Abstract
The attitude of a spacecraft is usually controlled by more than 3 reaction wheels. However, it is important to consider the attitude control by only 2 wheels for a fail safe. When the angular momentum of the body is not 0, it is known that the attitude cannot be controlled arbitrarily. Therefore, the purpose of this research is to control the direction of spacecraft's communication antenna. We separate the control law into two cases by the configuration of wheels; (1) One of the the wheel is set along the antenna, and (2) Both wheels are not set along the antenna. In the case (1), by using partial linearization and idea of equal ratio divergence, it can control the direction of antenna and stop rotation of the body. In the case (2), by using the output zeroing control, it can control the direction of the antenna and keep rotation around the antenna.
