This work presents the design and performance analysis of attitude determination algorithms for CubeSats that fuse rate gyros with a single vector measurement using a sensor set consisting of an inertial measurement unit and a three-axis magnetometer. An extended Kalman filter is used to fuse sensor measurements to estimate the spacecraft’s attitude statistics in three dimensions. The observability (deterministic and stochastic) of the algorithms is assessed for a variety of orbit geometries and CubeSat attitude dynamics. Further, a stochastic observability test is implemented to identify conditions under which the attitude determination filter will converge as the Earth’s magnetic field varies during orbit. This paper demonstrates that the filter converges within two orbits using CubeSat representative altitudes and estimate spacecraft attitude with bias of 2° and estimation errors of 3° (3-σ) using orbital simulations with a commercial-grade inertial measurement unit.
Bibliographical noteFunding Information:
The material in this paper is based on research supported by the National Science Foundation (NSF) under Grant No. 1841006 and the Air Force Office of Scientific Research (AFOSR) under Grant No. FA9550-19-1-0308. However, the views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the NSF, AFOSR, or the U.S. government.
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