Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 89 for “"helicopters"”.
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Hybrid Formation Control of Unmanned Helicopters
… control framework for the formation of unmanned helicopters as a cooperative task. This control structure has been constructed in two main steps. First, to have an autonomous flying system, a hierarchical hybrid control structure is developed for a single unmanned helicopter to capture the …
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Autonomous aerobatic maneuvering of miniature helicopters
… of aerobatic maneuvers with small-scale helicopters, and a low-order dynamic model which adequately describes a miniature helicopter in a wide range of flight conditions, including aerobatics. The control laws consist of steady-state trim trajectory controllers, used prior to, and upon …
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Effective platform designs for medium lift helicopters
… that the use of platform design for medium lift helicopters can provide opportunities for reduced time to market and faster return to service of helicopters through faster design generation and reduced planning requirements. Through historical review of the S70 helicopter and the derivatives oft …
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Contributions to the dynamics of helicopters with active rotor controls
This dissertation presents an aeromechanical closed loop stability and response analysis of a hingeless rotor helicopter with a Higher Harmonic Control (HHC) system for vibration reduction. The analysis includes the rigid body dynamics of the helicopter and blade flexibility. The gain matrix is …
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A viable multivariable adaptive controller with application to autonomous helicopters
Autonomous helicopters carry out missions in inaccessible hazardous environments. Their performance capability in speed, maneuverability and trajectory tracking must be comparable, if not superior, to manned vehicles. Control laws that meet desired performance specifications are difficult to design …
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An Integrated Platform to Increase the Range/Endurance of Unmanned Helicopters
<p>Class I (kg) autonomous helicopters are becoming increasingly popular for a wide range of non-military applications such as, surveillance, reconnaissance, traffic monitoring, emergency response, agricultural spraying, and many other "eye in the sky" missions. However, an efficient …
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Foundations for the Coupled Inflow and Structural Dynamics of Multi-rotor Helicopters
<p>In this work, the Peters-Seidel finite-state model is expanded to calculate the coupled inflow and rotor dynamics of tandem rotor configurations. This establishes the foundation for a more complete multi-rotor, dynamic inflow model with finite-state methods. The derivation presented in this work …
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Modeling and control techniques of autonomous helicopters for landing on moving platforms
En los últimos años se ha incrementado notablemente la investigación con sistemas de aeronaves no tripuladas (UAS por sus siglas en ingles). Actualmente existe cada vez más interés en la utilización de UAS en campos como la fotografía aérea, la inspección y vigilancia, medición, búsqueda y rescate …
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Estimation and Mapping of Ship Air Wakes using RC Helicopters as a Sensing Platform
… dissertation explores the applicability of RC helicopters as a tool to map wind conditions. This dissertation presents the construction of a robust instrumentation system capable of wireless in-situ measurement and mapping of ship airwake. The presented instrumentation system utilizes an RC …
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Modelling, estimation and control of a twin-helicopter slung load transportation system
… system to transport and assemble cargo using two helicopters is presented in this thesis. It is more economical to use multiple lower cost helicopters in a coordinated manner to carry cargo than to use a single high performance helicopter for the transportation task. The reason for the generally …
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Design of a four rotor unmanned aerial vehicle capable of sustaining zero-roll and zero-pitch flight using vector thrusting
… recent decades, remote controlled airplanes and helicopters equipped with video cameras have been used by the movie industry, photographers, and for surveillance. The military deploys these unmanned aerial vehicles (UAV's) to gather various types of reconnaissance. Recently, four-rotor …
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DESIGN OF AVIONICS AND CONTROLLERS FOR AUTONOMOUS TAKEOFF, HOVER AND LANDING OF A MINI-TANDEM HELICOPTER
… vehicles especially single rotor small scale helicopters. This thesis focuses on a small scale twin rotor helicopter. These helicopters are more useful because of their power efficiency, scalability, long range of center of gravity, shorter blades and most importantly their "all lift" feature. …
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Behavioral representation of military tactics for single-vehicle autonomous rotorcraft via statecharts
… aerospace companies have developed unmanned helicopters suitable for integration into military operations as reconnaissance platforms. These rotorcraft, however, require ground-based human controllers varying in number based on the size and complexity of the system controlled. The automation …
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Design of a Helicopter Slung Vehicle for Actuated Payload Placement
Helicopters have been used in applications where they need to carry a slung load for years. More recently, unmanned (UAV) helicopters are being used to deliver supplies to military units on the ground in theaters of war. This thesis presents a helicopter slung vehicle used to carry the payload and …
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Empirical Evaluation of Ground, Ceiling, and Wall Effect for Small-Scale Rotorcraft
… when it flies close to the ground. For helicopters, this effect has been modeled since the 1950's based on the work of Cheeseman and Bennett, perhaps the most common method for predicting hover performance due to ground effect. This model, however, is based on assumptions that are often …
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Effect of tip-speed ratio on induced velocities near a lifting rotor
… interference between wing and rotor of compound helicopters and convertiplanes. In addition the results should be applicable to the problem of mutual interference between rotors of multi-rotor helicopters.
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An Analysis of Helicopter EMS Accidents using HFACS: 2000-2012
… United States began operations. While the use of helicopters to transport medical casualties started decades previously, St. Anthony Flight for Life represented the start of an industry that would grow rapidly in the years to follow, both in the US and around the world (Flight for Life Colorado, …
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Data Management in Certified Avionics Systems
… gained in a semi-structured interview at Airbus Helicopters, industrial established approaches to implement qualified avionics software are assessed at first and compared with respect to strengths and weaknesses for data-management afterwards. As a result, a novel development approach is …
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Advanced signal processing solutions for ATR and spectrum sharing in distributed radar systems
… algorithm is developed for the identification of helicopters. The approach relies on the proposed sparse representation of the signal scattered from the helicopter’s rotor and received bythe radar. Such a sparse representation is obtained through the application of a greedy sparse recovery …
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VERTICAL REPLENISHMENT BY UNMANNED AERIAL VEHICLES.
Helicopters are extensively used for vertical replenishment, which is a type of underway replenishment for seaborne vessels. This operation is commonly done by manned helicopter, which is usually labor-inefficient and possesses potential risks for pilots and ground crews especially in extreme …
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