Browsing by Author "Hughes, Merrick"

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    Autonomous guidance and conflict avoidance for multiple Unmanned Aerial Vehicles (UAVs) in urban environments
    (Stellenbosch : Stellenbosch University, 2024-03) Hughes, Merrick; Engelbrecht, Japie; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.
    ENGLISH ABSTRACT: This thesis presents an autonomous guidance and conflict avoidance system for multiple unmanned aerial vehicles (UAVs) in urban environments. The guidance system comprises a long-term route planner and a short-term cooperative conflict avoidance function. The route planner generates long-term routes for the UAVs to follow to satisfy their missions, whereas the conflict avoidance function continuously predicts and resolves short-term impending collisions/conflicts with terrain and other UAVs. These conflicts are resolved cooperatively between all UAVs involved while attempting to minimise each UAV’s deviation from its long-term route during conflict avoidance. The guidance system is conceptualised to support multiple independent UAVs flying within an urban environment that contains terrain as well as wind. A 3D model of real urban terrain is implemented using established computational geometry techniques and the motion constraints of the UAVs are set to replicate those of real-life UAVs. Monte Carlo simulations are designed to evaluate and compare the performance of the guidance system in different scenarios by analysing both illustrative and statistical results. The illustrative results indicate that the route planner and conflict avoidance function behave as expected in given scenarios. The statistical results confirm that the performance of the route planner decreases at lower altitudes and also suggest that it may struggle with grid-like terrain, while the failure rate of the conflict avoidance function does not appear to be strongly correlated with any given scenario. A combined set of avoidance manoeuvres is the most effective for conflict avoidance but has the longest execution times, whereas airspeed manoeuvres used in isolation are the least effective and horizontal manoeuvres are the least optimal with the largest average deviations from a UAV’s long-term route. A single avoidance manoeuvre type used in isolation exhibits promising execution times for a real-time application.