Browsing by Author "Parker, Mohamed Zahier"

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    Automated landing of a fixed-wing unmanned aircraft onto a moving platform
    (Stellenbosch : Stellenbosch University, 2023-03) Parker, Mohamed Zahier; Engelbrecht, Japie ; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.
    ENGLISH ABSTRACT: This thesis presents the development, implementation and practical testing of a control system that can automatically land a fixed-wing unmanned aerial vehicle (UAV) onto a moving platform. The control system consists of the flight control system and guidance control system. A landing strategy is proposed that is inspired by a real aircraft carrier landing, but is scaled down to the size of the fixed-wing UAV used in this research project. A prediction method is suggested to predict the touchdown point between the aircraft and the moving platform. A mathematical model of the fixed-wing aircraft was established to capture the aircraft’s flight dynamics. The model was used to design the flight control system. The flight control system architecture combines classical control with model predictive control to control the local states of the aircraft. The model predictive controller was added to improve the landing accuracy of the aircraft, by having improved airspeed and altitude control compared to classical controllers. The guidance control system contains a guidance algorithm, waypoint scheduler, landing position predictor, and state machine to allow the aircraft to navigate around the airfield and land on the moving platform. The control systems were then implemented in PX4 autopilot software, which together with the Gazebo simulator, was used to perform software-in-the-loop simulations to verify the control systems’ performance using a representative simulation model. A new avionics stack was developed for the physical fixed-wing UAV using commercially available hardware and open-source software. A new fixed-wing UAV was assembled by mounting the newly developed avionics stack into an existing airframe. A new moving platform was also assembled by mounting commercially available hardware onto an RC car chassis. Practical flight tests were performed using the physical UAV to validate the control system’s performance in practice. The developed control system was able to accurately land the physical fixed-wing UAV within a 3 m x 3 m static bounding box on a runway, and also on a virtual moving platform with the same dimensions travelling at 3 m/s (or 10 km/h).