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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Development of a simulation tool for flight dynamics and control investigations of articulated VTOL unmanned aircraft

Saghafi, F. January 1996 (has links)
A simulation tool for flight dynamics and control investigations of three different Vertical Take Off and Landing (VTOL) unmanned aircraft configurations has been developed. A control concept has been proposed in order to take advantage of the fast response characteristics of the ordinary small engine/propeller propulsion systems in such aircraft, as well as replacing the complex rotors used previously in VTOL concepts for small unmanned aircraft. The simulation model has been established on the basis of the proposed concept so that it can also be used to study the feasibility of this idea. An Object-based methodology has been introduced so as to reduce the amount of aerodynamic required data for the simulation model. The equations of motion associated with the aircraft multibody system with ten degrees of freedom have been derived using the Newton-Euler method. The modelling of various subsystems including the propeller model, the airframe aerodynamics and the engine model has been carried out. A method for calculating the propellers' slipstream effects on the other components has been presented. Input data for the simulation model have been estimated, using different sources. The Advanced Continuous Simulation Language (ACSL) has been used for the programming of the mathematical model. A series of comprehensive tests have been carried out in order to demonstrate the validity of the simulation model. The ability of the simulation model to explain the aircraft modes of motion as well as to discover unknown nonlinear behaviours and to describe them has been demonstrated.

Robust eigenstructure assignment for flight control applications

Davies, R. January 1994 (has links)
No description available.

Application of Eigenstructure Assignment to the control of powered lift combat aircraft

Smith, Phillip Raymond January 1990 (has links)
No description available.

Aileron augmented directional control and braking

Papadopoulos, Christopher A. January 2000 (has links)
Current landing and braking systems are associated with the approach, flare and rollout. Automatic and independent brake systems prevent skidding but do not restore the aircraft to the original trajectory. None use the normal aerodynamic surfaces to augment braking effectiveness to steer the aircraft during sudden changes in runway surface conditions. Many aircraft accidents occur during landing. The task of bringing the aircraft to a safe taxing speed from touchdown in variable weather conditions is the most difficult manoeuvre that a pilot has to make. There is no opportunity to recover or reattempt the manoeuvre. It is the only phase of the aircraft operation that has not been effectively improved through the use of autopilot control systems. Improving this regime of operation through the use of formally redundant aerodynamic control surfaces is the subject of this thesis. This thesis describes the development and testing of a controller, auto-pilot and ABS combination that uses ailerons to control the normal loading differential between the main gear of a B747-100 for the purpose of increasing the directional control so that is it possible to either minimising the centre line off-set or to maintain heading of a landing aircraft. The aileron based differential nonnal loading controller uses the brake line pressure differential as an input variable to control the ailerons during touchdown. During the II maximum braking case, the brake line pressure is proportional to the difference in runway friction coefficient, normal loading, and brake disk stack friction coefficient. Landing aircraft are extremely non-linear in function. To overcome this, a model and Controller that generates the appropriate non-linear mathematical description of the aircraft during the landing phase and generates an effective controller that effectively generates an increase in normal gear force on touch down of 100% and thereby allowing the aircraft to be controlled in direction during hazardous conditions was developed. The outcome of the work is that the use of a control scheme and unconventional use of ailerons can significantly improve aircraft landing characteristics during adverse landing weather conditions and reduce the number of accidents. Current advances in future aircraft design are tending towards tailless aircraft such as Boeing's Blended Wing Body aircraft and a similar study by Airbus. These aircraft do not have sufficient rudder or engine yaw control at landing speeds. This work provides a method of steering the aircraft from touchdown to taxi speed through normal force and brake augmentation.

The introduction of a condition monitoring approach into the design of aircraft systems

Chan, Kwok Wing January 1996 (has links)
No description available.

Aircraft load alleviation by specifying its closed-loop eigenstructure

Ali, Qazi R. January 1987 (has links)
Reduction of aircraft loads, arising as a result of manoeuvre commands or atmospheric turbulence, by means of active control is an important problem in flight control. A variety of methods of designing appropriate control systems to achieve such reduction are available, but not every method is effective. A feature of this research work is the use of an eigenvalue/eigenvector assignment method using full state variable feedback, to design aircraft load alleviation control systems.

Design of data structures for terrain reference navigation

Gia, M. C. January 1994 (has links)
This thesis describes the design of a data structure for use with Digitised Terrain Elevation Data (DTED) in Terrain Reference Navigation (TRN) systems. The data structure is based on a variant of quad-tree and oct-tree data structures to provide an efficient representation of terrain in terms of storage requirements and acccss operations. These data structure are applied to flight path planning operations in mission management applications. The algorithms developed for flight path planning have becri implemented in the C programming language for a standard PC. Current research in TRN systems is reviewed and attention is given to the use of hierarchical data structures to cope with the potentially large data base needed for DTED files. Data structure combining quad-trees and oct-trees are developed with an emphasis on data reduction using pointerless trees and the use of locational codes to provide straightforward mapping between quad-trees and oct-trees, in other words, between two-dimensional co-ordinates and three-dimensional co-ordinates. Analysis of these algorithms is described for two DTED files to illustrate storage improvements and to verify a set of database access operations. These data structures are applied to problems of flight path planning where the navigation space comprises objects above a specific altitude and this three-dimensional space is searched for a flight path which avoids the obstacles and satisfies specific operational criteria. Algorithms are developed to extract a visibility graph from the terrain database and to determine the preferred flight path from a set of paths which satisfy defined constraints. Several search techniques are developed which exploit the efficiency of the quad-tree and oct-tree data structures. These methods are extended to real-time flight-path planning where predicted times for access operations are used to direct flight path extraction by varying the tree resolution during computation of the flight path. A comprehensive set of results are provided to illustrate: the storage efficiency of quad-tree and oct-tree data structures the application of pyramid structures to represent navigation space analysis of the time to compute the visibility graph and to extract flight paths integration of these methods with a real-time mission management simulation on a PC The thesis draws conclusions on the efficiency of these techniques for the represcntation of DTEDs and to access objects in TRN systems. It is observed that the use of hierarchical data structures in the form of quad-trees and oct-trees offers significant improvement in accessing DTEDS, for future use in TRN systems. The thesis concludes by outlining areas of further work where the techniques can be further &N, cloped for applications in mission management and navigation using DTED files.

Control and optimization of aircraft trajectories

Daoud, Younis Sharif January 1991 (has links)
No description available.

An investigation into Kalman filter target tracking algorithms and their real time parallel transputer implementation

El-Mahy, Mohamed Kamel Sayed Ahmed January 1994 (has links)
This thesis reviews the applications of Kalman filtering estimation to the problem of target tracking. Both linear and nonlinear forms of Kalman filter are reviewed and models of target manoeuvre discussed. Manoeuvre adaptation schemes are examined to detect the onset and completion of manoeuvres. Target manoeuvre coordinates are also examined and a new target model proposed which significantly improves tracking performance. The new model includes turn rate estimation. The real-time implementation of tracking Kalman filters is also studied both for a simple processor and a multiple processor architecture. Tracking algorithms are coded in Parallel C and evaluated for speed and efficiency

Active control of V/STOL aircraft

Ashworth, Anthony Ian January 1995 (has links)
No description available.

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