Aerospace Engineering Commons^™

Safe Control Design For Quadruped Locomotion In Unstructured Environments Using Linear Transfer Operators, Sriram Sundar Krishnamoorthy Shankara Narayanan

All Dissertations

Deploying quadruped robots in unstructured, obstacle-rich environments requires control and planning methods that remain safe and reliable despite complex terrain geometry, limited sensing, and inevitable modeling errors. This thesis develops operator-theoretic tools for safe control design of robotic systems using linear transfer operators, with a focus on quadruped locomotion in unstructured environments. The central goal is to develop a unified operator-theoretic framework for safe control design based on the Perron–Frobenius (P–F) and Koopman operators. In particular, the thesis leverages \emph{density functions} to develop safe navigation frameworks in the dual space of densities. In the operator-theoretic perspective, the P–F operator governs …

Adaptive Artificial Potential Field Guidance And Control For Autonomous Docking With Uncooperative And Unknown Spacecraft, Steven Holmberg

Theses and Dissertations

The increasing demand for on-orbit servicing (OOS), active debris removal (ADR), and space domain awareness (SDA) missions has increased the need for autonomous spacecraft rendezvous and proximity operations (RPO) with uncooperative and unknown targets. Traditional guidance and control methods are typically designed for cooperative systems with known geometry and state information. This work builds on previous research to develop and evaluate an artificial potential field (APF)-based control framework capable of autonomous operation with minimal prior target knowledge and applicability to both relatively static and tumbling spacecraft.

The proposed APF formulation incorporates established safety constructs from cooperative docking systems, including an …

Digital Twin–Oriented Certification Architecture For Advanced Air Mobility, Daniel Pleffken

International Journal of Aviation, Aeronautics, and Aerospace

Advanced Air Mobility (AAM) systems introduce certification challenges associated with distributed propulsion, increasing software reliance, and tightly coupled architectures. These characteristics evolve within regulatory environments that are still adapting to emerging vehicle concepts. While digital engineering practices are increasingly adopted during system development, certification workflows remain largely document-centric, limiting lifecycle traceability and consistent reasoning about change impacts as designs and regulatory interpretations evolve. This paper proposes a Digital Twin–oriented certification architecture that integrates regulatory knowledge, system representations, Means of Compliance (MoCs), and verification artifacts within a unified model-based environment. The architecture is organized around four elements: regulatory structuring, Model-Based Systems …

Design And Development Of A Passive Dust Protection System For Lunar Docking Operations, Simon Thengvall

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Lunar docking systems face a unique set of environmental conditions that can create significant challenges for mechanical design. Among these, the abrasive nature of lunar regolith can impair the kinematic function of traditional terrestrial mechanisms as well as contaminate critical spacecraft components such as environmental seals, causing them to fail. For crew-rated docking systems, failure of these systems not only threatens mission success, but also crew safety, so dust protection is crucial for docking components. To address the concerns of regolith intrusion, the Simple External Attachment for Lunar Openings (SEALO) is developed as a key architecture for mechanism evaluation when …

Numerical Investigation On Lightning Survivability And Residual Strength Of Scarf-Patched And Z-Pinned Cfrp Composites, Logan Hales

All Graduate Theses and Dissertations, Fall 2023 to Present

Carbon fiber reinforced polymer (CFRP) composites are critical in aerospace applications yet remain vulnerable to lightning strikes due to orthotropic electrical conductivity and poor thermal resistance. Over the past decades, lightning-strike damage in pristine CFRP has been extensively investigated. However, the response of damaged and subsequently repaired laminates remains poorly understood, raising concerns about the structural integrity of repaired aircraft. This study aims to develop a sequentially coupled thermo-structural modeling framework to quantify how two common composite repair strategies (scarf patching and z-pinning), along with patch size, pin material, and configuration, influence lightning-induced damage and the residual flexural strength of …

Measurements And Scaling Of Ion Propulsion Impulse During Driven Magnetic Reconnection, Fatima Ebrahimi, Nicholas A. O'Gorman, Kush Maheshwari, Jongsoo Yoo, Alexandre Sainterme, Hantao Ji

Faculty Publications

Impulse scaling during magnetic reconnection, the magnetic energy conversion to kinetic energy, via direct Mach probe measurements in Magnetic Reconnection Experiment is examined. Ion exhaust velocity and impulse scalings with reconnecting magnetic field during the push phase of driven reconnection are presented. The outflows and impulse measurements are compared with global MHD simulations. Both measurements and simulations reveal a favorable scaling, greater than linear, of impulse with reconnecting field. These scaling results establish that magnetic reconnection could be utilized for plasma propulsion.

Relaxed Convex Approximation For Optimal Control In Cislunar Space, Jondavid K. Hertzel

All Graduate Theses and Dissertations, Fall 2023 to Present

This thesis develops a method of optimal control for a spacecraft in the region between the Earth and the Moon known as cislunar space. The optimal control method is developed through a modern optimization technique called “convex relaxation” to achieve a formulation that can be reliably solved by numerical computation tools. The primary research objective is to evaluate the efficacy of this method in accommodating the physical thrust constraints of a spacecraft. This approach is tested in simulation with an unstable halo orbit around the Moon in the circular restricted three-body problem (CR3BP) model. The simulation incorporates realistic disruptions from …

Two Applications Of Lifting-Line Theory For The Design Of Efficient Aircraft, Amanda K. Olsen

All Graduate Theses and Dissertations, Fall 2023 to Present

Numerical lifting-line is a tool that can be used to evaluate the forces and moments of an aircraft wing. This method has limitations but it is beneficial in obtaining a large set of results with relatively little computational power. This research seeks to analyze two different flight scenarios through the use of two numerical lifting-line tools developed at the Utah State University AeroLab. The first scenario involves an aircraft in ground effect flight. When an aircraft flies close to the ground, a phenomenon called ground effect occurs where the lift is increased and the induced drag is decreased. Therefore, flying …

Manned Exploration Of Satellites Of The Outer Planets: An Analysis Of Current Technologies And A Discussion Of Advancements Required, Joshua Carson Meador

Theses and Dissertations

The Solar System’s outer planets have many satellites, some of which are known to be the most likely places to find extraterrestrial life in our celestial backyard. Multiple scientific missions have been sent to glean information from these satellites, yet the possibility of a manned expedition has long been exclusive to science fiction stories. This paper intends to collect and analyze the current state of space travel technology to explore the feasibility of such a mission with modern technology and to discuss which future advancements should be the focal point for making such missions a reality. To begin, data on …

Aircraft Fault Detection Via Weight And Bias Analysis Of A Custom First Neural Network Layer, George Harrison Chen

Theses and Dissertations

Fault detection in aircraft is traditionally handled through redundant hardware and comparison algorithms to detect failures. Alternatives like model-based residual generation and data-driven approaches such as supervised fault classification and unsupervised anomaly detection have been explored, but they suffer from practical limitations; model-based methods require accurate system models, and data-driven methods have large constraints on the data limiting scalability and adaptability. This work presents a purely data-driven neural network architecture featuring a custom first layer designed for real-time fault detection where the weights and biases of this layer are used to detect faults. The network requires zero supervision and complements …

Analysis Of Oscillating Flow Over A 2-D Airfoil With Flow Reversal, Colter Couillard-Rodak

McKelvey School of Engineering Graduate Student Theses & Dissertations

Finite-state models are useful tools in modeling the aerodynamics of rotorcraft in flight simulators. 2-D and 3-D finite-state models have been developed and compared to closed form solutions, however these models are currently unable to handle situations where the freestream changes directions and the rotor re-enters its own wake. A 2-D finite state model was previously developed that includes a parameter that accounts for the change in free stream. This model, however, contains an inherent stability issue at the instant that the velocity changes direction.

The effects of this instability can be mitigated in certain flow conditions. A purely oscillatory …

The Pid-Based Three Quadcopter Uavs Formation Control Under External Disturbance, Vo Van An, Trinh Luong Mien

Makara Journal of Technology

This paper presents the design and evaluation of a formation control strategy for three quadcopter UAVs, based on a PID controller in a leader–follower structure, under the influence of external disturbances. Each UAV employs a six-degree of-freedom dynamic model and utilises a cascade PID control architecture, in which the inner control loop stabilises the attitude. In contrast, the outer control loop regulates position and maintains the formation. The PID parameters are tuned using the Ziegler–Nichols method to ensure simple implementation and low computational cost. The performance of the control system is evaluated through simulations in the MATLAB environment for two …

Program And Proceedings, The Nebraska Academy Of Sciences 1880–2026: 146th Anniversary Year, One Hundred-Thirty-Sixth Annual Meeting

Nebraska Academy of Sciences: Programs and Proceedings

Program and abstracts of the proceedings for the Nebraska Academy of Sciences 136th annual meeting, 2025

Sessions

Aeronautics and Space Science

Anthropology

Biological and Medical Sciences

Earth Sciences

Ecology, Sustainability, and Environmental Science

Physics and Engineering

General Poster Session

2026 Maiben Lecture: Shifting Extremes: Understanding Nebraska’s Changing Climate and Preparing for What Lies Ahead, Deborah Bathke

2026 Friends of Science Awards: Julie Shaffer and Irina Filina

2026 C. Bertrand and Marian Othmer Schultz Colleaguate Schoalrship Award: Piper Ryschon and Bryce Reeson

In Memoriam: Paul Royster

Analysis Toolkit For Potential Lunar Landing Zones, Jacobo Matallana

Morehead State Theses and Dissertations

A thesis presented to the faculty of the College of Science and Engineering Morehead State University in partial fulfillment of the requirements for the Degree Master of Science by Jacobo Matallana on April 24, 2026.

Saber – Stability Analysis Through Bipropellant Engine Research, S. Conley, R. Gaulin, E. Lucas, A. Ramirez, N. Reese, W. Reinkoester, J. Sadler, W. Tinelli, B. Varozza

Aerospace, Physics, and Space Science Student Publications

Stability Analysis through Bipropellant Engine Research (SABER) is a small-scale, compressed air and propane bipropellant rocket engine designed as the test subject of a combustion instability analysis. Through various static fires at varying combustion chamber lengths, the project demonstrates that less combustion instabilities are experienced at smaller characteristic lengths.

Automatic Determination Of Mechanical Properties From Molecular Dynamic Stress-Strain Curves Using Regression Fringe Response, Josh Kemppainen, Tristan Muzzy, Travis Wavrunek, Gregory Odegard

Michigan Tech Publications

Molecular dynamics (MD) simulations have become a powerful tool for studying polymers, designing new materials, and composites. Mechanical behavior in MD simulations are typically evaluated through stress-strain curves. However, MD-generated stress-strain curves are often obscured by thermal noise from atomic vibrations. This noise complicates the reliable derivation of mechanical properties and hinders objective and reproducible analysis. The noise in the stress-strain curves has been removed by using a Butterworth low-pass filter, enabling clearer interpretation of stress-strain data. Building on this, a novel analysis framework the Regression Fringe Response (RFR) is introduced to systematically determine the Young's modulus, yield strength, and …

Applications Of Suas Thermal Imaging And Lidar At Letort Spring Garden Preserve: An Independent Study, Kelsey Wardell

Harrisburg University Other Works

No abstract provided.

Experimental Investigation Of Mode-Ii Interlaminar Fatigue Damage In Stitched And Unstitched End-Notched Flexure Carbon Fiber Composites, Madelyn Sloan Berry

Honors Theses

Composite materials are increasingly used in aerospace structures due to their high strength-to-weight ratio, but their susceptibility to interlaminar fatigue damage remains a critical concern, particularly under mode-II shear loading. This study investigates the fatigue behavior of stitched and unstitched quasi-isotropic carbon fiber composite specimens made of SAERTEX Class-75 non-crimp fabrics and Hexcel 1078-1 epoxy via vacuum assisted resin transfer molding. Global fatigue behavior was analyzed using displacement and crack length cycle relationships derived from compliance calibration methods (CCM), while local behavior was examined using digital image correlation (DIC). Unstitched specimens exhibited a single rapid crack growth associated with unstable …

Energetic Characterization Of 3-D Printed Acrylonitrile Butadiene Styrene Fuels For Hybrid Rocket Propulsion Applications, Stephen A. Whitmore, Ryan J. Thibaudeau, Ava T. Wilkey

Mechanical and Aerospace Engineering Faculty Publications

Hybrid rocket technologies are gaining recognition as eco-friendly alternatives to traditional propulsion systems. Utah State University’s Propulsion Research Laboratory has developed a High-Performance Green Hybrid Propulsion (HPGHP) technology, leveraging 3D-printed ABS fuel for reliable, low-energy ignition. Among tested materials, only ABS shows suitable electrical-breakdown properties for arc ignition. Unfortunately, due to the proprietary formulations in commercial ABS blends, and its limited use as a rocket-propellant, related composition and combustion data are limited. This study uses spectroscopic evaluation and bomb calorimetry to estimate material compositions, enthalpies of formation, and combustion energies for multiple commercially available 3-D print feed stock ABS types, …

Space Degradable Pyrotechnic Fastener, Jonathan Baker

Honors Theses

Space debris has become a critical threat to orbital operations, with over 30,000 tracked objects currently circling Earth. Traditional separation charges used in satellite launches contribute significantly to this problem by generating unpredictable shrapnel that can remain in orbit for decades or centuries. This project proposes the design and development of a spacedegradable explosive bolt that exploits the harsh space environment to accelerate material breakdown after use.

The design utilizes advanced polymer materials selected for their susceptibility to degradation from UV radiation — an environmental factor abundant in Low Earth Orbit (LEO). Our prototype will be engineered to meet industry-standard …