Design and Test of a CubeSat Reaction Wheel Control Subsystem

Abstract

The ability of a spacecraft to change attitude and stabilize against disturbances while in orbit is critical to mission success. This thesis aims to design, build, and test a prototype CubeSat reaction wheel control subsystem (RWCS) to integrate into the TigerSats Lab student-build CubeSat Kit. As the most capable three-axis control method commonly used in CubeSats, this RWCS will provide momentum storage and slew torque capabilities for worst-case theoretical 1U CubeSat mission parameters, and lay the groundwork for future subsystem space-qualification efforts. First, detailed characterization of orbital and ground testing environments was calculated to determine minimum performance specifications. Motors and hardware were extensively traded to ensure the RWCS can integrate with existing TigerSats components, followed by custom design and in-house manufacturing of the reaction wheels, motor housing, and printed circuit board. An air bearing was selected and set up with custom mounting fixtures to provide a RWCS test platform within the TigerSats Lab, and detailed CAD mass models were used to calculate reaction wheel speeds necessary for desired slew maneuvers. Testing on this frictionless platform validated the ability of the RWCS to perform slews on all 3 motor axes. A major capstone of this thesis involves preparing the RWCS to be brought onboard a Zero-G parabolic flight, which will allow for testing of the system (along with other critical TigerSats hardware) in a real microgravity environment. This flight will help calibrate RWCS and test platform performance by directly comparing slew data via video analysis. Overall, this project paves the way forward for the TigerSats Lab to produce both a space-qualified RWCS and in-house attitude determination and control system test facility in the future.