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 41

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
Judicial Evidential Reasoning for Decision Support Applied to Orbit Insertion Failure

(Georgia Institute of Technology, 2017-11) Jaunzemis, Andris D. ; Minotra, Dev ; Holzinger, Marcus J. ; Feigh, Karen M. ; Chan, Moses W. ; Shenoy, Prakash P.

Realistic decision-making often occurs with insufficient time to gather all possible evidence before a decision must be rendered, requiring an efficient process for prioritizing between potential action sequences. This work aims to develop a decision support system for tasking sensor networks to gather evidence to resolve hypotheses in the face of ambiguous, incomplete, and uncertain evidence. Studies have shown that decision-makers demonstrate several biases in decisions involving probability judgement, so decision-makers must be confident that the evidence-based hypothesis resolution is strong and impartial before declaring an anomaly or reacting to a conjunction analysis. Providing decision-makers with the ability to estimate uncertainty and ambiguity in knowledge has been shown to augment effectiveness. The proposed framework, judicial evidential reasoning (JER), frames decision-maker questions as rigorously testable hypotheses and employs an alternating-agent minimax optimization on belief in the null proposition. This approach values impartiality in addition to time efficiency: an ideal action sequence gathers evidence to quickly resolve hypotheses while guarding against bias. JER applies the Dempster-Shafer theory of belief functions to model knowledge about hypotheses and quantify ambiguity, and adversarial optimization techniques are used to make many-hypothesis resolution computationally tractable. This work includes derivation and application of the JER formulation to a GTO insertion maneuver anomaly scenario.
Real-Time Hardware-in-the-Loop Hand-Off from a Finder Scope to a Larger Telescope

(Georgia Institute of Technology, 2017-11) Aguilar-Marsillach, Daniel ; Virani, Shahzad ; Holzinger, Marcus J.

Electro-optical sensors play an increasingly important role in the SSA domain for tracking satellites and debris objects. Such sensors provide data that complement other methods, like radar based sensing, by providing a higher angular resolution, and thus improving the estimation of an object’s orbit, attitude and physical properties. The acquisition of such data is invaluable for obtaining more accurate collision risk assessments and formulating improved debris mitigation efforts. The Georgia Tech - Space Object Research Telescope aims to improve detection and tracking for agile Raven-class telescopes with narrow fields of view and high angular resolutions. A secondary imaging system was used to correct the Georgia Tech - Space Object Research Telescope’s pointing errors for tracking objects at high angular rates using a closed-loop controller. This paper will focus on the development and results of a real-time hardware-in-the-loop hand-off from a finder scope to a larger telescope.
Preliminary CubeSat Design for Laser Remote Maneuver of Space Debris at the Space Environment Research Centre

(Georgia Institute of Technology, 2017-09) Dixon, Jefferson ; DiPrete, John ; Green, Jacquilyn ; Healy, Christopher ; Underwood, William ; Wittenstein, Isaac ; Smith, Liam ; Wingate, Kathryn A. ; Holzinger, Marcus J.

The Space Environment Research Centre (SERC) endeavors to demonstrate the ability to maneuver high area to mass ratio objects using ground based lasers. Lockheed Martin has been leading system performance modeling for this project that includes high power laser propagation through the atmosphere, targeted interactions, and subsequent orbital maneuver of the object. This paper describes a CubeSat that could be used as a potential target to demonstrate the maneuver system. The model assumptions and performance estimates for an on-orbit laser maneuver demonstration are discussed.
Generalized Minimum-Time Follow-up Approaches Applied to Tasking Electro-Optical Sensor Tasking

(Georgia Institute of Technology, 2017-09) Murphy, Timothy S. ; Holzinger, Marcus J.

This work proposes a methodology for tasking of sensors to search an area of state space for a particular object, group of objects, or class of objects. This work creates a general unified mathematical framework for analyzing reacquisition, search, scheduling, and custody operations. In particular, this work looks at searching for unknown space object(s) with prior knowledge in the form of a set, which can be defined via an uncorrelated track, region of state space, or a variety of other methods. The follow-up tasking can occur from a variable location and time, which often requires searching a large region of the sky. This work analyzes the area of a search region over time to inform a time optimal search method. Simulation work looks at analyzing search regions relative to a particular sensor, and testing a tasking algorithm to search through the region. The tasking algorithm is also validated on a reacquisition problem with a telescope system at Georgia Tech.
Uninformative Prior Multiple Target Tracking Using Evidential Particle Filters

(Georgia Institute of Technology, 2017-09) Worthy, Johnny L., III ; Holzinger, Marcus J.

Space situational awareness requires the ability to initialize state estimation from short measurements and the reliable association of observations to support the characterization of the space environment. The electro-optical systems used to observe space objects cannot fully characterize the state of an object given a short, unobservable sequence of measurements. Further, it is difficult to associate these short-arc measurements if many such measurements are generated through the observation of a cluster of satellites, debris from a satellite break-up, or from spurious detections of an object. An optimization based, probabilistic short-arc observation association approach coupled with a Dempster-Shafer based evidential particle filter in a multiple target tracking framework is developed and proposed to address these problems. The optimization based approach is shown in literature to be computationally efficient and can produce probabilities of association, state estimates, and covariances while accounting for systemic errors. Rigorous application of Dempster-Shafer theory is shown to be effective at enabling ignorance to be properly accounted for in estimation by augmenting probability with belief and plausibility. The proposed multiple hypothesis framework will use a non-exclusive hypothesis formulation of Dempster-Shafer theory to assign belief mass to candidate association pairs and generate tracks based on the belief to plausibility ratio. The proposed algorithm is demonstrated using simulated observations of a GEO satellite breakup scenario.
Empirical Dynamic Data Driven Detection Tracking Using Detectionless and Traditional FiSSt Methods

(Georgia Institute of Technology, 2017-09) Virani, Shahzad ; Murphy, Timothy S. ; Holzinger, Marcus J. ; Jones, Brandon A.

Autonomous search and recovery of resident space object (RSO) tracks is crucial for decision makers in SSA. This paper leverages dynamic data driven approaches to improve methodologies used in real-time detection and tracking of RSOs with a low signal-to-noise ratio (SNR). Detected RSOs are assigned to be tracked using one of two simultaneously operating algorithms. The Gaussian Mixture Proability Hypothesis Density (GM-PHD) filter tracks all RSOs above a certain SNR threshold, while a Detectionless Multi-Bernoulli filter (D-MB) detects and tracks low SNR objects. The D-MB filter uses matched filtering for likelihood computation which is highly non-Gaussian for dim objects. Hence, the D-MB filter is particle based which leads to higher computational complexity. The primary idea proposed in this paper is to balance the computational efficiency of GM-PHD and high sensitivity of the D-MB likelihood computation by dynamically switching tracks between the two filters based on the SNR of the target; allowing for real-time detection and tracking. These algorithms are implemented and tested on real data of objects in the geostationary (GEO) belt using a wide field-of-view camera (18.2 degrees). A star tracking mount is used to inertially stare at the GEO belt and data are collected for 2 hours corresponding to RSOs being observed in 48.2 degrees of the GEO belt.
A Massive-Scale Satellite Constellation Hardware-in-the-Loop Simulator its Applications

(Georgia Institute of Technology, 2017-06) DeGraw, Christopher F. ; Holzinger, Marcus J.

Given the growing interest in satellite constellations, there is a surprising lack of rigorously tested operations and control methods for constellations larger than 30 to 50 spacecraft. The purpose of this paper is to discuss the development of a robust, modular and scalable system able to provide software-in-the-loop (SWIL) and hardware-in-the-loop (HWIL) simulation capabilities for the advancement of formation and constellation Flight Software Technology Readiness Levels (FSW TRL). The system being developed is called COSMoS (COnstellation Simulation on a Massive Scale). The goal of this system is to a) enable massive-scale (100+ satellite) realistic testing and characterization of formation control and operations techniques, b) examine the scaling of centralized and decentralized formation guidance, navigation, and control algorithms, and c) improve Technology Readiness Levels in realistic conditions. Examples of developing capabilities include the implementation of control schemes using a Minimum Lyapunov Error approach as well as semi- and fully-autonomous decision making systems.
Dempster-Shafer Theory Applied to Admissible Regions

(Georgia Institute of Technology, 2017-02) Worthy, Johnny L., III ; Holzinger, Marcus J.

The admissible region approach is often used a bootstrap method to initialize a Bayesian state estimation scheme for too-short-arc measurements. However, there are ambiguities in how prior probabilities are assigned for states in the admissible region. Several approaches have proposed methods to assign prior probabilities, however there are inconsistencies in how the prior probabilities can be manipulated. The application of Dempster-Shafer evidential reasoning theory to the admissible region problem can avoid these ambiguities by eliminating the need to make any assumptions on the prior probabilities. Dempster-Shafer theory also enables the testing of the validity of the assumptions used to construct the admissible region. This paper introduces Dempster-Shafer theory and formulates the admissible region in terms of plausibility and belief which reduce to traditional Bayesian probability once there is sufficient information in the system.
Reachability Subspace Exploration Using Continuation Methods

(Georgia Institute of Technology, 2017-02) Brew, Julian ; Holzinger, Marcus J. ; Schuet, Stefan

Reachability manifold computation suffers from the curse of dimensionality and for large state spaces is computationally intractable. This paper examines the use of continuation methods to address this issue by formulating the reachability subspace manifold calculation into a number of initial value problems. As a result of computing the reachability manifold for a subspace of interest, an exponential improvement in computational cost occurs. This concept is applied to a position subspace reachability problem of a spacecraft in a Keplerian orbit under maximum thrust constraints. Future work includes a comparison of the proposed method with computing reachability manifolds using viscosity solutions of the Hamilton Jacobi Bellman partial differential equation.