Model-Based Fault Detection and Diagnosis for Spacecraft with an Application for the SONATE Triple Cube Nano-Satellite

Kirill Djebko,Frank Puppe,Hakan Kayal

doi:10.3390/aerospace6100105

Abstract

The correct behavior of spacecraft components is the foundation of unhindered mission operation. However, no technical system is free of wear and degradation. A malfunction of one single component might significantly alter the behavior of the whole spacecraft and may even lead to a complete mission failure. Therefore, abnormal component behavior must be detected early in order to be able to perform counter measures. A dedicated fault detection system can be employed, as opposed to classical health monitoring, performed by human operators, to decrease the response time to a malfunction. In this paper, we present a generic model-based diagnosis system, which detects faults by analyzing the spacecraft’s housekeeping data. The observed behavior of the spacecraft components, given by the housekeeping data is compared to their expected behavior, obtained through simulation. Each discrepancy between the observed and the expected behavior of a component generates a so-called symptom. Given the symptoms, the diagnoses are derived by computing sets of components whose malfunction might cause the observed discrepancies. We demonstrate the applicability of the diagnosis system by using modified housekeeping data of the qualification model of an actual spacecraft and outline the advantages and drawbacks of our approach.

Highlights

Fault detection during spacecraft missions is classically done by human operators in a manual or semi-automatic fashion with the use of a telemetry client displaying the spacecraft’s housekeeping data
The housekeeping data was generated by the qualification model of the SONATE-Nano satellite and transmitted via UHF/VHF Radio to the receiver of the ground station where it was forwarded to the telemetry client, into which the fault detection system is integrated
We have presented a quantitative model-based fault detection and diagnosis system that strictly separates the model from the diagnosis algorithm and demonstrated its applicability by using a model of the power supply of the qualification model of the SONATE-Nano satellite

Summary

Introduction

Fault detection during spacecraft missions is classically done by human operators in a manual or semi-automatic fashion with the use of a telemetry client displaying the spacecraft’s housekeeping data. The main drawback of this process is that it relies on malfunctions, be it a component fault or failure, to be directly observable in the telemetry. The spacecraft’s components degrade slowly, which causes initial abnormal behavior to be very subtle and to increase in severity as the component deteriorates. These subtle changes in a components behavior are initially not observable in the telemetry data. Manual supervision by human operators is highly susceptible to overlook such subtle malfunctions, not directly visible while using the telemetry alone. The occurrence of a malfunction in form of a violated limit often indicates that a fault could not be spotted in time and may have already damaged the associated component

Methods

Discussion

Conclusion