2012.C.3.5 Attitude Control System for Arc-Second Stabilization of 30Kg Micro Astronomy Satellite

Author(s)

Takaya Inamori (1), Nobutada Sako (2) and Shinichi Nakasuka (1)

The University of Tokyo
Sinsyu University

Session

C.3 – Navigation, Control, Tracking, and Formation for Interplanetary CubeSat Missions

Keywords

attitude determination and control system, micro satellite, astronomy

Abstract

These days, small satellites provide space access to broader range of satellite developers and attract interests because of shorter development period at smaller cost.　These small satellites are applied to several sophisticated missions such as astronomical observation and remote sensing. An example of these satellites is a micro astronomy satellite, Nano-JAMSINE (Nano-Japan Astrometry Satellite Mission for INfrared Exploration), which has been developed at the University of Tokyo. The objective of the mission is to obtain three-dimensional position of stars. In order to obtain the scientific data, the satellite attitude should be stabilized to an accuracy of 1 arc-second, which is generally achieved with a conventional large satellite. The objective of the research is to propose methods to achieve the precise attitude control for small satellite sophisticated missions.

It is usually difficult to achieve precise attitude control in small satellites because of the following two reasons. Firstly, the effects of attitude disturbances are stronger because of smaller moment of inertia in a small satellite. Specifically, a magnetic torque is the dominant disturbance in a small satellite missions, even though the magnetic torque is small disturbance in a large satellite. Secondly, there are strict power, space, and weight constraints in small satellite missions. Therefore, precise ADCS devices are not available for a small satellite such as a ring laser gyroscope for the precise attitude rate estimation and a tip tilt mirror for the reduction of the RW disturbance effect.

This research proposes novel methods to solve these problems to achieve the precise attitude control in small satellites. For the first problem, the research proposes an in-orbit magnetic compensation method to reduce the effect of the magnetic disturbance using MTQs. For the second problem, the research proposes novel methods to use conventional devices effectively. For the precise attitude rate estimation, the research proposes a rate estimation method using star blurred images obtained by attitude sensors. For the reduction of the RW disturbance, the research proposes a novel attitude control strategy in which only smaller RWs are needed. Several these proposing methods are verified using an in-orbit remote sensing satellite PRISM. From simulation results and in-orbit performance, the research concludes that the methods are useful and effective to achieve the precise attitude control systems. The realization of a low-cost satellite with the precise control system in a short development period will clear the way for new space system applications for the future.