1-10 of 53 results
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Novel Space Science Test via Adaptive Control and Integral Concurrent Learning Leveraging On-Orbit CubeSat Structural Identification
PI Riccardo Bevilacqua
The objective of this work is to create the basic science underpinning the structural testing and evaluation framework and control for deployable large spacecraft.
The objective of this work is to create the basic science underpinning the structural testing and evaluation framework and control for deployable large spacecraft. Large space structures and those with high dimensional ratio between deployed and stowed configurations are extremely difficult to test on the ground. The AFRL’s Space Vehicle Directorate recently opened the new Deployable Structures Laboratory, or DeSeL, as evidence of a renewed interest towards these systems. DeSeL represents the state-of-the-art technology for on-the-ground experimentation of deployable systems. In particular, an active Gravity Off-Load Follower (GOLF) cart system is being currently developed, intended to have three degrees of freedom (attitude motion) which could foreseeably provide the capability for large low-frequency motions. The real capabilities of the GOLF system are yet to be determined, and this research effort will develop in parallel, assist, support and inform the development of this new facility at AFRL.
New testing and evaluation science to identify these systems’ behavior and control them, that are robust to large uncertainties in the structural dynamics are then needed, and the first time they deploy on orbit is the ultimate test.
We propose to obtain the objective by combining novel control and learning theory with ad-hoc experimental activities. The culmination of this effort will be a flight demonstration, where a CubeSat previously designed by the Advanced Autonomous Multiple Spacecraft (ADAMUS) laboratory will be modified in its design and perform autonomous on-orbit structural identification, control, and testing.
The flight demonstration will be based on measuring the natural frequencies, damping ratios and vibration mode shapes via excitation of the spacecraft, using reaction wheels on the main hub and potentially distributed small thrusters on the flexible bodies, emulating the configuration of the AFRL’s Space Solar Power Incremental Demonstrations and Research Project (SSPIDR).
Categories: Faculty-Staff
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GNC Efforts in Support of the University of Floridas Research for the NASA Instrument Incubator
PI Riccardo Bevilacqua
The following tasks will be performed by one Ph.D. student and Dr. Bevilacqua (PI at ERAU), in support of the University of Florida’s proposal for the NASA’s Instrument Incubator Program (IIP):
Year 1:
- Drag-compensation and test mass control design. Adaptive control combined with integral concurrent learning will be investigated to estimate, in real-time, the effects of drag on the spacecraft, to enable precise control of the test mass inside it. The PI has successfully used this technique for drag-based spacecraft formation flight, where online estimation of the ballistic coefficient of an unknown vehicle is critical.
- Support for drag-compensation thruster mapping. Lyapunov-based thruster selection principles, previously developed by the PI, will be used to simplify the thruster mapping problem, and prevent the use of any numerical iterations, to ease online implementation. An additional step will involve exploring the possibility to use adaptive + ICL control to also estimate the thrust errors and their misalignment.
Year 2:
- Spacecraft acceleration estimation based on S-GRS outputs. The test mass position and orientation are measured inside the sensor and the applied forces and torques on the test mass are known. How to use this information to optimally estimate the spacecraft acceleration and angular acceleration due to atmospheric drag remains a challenge. An approach based on a bank of Kalman (or Extended Kalman) Filters will be explored, possibly in iterative form, as previously done for spacecraft relative motion estimation by Dr. Gurfil at Technion and by the PI and one of his former students.
Year 3:
- Support for hardware-in-the-loop testing of the control system at UF. The PI and the PhD student will support experimentation at UF, to implement the above algorithms in hardware systems. The PI has over a decade of experience in on-the-ground testing of spacecraft GNC systems.
Year 1-3:
- Support for numerical simulation of the closed-loop system. High-fidelity orbital and attitude propagators will be used to test the algorithms developed. STK and NASA’s Spice will also be candidates for comparison.
Categories: Faculty-Staff
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CubeSats Hosting Flexible Appendages for On-Orbit Testing of Advanced Control Algorithms
PI Riccardo Bevilacqua
The objective of this work is to start the assembly of a CubeSat hosting specialized flexible appendages, taking inspiration from a previously designed spacecraft developed by the Advanced Autonomous Multiple Spacecraft (ADAMUS).
The objective of this work is to start the assembly of a CubeSat hosting specialized flexible appendages, taking inspiration from a previously designed spacecraft developed by the Advanced Autonomous Multiple Spacecraft (ADAMUS). This CubeSat will eventually enable testing of ADAMUS’ developed spacecraft control algorithms on-orbit.
Relevance to NASA: The innovation proposed herein lies in the ability to autonomously characterize and control complex space structures. This project will directly support NASA’s TA 4: Robotics and Autonomous Systems
Categories: Faculty-Staff
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A Machine Learning Based Transfer to Predict Warhead In-Flight Behavior from Static Arena Test Data
PI Riccardo Bevilacqua
The objective of this work is to combine high-fidelity numerical models with unique/ad-hoc experimental activities to strengthen basic science underpinning the test and evaluation framework for warhead fragmentation and fragments fly-out.
Warhead fragmentation predictions are based on either numerical simulations or static arena tests where detonations occur in unrealistic conditions (not flying). The first methodology presents many shortcomings: there is no agreement on the state of the art for simulations, and many tools ignore important aspects such as gravity, aerodynamic forces and moments, and rigid body motion of different shape fragments. Numerical simulations are also lengthy and cannot be used as online/on-the-battlefield tools. The experimental approach is also extremely limited, as it does not reproduce the real-world conditions of a moving warhead.
The objective of this work is to combine high-fidelity numerical models with unique/ad-hoc experimental activities to strengthen basic science underpinning the test and evaluation framework for warhead fragmentation and fragments fly-out. In particular, we will aim at combining the most advanced simulation capabilities with static experimental data, to obtain a transfer function predicting lethality and collateral damage of a given warhead in real-life conditions. Artificial neural networks and/or other machine learning tools (e.g., Random Forests) will be used to capture the underlying physics governing fragments dispersion under dynamic conditions, coming from NAVAIR’s Spidy software, and eventually combine this knowledge with real warhead characteristics, coming from the static test. This proposal is of high impact because of the existing gap in analytical tools to define and validate warhead fragmentation testing.
The broader impact (long term) of this work may be a software tool that the warfighter can use on the field to rapidly assess the effects of the arsenal at his disposal. This tool will be equally beneficial to designers and testers within the Air Force and the DoD in general.
Categories: Faculty-Staff
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Maritime RobotX Challenge
PI Eric Coyle
CO-I Patrick Currier
CO-I Charles Reinholtz
CO-I Brian Butka
The Maritime RobotX Challenge entails the development and demonstration of an autonomous surface vehicle (ASV). Embry-Riddle is one of three U.S. schools selected to compete in the challenge, which is co-sponsored by the Office of Naval Research (ONR) and the Association for Unmanned Vehicle Systems International (AUVSI) Foundation.
The 2014 ERAU platform, named Minion, is a 16-foot fully-autonomous Wave Adaptive Modular Vessel (WAM-V) platform and is registered as an autonomous boat in the state of Florida. Minion's development currently focuses on autonomous tasks of buoy channel navigation, debris avoidance, docking, target identification and sonar localization. To accomplishing these tasks, the team has developed as set of system software nodes including state estimation, object classification, mapping and trajectory planning. These nodes run in parallel across a set of networked computers for distributed processing. Minion's propulsion system is centered around a set rim-driven hubless motors attached to articulated motor pods. This design reduces the risk of entanglement, and provides consistent thrust by maintaining motor depth in rough seas.The group is currently developing the 2016 platform for the competition
Categories: Faculty-Staff
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Composite Wind Turbine Blade
PI Sathya Gangadharan
The world's primary energy needs are projected to grow by 56% between 2005 and 2030, by an average annual rate of 1.8% per year (International Energy Agency, 2012). Energy policy has confirmed the improvement of the environment sustainability of energy as a primary objective also though increasing use of renewable sources (Increasing Wind Energy's contribution to U.S. Electricity supply, 2008).
Wind energy research is being followed in the world as an alternative to fulfill increasing electricity power demand, United State Department of Energy is aiming to expand the wind power in the U.S. Currently, 15.4 GW of power are installed and operational, with an expected growth the U.S. wind capacity will be at 310 GW by 2030, representing 20% of the nation's power needs (Increasing Wind Energy's contribution to U.S. Electricity supply, 2008).
Research on composite wind turbine blade carried out in Embry-Riddle is described below:
FLUID-STRUCTURE INTERACTION AND MULTIDISCIPLINARY DESIGN ANALYSIS OPTIMIZATION OF COMPOSITE WIND TURBINE BLADE Mission:
To maximize aerodynamic efficiency and structural robustness while reducing blade mass and total cost.A multidisciplinary design analysis optimization (MDAO) process is defined for a composite wind turbine blade to optimize its aerodynamic and structural performance by developing a fluid-structural interaction (FSI) system. MDAO process is defined in conjunction with structural and aerodynamic performance of the blade which is divided into three steps and the design variables considered are related to the shape parameters, twist distributions, pitch angle, material and the relative thickness based on number of composite layers at different blade sections. Maximum allowable tip deformations, modal frequencies and allowable stresses are set as design constraints. Airfoil performance is predicted with 2D airfoils analysis, while 3D CFD analysis is performed by ANSYS CFX software. A parameterized finite element model of the blade created in ANSYS ACP composite prepost and used to define the composite layups of the blade. The results of the CFD and the structural analysis are used for the optimization process accompanied by the cost estimation to obtain a compromised solution between aerodynamic performance and structural robustness. For the MDAO process number of design of experiments (DOEs) is defined by G optimality method and a response surface is created. Sensitivity analysis is performed to observe the impact of input parameter on each output parameters for enhanced control of the MDAO process. Further, to improve aerodynamic performance of the blade, new design approach with modified Tip (winglet) and rotor section is studied and substantial improvement in power generated over high quality baseline wind turbine blade is presented.
A BASELINE STUDY AND CALIBRATION FOR MULTIDISCIPLINARY DESIGN OPTIMIZATION OF HYBRID COMPOSITE WIND TURBINE BLADE
Preliminary baseline finite element (FE) model calibrations and evaluations are developed to assist and guide multidisciplinary design optimization (MDO) of a large-scale hybrid composite wind turbine blade. The weight, displacement, and failure index are compared and used for calibration purposes. In addition, a cost estimation model is calibrated for labor hour, as well as labor cost, material cost and total cost. Stability of baseline wind turbine blade against harmonic resonance due to rotor rotation is validated by finite element analysis (FEA). A MDO process is proposed using the calibrated FE and cost estimation models. The MDO optimizes multiple objectives such as blade length, weight, manufacturing cost, and power production. For this analysis, the turbine blade is divided into regions and the sequence of hybrid laminate layup for each region is considered as design variables. Extreme wind condition for rotor rotation and rotor stop condition is considered as the applied load on the blade. The designed structural strength and stiffness are demonstrated to withstand the loads due to harmonic excitation from rotor rotation. A process of design procedure for obtaining an optimum hybrid composite laminate layup and an optimum blade length of a wind turbine blade structure is developed in this research.
Categories: Faculty-Staff
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Fuel Slosh
PI Sathya Gangadharan
2014 marks the eleventh year of Fuel Slosh studies that have been carried out at Embry-Riddle Aeronautical University. Initially funded by NASA Graduate Student Research Program (GSRP) along with Southwest Research Institute, the research was started by Keith Schlee, a graduate student, under the guidance of Dr. Sathya Gangadharan, professor at Embry-Riddle.
The research involved extensive theoretical and computational analysis. A fuel slosh test rig was set up at the structures lab for the students and researchers to conduct various experiments and validate their results.This research has evolved from the study of fuel slosh to the effect of diaphragms and baffles on slosh behavior and to the use of smart materials in actively damping the slosh. Tests on effectiveness of damping have also been carried out at NASA's Spinning Slosh Test Rig (SSTR) located at the Southwest Research Institute (SwRI) in San Antonio, Texas. Research works are frequently published at but not limited to American Institute of Aeronautics and Astronautics (AIAA), American Society of Mechanical Engineers (ASME), NASA Technical Reports Server (NTRS) and so on.A gist of some of the research works in Fuel Slosh carried out at Embry-Riddle is described below from the previous to the current on-going research:(Note: Only selective research works are mentioned below, for complete list of fuel slosh research works contact Dr. Sathya Gangadharan)
MODELING AND PARAMETER ESTIMATION OF SPACECRAFT FUEL SLOSH MODE
Mission:The research is directed toward modeling fuel slosh on spinning spacecraft using simple pendulum analogs. The pendulum analog will model a spherical tank with no PMD's. An electric motor will induce the motion of the pendulum to simulate free surface slosh. Parameters describing the simple pendulum models will characterize the modal frequency of the free surface sloshing motion. The one degree of freedom model will help to understand fuel sloshing and serve as a stepping stone for future more complex simulations to predict the NTC accurately with less time and effort.
A CFD APPROACH TO MODELING SPACECRAFT FUEL SLOSH
Mission: By using a Computational Fluid Dynamics (CFD) solver such as Fluent, a model for this fuel slosh can be created. The accuracy of the model must be tested by comparing its results to an experimental test case. Such a model will allow for the variation of many different parameters such as fluid viscosity and gravitational field, yielding a deeper understanding of spacecraft slosh dynamics.
MODELING OF FREE-SURFACE FUEL SLOSH IN MICROGRAVITY FOR OFF-AXIS SPACECRAFT PROPELLANT TANKS
Mission: MATLAB SimMechanics fuel slosh model can be used to estimate slosh parameters and predict dynamic effects on dependent systems. Comparative flight data was acquired by spinning a mock spacecraft with partially filled propellant tanks in a microgravity environment. Empirical and simulated NTC's are compared to validate a SimMechanics fuel slosh model.
A COMPUTATIONAL AND EXPERIMENTAL ANALYSIS OF SPACECRAFT PROPELLANT TANKS IMPLEMENTED WITH FLEXIBLE DIAPHRAGMS
Mission:The main objective of this research is to validate computational modeling of fuel slosh scenarios so that it may become the primary means of testing fuel slosh scenarios during initial spacecraft design. By expanding on past research objectives, this research aims at complementing the pre-existing data with new data from added computational and experimental simulations. Additionally, this research aims at conducting an extensive study of the computational fuel slosh models used in this investigation. The current research investigation presents detailed results of the fluid behavior within the tank and initiates an even more extensive investigation of fluid behavior for future fuel slosh research studies at ERAU.
AN INVESTIGATION OF BAFFLES AND ASPERITIES ON SLOSH BEHAVIOR IN PROPELLANT TANKS OF SPACECRAFT AND LAUNCH VEHICLES
Mission:The focus of this research is to investigate the fuel slosh behavior in propellant tanks. Different types of baffles and hemispherical asperities are introduced inside the tank to characterize the slosh behavior of the fluid. The modeling and the analysis of slosh is done using the CFD solver ANSYS CFX for tanks with and without baffles and for tanks with hemispherical asperities. Physical models are fabricated for experimental testing using the fuel slosh test facility at Embry Riddle Aeronautical University. Using the single axis linear actuator and fuel tank set up in the test facility, experimental results are obtained with and without baffles. The experiment and CFD modeling results are compared.
SLOSH DAMPING WITH FLOATING ELECTRO-ACTIVE MICRO-BAFFLES
Mission: Embedding floating micro-baffles with an electro-active material such that the baffle can be manipulated when exposed to a magnetic field preserves the benefits of both floating and static baffle designs. Activated micro-baffles form a rigid layer at the free surface and provide a restriction of the fluid motion. Proposed micro-baffle design and magnetic activation source method along with proof-of-concept experiments comparing the scope of this research to previous PMD methods are presented. A computational fluid dynamics approach is outlined. Preliminary proof-of-concept testing indicates floating electro-active micro-baffles reduce the damping time of sloshing by up to 88% as compared to the same slosh condition with the absence of any PMDs.
DEVELOPMENT OF A MAGNETOSTRICTIVE PROPELLANT MANAGEMENT DEVICE (MSPMD) FOR HYBRID ACTIVE SLOSH DAMPING IN SPACECRAFT APPLICATION
Mission:To study the use of a hybrid Magnetostrictive membrane as a Magnetostrictive Propellant Management Device (MSPMD) to actively control the free surface effect and reduce fuel slosh.. The viability of merging existing diaphragm membrane aka Propellant management device (PMD) with a magnetostrictive inlay embedded with the Terfenol-D matrix / MR-Fluid allows us to actively control the membrane during in-flight conditions. Apart from the development, analysis on the control of the hybrid active membrane and the use of the same to dampen fuel slosh is also performed in order to establish the proof of concept. During the development process of the hybrid active membrane, the geometric dependency of the meta-smart structure is analyzed to optimize the membrane shape, size and material.
Categories: Faculty-Staff
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Understanding the Coupled Dynamics of Particles and Wall Turbulence
PI Ebenezer Gnanamanickam
This work focuses on understanding the coupled interactions between large and heavy solid particles, on a particle bed, and a gaseous (air) carrier phase turbulent boundary layer developing over the bed.
Part I – The incipient mobilization of particles by the carrier phase is currently predicted by various measures of the mean shear of the carrier phase velocity field. However, there is increasing evidence that particle mobilization is an inherently unsteady process better correlated with the unsteady carrier phase eddies. The proposed work seeks to systematically quantify and understand these unsteady aspects of particle mobilization, particularly as a function of the energy and scale size of the carrier phase eddies. The proposed approach is to introduce flow scales of controlled energy and scale size into a turbulent boundary layer developing over a particle bed, while methodically characterizing the subsequent initiation of particle mobilization. The properties of the particles, namely the diameter and density, will be varied. As the carrier phase is fixed (air), the proposed approach will then describe the processes of particle mobilization as a function of not only the carrier phase eddy energy and size but also the particle Reynolds and Stokes numbers.
Part II – Once particles are mobilized, they form a saltating layer adjacent to the particle bed and become two-way coupled with the carrier phase flow. This interaction, thus far has been reported as modifications to the carrier phase turbulence statistics. However, the exact nature of this interaction has yet to be studied in any further detail. Specifically, the scale dependence or the energy transfer mechanism of this coupled interaction has yet to be described. To study this interaction, it is proposed to carry out careful measurements of the carrier phase turbulent boundary layer in the presence of a saltation layer.
In addition, during the course of both parts of the proposed work, detailed, simultaneous measurements of both phases will be carried out, in a time-resolved manner, to describe the scale dependent characteristics of the underlying physics. This will involve establishing an instantaneous shear velocity that initiates particle mobilization as a function of particle properties as well as carrier phase eddy scale and energy. While studying the interactions during mobilization and after a saltating layer is formed, the goal will be to establish scale dependent energy transfer pathways between the carrier and particle phases. To this end, the primary measurement technique used to characterize the carrier phase will be particle image velocimetry (PIV), while the particle phase velocity fields will be measured using particle tracking velocimetry (PTV). These PIV/PTV measurements will use multiple cameras at multi-scale, providing a detailed description of both phases of the flow at high spatial and temporal resolution. Together these techniques will then provide unique multi-scale, multi-phase measurement sets that will capture the detailed interactions of the particle and carrier phase, leading to new insights into the physics of these interactions.
Categories: Faculty-Staff
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Understanding the Coupled Interactions Between Hair-Like Micromechanoreceptors and Wall Turbulence
PI Ebenezer Gnanamanickam
This research focuses on understanding the interactions between turbulent flows and long (high aspect ratio), flexible hair-like microstructures or micropillars inspired by those encountered in nature. Some examples include lateral line sensors in fish, airflow sensors in bats and hair cover of animals such as seals and bats.
This research focuses on understanding the interactions between turbulent flows and long (high aspect ratio), flexible hair-like microstructures or micropillars inspired by those encountered in nature. Some examples include lateral line sensors in fish, airflow sensors in bats and hair cover of animals such as seals and bats. These structures perform several physiological functions such as balance and equilibrium sensors, flow sensors, flight control sensors, thermal regulators and water harvesters. Particularly, hair-cell sensors have such structures which in conjunction with the animal's nervous system forms a mechanoreceptive device i.e., they turn a force or displacement, in response to the flow energy, into a nervous system response. These structures that vibrate in response to the background flow are also important in energy harvesting systems. However, these interactions are poorly understood primarily due to the complexity of the underlying physics. Capturing this physics requires simultaneous, combined measurements of the micropillar motion and the flow velocities which are challenging. The proposed research will use advanced image-based flow diagnostic tools to measure in detail the interactions between arrays of these micropillars and the background flow. The planned outreach activities will target a group that is almost exclusively comprised of students who are under-represented in the sciences, while also being economically disadvantaged. The graduate student supported will be involved in outreach activities, inculcating a spirit of outreach into the next generation of engineers.
The interactions between wall turbulence and these micropillars occur in the following manner. Flow structures of scales spanning several orders of magnitude, present within wall turbulence, excites the response of the micropillars. The deflection or vibratory response of the micropillars will then feedback and modify the non-linear, background turbulence, resulting in a non-linearly coupled system. In addition, this interaction occurring at the wall can affect the entire layer resulting in a multiscale interacting layer. Of particular interest are energy transfer pathways between the micropillars and the background turbulence. To describe this coupled interaction and the associated energy transfer mechanisms, advanced diagnostic tools such as multi-camera, multi-resolution, mosaicing particle image velocimetry will be used to capture the dynamics of the background flow while simultaneously tracking the motion of relevant micropillars using particle tracking techniques. Together these tools will provide unique multiscale measurements that will elucidate the coupled physics, advancing fields ranging from physiology to aerospace engineering to non-linear energy systems.
Categories: Faculty-Staff
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Aeroelastic Gust-Airfoil Interaction Numerical Studies
PI Vladimir Golubev
The project conducted in collaboration with WPAFB and Eglin AFB AFRL scientists over the past 8 years employs DOD HPC and ERAU computer facilities to conduct high-fidelity, low-Reynolds, aeroelastic gust-airfoil interaction studies to model unsteady responses and their control for small UAVs operating, e.g., in highly unsteady urban canyons.
The focus is on modeling airfoil interactions with canonical upstream flow configurations including time-harmonic and sharp-edge gusts, vortices and synthetic turbulence with prescribed characteristics tailored to a specified unsteady flight-path environment. Note that this and other listed projects that include noise predictions and noise/flow control components are partially supported by Florida Center for Advanced Aero Propulsion (FCAAP) in these effortsCategories: Faculty-Staff
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