Development of an attitude control system for CubeSat application

Guidance, navigation, and control (GNC) systems are commonly found in vehicles, whether they be spacecraft, aircraft, seacraft or landcraft. These systems are designed to bring the vehicle to its desired position and/or orientation by sensing pose and making the necessary adjustments to onboard devices. With regard to satellites, GNC systems are divided into two segments: orbit control, which is concerned with the spacecraft’s position, and attitude control, which is concerned with the spacecraft’s orientation. The focus of this thesis is to develop the attitude control system of a CubeSat nanosatellite being designed for the University of Prince Edward Island’s SpudNik-1 mission. The objective of this study was to progress the design of the attitude control system (ACS) from its conceptual design phase to a state where it is ready for assembly, integration, and testing. To accomplish this, the engineering design process was applied. Accordingly, the fundamentals of attitude control were first reviewed in literature. Then, the system-level requirements were evaluated and the current design’s ability to meet them was assessed. After doing so, the necessary alterations were made to the conceptual design, such that it would meet the requirements, and the various methods of requirement verification were defined to verify that this is the case during the assembly, integration, and testing phase. Once the system-level design had been established, this process was repeated for the subsystem- and unit-level designs. In addition to contributing the detailed design of an attitude control system to the Spudnik-1 team, this work can also serve as a reference for other teams working toward space missions that require the use of an ACS by providing a comprehensive perspective that focuses on the identification, integration, and implementation of the major elements of an attitude control system. It not only offers detailed information on the definition, measurement, modeling, estimation, and control of a spacecraft’s attitude, but also identifies: the connections between these concepts; the hardware used to implement the concepts in a real-world application; and the various considerations that should be taken during this implementation. Aside from familiarizing the reader with the methodology behind an ACS system, this work also describes the procedure that was used to develop the attitude control subsystem of the SpudNik-1 CubeSat. It details: how the requirements of the attitude control subsystem were identified from the spacecraft’s mission and the corresponding system requirements; how the major components and concepts of the ACS are identified from the subsystem requirements, and integrated through the subsystem architecture; how the unit-level requirements are identified based on the subsystem-level design; and how the implementation of the various components and concepts is dependent on the unit level requirements. While a good deal of the design is standard with regard to CubeSats and other aerospace projects, the original aspects would relate to the in-house design of the reaction wheels and fine sun sensors. Being as there are a wide selection of ACS components available on the market, it is most common for CubeSat projects to procure their hardware. Although the lack of flight heritage did pose additional risk to the mission in comparison to using commercial equipment, the in-house design allowed the components to be both tailored to the mission and produced at a fraction of the cost. If the designs manage to gain flight heritage on-board of the SpudNik-1 CubeSat, then this work will provide readers with standard frameworks which will allow them to reap the same benefits, but at a lower level of risk