Research Article FDIR for the IMU Component of AOCS Systems Maurício N. Pontuschka 1 and Ijar M. da Fonseca 2 1 Department of Computer Science, PUC-SP, 01303-050 S˜ ao Paulo, SP, Brazil 2 Aeronautical Mechanics Division, Department of Mechatronics ITA and DMC/INPE, 12244-456 S˜ ao Jos´ e dos Campos, SP, Brazil Correspondence should be addressed to Maur´ ıcio N. Pontuschka; mauricio@realide.com Received 16 May 2014; Accepted 11 July 2014; Published 1 September 2014 Academic Editor: Antonio F. Bertachini A. Prado Copyright © 2014 M. N. Pontuschka and I. M. da Fonseca. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. he main objective of this paper is the study of a FDIR for an IMU aiming at space applications with focus on the gyro signal analysis and the tests of the iltering algorithms. he algorithms have been tested by using lab data provided by the DMC LABSIM (Physical’s Simulation Laboratory of the Space Mechanics and Control Division of INPE). he results have demonstrated good agreement with the concepts applied in this study. Automatic detection procedures are very important in the characterization of occurrence, deinition of criteria, and device types in the scenario of AOCS FDIR. An IMU comprised of four gyros in a tetrahedral coniguration is one of the assumed components for the AOCS (attitude and orbit control subsystem) considered in this work. he types of failures considered in this paper are the step abrupt change, ramp/drit/slow, stuck, cyclic, erratic, spike, and inally the stuck for variance alteration noise. An appropriate algorithm for the automatic detection of each type of fault is developed. he approach includes the mapping capability of fault event indicators to the IMU. his mapping is very important in the characterization of the occurrence, deinition of criteria, and device types as well as associated fault identiication for an AOCS. 1. Introduction he FDIR acronym refers to three main functions related to sotware (SW) and hardware (HW): fault detection, referring to the ability to discover faults or the process of determining that a fault has occurred; fault isolation being the function of fault localization within the system by providing information pinpointing it; fault recovery referring to the process of limiting the fault propagation and enabling the service to be restored to an acceptable state. FDIR belongs to a wide area called fault-tolerant con- trol systems (FTCS). In other words, FTCS refers to the control systems with capability to accommodate component failures automatically. Such systems are capable of maintain- ing overall system stability and performance in the event of failures. he FDIR enters in this process by detecting, isolating, and recovering the system being monitored in the event of fault occurrence [1, 2]. In the FTCS scenario, a closed-loop control system, which can tolerate component malfunctions while maintaining desirable performance and stability properties, is said to be a fault-tolerant control system. Despite the many individual research in this area, systematic concepts, design methods, and even terminology are still not completely standardized for the speciic area where FDIR and related literature appear [3]. As the subject is multidisciplinary considering the complete life cycle of FDIR systems, some standard terminologies come from sotware and hardware speciication and development as well as from quality assurance. he fundamental requirement for planning current space missions is autonomy. he autonomy aims the satellite’s architecture improvement and special attention to the FDIR to be implemented in space. Automatic actions have been included in space missions since the beginning of the space conquer. Nowadays automatism plus autonomy represent the state of the art of space missions requiring spacecrat with the capability to operate as intelligent robots. In such scenario the FDIR appear as one of the most important Hindawi Publishing Corporation Mathematical Problems in Engineering Volume 2014, Article ID 302716, 9 pages http://dx.doi.org/10.1155/2014/302716