GSAC Research Luncheons
The GSAC is an informal group of graduate students from each of the 5 major focus areas in the Aerospace Engineering Department at the University of Maryland. The committee was formed in the Fall 2012 semester in response to the requests of graduate students and department faculty, and seeks to foster camaraderie, growth and success among the graduate student body.
Research Luncheon Series
GSAC regularly hosts research luncheon speakers who discuss a variety of topics related to Aerospace Engineering.
Past Luncheon Research Speakers
May 2, 2014
Adviser: Sean Humbert
Aggressive Flight Control Development for a Micro-Quadrotor MAV
With potential missions for quadrotor MAVs calling for smaller, more agile vehicles, it is important to implement attitude controllers that allow the vehicle to reach any desired attitude without encountering computational singularities, as is the case when using an Euler angle representation. A quaternion-based state estimator is presented that enables ARL’s 100-gram micro-quadrotor to determine its attitude during agile maneuvers using only an on-board gyroscope and accelerometer. Inner and outer loop attitude and position controllers are also discussed that use the quaternion attitude representation to control the vehicle along aggressive trajectories with the assistance of an outside motion capture system. An optimal trajectory generation algorithm is then described that leverages the quadrotor’s dynamics to allow it to reach extreme attitudes for applications such as perching on walls or ceilings and flying through small openings. Lastly, a model-reference adaptive controller is presented as an extension to the trajectory tracking controller to improve the quadrotor’s trajectory following capabilities.
Graduate Research Assistant: David Mayo & James Lankford
Advisor: Dr. Inderjit Chopra, Alfred Gessow Professor and Director AGRC
Coupled CFD-CSD Predictions with Particle Image Velocimetry and Airloads Measurements for a MAV-scale Flapping Wing
This work seeks to refine and validate a state-of-the-art, coupled aeroelastic analysis tool capable of reliably predicting the performance and detailed aerodynamic environment surrounding a highly flexible flapping wing. Coupled CFD-CSD results are compared to PIV and direct force measurements. The end goal will be to carry out systematic parametric studies to come up with an optimized geometry and kinematics for efficient hover and forward flight performance of flapping-wing MAVs.
April 4, 2014
Adviser: Derek Paley
Bio-inspired Flow Estimation and Closed-Loop Control of an Underwater Vehicle
Bio-inspired sensing modalities enhance the ability of autonomous vehicles to characterize and respond to their environment. For example, the lateral line of cartilaginous and bony fish is sensitive to fluid motion and allows fish to sense oncoming flow and the presence of walls or obstacles. By employing bio-inspired sensing modalities like the lateral line, the performance of sensing and navigation strategies can be improved in dark, cluttered, or murky environments where traditional sensing modalities are hindered. This talk presents bio-inspired estimation and control strategies enabling an airfoil-shaped unmanned underwater vehicle to assimilate measurements from a multi-modal artificial lateral line to estimate flow properties used in feedback control. Feedback control strategies use the estimated flow properties to execute bio-inspired behaviors including rheotaxis, the tendency of fish to orient upstream, and station-holding, the tendency of fish to position behind an upstream obstacle. A robotic prototype outfitted with a multi-modal artificial lateral line composed of ionic polymer metal composite (IPMC) and embedded pressure sensors is used to experimentally demonstrate the distributed flow sensing and closed-loop control strategies.
Adviser: Norman Wereley
CAD Based Modeling of Advanced Rotary Wing Structures
Next generation rotor aeromechanic analyses are envisioned to combine high fidelity three-dimensional FEM structures within a multibody framework. This work explores the development of advanced rotor models for the application of such a solver.
March 7, 2014
Adviser: Dr. Flatau
Analytical and Experimental Investigation of Magnetic Domain Behavior in Magneto-Elastic Sensors
This research deals with understanding the evolution of magnetic domains in magnetostrictive bending sensors. It starts out with the design of a bending Fe-Ga alloy sensor prototype followed by the development of a hypothesis for the micro-scale magnetic response to macro-scale mechanical input. This hypothesis is substantiated with multi-physics simulations (magneto-mechanical modeling based on energy methods) and finally bolstered by actual magnetic domain images from Magneto-Optic Kerr Microscopy. The protocol for polishing soft alloys for domain imaging using optical methods will also be presented.
Adviser: Dr. Stuart Laurence
Boundary Layer Feature Identification in Schlieren Images from Hypersonic Tests
Hypersonic boundary layer transition is a difficult process to capture due to the high frequency components that dominate the transition process. As high speed cameras are able to capture higher quality images at faster rates there will be a need to use computers to identify images that are of interest for further analysis. The work that has been done thus far on developing such a program is presented along with ideas for future improvements.
February 7, 2014
Adviser: Dr. Raymond J. Sedwick
Parametric Study of Particle Size for PIV Measurements of Plasma Actuators
Plasma actuators have recently become popular as flow control devices. They work on the principles of dielectric barrier discharge operating at high voltages (10kV) and high frequencies (2kHz). Particle image velocimetry (PIV) is sometimes used to characterize plasma actuators. The authors researched the effect of the plasma on the PIV particles by comparing their flowfields using phase-locked PIV. There were four particle sizes used in the experiment: 1000nm, 600nm, 300nm, and 50nm. Results show a difference in the particles' flowfields albeit with large standard deviations.
Advisor: Dr. Yu
Active Combustion Control for Fuel Flexible Gas Turbine Operation
Combustion instability, in essence, is the destructive pressure oscillations that occur due to resonant coupling between heat release oscillation and combustor acoustics. Active combustion control is a means of disrupting the process that causes said instability, in our case by dynamically injecting secondary fuel. I look at how using alternative fuels affects controller performance and controller operations for suppressing combustion instability.
December 6, 2013
Adviser: Dr. Derek Paley
Bio-inspired flow sensing and control: Autonomous rheotaxis using distributed pressure measurements
This presentation presents the design and use of an artificial lateral-line system for a bio-inspired robotic fish capable of autonomous flow-speed estimation and rheotaxis (the natural tendency of fish to orient upstream), using only flow-sensing information. We first present a feedback controller based on the difference between pressure measurements collected on opposite sides of the fish robot. We then describe a dynamic rheotaxis controller based on a potential-flow model and a Bayesian observer that uses two or more pressure sensors in an arbitrary arrangement. Pressure sensor placements are selected based on nonlinear observability analysis. Experimental results demonstrate the advantages of the proposed scheme, which include robustness to model error and sensor noise. The primary contribution of this work is a framework for rheotaxis and flow-speed estimation based on pressure-difference information that does not require fitting model parameters to flow field conditions.
Captain Dan Brown
Adviser: Dr. Celi
Pilot response and rotorcraft handling specifications
Current rotorcraft handling quality specifications are fundamentally subjective in nature, relying mostly on pilot opinion. The present work looks to develop the building blocks needed to quantify pilot control response, so that aircraft flying qualities can be evaluated objectively. We have developed interactive, computer-based experiments that test pilots (and non-pilots alike) on their ability to perform idealized control tasks used in flight. The visual cues presented to the participants provide the basis for numerically characterizing pilot control response. The present work can be extended to aircraft control response in good weather, as well as flight into "Degraded Visual Environments" (DVE) resulting from rotorcraft brownout or adverse weather conditions.
November 1, 2013
Adviser: Dr. Ray Sedwick
RINGS (Resonant Inductive Near-field Generation System)
RINGS serves as a test bed for satellite clusters in conjunction with the SPHERES facility on the International Space Station. The interaction of electromagnetic fields produced by two RINGS units allows for electromagnetic formation flight (EMFF) and wireless power transfer through inductive coupling. This is the first six degree of freedom test bed for development of EMFF control algorithms and the first set of hardware to perform EMFF and wireless power transfer.
Adviser Anya Jones
Aerodynamics of a Rotor Blade in Reverse Flow
Reverse flow affects helicopters in forward flight and is located in a region of the rotor disk where the flight speed exceeds the local rotational velocity of the retreating rotor blade. This causes the flow to pass over the rotor blade “backwards” (from the geometric trailing edge towards the geometric leading edge). This talk aims to explore a fundamental model of this unusual flow regime using results from low-speed wind tunnel experiments. The aerodynamic performance of a conventional sharp trailing edge airfoil is compared with a blunt trailing edge airfoil. The two airfoil sections are evaluated in reverse flow and at high angles of attack using time-averaged and unsteady force and flow field measurements.
August 2, 2013
Adviser: Dr. M. Pino Martin
CRoCCo (Cluster for Research on Complex Computations) Laboratory (http://croccolab.umd.edu/index.php)
Analysis of the Large Eddy Simulation of a Shock Wave and Turbulent Boundary Layer Interaction
Presentation blurb: The large eddy simulation (LES) of a compression ramp shock wave and turbulent boundary layer interaction (STBLI) is presented. The ramp angle is 24 degrees and the incoming boundary layer flow conditions are Mach 2.9 and Re _theta 2900. The LES data cover approximately 1300 L_sep/U_inf to statistically resolve the aperiodic cycle of the low-frequency
unsteadiness that is characteristic of these types of flows. The dynamics of the flow downstream of the shock are characterized using this new numerical data set.
Adviser: Sean Humbert, Autonomous Vehicle Lab
Topic: Modeling and sensor design based on the ocellar visual sensing system in flying insects
Use of ocellar sensing with optic flow sensing for stabilization and navigation of micro-air vehicles discussed. The work demonstrates visual sensing that provides outer and inner loop control with characteristics that are implementable in analog VLSI.
June 7, 2013
Flight Dynamics and Control of a Rotorcraft Towing a Submerged Load
Analysis of helicopters towing loads that are submerged in water. Steady level flight as well as maneuvers typical of anti-submarine warfare are considered, yielding smooth control inputs as the rotorcraft-load combination travels along the target trajectory. Such work may be used to investigate or refine alternate search patterns.
April 5, 2013
Adviser: Dr. Chopra
Research Areas: Swashplateless rotors with brushless motor actuated flaps for primary control; Large actuation strokes of trailing edge flap with brushless DC motor as a novel on-blade actuator; Reduced drag and weight penalties by replacing hydraulic operated swashplate system.
Adviser: Dr. Humbert
Research Areas: Bio-inspired dynamics and control for flapping wing vehicles. A linear time
invariant model of insect flight in forward flight is found using small perturbation analysis.
Kinematics of free-flying insects are found using high-speed videography, and then aerodynamic
loads are calculated using the IBINS immersed boundary CFD solver. Biologically- inspired
control and sensing requirements to stabilize forward flight are investigated, and distinctions
between insect and avian flight will be discussed.
February 29, 2013
Adviser: Dr. Chopra-UMD and Dr. Rand-Technion Israel Institute of Technology
Research area: Simultaneous localization and Mapping in GPS-denied environments, for ground, humanoid, and aerial robots (uncoupled from the platform's dynamic model).
Application for aerial path planning for MAVs navigating to a defined goal position.
Working with laser range scanners to build maps and localize a robot in a previously unknown area, without the aid of any outside information (such as GPS).
Adviser: Dr. David Akin
Research Area: Dexterous space robotics, manipulation from free-flying spacecraft, precision motion control for grappling and servicing. Additional research areas include: Neutral buoyancy simulation, human factors, applications of artificial intelligence and the underlying fundamentals of space simulation.
January 25, 2013
Advisor: Dr. Yu
Research Areas: Isolator shock train characterization, dual layer schlieren imaging, focused schlieren imaging, and deflectometry. Works jointly in the UMD Mach 2.5 tunnel and at AEDC Hypervelocity Tunnel 9.