Fault Detection and Isolation of Satellite Gyroscopes Using Relative Positions in Formation Flying

TL;DR

This paper presents a fault detection and isolation method for satellite gyroscopes using relative position measurements, which is effective even with time-varying faults and does not require additional subsystems.

Contribution

It introduces a novel fault detection algorithm based on a constant of motion derived from relative satellite positions, applicable in formation flying scenarios.

Findings

Algorithm detects gyroscope faults effectively under measurement noise.

Performance degrades near certain fault parameter values.

Orbital perturbations have negligible impact on fault isolation.

Abstract

A fault detection and isolation method for satellite rate gyros is proposed based on using the satellite-to-satellite measurements such as relative position beside orbit parameters of the primary satellite. By finding a constant of motion, it is shown that the dynamic states in a relative motion are restricted in such a way that the angular velocity vector of primary satellite lies on a quadratic surface. This constant of motion is then used to detect the gyroscope faults and estimate the corresponding scale factor or bias values of the rate gyros of the primary satellite. The proposed algorithm works even in time variant fault situations as well, and does not impose any additional subsystems to formation flying satellites. Monte-Carlo simulations are used to ensure that the algorithm retains its performance in the presence of uncertainties. In presence of only measurement noise, the isolation process performs well by selecting a proper threshold. However, the isolation performance degrades as the scale factor approaches unity or bias approaches zero. Finally, the effect of orbital perturbations on isolation process is investigated by including the effect of zonal harmonics as well as drag and without loss of generality, it is shown that the perturbation effects are negligible.