Mechanical and Aerospace Engineering Faculty PublicationsCopyright (c) 2016 Utah State University All rights reserved.
http://digitalcommons.usu.edu/mae_facpub
Recent documents in Mechanical and Aerospace Engineering Faculty Publicationsen-usTue, 13 Dec 2016 10:09:14 PST3600Software- and hardware-in-the-loop verification of flight dynamics model and flight control simulation of a fixed-wing unmanned aerial vehicle
http://digitalcommons.usu.edu/mae_facpub/109
http://digitalcommons.usu.edu/mae_facpub/109Wed, 16 Nov 2016 13:07:26 PST
Unmanned aerial system (UAS) use is ever-increasing. In this paper, it is shown that even with low-cost hardware and open-source software, simple numerical testing practices (software- and hardware-in-the-loop) can prove the accuracy and usefulness of an aeronautical flight model, as well as provide valuable pre-flight testing of many situations typically only encountered in flight: high winds, hardware failure, etc. Software and hardware simulation results are compared with actual flight testing results to show that these modeling and testing techniques are accurate and provide a useful testing platform for a small unmanned aerial vehicle. Source code used in simulation is open and provided to the community.
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C. Coopmans et al.Survey of Selected Additively Manufactured Propellant for Arc-Ignition of Hybrid Rockets
http://digitalcommons.usu.edu/mae_facpub/115
http://digitalcommons.usu.edu/mae_facpub/115Wed, 16 Nov 2016 10:21:34 PST
Results of a testing campaign to assess multiple commercially available three-dimensional printer materials for effectiveness in an arc-ignition system for hybrid rockets are presented. Previously, a form of additive manufacturing known as fused deposition modeling was used to fabricate high-density acrylonitrile butadiene styrene (ABS) fuel grains so that, when properly layered, they possess unique electrical breakdown properties. When subjected to an inductive charge, an electrical arc flows along the layered material surface and seeds combustion when the arc occurs simultaneously with the introduction of an oxidizing flow. This study investigates commercially available three-dimensional printable materials to search for equivalent or possibly superior fuel alternatives to ABS. Test specimens include photopolymers processed using polyjet (stereolithography) and fused-deposition printing. Comparison metrics include general arc ability, pyrolysis rate, dissipated power, characteristic velocity, and ability for multiple restarts. Initially, an ensemble of eight commonly available “printable” polymers was evaluated, and only four printable materials (high- and low-density ABS, VeroClear^{®}, and white polycarbonate) were found to possess effective sparking properties. In follow-on burn tests, only high- and low-density ABS and VeroClear performed effectively as fuel materials. White polycarbonate would not ignite using the arc method. High-density ABS exhibited the best overall ignition properties and characteristic velocity.

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Stephen A. Whitmore et al.Feasibility of wireless power transfer for electrification of transportation: Techno-economics and life cycle assessment
http://digitalcommons.usu.edu/mae_facpub/114
http://digitalcommons.usu.edu/mae_facpub/114Fri, 11 Nov 2016 11:01:43 PST
Integration of wireless power transfer (WPT) systems in roadways and vehicles represents a promising alternative to traditional internal combustion transportation systems. The economic feasibility and environmental impact of WPT applied to the transportation system is evaluated through the development of engineering system models. For a 20% penetration of the WPT technology in vehicles, results show a 20% reduction in air pollutants, 10% reduction in energy use and CO2 emissions and a societal level payback (defined as total cost of ownership savings compared to a traditional vehicle equal to roadway infrastructure) of 3 years. The modeled system covers 86% of all traffic in the US, impacts 40% of all roadways and shifts $180 billion per year from oil production to jobs in local power generation and development, construction, and maintenance of electrified roadways and new electric vehicles. Results on model sensitivity to energy prices, payback as a function of penetration, and trucking vs light duty use are presented.
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Jason C. Quinn et al.Small low cost unmanned aerial
vehicle system identification: a survey and categorization
http://digitalcommons.usu.edu/mae_facpub/112
http://digitalcommons.usu.edu/mae_facpub/112Tue, 25 Oct 2016 16:47:30 PDT
Small low-cost unmanned aerial vehicles (UAVs) provide greater possibilities for personal scientific research than other conventional platforms such as satellites or manned aircraft. In order to provide precision aerial imagery or other scientific data, an accurate model of vehicle dynamics is needed for controller development and tuning. The purpose of this paper is to provide a survey of current methods and applications of system identification (system ID) for small low-cost UAVs. This survey divides UAVs into 5 groups: helicopter, fixed-wing, multirotor, flapping-wing, and lighter-than-air. The current state of system ID research with respect to various types of UAVs is reviewed based on research literature. System ID methods and application are tabulated for further research. Concluding remarks are given and applications for system ID methods to small low-cost UAVs are recommended. Index Terms—System Identification; UAV, Helicopter, Fixedwing, Multirotor, Flapping-wing, Lighter-than-air, Least squares, Levenberg Marquardt, Kalman filter, EKF, UKF, Observer/Kalman identification, Autoregressive exogenous inputs, ARMAX, Box Jenkins, Prediction-error method, Output-error method, Neural network, Fuzzy identification, Time domain, Frequency domain, State-space, Subspace, CIFER
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Nathan V. Hoffer et al.Small low-cost unmanned
aerial vehicle system identification: Brief sensor survey and data quality, consistency checking, and reconstruction
http://digitalcommons.usu.edu/mae_facpub/111
http://digitalcommons.usu.edu/mae_facpub/111Tue, 25 Oct 2016 16:47:27 PDT
This paper serves as the next chapter in a series of papers on system identification (system ID) for small low-cost unmanned aerial vehicles (UAVs). The purpose of this paper is to answer the question of, what is the next step in the process of system ID once a method of system ID and a model type have been selected? The focus of this paper is to show how sensors, data quality, and data consistency and reconstruction techniques provide an answer to this question. The paper also provides a broader scope for utilizing data consistency and reconstruction in small low-cost UAVs and how it can increase mission assurance and fault tolerance. A brief survey of small low-cost Micro-Electro-Mechanical systems (MEMS) sensors used in UAVs is given. Included in the survey is the data types provided by each sensor and issues of each sensor from a system ID perspective. The process of determining and improving data quality, utilizing data consistency checking and reconstruction techniques is outlined. The paper concludes with guidelines and lessons learned about sensor data for system ID and a future research direction.
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Nathan V. Hoffer et al.Small low-cost unmanned
aerial vehicle System identification by Error Filtering Online Learning (EFOL)
enhanced least squares method
http://digitalcommons.usu.edu/mae_facpub/110
http://digitalcommons.usu.edu/mae_facpub/110Tue, 25 Oct 2016 16:47:24 PDT
This paper presents the results of system identification (system ID) of a small fixed-wing low-cost unmanned aerial vehicle (UAV). The system ID estimates the aerodynamic coefficients of the linear longitudinal equations of motion using batch least squares enhanced with an Error Filtering Online Learning (EFOL) scheme. EFOL estimates the state derivatives using filtering without taking the derivative, making the least squares more robust. Thus, this method of system ID only requires flight data of the states and not the state derivatives. This is advantageous due to the limitations of low-cost sensors including GPS-aided INS systems. The derivation and benefits of least squares with EFOL are briefly described here in. The main contribution of this paper is the identification of the aerodynamic force and moment coefficients for the linear longitudinal model of the UAV. The error between the flight data and the model response are also presented. The identified model shows good correlation to the training data. The model predicts well the short period flight characteristics of the fixed-wing UAV but does not fully capture the long period dynamics. Solutions to this issue are presented and discussed.
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Nathan V. Hoffer et al.Development and Transient Analysis of a Helical-coil Steam Generator for High Temperature Reactors
http://digitalcommons.usu.edu/mae_facpub/108
http://digitalcommons.usu.edu/mae_facpub/108Tue, 25 Oct 2016 16:47:21 PDT
A high temperature gas-cooled reactor (HTGR) is under development by the Next Generation Nuclear Plant (NGNP) Project at the Idaho National Laboratory (INL). Its design emphasizes electrical power production which may potentially be coupled with process heat for hydrogen production and other industrial applications. NGNP is considering a helical-coil steam generator for the primary heat transport loop heat exchanger based on its increased heat transfer and compactness when compared to other steam generators. The safety and reliability of the helical-coil steam generator is currently under evaluation as part of the development of NGNP. Transients, such as loss of coolant accidents (LOCA), are of interest in evaluating the safety of steam generators. In this study, a complete steam generator inlet pipe break (double ended pipe break) LOCA was simulated by an exponential loss of primary side pressure. For this analysis, a model of the helical-coil steam generator was developed using RELAP5-3D, an INL in-house systems analysis code. The steam generator model behaved normally during the transient simulating the complete steam generator inlet pipe break LOCA. Further analysis is required to comprehensively evaluate the safety and reliability of the helical-coil steam generator design in the NGNP setting.
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Nathan V. Hoffer et al.Design, modeling and validation of a t-tail unmanned aerial vehicle
http://digitalcommons.usu.edu/mae_facpub/107
http://digitalcommons.usu.edu/mae_facpub/107Tue, 25 Oct 2016 16:47:18 PDT
This paper addresses the design and modeling process of a T-tail unmanned aerial vehicle (UAV). A methodology is presented of how to make tradeoffs among the payload requirements, energy efficiency and aerodynamic stability. A linear decoupled model of longitudinal and lateral dynamics is abstracted from a physical airframe. Instead of subjectively estimating the order, error and time delay for system identification (system ID), equations of motion derived from aerodynamics are employed to provide more precise estimation of the model structure. System ID is carried out with regard to the flight data collected by the autopilot data logger. The resulted model is refined based on the simulation and comparison.
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Z. Li et al.A Survey and Categorization of Small Low-Cost Unmanned Aerial Vehicle system Identification
http://digitalcommons.usu.edu/mae_facpub/106
http://digitalcommons.usu.edu/mae_facpub/106Tue, 25 Oct 2016 16:47:15 PDT
Remote sensing has traditionally be done with satellites and manned aircraft. While these methods can yield useful scientific data, satellites and manned aircraft have limitations in data frequency, process time, and real time re-tasking. Small low-cost unmanned aerial vehicles (UAVs) can bridge the gap for personal remote sensing for scientific data. Precision aerial imagery and sensor data requires an accurate dynamics model of the vehicle for controller development. One method of developing a dynamics model is system identification (system ID). The purpose of this paper is to provide a survey and categorization of current methods and applications of system ID for small low-cost UAVs. This paper also provides background information on the process of system ID with in-depth discussion on practical implementation for UAVs. This survey divides the summaries of system ID research into five UAV groups: helicopter, fixed-wing, multirotor, flapping-wing, and lighter-than-air. The research literature is tabulated into five corresponding UAV groups for further research.
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Nathan V. Hoffer et al.Rudder Augmented Trajectory Correction for Small Unmanned Aerial Vehicles and the Effects on Fixed Camera Imagery
http://digitalcommons.usu.edu/mae_facpub/113
http://digitalcommons.usu.edu/mae_facpub/113Tue, 25 Oct 2016 15:29:56 PDT
In this paper, we develop a rudder augmented trajectory correction method for small unmanned aerial vehicles. The goal of this type of controller is to minimize the lateral image errors of body fixed non-gimbaled cameras when aiding remote-sensing missions. A comparison to current aileron only trajectory correction autopilots and the analytical derivation of the rudder augmented trajectory correction controller is presented. Effects of rudder control input on roll/bank angle is also investigated. Simulation results are presented that show significant reduction in the roll angle present during trajectory correction. This in turn has a large effect on total flight line image deviations. Error reductions of over 1000% are achievable.
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Thomas FisherPropulsion Theory of Flapping Airfoils, Comparison with Computational Fluid Dynamics
http://digitalcommons.usu.edu/mae_facpub/105
http://digitalcommons.usu.edu/mae_facpub/105Tue, 11 Oct 2016 13:37:19 PDT
It is shown that the time-dependent aerodynamic forces acting on a flapping airfoil in forward flight are functions of both axial and normal reduced frequencies. The axial reduced frequency is based on the chord length, and the normal reduced frequency is based on the plunging amplitude. Furthermore, the time-dependent aerodynamic forces are related to two Fourier coefficients, which are evaluated here from computational results. Correlation equations for these Fourier coefficients are obtained from a large number of grid- and time-step-resolved inviscid computational-fluid-dynamics solutions, conducted over a range of both axial and normal reduced frequencies. The correlation results can be used to predict the thrust, required power, and propulsive efficiency for airfoils in forward flight with sinusoidal pitching and plunging motion. Within the range of parameters typically encountered in the efficient forward flight of birds, results obtained from the correlation equations match the computational-fluid-dynamics results more closely than do those obtained from the classical Theodorsen model.
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Doug F. Hunsaker et al.A Numerical Vortex Approach to Aerodynamic Modeling of SUAV/VTOL Aircraft
http://digitalcommons.usu.edu/mae_facpub/104
http://digitalcommons.usu.edu/mae_facpub/104Thu, 18 Feb 2016 14:15:35 PST
A numerical lifting line method, coupled with a numerical blade element method, is presented as a low computational cost approach to modeling slipstream effects on a finite wing. This method uses a 3D vortex lifting law along with known 2D airfoil data to predict the lift distribution across a wing in the presence of a propeller slipstream. The results are of significant importance in the development of an aerodynamic modeling package for initial stages of vertical take-off and landing (VTOL) aircraft design. An overview of the algorithm is presented, and results compared with published experimental data.
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Doug F. HunsakerPost Stall Behavior of a Lifting Line Algorithm
http://digitalcommons.usu.edu/mae_facpub/103
http://digitalcommons.usu.edu/mae_facpub/103Thu, 18 Feb 2016 14:15:33 PST
A modified lifting line algorithm is considered as a low-cost approach for calculating lift characteristics of wings above stall. The model employs a numerical lifting-line method utilizing the 3D vortex lifting law along with known 2D airfoil data to predict the lift distribution across a wing. This method is expected to be of significant importance in the design of tail-sitter vertical take-off and landing (VTOL) aircraft where the aircraft experiences stall conditions during important flight maneuvers. The algorithm is presented, and results compared with published experimental data.
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Doug F. HunsakerEvaluation of an Alternate Incompressible Energy-Enstrophy Turbulence Model
http://digitalcommons.usu.edu/mae_facpub/102
http://digitalcommons.usu.edu/mae_facpub/102Thu, 18 Feb 2016 14:15:31 PST
A concise overview of turbulence modeling challenges is presented along with developmental concerns of traditional turbulence models. An alternate energy- enstrophy turbulence model developed by Dr. Warren Phillips is given followed by plans for closing the new model and evaluating the subsequent closure coefficients. This paper is effectively an overview of a PhD dissertation proposal and includes only a brief description of the project outline.
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Doug F. HunsakerApplication of a Coordinate Transformation and Discretization Method for Computational Fluid Dynamics
http://digitalcommons.usu.edu/mae_facpub/101
http://digitalcommons.usu.edu/mae_facpub/101Thu, 18 Feb 2016 14:15:29 PST
An overview of the computational methods implemented in a two-dimensional laminar flow solver is presented. The methods discussed include coordinate transformations making the code capable of solving flow in non-rectilinear domains, a discretization method implemented in the computational domain, and a pressure- coupling method which is used to enforce the continuity equation. Results of the numerical solver for laminar flow are presented and discussed.
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Doug F. HunsakerA One-Dimensional Finite-Difference Solver for Fully-Developed Pipe and Channel Flows
http://digitalcommons.usu.edu/mae_facpub/100
http://digitalcommons.usu.edu/mae_facpub/100Thu, 18 Feb 2016 14:15:27 PST
An algorithm is developed to solve the fundamental flow cases of fully-developed turbulent flow in a pipe and in a channel. The algorithm uses second-order finite-difference approximations for nonuniform grid spacing and is developed in such a way as to easily facilitate the implementation of several two-equation, Reynolds- Averaged-Navier-Stokes turbulence models. Results are included for the Wilcox 1998 k-ω model.
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Doug F. HunsakerA Numerical Lifting-Line Method Using Horseshoe Vortex Sheets
http://digitalcommons.usu.edu/mae_facpub/99
http://digitalcommons.usu.edu/mae_facpub/99Thu, 18 Feb 2016 14:15:24 PST
A numerical method based on the original lifting- line theory of Prandtl is developed which includes the influence of horseshoe vortex sheets. The method is an attempt at developing a higher-order method than previous delta-function methods of the same type. The definition of a horseshoe vortex sheet singularity is introduced and the velocity induced at an arbitrary point in space by the singularity is developed. No closed-form solution for this induced velocity was found for points not collinear with the bound portion of the singularity. Additionally, the velocity induced along the bound portion of a horseshoe vortex sheet with sweep is indeterminate. The singularity was used to develop a numerical method capable of predicting the aerodynamic forces and moments on a system of lifting surfaces. The method gives results within the accuracy of other similar methods, but requires higher grid refinement and more computation than previous methods.
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Doug F. HunsakerPerspectives on UAV Airframe Design
http://digitalcommons.usu.edu/mae_facpub/98
http://digitalcommons.usu.edu/mae_facpub/98Thu, 18 Feb 2016 14:15:21 PST
A perspective on how unmanned airframes may be efficiently and quickly developed as the UAV industry grows.
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Doug F. HunsakerOptimization of Flapping-Flight Using Numerical Lifting-Line Analysis
http://digitalcommons.usu.edu/mae_facpub/97
http://digitalcommons.usu.edu/mae_facpub/97Thu, 18 Feb 2016 14:15:18 PST
Progress in modeling and optimization of efficient flapping-flight aircraft.
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Doug F. HunsakerA Fundamental Approach to Modeling Flapping Flight
http://digitalcommons.usu.edu/mae_facpub/96
http://digitalcommons.usu.edu/mae_facpub/96Thu, 18 Feb 2016 14:15:15 PST
A viable approach to the modeling and development of efficient flapping-flight unmanned systems.
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Doug F. Hunsaker