Master thesis and internship[BR]- Master's thesis : Advanced Torque Allocation Strategies for ADCS Actuators on the CubeSpec Mission[BR]- Integration Internship : Arcsec

Abstract

Reaction wheels are highly efficient tools for the spacecraft attitude management. As redundancy in satellites is now more of a necessity to avoid failure risks, four reaction wheels are often integrated in contemporary spacecraft, requiring a careful optimization of torque control via a well-designed allocation algorithm.

Initiated by arcsec's endeavor to improve their Attitude Determination and Control System (ADCS), this thesis explores the complexities of reaction wheel operations. The study has an emphasis on comprehending and mitigating any complications associated with saturation and stiction within the reaction wheels, which were demonstrated by unusual incidents encountered when Simba CubeSat was in operation. This thesis fundamentally introduces a fresh "Envelope Representation" to effectively depict the intricate possibilities offered by redundancy, while bypassing the cumbersome conventional techniques. Moreover, strategies are formulated and designed to avoid stiction and saturation through the new representation.

The analysis revealed remarkable results in tackling the challenges of stiction and saturation with reaction wheels. All proposed strategies outshone the prevailing Moore-Penrose pseudoinverse method, proving their worthiness. A novel desaturation approach proves to be an attractive alternative to traditional methods, especially during dynamic maneuvers. The established strategies and methods show a promising potential to enhance the torque allocation of the ADCS actuators.

This work establishes approaches to address stiction and saturation issues associated with reaction wheels on spacecraft. The Envelope Representation approach provides a promising outlook in dealing with various actuator-related issues, providing novel solutions in contrast to established techniques. The developed strategies occasionally come at the cost of reduced pointing accuracy, prompting a thoughtful trade-off in specific scenarios. These algorithms mark the first iteration in a journey of potential optimization and progression.