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Scott, Kevon KOcclusion-Aware Sensing and Coverage in Unmanned Aerial Vehicle (UAV) Networks
MS, University of Cincinnati, 2016, Engineering and Applied Science: Computer Engineering
The use of small and miniature Unmanned Aerial Vehicles (UAVs) for remote sensing and surveillance applications has become increasingly popular in the last two decades. Networks of UAVs, capable of providing flexible aerial views over large areas, are playing important roles in today's distributed sensing systems. Since camera sensors are sensitive to occlusions, it is more challenging to deploy UAVs for sensing in geometrically complex environments, such as dense urban areas and mountainous terrains. The intermittent connectivity in a sparse UAV network also makes it challenging to efficiently gather sensed multimedia data. This thesis is composed of two pieces of work. In the first piece of work, a new occlusion-aware UAV coverage technique with the objective of sensing a target area with satisfactory spatial resolution subject to the energy constraints of UAVs is proposed. An occlusion-aware waypoint generation algorithm is first designed to find the best set of waypoints for taking pictures in a target area. The selected waypoints are then assigned to multiple UAVs by solving a vehicle routing problem (VRP), which is formulated to minimize the maximum energy for the UAVs to travel through the waypoints. A genetic algorithm is designed to solve the VRP problem. Evaluation results show that the proposed coverage technique can reduce energy consumption while achieving better coverage than traditional coverage path planning techniques for UAVs. In the second piece of work, a communication scheme is designed to deliver the images sensed by a set of mobile survey UAVs to a static base station through the assistance of a relay UAV. Given the planned routes of the survey UAVs, a set of relay waypoints are found for the relay UAV to meet the survey UAVs and receive the sensed images. An Online Message Relaying technique (OMR) is proposed to schedule the relay UAV to collect images. Without any global collaboration between the relay UAV and the survey UAVs, OMR utilizes a markov decision process (MDP) that determines the best schedules for the relay UAV such that the image acquisition rate could be maximized. Evaluation results show that the proposed relaying technique outperforms traditional relaying techniques, such as the traveling salesman problem (TSP) and the random walk, in terms of end-to-end delay and frame delivery ratio.

Committee:

Rui Dai, Ph.D. (Committee Chair); Dharma Agrawal, D.Sc. (Committee Member); Carla Purdy, Ph.D. (Committee Member)

Subjects:

Computer Engineering

Keywords:

Unmanned Aerial Vehicle;UAV;Occlusion;FANET;Flying Ad-Hoc Networks;Remote Sensing

Landolfo, GiuseppeAerodynamic and Structural Design of a Small Nonplanar Wing UAV
Master of Science (M.S.), University of Dayton, 2008, Aerospace Engineering
The overall air vehicle performance of a multiple lifting surface configuration has been studied with respect to both structural and aerodynamic considerations for a candidate mission similar to that of the AeroVironment Raven. The configuration studied is a biplane joined at the tips with endplates. More specifically, this study aims to determine if this particular nonplanar wing concept can meet the requirements of the mission for a small Reconnaissance, Surveillance and Target Acquisition UAV. The mission capabilities of small UAVs are constantly growing by implementing recent developments in miniature computers and peripherals, electronic sensors, and optical sensing equipment at affordable cost. The requirements for the mission profile of a small UAV using the aforementioned equipment are defined with an emphasis on the potential advantages that can be offered by the nonplanar concept wing under investigation. A structural analysis using the finite element software ADINA and an aerodynamic analysis based on wind tunnel experimental data and vortex panel code results are performed. The results, compared under varying assumptions specific to an equivalent monoplane and a biplane, suggest potential efficiency gains for the new configuration may be possible using the nonplanar wing configuration under explicit conditions. The results also show structural characteristics and not aerodynamics alone are critical in determining the utility of this nonplanar concept.

Committee:

Aaron Altman (Advisor)

Subjects:

Engineering

Keywords:

Aerospace; aircraft design; aerodynamics; structural analysis; UAV; unmanned aircraft; biplane

Ernest, Nicholas D.UAV Swarm Cooperative Control Based on a Genetic-Fuzzy Approach
MS, University of Cincinnati, 2012, Engineering and Applied Science: Aerospace Engineering

The ever-increasing applications of UAV’s have shown the great capabilities of these technologies. However, for many cases where one UAV is a powerful tool, an autonomous swarm all working cooperatively to the same goal presents amazing potential. Environment that are dangerous for humans, are either too small or too large for safe or reasonable exploration, and even those tasks that are simply boring or unpleasant are excellent areas for UAV swarm applications. In order to work cooperatively, the swarm must allocate tasks and have adequate path planning capability.

This paper presents a methodology for two-dimensional target allocation and path planning of a UAV swarm using a hybridization of control techniques. Genetic algorithms, fuzzy logic, and to an extent, dynamic programming are utilized in this research to develop a code known as “UNCLE SCROOGE” (UNburdening through CLustering Effectively and Self-CROssover GEnetic algorithm). While initially examining the Traveling Salesman Problem, where an agent must visit each waypoint in a set once and then return home in the most efficient path, the work’s end goal was a variant on this problem that more closely resembled the issues a UAV swarm would encounter.

As an extension to Dr. Obenmeyer’s “Polygon-Visiting Dubins Traveling Salesman Problem”, the Multi-Depot Polygon-Visiting Dubins Multiple Traveling Salesman Problem consists of a set number of visibility areas, or polygons that a number of UAV’s, based in different or similar depot must visit. While this case is constant altitude and constant velocity, minimum turning radii are considered through the use of Dubins curves. UNCLE SCROOGE was found to be adaptable to the PVDTSP, where it competed well against the methods proposed by Obenmeyer. Due to limited benchmarking ability, as these are newly formed problems, Obenmeyer’s work served as the only basis for comparison for the PVDTSP. UNCLE SCROOGE brought a 9.8% increase in accuracy, and a run-time reduction of more than a factor of ten for a 20 polygonal case with strict turning requirements. This increase in performance came with a 99% certainty of receiving the best found solution over the course of 100 runs. With only a 1% chance for error in this particular case, the hybridized method has been shown to be quite powerful.

While no comparison is currently possible for MDPVDMTSP solutions, UNCLE SCROOGE was found to develop promising results. On average, it takes the code 25.62 seconds to approximately solve a 200 polygon, 4 depot, 5 UAV’s per depot problem. This polygon count was increased even up to 2,500, with a solution taking 9.8 hours. It has been shown that UNCLE SCROOGE performs well in solving the MDPVDMTSP and has acceptable scalability.

Committee:

Kelly Cohen, PhD (Committee Chair); Manish Kumar, PhD (Committee Member); Bruce Walker, ScD (Committee Member)

Subjects:

Aerospace Materials

Keywords:

UAV Swarm;Cooperative Control;Genetic Algorithm;Fuzzy Logic;Traveling Salesman Problem;;

Sabo, ChelseaRouting and Allocation of Unmanned Aerial Vehicles with Communication Considerations
PhD, University of Cincinnati, 2012, Engineering and Applied Science: Aerospace Engineering

Cooperative Unmanned Aerial Vehicles (UAV) teams are anticipated to provide much needed support for human intelligence, measurement and signature intelligence, signals intelligence, imagery intelligence, and open source intelligence through algorithms, software, and automation. Therefore, it is necessary to have autonomous algorithms that route multiple UAVs effectively and efficiently throughout missions and that these are realizable in the real-world given the associated uncertainties. Current routing strategies ignore communication constraints altogether. In reality, communication can be restricted by bandwidth, line-of-sight, maximum communication ranges, or a need for uninterrupted transmission. Generating autonomous algorithms that work effectively around these communication constraints is key for the future of UAV surveillance applications.

In this work, both current and new routing strategies for UAVS are analyzed to determine how communications impact efficiency of information return. It is shown that under certain communication conditions, a new approach on routing can be more efficient than typically adopted strategies. This new approach defines and presents a new formulation based on a minimum delivery latency objective function. The problem is formulated such that information is not considered delivered until it is returned back to a high-bandwidth connection (depot) which is common when communication is restricted. The size of the region is shown to be dependent upon distance between requests, UAV bandwidth, UAV velocity, and data size, but it was shown that for large-sized data, long distances, and low bandwidth, it is generally better to route UAVs with this new minimum latency objective.

With the added decision of when to deliver information to a high-bandwidth connection, an already computationally complex problem grows even faster. Because of scaling issues, a heuristic algorithm was developed that was constructed by analyzing the optimal solution. The algorithm is a cluster-first, route-second approach, but differs from conventional Vehicle Routing Problem (VRP) solutions in that the number of clusters is not necessarily equal to the number of vehicles. Because of this, a unique approach to clustering is adopted to form clusters using hierarchical agglomerative clustering and fuzzy logic. Based on a detailed Monte Carlo analysis, the heuristic algorithm showed near-optimal (within ~5%) results calculable in real-time (allowing it to be used in dynamic scenarios too) and scaled to much larger problem sizes. Furthermore, the performance was analyzed under varying degrees of dynamism and arrival rates. Results showed good performance, and found the boundaries for the regions of light and heavy load cases for a single vehicle to be about 0.3 and 4 requests an hour, respectively. Finally, both static and dynamic cases were validated in flight testing, highlighting the usability of this approach.

Committee:

Kelly Cohen, PhD (Committee Chair); Derek Kingston, PhD (Committee Member); Manish Kumar, PhD (Committee Member); Grant Schaffner, PhD (Committee Member)

Subjects:

Aerospace Materials

Keywords:

UAV; Vehicle Routing; Task Allocation; Communication

Nemati, AlirezaDesigning, Modeling and Control of a Tilting Rotor Quadcopter
PhD, University of Cincinnati, 2016, Engineering and Applied Science: Electrical Engineering
The aim of the present work is to model, design, control, fabricate and experimentally study quadcopter with tilting propellers. A tilting quadcopter is an aerial vehicle whose rotors can tilt along axes perpendicular to their respective axes of rotation. The tilting rotor quadcopter provides the added advantage in terms of additional stable configurations, made possible by additional actuated controls, as compared to a traditional quadcopter without titling rotors. The tilting rotor quadcopter design is accomplished by using an additional motor for each rotor that enables the rotor to rotate along the axis of the quadcopter arm. Conventional quadcopters, due to limitation in mobility, belong to a class of underactuated robots which cannot achieve any arbitrary desired state or configuration. For example, the vehicle cannot hover at a defined point at a tilted angle. It needs to be completely horizontal in order to hover. An attempt to achieve any pitch or roll angle would result in forward (pitch) motion or lateral (roll) motion. This proposed tilting rotor concept turns the traditional quadcopter into an over-actuated flying vehicle allowing us to have complete control over its position and orientation. In this work, a dynamic model of the tilting rotor quadcopter vehicle is derived for flying and hovering modes. The model includes the relationship between vehicle orientation angles and rotor tilt-angles. Furthermore, linear and nonlinear controllers have been designed to achieve the hovering and navigation capability while having any desired pitch and/or roll orientation. In the linear approach, the four independent speeds of the propellers and their rotations about the axes of quadcopter arms have been considered as inputs. In order to start tracking a desired trajectory, first, hovering from the initial starting point is needed. Then, the orientation of the vehicle to the desired pitch or roll angle is obtained. Subsequently, any further change in pitch or roll angles, obtained using a linear controller, result in motion of the quadcopter along the desired trajectory. The dissertation then presents a nonlinear strategy for controlling the motion of the quadcopter. The overall control architecture is divided into two sub-controllers. The first controller is based on the feedback linearization control derived from the dynamic model of the tilting quadcopter. This controls the pitch, roll, and yaw motions required for movement along an arbitrary trajectory in space. The second controller is based on two Proportional Derivative (PD) controllers which are used to control the tilting of the quadcopter independently along the pitch and the yaw directions respectively. The overall control enables the quadcopter to combine tilting and movement along a desired trajectory simultaneously. Furthermore, the stability and control of tilting-rotor quadcopter is presented upon failure of one propeller during flight. On failure of one propeller, the quadcopter has a tendency of spinning about the primary axis fixed to the vehicle as an outcome of the asymmetry about the yaw axis. The tilting-rotor configuration is an over-actuated form of a traditional quadcopter and it is capable of handling a propeller failure, thus making it robust in one propeller failure during the flight. The dynamics of the vehicle once the failure accrued is derived and a controller is designed to achieve hovering and navigation capability. The dynamic model and the controller of the vehicle were verified with the help of numerical studies for diff erent flight scenarios as well as failure mode. Subsequently, two diff erent models of the vehicle were designed, fabricated and tested. Experimental results have validated the dynamical modeling and the flight controllers.

Committee:

Manish Kumar, Ph.D. (Committee Chair); Ali Minai, Ph.D. (Committee Chair); Raj Bhatnagar, Ph.D. (Committee Member); Kelly Cohen, Ph.D. (Committee Member); Rui Dai, Ph.D. (Committee Member)

Subjects:

Electrical Engineering

Keywords:

UAV;Tilt-Rotor Quadcopter;Nonlinear Control;Modeling

Gunn, Daniel VictorTarget Acquisition with UAVs: Vigilance Displays and Advanced Cueing Interfaces
PhD, University of Cincinnati, 2002, Arts and Sciences : Psychology
Future Uninhabited Aerial Vehicles (UAVs) will require operators to switch quickly and efficiently from supervisory to manual control. Utilizing a vigilance task in which threat detections (critical signals) led observers to perform a subsequent manual target acquisition task, the present investigation revealed that the type of vigilance display might have important design implications for future UAV systems. A sensory display format resulted in more threat detections, fewer false alarms, and faster target acquisition times and imposed a lighter workload than a cognitive display format. Thus, the former may be the best display arrangement for future UAV controllers. Additionally, advanced visual, spatial audio, and haptic cueing interfaces enhanced acquisition performance over no cueing in the target acquisition phase of the task, and did so to a similar degree. This finding suggests that advanced cueing interfaces may also prove useful in future UAV systems and that these interfaces are functionally interchangeable.

Committee:

Dr. Joel S. Warm (Advisor)

Subjects:

Psychology, Experimental

Keywords:

target acquisition; UAV; vigilance; advanced cueing interaces; spatial audio

Diskin, YakovDense 3D Point Cloud Representation of a Scene Using Uncalibrated Monocular Vision
Master of Science (M.S.), University of Dayton, 2013, Electrical Engineering
We present a 3D reconstruction algorithm designed to support various automation and navigation applications. The algorithm presented focuses on the 3D reconstruction of a scene using only a single moving camera. Utilizing video frames captured at different points in time allows us to determine the depths of a scene. In this way, the system can be used to construct a point cloud model of its unknown surroundings. In this thesis, we present the step by step methodology of the development of a reconstruction technique. The original reconstruction process, resulting with a point cloud was computed based on feature matching and depth triangulation analysis. In an improved version of the algorithm, we utilized optical flow features to create an extremely dense representation model. Although dense, this model is hindered due to its low disparity resolution. As feature points were matched from frame to frame, the resolution of the input images and the discrete nature of disparities limited the depth computations within a scene. With the third algorithmic modification, we introduce the addition of the preprocessing step of nonlinear super resolution. With this addition, the accuracy of the point cloud which relies on precise disparity measurement has significantly increased. Using a pixel by pixel approach, the super resolution technique computes the phase congruency of each pixel’s neighborhood and produces nonlinearly interpolated high resolution input frames. Thus, a feature point travels a more precise discrete disparity. Also, the quantity of points within the 3D point cloud model is significantly increased since the number of features is directly proportional to the resolution and high frequencies of the input image. Our final contribution of additional preprocessing steps is designed to filter noise points and mismatched features, giving birth to the complete Dense Point-cloud Representation (DPR) technique. We measure the success of DPR by evaluating the visual appeal, density, accuracy and computational expense of the reconstruction technique and compare with two state-of-the-arts techniques. After the presentation of rigorous analysis and comparison, we conclude by presenting the future direction of development and its plans for deployment in real-world applications.

Committee:

Asari Vijayan, PhD (Committee Chair); Raul Ordonez, PhD (Committee Member); Eric Balster, PhD (Committee Member)

Subjects:

Electrical Engineering; Engineering

Keywords:

monocular vision; 3D Scene Reconstruction; Dense Point-cloud Representation; Point Cloud Model; DPR; Super Resolutoin; Vision Lab; University of Dayton; Computer Vision; Vision Navigation; UAV; UAS; UGV; RAIDER; Yakov Diskin; Depth Resolution Enhancement

Resor, Michael IrvinCOMPUTATIONAL INVESTIGATION OF ROTARY ENGINE HOMOGENEOUS CHARGE COMPRESSION IGNITION FEASIBILITY
Master of Science in Engineering (MSEgr), Wright State University, 2014, Mechanical Engineering
The Air Force Research Laboratory (AFRL) has been investigating the heavy fuel conversion of small scale Unmanned Aerial Vehicles (UAV). One particular platform is the Army Shadow 200, powered by a UEL Wankel rotary engine. The rotary engine historically is a proven multi-fuel capable engine when operating on spark ignition however, little research into advanced more efficient compression concepts have been investigated. A computational fluid dynamics model has been created to investigate the feasibility of a Homogeneous Charge Compression Ignition (HCCI) rotary engine. This research evaluates the effects, rotor radius to crankshaft eccentricity ratio, known as K factor, equivalence ratio, and engine speed and how they affect the response of horsepower, maximum temperature, and peak pressure to determine the feasibility of HCCI operation. The results show that the advanced HCCI strategy is promising to significantly improve efficiency of the rotary engine.

Committee:

George Huang, Ph.D. (Advisor); Haibo Dong, Ph.D. (Advisor); Greg Minkiewicz, Ph.D. (Committee Member); Scott Thomas, Ph.D. (Committee Member); Zifeng Yang, Ph.D. (Committee Member)

Subjects:

Aerospace Engineering; Automotive Engineering; Fluid Dynamics; Mechanical Engineering

Keywords:

Rotary Engine Wankel HCCI Homogeneous Charge Compression Ignition UAV Fluid Dynamics CFD

Tan, RuoyuTracking of Ground Mobile Targets by Quadrotor Unmanned Aerial Vehicles
MS, University of Cincinnati, 2013, Engineering and Applied Science: Mechanical Engineering
An Unmanned Air Vehicle (UAV) is an aircraft without a human pilot on board. It can be controlled either autonomously by computers onboard, or using a remote control by a pilot on the ground, or in another vehicle. In both military and civilian sectors, UAVs are quickly obtaining popularity and expected to expand dramatically in the years to come. As UAVs gain more attention, one of the immediate requirements would be to have UAVs work as much autonomously as possible. One of the common tasks that UAVs would be engaged in is target tracking which has various potential applications in military field, law-enforcement, wildlife protection effort, and so on. This thesis focuses on development of a controller for UAVs to track ground target. In particular, this thesis focuses on quadrotor UAV, which is a multicopter that is lifted and propelled using four motors. Admittedly, several target tracking control methods have been developed in recent years. However, only a few of them have been applied on a quadrotor. Most of these tracking methods, particularly those based on Proportional Derivative (PD) control laws, which have been applied on quadrotors, are not time efficient due to practical acceleration constraint and a number of parameters that need to be tuned. The UAV control problem can be divided into 4 sub-problems: Position Control, Motor Control, Trajectory Tracking and Trajectory Generation. In this thesis, the dynamic equations of motion for quadrotors and a Proportional Derivative control law is derived to solve the problems of Position Control, Motor Control and Trajectory Tracking. A Proportional Navigation (PN) based switching strategy is proposed to address the problem of Trajectory Generation. The experiments and numerical simulations are performed using non-maneuvering and maneuvering targets. The simulation results show that the proposed PN based switching strategy not only carries out effective tracking but also results into smaller oscillations and errors when compared to the widely used PD tracking method. The switching strategy, as proposed as a solution to target tracking problem, leaves an important question with regard to when should the switching happen. It is intuitive that the time of switching will play a role in how fast the UAV converges to the target. The second problem considered in this thesis relates to the optimal time of switching that would minimize the positional error between the UAV and the target. An optimal switching strategy is proposed to obtain the optimal switching time for both non-maneuvering and maneuvering targets. Analytical solutions that generate trajectories based on PN and PD methods are used in this strategy. The numerical simulations validate the optimality, reliability, and accuracy of the proposed method for both non-maneuvering and maneuvering targets.

Committee:

Manish Kumar, Ph.D. (Committee Chair); Kelly Cohen, Ph.D. (Committee Member); David Thompson, Ph.D. (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

Unmanned Air Vehicle;quadrotor UAV;multicopter;Proportional Navigation;Trajectory Generation

Calhoun, Sean M.Six Degree-of-Freedom Modeling of an Uninhabited Aerial Vehicle
Master of Science (MS), Ohio University, 2006, Electrical Engineering & Computer Science (Engineering and Technology)

Developing a six degree-of-freedom (6-DOF) aircraft model has many practical purposes, especially in these times of rapidly growing Uninhabited Air Vehicle (UAV) technologies. This thesis covers some of the various topics involved in the development of such a model. The research performed was conducted at the Avionics Engineering Center, utilizing the Brumby R/C aircraft. Topics include a brief overview of the instrumentation system, techniques for inertia estimation, and system identification using the Ordinary Least Squares (OLS) method. Finally, the design and development of a Matlab/SIMULINK model will be covered, which will illustrate the accuracy and validity of the 6-DOF model.

Committee:

Douglas Lawrence (Advisor)

Subjects:

Engineering, Aerospace

Keywords:

UAV; Unmanned Vehicle; 6-DOF Model; System Identification; Brumby

Findler, Michael JamesCognitively Sensitive User Interface for Command and Control Applications
Doctor of Philosophy (PhD), Wright State University, 2011, Engineering PhD
While there are broad guidelines for display or user interface design, creating effective human-computer interfaces for complex, dynamic systems control is challenging. Ad hoc approaches which consider the human as an afterthought are limiting. This research proposed a systematic approach to human / computer interface design that focuses on both the semantic and syntactic aspects of display design in the context of human-in-the-loop supervisory control of intelligent, autonomous multi-agent simulated unmanned aerial vehicles (UAVs). A systematic way to understand what needs to be displayed, how it should be displayed, and how the integrated system needs to be assessed is outlined through a combination of concepts from naturalistic decision making, semiotic analysis, and situational awareness literature. A new sprocket-based design was designed and evaluated in this research. For the practical designer, this research developed a systematic, iterative design process: design using cognitive sensitive principles, test the new interface in a laboratory situation; bring in subject matter experts to examine the interface in isolation; and finally, incorporate the resulting feedback into a full-size simulation. At each one of these steps, the operator, the engineer and the designer reexamined the results.

Committee:

S. Narayanan, PhD (Committee Chair); Misty Blue-Terry, PhD (Committee Member); Mateen Rizki, PhD (Committee Member); Joseph Litko, PhD (Committee Member); Yan Liu, PhD (Committee Member)

Subjects:

Industrial Engineering

Keywords:

Unmanned aerial vehicles; UAV; Visual Thinking; Naturalistic Decision Making; Situation Awareness

Charvat, Robert C.Surveillance for Intelligent Emergency Response Robotic Aircraft (SIERRA Project)
MS, University of Cincinnati, 2012, Engineering and Applied Science: Aerospace Engineering

Unmanned Aerial Systems (UASs) have proven their potential in wartime environments by providing an alternative to manned technologies that risk human life. UASs are able to perform in situations that are dangerous or undesirable to humans. Also, UASs allow for miniaturization of technologies previously used for these tasks, which provides higher task performance at a lower cost. By combining miniaturized technology platforms with already existing technologies from the public domain, this technology has proved to be beneficial to emergency management operations.

Wildland fires are a source of concern to emergency management organizations and, as a natural occurrence, will continue to be concern in the future. As the world's population continues to grow, and people continue to spread into more rural environments, wildland fires are an increasing risk to life and infrastructure. For many locations, these risks can be managed with prevention programs and risk mitigation strategies. Such methods of prevention and mitigation include pre-existing fire lines and management of flammable materials near infrastructure. However, in many locations the primary form of risk reduction is a proper response to fires. As fire size tends to grows in an exponential manner with time, a quick response is essential to combating disaster. Rapid action requires significant surveillance to support situational awareness. Technology that can provide this situational awareness would be a significant advancement over current manned aerial platforms.

The Surveillance for Intelligent Emergency Response Robotic Aircraft (SIERRA) Project is aimed at partnering government, manufacturing, emergency response, and academic expertise to develop unmanned aerial systems for use in emergency management environments. The SIERRA Project focuses on three areas of this development: Potential application of this technology with current fire tactics at the operational level, current technology capabilities and systems engineering requirements for this type of system, and analysis of flight data of the Zephyr (a tactical UAS platform weighing less than 10 pounds). After this research is completed, it will allow for the introduction of research into the concept of a wildland fire agency air force. This allows wildland fire forces to have full fleet capability, which will revolutionize wildland fire response and the recommended requirements for the next generation of tactical UAS platforms.

Committee:

Kelly Cohen, PhD (Committee Chair); Eugene Rutz, MS (Committee Member); Manish Kumar, PhD (Committee Member); Gary Slater, PhD (Committee Member)

Subjects:

Aerospace Materials

Keywords:

SIERRA;UAS;Systems Engineering;Unmanned Aerial System;Drone;UAV;

Geyman, Matthew KennethWing/Wall Aerodynamic Interactions in Free Flying, Maneuvering MAVs
Master of Science (M.S.), University of Dayton, 2012, Aerospace Engineering
Micro Air Vehicles (MAVs) are small remotely piloted air vehicles that can be flown between or inside of buildings for military or surveillance purposes. This type of flight in the urban environment involves many aerodynamic hazards. The research in this thesis investigates how the aerodynamic interactions between a maneuvering MAV’s wingtip vortex and its distance away from a building wall could affect the MAV’s flight controls. Free flight particle image velocimetry (PIV) testing and wind tunnel testing are used to investigate the aerodynamic interactions between a MAV wingtip vortex and a wall. Elliptical instabilities and a vortex rebound off of the wall are discovered in the PIV testing while the wind tunnel results show a higher aircraft coefficient of lift near the wall. All of these results force the aircraft to experience a rolling motion while flying along a wall. It is imperative that a MAV anticipate this motion and adjust its flight controls in order to accurately fly along a wall and successfully complete its mission in an urban environment.

Committee:

Aaron Altman, PhD (Committee Chair); Gregory Parker, PhD (Committee Member); Markus Rumpfkeil, PhD (Committee Member)

Subjects:

Aerospace Engineering

Keywords:

MAV; UAV; aerodynamics; wall effect; wingtip vortex; PIV; wind tunnel; micro air vehicle; vicon

Belzer, Jessica A.Unmanned Aircraft Systems in the National Airspace System: Establishing Equivalency in Safety and Training Through a Fault Tree Analysis Approach
Master of Science (MS), Ohio University, 2017, Electrical Engineering & Computer Science (Engineering and Technology)
With approval of UAS for civilian use in the National Airspace System, comes the need for formal integration. Manned and unmanned aircraft will share the same volumes of airspace, for which the safety standards must be upheld. Under manned aircraft operations, certain implicit assumptions exist that must be made explicit and translatable to the unmanned aircraft context. A formal system safety assessment approach through a fault tree analysis was used to identify assumptions contingent on a pilot’s presence inside the fuselage and areas of weakness in operational equivalency of UAS. The UAS fault tree framework developed is applicable to unmanned aircraft systems of different sizes and complexity, while maintaining a semblance to the framework accepted within the manned aircraft community. In addition, a database of UAS incidents and accidents occurring internationally 2001-2016 was developed from published materials and databases of various sources. Database events were categorized according to the UAS Fault Tree Framework Level 1 Subsystems, the International Civil Aviation Organization (ICAO) Aviation Occurrence Categories, and the Human Factors Analysis and Classification System (HFACS). ICAO Aviation Occurrence Category specific fault trees were constructed for the three most commonly occurring categories in the database results. Significant sources of risk for UAS operations lie in Aircraft/System and Flight Crew/Human Factors failures. Commonly occurring Occurrence Categories in the results of the UAS database were different than those identified for fatal accidents occurring in manned commercial aviation operations. Increased system reliability and standardization is needed to ensure equivalent levels of safety for UAS operations in the NAS. Additionally, needs of UAS pilots are different than those for manned and model aircraft. Training requirements must be approached independently and formally evaluated for their effectiveness in risk mitigation.

Committee:

Frank van Graas, Ph.D. (Advisor); Maarten Uijt de Haag, Ph.D. (Committee Member); Jeffrey Dill, Ph.D. (Committee Member); Robert Stewart, Ph.D. (Committee Member)

Subjects:

Engineering

Keywords:

Fault Tree Analysis; UAS; UAV; Unmanned Aircraft System; FTA; System Safety Assessment; SSA; sUAS;

McCrink, Matthew HDevelopment of Flight-Test Performance Estimation Techniques for Small Unmanned Aerial Systems
Doctor of Philosophy, The Ohio State University, 2015, Aero/Astro Engineering
This dissertation provides a flight-testing framework for assessing the performance of fixed-wing, small-scale unmanned aerial systems (sUAS) by leveraging sub-system models of components unique to these vehicles. The development of the sub-system models, and their links to broader impacts on sUAS performance, is the key contribution of this work. The sub-system modeling and analysis focuses on the vehicle’s propulsion, navigation and guidance, and airframe components. Quantification of the uncertainty in the vehicle’s power available and control states is essential for assessing the validity of both the methods and results obtained from flight-tests. Therefore, detailed propulsion and navigation system analyses are presented to validate the flight testing methodology. Propulsion system analysis required the development of an analytic model of the propeller in order to predict the power available over a range of flight conditions. The model is based on the blade element momentum (BEM) method. Additional corrections are added to the basic model in order to capture the Reynolds-dependent scale effects unique to sUAS. The model was experimentally validated using a ground based testing apparatus. The BEM predictions and experimental analysis allow for a parameterized model relating the electrical power, measurable during flight, to the power available required for vehicle performance analysis. Navigation system details are presented with a specific focus on the sensors used for state estimation, and the resulting uncertainty in vehicle state. Uncertainty quantification is provided by detailed calibration techniques validated using quasi-static and hardware-in-the-loop (HIL) ground based testing. The HIL methods introduced use a soft real-time flight simulator to provide inertial quality data for assessing overall system performance. Using this tool, the uncertainty in vehicle state estimation based on a range of sensors, and vehicle operational environments is presented. The propulsion and navigation system models are used to evaluate flight-testing methods for evaluating fixed-wing sUAS performance. A brief airframe analysis is presented to provide a foundation for assessing the efficacy of the flight-test methods. The flight-testing presented in this work is focused on validating the aircraft drag polar, zero-lift drag coefficient, and span efficiency factor. Three methods are detailed and evaluated for estimating these design parameters. Specific focus is placed on the influence of propulsion and navigation system uncertainty on the resulting performance data. Performance estimates are used in conjunction with the propulsion model to estimate the impact sensor and measurement uncertainty on the endurance and range of a fixed-wing sUAS. Endurance and range results for a simplistic power available model are compared to the Reynolds-dependent model presented in this work. Additional parameter sensitivity analysis related to state estimation uncertainties encountered in flight-testing are presented. Results from these analyses indicate that the sub-system models introduced in this work are of first-order importance, on the order of 5-10% change in range and endurance, in assessing the performance of a fixed-wing sUAS.

Committee:

James W. Gregory (Advisor); Charles Toth (Committee Member); Cliff Whitfield (Committee Member); Jeffery P. Bons (Committee Member)

Subjects:

Aerospace Engineering

Keywords:

UAS, UAV, Propulsion systems, aircraft design, inertial navigation, Kalman filter, sensor calibration, flight testing, HIL

Fuller, Ryan MichaelAdaptive Noise Reduction Techniques for Airborne Acoustic Sensors
Master of Science in Engineering (MSEgr), Wright State University, 2012, Electrical Engineering
Ground and marine based acoustic arrays are currently employed in a variety of military and civilian applications for the purpose of locating and identifying sources of interest. An airborne acoustic array could perform an identical role, while providing the ability to cover a larger area and pursue a target. In order to implement such a system, steps must be taken to attenuate environmental noise that interferes with the signal of interest. In this thesis, we discuss the noise sources present in an airborne environment, present currently available methods for mitigation of these sources, and propose the use of adaptive noise cancellation techniques for removal of unwanted wind and engine noise. The least mean squares, affine projection, and extended recursive least squares algorithms are tested on recordings made aboard an airplane in-flight, and the results are presented. The algorithms provide upwards of 37dB of noise cancellation, and are able to filter the noise from a chirp with a signal to noise ratio of -20db with minimal mean square error. The experiment demonstrates that adaptive noise cancellation techniques are an effective method of suppressing unwanted acoustic noise in an airborne environment, but due to the complexity of the environment more sophisticated algorithms may be warranted.

Committee:

Brian Rigling, PhD (Committee Chair); Kefu Xue, PhD (Committee Member); Fred Garber, PhD (Committee Member)

Subjects:

Acoustics; Aerospace Engineering; Applied Mathematics; Electrical Engineering; Engineering; Remote Sensing

Keywords:

Adaptive Noise Cancellation; Adaptive Algorithms; Acoustic Sensors; Acoustic Eavesdropping; UAV; Unmanned Aerial Vehicle; Active Noise Reduction; Remote Sensing; Signal Processing; Acoustics

Sabo, ChelseaUAV Two-Dimensional Path Planning In Real-Time Using Fuzzy Logic
MS, University of Cincinnati, 2011, Engineering and Applied Science: Aerospace Engineering
There are a variety of scenarios in which the mission objectives rely on a UAV being capable of maneuvering in an environment containing obstacles in which there is little prior knowledge of the surroundings. In these situations, not only can these obstacles be dynamic, but sometimes there is no way to plan ahead of the mission to avoid them. Additionally, there are many situations in which it is desirable to send in an exploratory robot where the environment is dangerous/ contaminated and there is a great deal of uncertainty. These scenarios could either be too risky to send people or not available to humans. With an appropriate dynamic motion planning algorithm in these situations, robots or UAVs would be able to maneuver in any unknown and/or dynamic environment towards a target in real-time. An autonomous system that can handle these varying conditions rapidly and efficiently without failure is imperative to the future of unmanned aerial vehicle (UAV). This paper presents a methodology for two-dimensional path planning of a UAV using fuzzy logic. This approach is selected due to its ability to emulate human decision making and relative ease of implementation. The fuzzy inference system takes information in real time about obstacles (if within the agent’s sensing range) and target location and outputs a change in heading angle and speed. The FL controller was validated for both simple (polygon obstacles in a sparse space) and complex environments (i.e. non-polygon obstacles, symmetrical/concave obstacles, dense environments, etc). Additionally, Monte Carlo testing was completed to evaluate the performance of the control method. Not only was the path traversed by the UAV often the exact path computed using an optimal method, the low failure rate makes the Fuzzy Logic Controller (FLC) feasible for exploration. The FLC showed only a total of 3% failure rate, whereas an Artificial Potential Field (APF) solution, a commonly used intelligent control method, had an average of 18% failure rate. Also, the APF method failed about 1/3 of the time for very dense environments (the FLC only had 5% failure rate). These results highlighted one of the advantages of the FLC method: its adaptability to additional rules while maintaining low control effort. Furthermore, the solutions showed superior results when compared to the APF solutions when compared to distance traversed. Overall, the FLC produced solutions that were on average only about 7.7% greater distance traveled (as opposed to 9.7% for the APF).

Committee:

Kelly Cohen, PhD (Committee Chair); Shaaban Abdallah, PhD (Committee Member); Manish Kumar, PhD (Committee Member)

Subjects:

Aerospace Materials

Keywords:

UAV;Path Planning;Fuzzy Logic;Online;Real-Time;Motion Planning

Brezina, Aron JonMeasurement of Static and Dynamic Performance Characteristics of Electric Propulsion Systems
Master of Science in Engineering (MSEgr), Wright State University, 2012, Mechanical Engineering
Today's unmanned aerial vehicles are being utilized by numerous groups around the world for various missions. Most of the smaller vehicles that have been developed use commercially-off-the-shelf parts, and little information about the performance characteristics of the propulsion systems is available in the archival literature. In light of this, the aim of the present research was to determine the performance of various small-scale propellers in the 4.0 to 6.0 inch diameter range driven by an electric motor. An experimental test stand was designed and constructed in which the propeller/electric motor was mounted in a wind tunnel for both static and dynamic testing. Both static and dynamic results from the present experiment were compared to those from previous studies. For static testing, the coefficient of thrust, the coefficient of propeller power, and the overall efficiency, defined as the ratio of the propeller output power to the electrical input power, were plotted versus the propeller rotational speed. For dynamic testing, the rotational speed of the propeller was held constant at regular intervals while the freestream airspeed was increased from zero to the windmill state. The coefficient of thrust, the coefficient of power, the propeller efficiency and the overall efficiency were plotted versus the advance ratio for various rotational speeds. The thrust and torque were found to increase with rotational speed, propeller pitch and diameter, and decrease with airspeed. Using the present data and data from the archival and non-archival sources, it was found that the coefficient of thrust increases with propeller diameter for square propellers where D = P. The coefficient of thrust for a family of propellers (same manufacturer and application) was found to have a good correlation from static conditions to the windmill state. While the propeller efficiency was well correlated for this family of propellers, the goodness of fit parameter was improved by modifying the propeller efficiency with D/P.  

Committee:

Scott K. Thomas, PhD (Committee Chair); Haibo Dong, PhD (Committee Member); Zifeng Yang, PhD (Committee Member); Mitch Wolff, PhD (Committee Member)

Subjects:

Aerospace Engineering; Engineering; Mechanical Engineering

Keywords:

Propeller; Small Unmanned Aerial Vehicle; UAV; Electric Propulsion System; Advance Ratio; Low Reynolds Number; Wind Tunnel Testing

Kresge, Jared T.Telerobotic System Design for a Remotely Operated Lightweight Park Flyer Mirco Aerial Vehicle
Master of Science (MS), Ohio University, 2006, Electrical Engineering & Computer Science (Engineering and Technology)

The development of unmanned aerial vehicles (UAV) has recently become a popular topic at research institutions. These new UAV designs tend to create smaller, lighter, and application specific vehicles. This thesis describes the design of a telerobotically controlled UAV system and the development of hardware and software for an instrumentation system to be used on a lightweight radio controlled (R/C) park flyer aircraft. This requires that the instrumentation system meet the size and weight constraints as well as measure the dynamics of the aircraft using a set of minimal sensors with limited processing capabilities.

Committee:

Frank van Graas (Advisor)

Keywords:

UAV; MAV; Instrumentation; Aircraft Control; Aircraft Modeling; Flight Testing

Radmanesh, MohammadrezaUAV Traffic Management for National Airspace Integration
MS, University of Cincinnati, 2016, Engineering and Applied Science: Mechanical Engineering
This thesis focuses on developing optimization algorithms for path planning of single and cooperating Unmanned Air Vehicles (UAVs), operating in National Air Space (NAS), in presence of other moving and/or stationary obstacles. The problem is formulated in the framework of Mixed Integer Linear Programming (MILP) which has been proven to be efficient in literature for solving optimization problems in other domains well as path planning problems. This thesis extends the works carried out in literature via proposing the cost-to-go function that incorporates a number of criteria such as path length, uncertain nature of NAS environment, and time and energy consumption based on detailed dynamical model of motion in three dimensions taking into consideration various UAV constraints. The problem is first formulated using single vehicle and then extended to multiple vehicles having a common goal which is incorporated using motion constraints. The solution of the MILP is based on a fast Floating Point (FP) method and is provided in detail in this thesis. This method results in decrease of the computational effort. Incorporation of the moving obstacles or Intruder Aircrafts (IAs) in the problem is done using Kalman filter and Bayesian framework that enable us to simulate uncertainty in motion of obstacles (or intruder aircraft) and maintain the distance between the UAV fleet and other non-cooperative airplanes in NAS. In result, this approach enables simulation of vehicles in team while guaranteeing the robust fleet in uncertain domain. Bayesian method helps us to overcome the hindrance of implementing this algorithm in dynamic and uncertain environment including IAs and pop-up threats. The proposed methodology for solving cooperative form of centralized control in the framework of MILP for cooperative UAVs is shown to result in robust solutions and improves overall team performance. All the algorithms are tested and demonstrated via a number of numerical studies. The results indicate that the proposed algorithms are successful in obtaining optimal solutions in a computationally efficient manner that can be applied to online path planning in dynamic and uncertain situations.

Committee:

Manish Kumar, Ph.D. (Committee Chair); Kelly Cohen, Ph.D. (Committee Member); Ali Minai, Ph.D. (Committee Member); David Thompson, Ph.D. (Committee Member)

Subjects:

Engineering

Keywords:

National Air Space;Mixed Integer Linear Programming;Obstacle Avoidance;Trajectory Planning;UAV;Optimization

Duffy, Sean DavidWhy the Rise in Drones
Master of Arts (MA), Wright State University, 2015, International and Comparative Politics
What are the reasons for the increasing number of drone strikes between 2002 and 2012 by the United States? This study examines the various aspects of the United States government which led to this increase in the number of strikes. Specifically, this study examines the military capabilities, the military leadership bureaucracy and presidential aspects of drone use. Through the division of this time period into three sections, this study seeks to find explain the events which led to the increase in the use of drones by the United States. This study concludes with a discussion on what the future may hold for the United States Unmanned Aerial Combat Vehicle program.

Committee:

Vaughn Shannon, Ph.D. (Committee Chair); Jonathan Winkler, Ph.D. (Committee Member); R. William Ayres IV, Ph.D. (Committee Member)

Subjects:

International Relations; Military History; Military Studies; Political Science

Keywords:

Drones; UCAV; Robotics; Military Doctrine; UAV; Reaper; Predator; Rumsfeld; Gates; Bush; Drone Strike;

Cook, Brandon MMulti-Agent Control Using Fuzzy Logic
MS, University of Cincinnati, 2015, Engineering and Applied Science: Aerospace Engineering
In the coming years, operations in low altitude airspace will vastly increase as the capabilities and applications of Unmanned Aerial Systems (UAS) continue to multiply. Therefore, solutions to managing vehicles in highly congested airspace must be explored. In this study, an intelligent systems approach was used to help mitigate the risk of collision between aircraft in uncontrolled airspace using a UAS Traffic Management (UTM) System. To test the effectiveness of this system, a three-dimensional environment was created using MATLAB to simulate a fully autonomous heterogeneous fleet of UAS attempting to accomplish a variety of realistic missions, including precision agriculture, package delivery services, natural resource monitoring, and disaster management. Main research challenges include situational awareness, decision making, and multi-agent control in an uncertain, time-critical, spatio-temporal environment. To gain the knowledge, experience, and expertise necessary to solve this large-scale real-world problem, two preliminary research efforts were conducted. First, a simulated gaming platform known as Pong, originally created by ATARI, was used to demonstrate the effectiveness of a fully autonomous team to accomplish a desired task using a cascading Fuzzy system. With this knowledge, a simplified UTM system was developed to test a preliminary design of a fuzzy collision avoidance system. Once complete, this knowledge was used to develop the final UTM system platform capable of using intelligent separation assurance and collision avoidance techniques to mitigate the risk for Near Mid-Air Collisions between aircraft. This fuzzy solution utilizes only current state information and can resolve potential conflicts without knowledge of intruder intent. The collision avoidance system was tested in extreme conditions, including close proximity, high closure rates, and conservative maximum turn rates. In the preliminary homogenous case, the collision avoidance techniques were on average 99.977% successful over a span of nearly 2,485 flight hours. Whereas, in the final UTM platform consisting of heterogeneous agents, the collision avoidance system was on average 99.88% successful over a span of 16,255 flight hours. Lastly, it was found that the techniques employed for separation assurance drastically mitigated the risk for Near Mid-Air Collisions. Comparing the unmitigated and mitigated cases, the number of losses of separation between aircraft reduced from one loss of separation per two flight hours, to one loss of separation per ten flight hours. This mitigated separation assurance platform was successful at preventing a loss of separation 88.47% of the time, over a span of 7,545 flight hours.

Committee:

Kelly Cohen, Ph.D. (Committee Chair); Manish Kumar, Ph.D. (Committee Member); Grant Schaffner, Ph.D. (Committee Member); Gary Slater, Ph.D. (Committee Member)

Subjects:

Aerospace Materials

Keywords:

Fuzzy Logic;UAS Traffic Management;Unmanned Aerial Systems;Intelligent Systems;UAV Collision Avoidnace;Multi-Agent Control

Fan, JiankunOptimal Path Planning and Control of Quadrotor Unmanned Aerial Vehicle for Area Coverage
Master of Science, University of Toledo, 2014, Mechanical Engineering
An Unmanned Aerial Vehicle (UAV) is an aircraft without a human pilot on board. Its flight is controlled either autonomously by computers onboard the vehicle, or remotely by a pilot on the ground, or by another vehicle. In recent years, UAVs have been used more commonly than prior years. The example includes areo-camera where a high speed camera was attached to a UAV which can be used as an airborne camera to obtain aerial video. It also could be used for detecting events on ground for tasks such as surveillance and monitoring which is a common task during wars. Similarly UAVs can be used for relaying communication signal during scenarios when regular communication infrastructure is destroyed. The objective of this thesis is motivated from such civilian operations such as search and rescue or wildfire detection and monitoring. One scenario is that of search and rescue where UAV’s objective is to geo-locate a person in a given area. The task is carried out with the help of a camera whose live feed is provided to search and rescue personnel. For this objective, the UAV needs to carry out scanning of the entire area in the shortest time. The aim of this thesis to develop algorithms to enable a UAV to scan an area in optimal time, a problem referred to as “Coverage Control” in literature. The thesis focuses on a special kind of UAVs called “quadrotor” that is propelled with the help of four rotors. The overall objective of this thesis is achieved via solving two problems. The first problem is to develop a dynamic control model of quadrtor. In this thesis, a proportional-integral-derivative controller (PID) based feedback control system is developed and implemented on MATLAB’s Simulink. The PID controller helps track any given trajectory. The second problem is to design a trajectory that will fulfill the mission. The planed trajectory should make sure the quadrotor will scan the whole area without missing any part to make sure that the quadrotor will find the lost person in the area. The generated trajectory should also be optimal. This is achieved via making some assumptions on the form of the trajectory and solving the optimization problem to obtain optimal parameters of the trajectory. The proposed techniques are validated with the help of numerous simulations.

Committee:

Manish Kumar (Committee Chair); Mohammad Elahinia (Committee Member); Mehdi Pourazady (Committee Member)

Subjects:

Engineering; Robotics; Robots

Keywords:

UAV, Quadrotor, Path Planning, Optimal control

Simon, Jerry N.A Systems Approach to the Formulation of Unmanned Air Vehicle Detect, Sense, and Avoid Performance Requirements
Master of Science (MS), Ohio University, 2009, Electrical Engineering (Engineering and Technology)
Unmanned Aerial Vehicles (UAVs) are becoming more prevalent in military applications and through the success of these applications, many commercial usages have been derived. However, due to the recent development of UAVs, the Federal Aviation Administration (FAA) has not yet been able to develop performance requirements for the Detect, Sense, and Avoid (DSA) system of UAVs. For this reason, this study serves to explore the current capabilities of human general aviation (GA) pilots with regards to their see-and-avoid abilities. The midair collision rate over the past ten years and the average traffic around an average airport are also explored. With the analyzed data, a model is developed in order to extract the grounds for performance requirement for DSA systems. The determined DSA performance estimate can be used to further aid in the development of overall performance requirements for DSA systems.

Committee:

Michael Braasch, PhD (Advisor); Chris Bartone, PhD (Committee Member); Maarten Uijt De Haag, PhD (Committee Member); Zhen Zhu, PhD (Committee Member); William Kaufman, PhD (Other)

Subjects:

Electrical Engineering; Engineering

Keywords:

Unmanned Aerial Vehicle; UAV; Detect Sense and Avoid; DSA; See and Avoid

Kephart, Ryan J.Comparison of See-and-Avoid Performance in Manned and Remotely Piloted Aircraft
Master of Science (MS), Ohio University, 2008, Electrical Engineering (Engineering and Technology)

See-and-avoid is the current FAA approved method for pilots to avoid objects and other aircraft while flying in visual meteorological conditions (VMC). Although fully autonomous ‘sense-and-avoid' or ‘detect-and-avoid' systems are in development, none are currently certified. Thus existing unmanned aerial vehicle (UAV) operations are limited to case-by-case restricted airspace or require escort by manned aircraft [1], [2]. Many UAVs are equipped with at least a forward-looking camera. In the transition between current technology and future fully autonomous, certified sense-and-avoid systems, it seems reasonable to require a ground-based operator to perform the see-andavoid function.

This thesis discusses the flight-testing performed to establish air traffic detection ranges for low-time pilots, and for a low-cost UAV camera system. The system was evaluated to determine if it could provide the equivalent see-and-avoid performance as the tested pilots.

Committee:

Michael Braasch, PhD (Advisor); Maarten Uijt de Haag, PhD (Committee Member); Zhen Zhu, PhD (Committee Member); William Kaufman, PhD (Committee Member)

Subjects:

Electrical Engineering

Keywords:

UAV; air traffic range; see and avoid; aircraft detection range; navigation; avionics, camera range

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