Magnetic Attitude Control for Small Satellites with Orbit-Independent Missions and Modest Pointing Constraints

Magnetic Attitude Control for Small Satellites with Orbit-Independent Missions and Modest Pointing Constraints

As the need for small satellite missions increases, the practice of launching multiple satellites from a single launch vehicle is also likely to increase. Small satellite missions are often flexible enough that a variety of orbits will be satisfactory, which increases the possibility of coordinated, multi-satellite launches; unfortunately, various satellite subsystems may impose restrictions on the possible orbit parameters. Since magnetic attitude control algorithms are typically tuned to a particular orbit, the performance of the control system is often adversely affected if the selected orbit is not particularly close to the orbit parameters for which the system was originally designed. This paper describes the expansion of a linear quadratic regulator routine. The routine has been adapted using a magnetic-inclination-dependent gain scheduling technique that allows a single algorithm to be used in a wide range of orbits. The system presented has been shown to be effective over a range of inclinations and altitudes. The inclusion of internal momentum bias is not necessary; but it does significantly improve the performance.