Design and verification of the operating procedure of attitude determination and control subsystem of a nanosatellite

This paper discusses the design and verification of the operating procedure of the Attitude Determination and Control Subsystem (ADCS) of PHOENIX nanosatellite. As one of the satellites which joins the QB50 project, the main objective of PHOENIX is to perform in-situ measurements in the lower thermosphere. In order to meet the mission requirements, the attitude control system is required to stabilize the nanosatellite and maintain it to the desired orientation down to 200 km. The design is challenging since three-axis stabilization control is necessary to reorient PHOENIX into the desired attitude. A simulation environment in MATLAB and Simulink including physical models, estimators, and controllers are built to investigate and confirm the designed control procedure. Typically, the ADCS is divided into two parts including attitude determination to estimate the current satellite's attitude, and attitude control to properly adjust the attitude. Attitude sensing using sun sensor, nadir sensor, magnetometer, and MEMS rate sensor together with attitude estimators using Kalman filter are utilized to determine the satellite's attitude and angular velocity. For attitude control, magnetic control and single axis wheel control are applied within the control procedure to achieve the three-axis stabilization. The control procedure employs these filters and control laws to stabilize the satellite, and they are verified by the simulation built in this paper.