Perpustakaan Digital ITB

This undergraduate thesis focuses on the modeling and analysis of the rotational dynamics of a reaction sphere as an actuation device capable of reorienting satellite attitude. By using the rotor and stator configuration as described in the Northrop Grumman patent, this study aims to understand the characteristics and performance of the reaction sphere in controlling satellite rotation along all three axes. The research begins by modeling the interaction between electromagnets and permanent magnets located on the stator and rotor using MATLAB Simulink. Initial simulations were performed using a planar model, which was subsequently extended to a three-dimensional framework. The aim was to create a dynamic model of the reaction sphere to accurately simulate its rotational behavior. The magnetic model demonstrates that the interaction between 8 electromagnets and 12 permanent magnets can generate torque along specific axes. Simulation results show that the reaction sphere can rotate along all three axes but can only be controlled along the Z-axis due to its electromagnetic configuration. To enhance the performance of the reaction sphere, adjustments to the initial rotor position and variations in the current limits of each electromagnet, particularly those aligned with the rotational axis, are recommended. Additionally, adding a pair of electromagnets in a tetrahedron configuration on the X and Y axes has the potential to enable control over those axes. In future research, the magnetic model should be developed using the finite element method and integrated with a levitation system to levitate and maintain the rotor position, as well as to implement an appropriate control strategy.