Theoretical and Numerical Analysis of the Attitude Control of a 3U CubeSat - Iraqi Satellite (TIGRISAT)

Abstract

TIGRISAT is a small satellite, three units (3U) CubeSat which has a mission concerned to dust storms observation. For this purpose, Earth's Nadir pointing has been applied to achieve that mission. The attitude determination and control system (ADCS) must have the capability to provide continuous roll (∅), pitch (\theta) and yaw (\psi)  steering. Hence, Nadir pointing set to be at (x - axis) of TIGRISAT where the camera is fixed, and roll angle govern this axis.

While TIGRISAT is a small satellite with a low weight (4Kg), torque coils used to generate magnetic dipole moment for attitude and angular momentum control. They are also used to compensate the residual spacecraft biases and to counteract the attitude drift due to environmental disturbance torques. Two pair of coils have been used for each axis. Each side coil has (220 turn), while the upper and lower coil has (320 turn) for each one. The maximum torque produced by these coils is (0.0386 N.m) and this value of torque is quite enough to overcome the total disturbance torques and to provide the desired orientation. An algorithm has been designed to produce a magnetic dipole moment that is constantly orthogonal to the geomagnetic field vector, independently of the attitude and the angular rate of the rigid spacecraft. This algorithm gives the current needed to stabilize each axis of TIGRISAT, power consumption, kinetic energy, and the angular rates.