Masters Degrees (Electrical and Electronic Engineering)

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Browsing Masters Degrees (Electrical and Electronic Engineering) by Author "Avenant, Gerrit Christiaan"

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    Autonomous flight control system for an airship
    (Stellenbosch : University of Stellenbosch, 2010-03) Avenant, Gerrit Christiaan; Steyn, W. H.; University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.
    ENGLISH ABSTRACT: In recent years, the use of airships has become popular for observation purposes since they provide a cost effective alternative to other aircraft. For this project a lateral and longitudinal flight control system are required for waypoint navigation flight of an 8m long, non-rigid airship. The airship’s actuators include a rudder, elevator and a propulsion system which can be vectored longitudinally. Two airship models are evaluated for this project. A chosen model is linearised and a modal analysis is done. The modal analysis is compared to a previous modal study done on the YEZ-2A airship and is found to compare well. Each airship mode is discussed and the linear behaviour is compared to the behaviour of the non-linear model. A fuzzy logic controller design approach was undertaken for the design of speed, heading and height controllers. These non-linear controllers were designed for the non-linear model, due to the following reasons: Fuzzy logic controllers show tolerance to model inaccuracies. Complexity of design is simple. Controllers can be adjusted intuitively. Fuzzy logic controllers can be combined with conventional control techniques. Simulation results showed adequate lateral and longitudinal performance, even when subjected to light wind conditions and disturbances. The inertial measuring unit implemented in a previous project is used and additional hardware is designed and implemented for the control of the airship’s actuators. Several improvements are made to the groundstation software to allow for activation of different controllers as well as for setting up the desired flight plan. The controller performance is tested through flight tests and shows adequate performance as well as controller potential. Although further work is still required for improving the controllers’ performance, this thesis acts as a platform for future research.