Autonomous flying hydrophones: the design of a multirotor UAV platform for the monitoring of harbour porpoises in Special Areas of Conservation in the United Kingdom

This thesis describes the development of a multirotor Uncrewed Aerial Vehicle (UAV) system aimed at assisting with the monitoring of harbour porpoises in Special Areas of Conservation in the United Kingdom. As UAVs become a more popular tool in the observation and study of marine mammals, it is becoming increasingly important to exploit their full capabilities in marine mammal research.

The work presented in this thesis focuses on the development of a novel platform and framework for enabling the use of UAVs in the passive acoustic monitoring of harbour porpoises. An autonomous UAV platform designed to enable the recording of harbour porpoise vocalisations is developed and validated. The platform described in this thesis is capable of autonomous navigation, persistent landing, take-off and automatic data acquisition at specified waypoints. The system architecture described also includes methods for control and waypoint planning strategies that enable autonomous UAV flight modes in the system. This solution is also extended to a multiple UAV scenario where a centralised system is used to coordinate missions to enable up to 4 UAVs to autonomously navigate to specified areas and record acoustic data.

Data acquisition by means of passive acoustic monitoring is provided by a bespoke underwater acoustic recorder (PorpDAQ), the design of which is also described in detail in this thesis. This device, capable of recording acoustic signals from within the harbour porpoise’s frequency band is highly integrated with the UAV platform and offers a suitable low-cost and relevant solution compared to current off-the-shelf solutions.