Design of Magnetorquer-Based Attitude Control Subsystem for FORESAIL-1 Satellite

Abstract

Magnetorquer based attitude control system capable of attaining high spin rates and precise pointing control is required for a 3U CubeSat satellite FORESAIL-1. The satellite, developed by Finnish Centre of Excellence, needs to maintain a spin rate of 24 • /s and precise pointing of the spin axis toward the Sun for the particle telescope instrument, as well as to reach 130 • /s spin rate for the deployment of the plasma brake. Mission requirements analysis and attitude system requirements derivation are presented, followed by actuator trade-off and selection, with detailed design of the complete attitude control system, including air-cored type of magnetorquer actuators and their drivers, made of H-bridge and filtering components. The design is based on several theoretical and practical considerations with emphasis on high power efficiency, such as effects of parallel and serial magnetorquer connections, modelling the magnetorquers with equivalent circuit models for finding of suitable driving frequency and extrapolation methods for efficient dipole moment usage. In-house manufacturing process of magnetorquers, using a custom 3D-printer setup, is described. Lastly, the testing and verification are performed, by measuring the performance of the manufactured hardware, circuit simulations and attitude control simulations. It is shown that the manufactured attitude control system fulfils all system requirements. Simulations also confirm the capability to satisfy mission requirements.