121-130 of 201 results
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Flexible Body Control Using Fiber Optic Sensors, Florida Space Grant Consortium
PI Morad Nazari
CO-I Daewon Kim
This project would build on previous research that developed the dynamics formulation and control of a rigid-flexible system.
This project would build on previous research that developed the dynamics formulation and control of a rigid-flexible system. A cantilevered beam attached to a rotating central body is considered and analyzed through the finite element method. A set of matrix differential equations are obtained to describe the dynamic behavior of the system, and a control law based on a Lyapunov function is obtained and applied to the system. The development of this dynamics formulation and control also considers the rigid-flexible coupling present in the system. The control law is designed such that the system can achieve and maintain a set of desired states for the central rigid body and flexible structure. The experimental measurements obtained from the implementation of FOS sensors on the flexible body and inertial sensors on the rigid body will be utilized as the input in this control design. The research portion of the project is anticipated to require one or two graduate student research assistants and a part-time academic advisor over a one-year period.
Categories: Faculty-Staff
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Reconfigurable Guidance and Control Systems for Emerging On-Orbit Servicing, Assembly and Manufacturing (OSAM) Space Vehicles
PI Morad Nazari
CO-I Kadriye Merve Dogan
In this project, the ControlX team with ERAU partnership will develop agile, reconfigurable, and resilient dynamics and G&C algorithms for on-orbit servicing to capture a broad set of OSAM applications such as remediation of resident space object (RSO) (e.g., via de-orbiting, recycle, end-of-life servicing, satellite refueling, etc.) using effective tools and methods involving geometric mechanics, constrained G&C synthesis, and reconfigurable robotic manipulators (RRMs).
Dynamic response to emergent situations is a necessity in the on-orbit servicing, assembly and manufacturing (OSAM) field because traditional on-orbit guidance and control (G&C) cannot respond efficiently and effectively to such dynamic situations (i.e., they are based on either constant mass or diagonal matrix of inertia). In these circumstances, the current challenge is to develop modeling strategies and control systems that exhibit intelligence, robustness and adaptation to the environment changes and disturbances (e.g., uncertainties, constraints and flexible dynamics). Note that the current state-of-the-art methods do not offer a reliable, accurate framework for real-time, optimal accommodation of constraints in the system dynamics that account for orbital-attitude coupling in the motion of the bodies without encountering singularity or non-uniqueness issues. In this project, the ControlX team with ERAU partnership will develop agile, reconfigurable, and resilient dynamics and G&C algorithms for on-orbit servicing to capture a broad set of OSAM applications such as remediation of resident space object (RSO) (e.g., via de-orbiting, recycle, end-of-life servicing, satellite refueling, etc.) using effective tools and methods involving geometric mechanics, constrained G&C synthesis, and reconfigurable robotic manipulators (RRMs).
The proposed work in this Phase I includes reconfigurable systems for on-orbit servicing, assembly and manufacturing with learning control methods that minimize tracking error of the end-effector of the RRM in the presence of uncertainties, optimize configuration and accommodate constraint-changing scenarios. Our developments will avoid singularity; not rely on the concept of costates or Lagrange multipliers that are restrictive; handle system uncertainties while enforcing the constraints; use RRMs in different tasks (recycle, debris removing, maintenance, etc.); not need in sensors or exact model knowledge for robotic arms. Specifically, constrained space vehicle control (predicated on Udwadia and Kalaba (UK) formalism) will offer not only accurate and resilient design but also reconfigurability in that G&C algorithms can easily be modified to suit a wide spectrum of OSAM applications. ControlX team will also consider the feasibility of hardware implementation. The selection of sensors, actuators and onboard computers will be an important trade-off between among size, weight, and power (SWaP) constraints, reliability, and computing performance. A real-time operating system (RTOS) is planned to meet timing and memory management constraints, partitioning hardware resources to control software application interactions. An analysis suite for the autonomous system implementation, based on system modeling and learning techniques, will provide onboard analysis, enabling decision-making as to whether the system can continue to meet mission requirements.
Categories: Faculty-Staff
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Aviation Management Education Study (AMES)
PI Jason Newcomer
CO-I James Marion
CO-I Matthew Earnhardt
The Aviation Management Education Study (AMES) is a longitudinal effort consisting of a series of research papers covering various facets of aviation education as it pertains to managers in the field and hiring of industry professionals.
In the last 34 years, corporate America and the aviation professions have changed due to (a) increased air travel, (b) outsourcing functions, (c) aviation research, (d) federal regulation, and (e) the changed U.S. economy (Katkin, et al., 2013; Mootien, Warren, Morris, & Enoch, 2013; Quinlan, Hampson, & Gregson, 2013; Rango & Laliberte, 2010). The specific business problem is the lack of current, correlated demographic data of aviation managers, as well as any resultant significance testing of the aforementioned data to determine if there are necessary academic pre-requisites to obtaining management positions in aviation.
Categories: Faculty-Staff
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Cross-Scale Wave Coupling Processes in Kelvin-Helmholtz Structures
PI Heidi Nykyri
Project investigates cross-scale wave coupling processes and their role on ion heating, mixing and diffusion.
One of the pending problems in collisionless plasmas is to understand the plasma heating and transport across three fundamental scales: fluid, ion and electron. The plasma inside Earth’s magnetotail plasma sheet is ~50 times hotter than in the magnetosheath. Furthermore, the specific entropy increases by two orders of magnitude from the magnetosheath to the magnetosphere, which is a signature of a strong non-adiabatic heating. Also, the cold component ions are hotter by ~30 % at the dawnside compared to those measured on the duskside. Our recent statistical study using THEMIS data indicates that the magnetosheath seed population is not responsible for this asymmetry so additional physical mechanisms at the magnetopause or plasma sheet must be at work to explain this asymmetric heating. Recent works suggest that dawn-flank magnetopause boundary is more prone to the fluid-scale Kelvin-Helmholtz instability (KHI) as well as to the ion-scale electromagnetic wave activity, which may help explain the observed plasma sheet asymmetry. Project uses numerical simulations, plasma theory and spacecraft observations to understand relation of small-scale waves to large-scale velocity driven modes and evaluate their role in mixing, diffusion, and heating of ions.
Categories: Faculty-Staff
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Experimental Identification of Plasma Wave Modes in Vicinity of KH Vortices and in Plasma ’Mixing’ Regions in Low Latitude Boundary Layer (Ion scales)
PI Heidi Nykyri
Project uses Cluster spacecraft data to identify ion-scale waves within Kelvin-Helmholtz waves.
Project uses Cluster spacecraft data to identify ion-scale waves within Kelvin-Helmholtz waves.Categories: Faculty-Staff
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Statistical correlation study between solar wind, magnetosheath and plasma sheet properties
PI Heidi Nykyri
CO-I Xuanye Ma
Statistical study of the solar wind, magnetosheath, and magnetospheric plasma properties usinng 8+ years of THEMIS data.
The study will utilize recently developed statistical tool developed under Nykyri's NSF CAREER grant to present 8+ years of THEMIS spacecraft data in the coordinate system that takes into account the motion of the magnetopause and bow shock and will organize THEMIS observations into spatial bins with respect to physical boundaries under prevailing solar wind conditions. The study will address how do the plasma sheet properties such as number density, temperature, electron to ion temperature ratio and specific entropy vary during a) Parker-Spiral, Ortho-parker spiral, Northward and Southward IMF, and b) during high and slow solar wind speed, and how are these correlated with corresponding magnetosheath properties?
Categories: Faculty-Staff
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NSF Career Award: Effects of Magnetosheath properties on the dynamics and plasma transport produced by the Kelvin-Helmholtz Instability and on the Plasma Sheet Anisotropies
PI Heidi Nykyri
Project investigates impact of magnetosheath properties on Kelvin-Helmholtz instability
The magnetosheath processes will be studied by doing a statistical study of the magnetosheath properties using THEMIS data and by utilizing global hybrid (fluid electrons, particle ions) simulations. In addition, the MHD-scale KHI will be compared with hybrid and particle simulations of the instability.
Categories: Faculty-Staff
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Turbulence and Structure in the Magnetospheric Cusps: Cluster spacecraft observations
PI Heidi Nykyri
Project analyzes the structure, origin of fluctuations and high-energy particles in the high-altitude cusp regions
Project uses Cluster data and high-resolution local 3-D MHD simulations with test particles to determine the structure and origin of high-energy particles in the high-altitude cuspCategories: Faculty-Staff
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Magnetospheric Multi-Scale (MMS) Observations and simulations of high-energy electrons in the dayside magnetosheath
PI Heidi Nykyri
CO-I Brandon Burkholder
CO-I Xuanye Ma
The key objective of this study is to better understand the source and cause of high-energy electrons observed by the MMS in the dayside magnetosheath.
The key objective of this study is to better understand the source and cause of high-energy electrons observed by the MMS in the dayside magnetosheath. The Magnetospheric Multi-Scale (MMS) mission is a four-spacecraft constellation orbiting in formation around Earth with a main goal to study the microphysics of magnetic reconnection at the dayside magnetopause. Recent MMS observations showed high energy (40 keV) electrons leaking into the magnetosheath. However, the dominant leaking mechanism has not been fully understood. Global Lyon-Fedder-Mobarry (LFM) with test particle simulations suggest that low latitude reconnection and the nonlinear Kelvin-Helmholtz (KH) instability can cause the leak of high energy electrons into the magnetosheath. But it is important to notice that many of the electrons leaking events were observed close to Fall Equinox when the MMS orbit has a significant y-component and the z_GSM coordinate can be substantial (up to ~7 R_E). Therefore, MMS high-energy electron events may have a high-latitude source. For instance, it is well demonstrated that magnetic reconnection between the Interplanetary Magnetic Field (IMF) and Earth's magnetic field surrounding the cusps can lead to the formation of cusp diamagnetic cavities (Nykyri et al., JGR 2011a,b; Adamson et al., angeo 2011), extended regions of decreased magnetic field, which can be filled with higher energy (>30 keV) electrons, protons and O+ ions. Cluster observations revealed 90-degree pitch angle electrons in the cavity, strongly suggestive of a local acceleration mechanism (Walsh, angeo 2010; Nykyri et al, JASTP 2012). Test particle simulations in a high-resolution 3D cusp model uncovered that trapped particles in the diamagnetic cavities can be accelerated when their drift paths go through regions of "reconnection quasi-potential" (Nykyri et al, JASTP 2012). Once the IMF orientation changes it is possible for trapped particles in the cavity to end up into the loss cone and "leak out" of the cavity. A systematic approach to our science objective addresses the following compelling science questions by synergy using MMS observational data and numerical simulation.
Categories: Faculty-Staff
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Science and engineering proof of concept study for the Next generation Space Weather Prediction mission and space weather model development
PI Heidi Nykyri
Project analyzes astrodynamics (transfer trajectories) and spacecraft constellation stability about all Lagrange points for Mercury, Venus, Earth, Mars system for the "next generation" space weather prediction mission, and develops a solar wind model which will use data from this mission
Project analyzes astrodynamics and constellation stability for the "next generation" space weather prediction mission, and develops a solar wind model which will use data from this missionCategories: Faculty-Staff
121-130 of 201 results