UC Davis

Reaction wheels play an essential role in the attitude control of small satellites; however, the trade-off between cost and reliability of commercial and in-house manufactured reaction wheels is a common pain point for small satellite developers. Hard disk drives (HDDs) repurposed as reaction wheels (HDD-RWs) are a low-cost, commercial-off-the-shelf (COTS) solution to the cost versus reliability trade-off for small satellite reaction wheels - they are one to three orders of magnitude less expensive than commercial reaction wheels and demonstrate competitive performance. HDD-RWs have the potential to dramatically lower barriers to entry, allowing resource-constrained organizations to develop CubeSat missions with reliable attitude control.

This thesis presents the research efforts to develop, test, and demonstrate the HDD-RW technology. Lab testing of the HDD-RW was performed to identify a working hardware configuration for the HDD-RWs and develop an actuator model. Preliminary environmental testing was conducted to ensure the HDD-RW can survive vibration loads and a vacuum environment. Single-axis ground testing of the attitude controller using the HDD-RWs was performed to verify its performance. Demonstration of three-axis attitude control using the HDD-RWs was performed through microgravity parabolic flight testing. Successful demonstrations of stabilization and pointing of a HDD-RW CubeSat testbed in microgravity environment raised the Technology Readiness Level (TRL) of the HDD-RW technology from TRL 4 to TRL 6. Data from parabolic flight testing is used to perform system identification of the HDD-RWs and CubeSat system. Simulation results based on the system model further demonstrates pointing control with the HDD-RWs for various target attitudes and stabilization from various initial rotation rates. A guide for using HDD-RWs and developing a controller is presented. Recommendations and lessons learned are provided, and next steps for the HDD-RW technology are discussed.