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Nashua, NH, United States

Daniel Webster College is a for-profit college owned by ITT Educational Services, Inc, in Nashua, New Hampshire, United States, with a professions focus. Wikipedia.

Sadraey M.,Daniel Webster College
AIAA AVIATION 2014 -14th AIAA Aviation Technology, Integration, and Operations Conference

Recent technology advances and customer acceptance have led to the widespread employment of unmanned aerial vehicles. Wind energy is a free, abundant, and renewable one. This paper presents the application of robust control to unmanned aircraft where the wind power in employed as the source of energy. The wind speed not only generates energy for the engine, but also provides airspeed environment for a trimmed, stable, and controlled flight. The wind powered unmanned aerial vehicle (WPUAV) is tethered to a ground base with a long light weight wire, so the UAV flies over a target area. The application of wind energy in an unmanned flight for a fixed space requires special control framework. This paper also presents a novel technique to real-time guidance and control for an UAV with wind power when it is employed in a fixed target field. When the wind speed is out of the desired range, the UAV is commanded to approach and land in a nearby field using the robust control technique. MATLAB/Simulink is used to implement the simulation; the final results are documented by analyzing the resulting trajectories and control deflections. Source

Sadraey M.,Daniel Webster College
AIAA Guidance, Navigation, and Control Conference 2011

This paper presents an integrated guidance and control design for a formation flight of multiple Unmanned Aerial Vehicles (UAVs). The guidance law is based on the line-of-sight (LOS) method which has ability to transfer UAVs to different formation patterns through a single parameter change. The guidance law is integrated with the optimal control law and is applied to a linear dynamic model. The problem is formulated as a linear quadratic regulator (LQR) control problem for a line-of-sight based circular coordination formation flight configuration of a leader and three follower UAVs. The mission is to have a coordinated encirclement around a ground maneuvering target. The design objective is to achieve a zero vertical spatial offset (i. e. same commanded altitude) and a 90 degree horizontal angular offset among four UAVs. In order to verify the performance of the proposed system, numerical simulation using a linear coupled six-degree-of-freedom (6-DOF) model is demonstrated for a circular multi-vehicle coordination flight of four UAVs. Source

Guo X.,Daniel Webster College
Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

A study is undertaken to improve the linear normal mode selection procedure using the energy information of the proper orthogonal modes generated in the full physical simulation of a nonlinear system. In a typical reduced-order simulation using proper orthogonal decomposition, system identification is performed to simulation data in physical DoFs by means of proper orthogonal decomposition. However, frequency information is also acquired so that the energy participation factor of each proper orthogonal mode can be obtained. In this paper, first, the frequency estimation of resulting proper orthogonal modes is performed by using the modal kinetic energy without using complicated smooth orthogonal decomposition. Second, the similarity matrix between the proper orthogonal modes and the linear normal modes are weighted with energy participation of proper orthogonal modes so that the selected linear normal modes are not only similar to corresponding proper orthogonal modes, but also based on the most energy contributing ones. Linear and nonlinear simulations of a simply-supported plate structure subjected to free vibrations, and random pressure excitations are examined as the application examples. Initial examples show that the proposed technique enables accurate and efficient frequency estimation of proper orthogonal modes and has the potential of improving the mode selection procedure for reduced-order nonlinear simulations. Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc. Source

Sadraey M.,Daniel Webster College
10th AIAA Aviation Technology, Integration and Operations Conference 2010, ATIO 2010

Complex UAV systems, due to the high cost and the risks associated with their development become a prime candidate for the adoption of systems engineering methodologies. A successful UAV designer needs not only a good understanding of design, but also systems engineering approach. The design of a UAV begins with the requirements definition and extends through functional analysis and allocation, design synthesis and evaluation, and finally validation. An optimized UAV, with a minimum of undesirable side effects, requires the application of an integrated life-cycle oriented "system" approach. In this paper, conceptual design, preliminary design and detail design of an UAV based on systems engineering approach are introduced. In each stage, application of this approach is described by presenting the design flow chart and practical steps of design. A fair amount of the paper is devoted to the detail design phase. © 2010 by the American Institute of Aeronautics and Astronautics. Source

Przekop A.,ASM Corporation | Guo X.,Daniel Webster College | Rizzi S.A.,NASA
Journal of Sound and Vibration

Three procedures to guide selection of an efficient modal basis in a nonlinear random response analysis are examined. One method is based only on proper orthogonal decomposition, while the other two additionally involve smooth orthogonal decomposition. Acoustic random response problems are employed to assess the performance of the three modal basis selection approaches. A thermally post-buckled beam exhibiting snap-through behavior, a shallowly curved arch in the auto-parametric response regime and a plate structure are used as numerical test articles. The results of a computationally taxing full-order analysis in physical degrees of freedom are taken as the benchmark for comparison with the results from the three reduced-order analyses. For the cases considered, all three methods are shown to produce modal bases resulting in accurate and computationally efficient reduced-order nonlinear simulations. © 2012 Elsevier Ltd. Source

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