Organizational Unit:

Space Systems Design Laboratory (SSDL)

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https://hdl.handle.net/1853/70747

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Organizational Unit

Daniel Guggenheim School of Aerospace Engineering

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https://finding-aids.library.gatech.edu/agents/corporate_entities/1138

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Publication Search Results

Now showing 1 - 10 of 253

Relative Positioning and Tracking of Tethered Small Spacecraft Using Optical Sensors

(Georgia Institute of Technology, 2018-12) Guo, Yanjie
On-Board Model-Based Fault Diagnosis for Autonomous Proximity Operations

(Georgia Institute of Technology, 2018-09) Schulte, Peter Z. ; Spencer, David A.

Because of their complexity and the unforgiving environment in which they operate, aerospace vehicles often require autonomous systems to respond to mission-critical failures. Fault Detection, Isolation, and Recovery (FDIR) systems are used to detect, identify the source of, and recover from faults. Typically, FDIR systems use a rule-based paradigm for fault detection, where telemetry values are monitored against specific logical statements such as static upper and lower limits. The model-based paradigm allows more complex decision logic to be used for FDIR. This study focuses on a state machine approach toward model-based FDIR. The state machine approach is increasingly utilized for FDIR of complex systems because it is intuitive, logic-based, and simple to interpret visually. In current practice, the detection of specific symptoms is directly mapped to the appropriate response for a pre-diagnosed fault, as determined by FDIR engineers at design time. This study advances the state-of-the-art in state machine fault protection by developing an on-board diagnostic system that will assess symptoms, isolate fault sources, and select corrective actions based on models of system behavior. This state machine architecture for FDIR is applicable for a broad range of aerospace vehicles and mission scenarios. To demonstrate the broad applicability of the FDIR approach, two case studies are evaluated for scenarios in very different domains. The first is a terrestrial application involving the use of multi-rotor unmanned aerial vehicles (UAVs). The second is a space-based scenario involving autonomous proximity operations for orbital capture of a Mars Sample Return capsule. The efficacy of the state machine FDIR system is demonstrated via flight testing for the UAV case study and through software-in-the-loop testing in a flight-like simulation environment for the Mars Sample Return case. In each case, the FDIR system is focused on the Guidance, Navigation and Control subsystem. This approach has been successfully shown to detect, diagnose, and respond to faults during testing. State machines allow the autonomous system to handle distinct faults with identical symptoms for initial detection. Each fault has a separate diagnosis and response procedure, and the proper procedure is selected by the state machine. This study demonstrates how a fault protection system may diagnose these faults on-board rather than relying upon a priori ground diagnosis.
A Preliminary Assessment of the RANGE Mission's Orbit Determination Capabilities

(Georgia Institute of Technology, 2018-08) Claybrook, Austin W.
Methodology for Optimal Design of a Conformal Ablative Heatshield

(Georgia Institute of Technology, 2018-06) Sidor, Adam T. ; Braun, Robert D. ; Kennedy, Graeme J.

Conformal ablators are low density composite materials comprised of a flexible fibrous substrate and polymer matrix. Recent advancements have improved the efficiency of conformal ablator fabrication through vacuum infusion processing where resin is directly injected into a fiber substrate enclosed in a matched mold. This mold filling process can be numerically simulated to inform mold and process design. An automated methodology pairing a mold filling simulation with an approach for tiling a heatshield geometry leads to designs optimized for manufacturing. Material property estimation generalizes the approach to a range of constituent materials, enabling rapid conceptual evaluation of a conformal ablative heatshield. This work improves on the state of the art which relies on heuristic methods tailored to a particular material and aeroshell geometry. Results for a 4.5 meter, 70 degree sphere-cone aeroshell demonstrate the power of an integrated approach.
Probabilistic Resident Space Object Detection Using Archival THEMIS Fluxgate Magnetometer Data

(Georgia Institute of Technology, 2018-05-02) Brew, Julian ; Holzinger, Marcus J.

Although the detection of Earth-orbiting space objects is generally achieved using optical and radar measurements, these methods are limited in the ca pability of detecting small space objects at geosynchronous altitudes. This paper examines the use of magnetometers to detect plausible flyby encoun ters with charged space objects using a matched filter signal existence binary hypothesis test approach on archival fluxgate magnetometer data from the NASA THEMIS mission. Relevant data-set processing and reduction is dis cussed in detail. Using the proposed methodology, 285 plausible detections are claimed and several are reviewed in detail. Keywords: resident space objects; matched filter; admissible region; geostationary orbit; binary hypothesis testing
A scalable hardware-in-the-Loop simulation for satellite constellations and other multi-agent networks

(Georgia Institute of Technology, 2018-05-01) DeGraw, Christopher F.
Coulomb-Force Based Control Methods for an n-Spacecraft Reconfiguration Maneuver

(Georgia Institute of Technology, 2018-05-01) Swenson, Jason C.

In an electrically-charged space plasma environment, spacecraft Coulomb forces are shown as a potential propellant-free alternative for an n-spacecraft formation reconfiguration maneu ver with nd deputy spacecraft. Two Coulomb force based methods (and one method without Coulomb forces) for reconfiguration maneuvers are developed, tested, and evaluated. Method 1a applies Direct Multiple Shooting in order to calculate the optimal thrust inputs of a min imum fuel trajectory. Method 1b uses the results from Method 1a to compare the optimal thrust input to the set of all possible resultant Coulomb force vectors at each point in time along a trajectory. Method 2, formulated from optimal control theory, solves directly for nd spacecraft charge states at each point in time with Clohessy-Wiltshire relative dynamics and minimizes the final relative state vector error. The overall performance of Method 2 is shown to be superior than that of Method 1b in terms of both relative state vector error and total computational time. Furthermore, Method 2 shows performance comparable to the optimal minimum fuel trajectory calculated in Method 1a.
Early Collision and Fragmentation Detection of Space Objects without Orbit Determination

(Georgia Institute of Technology, 2018-05-01) Axon, Lyndy E.

This paper demonstrates that from using the hypothesized constraint of the admissible regions it is possible to determine if a combination of new uncorrelated debris objects have a common origin that also intersects with a known catalog object orbit, thus indicating a collision or fragmentation has occurred. Admissible region methods are used to bound the feasible orbit solutions of multiple observations using constraints on energy and radius of periapsis, propagating them to a common epoch in the past, and using sequential quadratic programming optimization to find a set of solution states that minimize the Euclidean distance between the observations at that time. If this given this set of solutions intersects with a catalog object orbit, then that object is the probabilistic source of the debris objects. This proposed method is demonstrated on an example of a low-earth object observation.
Algorithmic Insufficiency of RSSI Based UKF for RFID Localization Deployment On-Board the ISS

(Georgia Institute of Technology, 2018-05-01) Carnes, Joshua T.

This work evaluates the application of Unscented Kalman Filter (UKF) to generate stochastic localizations of radio frequency identification (RFID) chips in a sensor poor, highly reflective environment. Localization is done through the application of kNN algorithms and UKF methods to assign to reference RFID tags. The research is conducted in response to the needs of NASA for an application on the International Space Station. While the UKF has been shown to be effective on RFID streams, the sensor poor environment and difficult conditions aboard the ISS cause a loss of localization. This work shows that a UKF alone is insufficient for deployment on the ISS and proposes an alternative. Validation methods are proposed, and initial results are generated. Current industry methods are explored as benchmarks for algorithm performance.
Strategic Planning of Abort Trajectories for Manned Lunar Missions

(Georgia Institute of Technology, 2018-05-01) Yuricich, Jillian

A resurgence in manned lunar missions is on the horizon with private space companies and nation states alike competing to be the first to return to the Moon since the Apollo program ended in 1972. Technology and mission planning abilities have expanded im mensely in the almost half century of time that has elapsed since Apollo 11 first landed on the Moon. It is therefore necessary to evaluate and update how abort procedures should be strategized given the increase in volume of crewed missions planned for the Moon and beyond. This research seeks to investigate three abort strategies for space vehicles in or bit around the Moon and provide a high-level road map of options based on their fuel costs and time of flight to return to the Earth. By investigating previous historic works in combination with more recent research, this paper intends to capitalize on previous math ematical derivations and combine multiple abort strategies into a coherent simulation tool. It is expected that given the nominal trajectory of a circular lunar orbit, a specific abort strategy with options ranging from single to triple-impulse requirements can be selected as the optimal trajectory for a return to Earth. This research provides a high-level road map of contingency plans and fills a gap in understanding abort strategies from lunar orbit.