Advances in MEMS IMU Cluster Technology for Small Satellite Applications

Abstract

In recent years, there has been increased interest in Micro-Electro Mechanical Systems (MEMS) Inertial Measurement Units (IMUs) due to their relatively small volumetric footprint and low-cost. Although this advantage far outweighs the volumetric footprint and cost of traditional high-performance IMUs, MEMS technology has yet to match the performance of such devices. In spite of this, it has been shown in theory that a cluster of MEMS IMUs may significantly improve the performance over a single MEMS IMU. To further develop this theory, two prototype boards have been designed and constructed that include 16 MEMS accelerometers and gyroscopes affixed to a single Printed Circuit Board (PCB). To prove this technology, hardware and software has been developed for calibration and fault detection, which represents the majority of the body of this thesis. An apparatus has been designed to easily acquire three-axis measurements from the cluster prototype on a single-axis rate table. These measurements may then be placed into a Maximum Likelihood Estimation (MLE) algorithm in order to acquire the necessary error coefficients incorporated in IMU measurements. Once these error coefficients are accurately determined, future measurements may be calibrated. Finally, a fault detection, isolation, and recovery (FDIR) architecture was developed and simulated to determine faulty measurements in real-time, so that bad measurements may not be placed into downstream navigation filters. The hardware, software, and testing developed and performed in this thesis will be used in the verification process of an IMU cluster to help prove its worthiness in modern day small satellite applications. This journey would not have been possible without the support of my friends, family, professors, and mentors. To my family, thank you for encouraging me to constantly pursue higher education and continued learning. Especially to my parents, without your emotional and financial support along the way, I would not be where I stand today. To all of my friends and roommates at PSU and WVU, thank you for listening, providing advice, and supporting me through the last six years. It has been a wild ride, but knowing that you were always there made it all the more comforting. I am very grateful to all the professors and mentors during my time at Penn State Altoona and at West Virginia University. Specifically, I would like to thank Dr.Grant Risha of Penn State Altoona, for your knowledge, expertise, research, and teaching led me to where I am today. Early in my time at PSU you saw the potential and mentored me through my undergraduate academic career and for that I am forever grateful. To Dr.John Christian, thank you for providing me with the opportunity to work in aerospace navigation. You have greatly helped diversify my engineering background with inertial navigation and I am very appreciative of your continued support, advising, expertise, and effort through the completion of this thesis. I am also very appreciative to all the members of the ASEL team for ...

A Sensitivity Study of POD Using Dual-Frequency GPS for CubeSats Data Limitation and Resources

“…Due to the limitation of the CubeSats in terms of their size, power, and capacity to install extra sensors, the antenna attitude information may not be well measured, estimated, documented, and transferred back to the GPC with sufficient details. For example, due to power management needs, the IMU under its own high-accuracy experiment [25] onboard the CubeSat Simulation To Flight-1 (STF-1), investigated by NASA's Katherine Johnson Independent Verification and Validation (IV&V) Facility and West Virginia University [21,26], was unable to be activated during the GNSS data collection. Depending on the latency requirements of the CubeSat orbits, the high-accuracy GNSS satellite orbits and clocks might not be available for the processing, e.g., the international GNSS service (IGS) final products [27,28], which has a latency of 12-18 days.…”