Controller Design for CubeSat Attitude Control with BLDCM and Raction Wheels

For all satellites, attitude, orientation and orbit-propagation are critical to mission success. The attitude control system (ACS) usually has different operation modes for various situations of the task; for example, detumbling, three-axis stabilization, pointing... etc. The purpose of this article is to establish a dynamic mathematical model for simulating a small satellite in Low-Earth Orbit (LEO), and to design relevant controllers to implement attitude-pointing. In particular, the CubeSat applies a permanent magnet brushless DC-motor (BLDCM) connected with a reaction-wheel as an actuator, which generates control torque imposing angular velocity on satellite body to track the expected attitude signal. In the satellite attitude control subsystem, there are three control loops from inner the BLDCM to the outer CubeSat: (1) the current loop of the actuator, (2) the angular velocity of the satellite body and (3) the attitude angle loop, which need to be regulated simultaneously. In this article, Matlab-Simulink is applied to construct dynamic mathematical models including the CubeSat body (kinematics, dynamics) module, the three-axis actuator module (BLDCM, reaction wheel), and the active controllers based on the actuator. Specifically, according to the multi-loop control architecture, individual loop controllers are designed through closed-loop system response simulation to complete the coupled cascades interaction between the satellite body and the reaction wheels. Among them, a ?P+PI? type control law is proposed, which can achieve precise attitude pointing in terms of time efficiency, stability and robustness as the system control requirements.