability. The spacecraft AOCS (Attitude and Orbit Control Subsystem) includes components such as sensors and actuators. This work belongs to this area and is addressed in the scenario of the orbital dynamics for spacecraft AOCS including inertial measurement unities (IMU) and FDIR software. The methodology is based on signal processing techniques developed for an inertial measurement unit (IMU) with minimal redundancy of fiber optic gyros.

Objectives

Results

Conclusion