Micro-satellite Attitude Determination and Control Subsystem Design and Implementation: Software-in-the-loop Approach

The paper describes the development of a micro-satellite attitude determination and control subsystem (ADCS) and verification of its functionality by software-in-the-loop (SIL) method. The role of ADCS is to provide attitude control functions, including the de-tumbling and stabilizing the satellite angular velocity, and as well as estimating the orbit and attitude information during the satellite operation. In Taiwan, Air Force Institute of Technology (AFIT), dedicating for students to design experimental low earth orbit micro-satellite, called AFITsat. For AFITsat, the operation of the ADCS consists of three modes which are initialization mode, de-tumbling mode, and normal modes, respectively. During the initialization mode, ADCS collects the early orbit measurement data from various sensors so that the data can be downlinked to the ground station for further analysis. Particularly emphasized in this article, during the de-tumbling mode, ADCS implements the thrusters in plus-wide modulation control method to decrease the satellite angular velocity. ADCS provides the attitude determination function for the estimation of the satellite state, during normal mode. The three modes of microsatellite are adopted Kalman filter algorithm estimate microsatellite attitude. This article will discuss to use the SIL validation ADCS function and verify its feasibility.