HAUSAT-2 nanosatellite ADCS performance analysis and commissioning

Abstract

The HAUSAT-2 is a 25kg class nanosatellite which is being developed by graduate students at the Space System Research Laboratory (SSRL). The HAUSAT-2 implements a pitch bias momentum method for 3-axis stabilization, consisting of one momentum wheel in pitch axis and 3-axis magnetic torquers. 2-axis sun sensors, a 3-axis magnetometer, and a star tracker are used to determine the attitude. This paper describes two primary attitude control modes and control performances to perform the following functions: 1) initial acquisition (initial attitude acquisition mode), 2) 3-axis stabilization (mission mode). In addition to two operation modes, momentum wheel start-up method was also simulated using MATLAB. For detumbling the satellite, the initial mode uses a momentum wheel and magnetic torquers with B-dot control law. The mission mode also uses a momentum wheel and magnetic torquers to maintain 3-axis stabilization. A momentum wheel will have to be started from rest before it is fully operated. If the wheel speed is suddenly increased to nominal wheel RPM, the angular momentum produced can cause instability to satellite's body. In this paper, effective wheel start-up method of ultra-small satellite equipped with momentum wheel and magnetic torquers has been studied. Also, a momentum dumping method using magnetic torquers was considered.