Attitude Determination and Control System Design of Sub-Arcsecond Pointing Spacecraft
Divya Bhatia
Abstract
Spacecraft pointing accuracies with sub-arcsec to milli-arcsec levels are becoming a norm for the future space missions, which is mainly achieved by employing mission-specific fine guidance sensor (FGS). European Space Agency’s Herschel is the only spacecraft to date that has achieved an accuracy between 0.8 and 0.9 arcsec without employing FGS and by using only precise commercial-off-the-shelf (COTS) sensors. This paper improves upon Herschel’s pointing accuracy by at least [314, 925, 925]% for German Aerospace Center’s future mission named “Infrared Astronomy Satellite Swarm Interferometer (IRASSI).” IRASSI’s closed-loop attitude determination and control system (ADCS) is carefully developed by selecting high-precision COTS sensors and actuators, implementing two optimal attitude estimation algorithms for the sensor data fusion, three robust control algorithms for the attitude control, and a pseudoinverse distribution algorithm for spacecraft momenta allocation among the redundant reaction wheels in three different configurations. Monte Carlo simulations of IRASSI’s ADCS demonstrate that an unprecedented three-axis absolute pointing error of [0.193, 0.078, 0.078] arcsec is achieved. Furthermore, performance comparison between the rate-integrating and rate-gyroscope-based multiplicative extended Kalman filter for this mission is demonstrated. Finally, performance comparison of three attitude controllers establishes their feasibility for this mission.