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MSR capture performance: position misalignment on +X face (top left), lateral velocity (top right) and longitudinal velocity (bottom) requirements
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The presented work is a result of a research collaboration between European Space Agency, Thales Alenia Space and IMS Laboratory with the aim of promoting fault-tolerant control strategies to advance spacecraft autonomy. A multiple observer based scheme is proposed jointly with an online constrained allocation algorithm to detect, isolate and accom...
Context in source publication
Context 1
... 2 clearly illustrates the consequence when the fault is not accommodated, i.e. chaser miss the target and the mission is lost. On the other hand, when the proposed approach is active, the chaser maintains nominal trajectory, i.e. stays inside the rendezvous corridor and the MSR capture requirements are met, see Fig.3. Furthermore, it can be inferred from Fig.2 that the chaser keeps its attitude pointing towards the target. ...
Citations
... The proposed approach is based on both state estimation of an accurate linear model for the satellite system and unknown input decoupling to achieve robust FDI in the presence of dynamic uncertainty during main engine deployment. The work reported in (Henry et al., 2011;Fonod et al., 2014a;LePeuvédic et al., 2014;Fonod et al., 2015) addressed the problem of thruster fault diagnosis of the MSR orbiter during the terminal rendezvous phase. Henry et al. (2011) proposed a method based on a H(0) filter with robust poles assignment technique. ...
... This detector offers enhanced robustness against time-varying input delays. The original idea of the two-stage isolation strategy proposed in this paper initiates from (Fonod et al., 2014a), where a bank of asymptotically stable Nonlinear Unknown Input Observers (NUIOs) has been used for the first stage and a simple residual vector matching approach for the second stage. Here, a bank of 5 robust NUIOs together with an EKF-based torque bias direction estimator is considered. ...
This paper deals with the design and validation of an active fault-tolerant control system to detect, isolate and accommodate a single thruster fault affecting the thruster-based propulsion system of an autonomous spacecraft. The proposed method consists of a fault detector for robust and quick fault detection, a two-stage hierarchical isolation strategy for fault isolation, and an online control allocation unit scheduled by the isolation scheme for fault tolerance. A new factorization approach for the uncertain inertia matrix inverse is proposed. Thanks to this factorization, a novel robust Nonlinear Unknown Input Observers (NUIO) approach is proposed based on LMIs which ensure maximization of the admissible Lipschitz constant while at the same time satisfying an L2 gain bound and some constraints on the observer dynamics. At the first stage of the isolation scheme, a bank of NUIOs is used to identify a subset of possible faulty thrusters. Then, at the second stage, an EKF is introduced to estimate the torque bias directions. Using these directions, jointly with the detector׳s residual and the information obtained from the first stage, a set of explicit rules is derived to unambiguously isolate the faulty thruster. A Monte Carlo campaign, based on a simulator developed by Thales Alenia Space industries, is conducted in the context of a terminal rendezvous phase of the Mars Sample Return mission. Mission oriented criteria demonstrate that the proposed strategy is able to cope with a large class of realistic thruster faults and to achieve mission success.
... In this paper, we consider a NUIO based FDI scheme design problem for a class of nonlinear Lipschitz systems. We extend the results presented in [14] by constraining the observer error dynamics in a prescribed LMI region. The observer synthesis is achieved by solving a LMI feasibility problem together with a pole assignment in LMI regions. ...
In this paper, the problem of Nonlinear Unknown Input Observer (NUIO) based Fault Detection and Isolation (FDI) scheme design for a class of nonlinear Lipschitz systems is studied. The proposed FDI method is applied to detect, isolate and accommodate thruster faults of an autonomous spacecraft involved in the rendezvous phase of the Mars Sample Return (MSR) mission. Considered fault scenarios represent fully closed thruster and thruster efficiency loss. The FDI scheme consists of a bank of NUIOs with adjustable error dynamics, a robust fault detector that is based on judiciously chosen frame and an isolation logic. The bank of observers is in charge of confining the fault to a subset of possible faults and the isolation logic makes the final decision about the faulty thruster index. Finally, a thruster fault is accommodated by re-Allocating the desired forces and torques among the remaining healthy thrusters and closing the associated thruster valve. Monte Carlo results from 'high-fidelity' MSR industrial simulator demonstrate that the proposed fault tolerant strategy is able to accommodate thruster faults that may have effect on the final rendezvous criteria.
The research work presented in the paper addresses the design of a model-based fault diagnosis and fault recovery system for any faults occurring in the actuator and sensor units of the chaser spacecraft of the ESA Mars Sample Return (MSR) mission. Key features of the proposed method are the use of a parity space and covariance-based strategy with jointly a H∞ observer for fault diagnosis of sensor faults, a H∞/H- filter for robust fault detection of actuator faults and a bank of unknown input observers jointly used with a dot product of vectors strategy for actuator faults. For fault accommodation, a ”retreat” FDIR strategy scheduled by the FDI unit, is retained. The proposed FDIR architecture obeys to a hierarchical one and fits the industrial requirements. Especially, it is compliant with the Aurora avionics architecture. A simulation campaign, based on a nonlinear high-fidelity simulator developed by GMV space and Thales Alenia Space industries, is conducted under highly realistic conditions.
