Study of Strapdown Inertial Optical Systems (SIOS) for Future ESA Spacecraft, Volume 1

摘要

A baseline (Kalman filter) SIOS, consisting of a set of high performance gyros, two or more star mappers and an onboard processor, is described. Centralized and modular data processing are considered. Control systems are specified and the performance of the attitude measurement and control system, using a Kalman filter, is simulated for low orbit Earth pointing cases and for a celestial target mission. Geostationary mission studies assumed the use of a simple constant gain filter and RF sensor, although results with the baseline system are included. The former approach is adequate, but the autonomy of optical systems is attractive. Kalman filter system performance is impressive for an Earth pointing satellite, and the whole system is immune to high noise levels, but geometrical misalignments limit absolute pointing accuracy. Analysis reveals doubt as to whether the Kalman filter is necessary, although its inclusion is not difficult.