The Mapkey: Preliminary Design, Construction and Testing of a Novel UAV Platform for Cavity Surveying

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Mitchell, Jordan
Unmanned Aerial Vehicle , Autorotation , 3D Surveying , Underground
This thesis presents research related to the preliminary design, construction and testing of a novel autorotating unmanned aerial vehicle (UAV) for gathering 3D maps of underground cavities. The novel UAV is called "The Mapkey". Current underground cavity surveying is conducted by using a stationary light detection and ranging (LiDAR) sensor extended into a void to collect a 3D point cloud. This method is costly and takes a significant amount of time. An autorotating UAV equipped with a LiDAR payload was constructed to collect a 3D point cloud as it flies along the vertical extent of an underground cavity. The potential benefits of this novel surveying method include: cost reduction, increased survey accuracy and reduced survey times. Autorotation is the state of flight where the main rotor rotates due to the flow of air upwards through the rotor. The constructed autorotating UAV passively falls through the cavity and rotates as it falls. A single-beam LiDAR payload attached to the UAV collects range data from the surrounding environment and monitors the relative position and orientation of the UAV as it falls. The vertical descent and rotation of the LiDAR payload maps the surrounding environment by way of a 3D helical scan pattern. Data is retrieved and post processed to create a 3D map of the cavity. Applications for the acquired data could be to estimate the volume of the cavity or to identify interesting features such as overhangs. This device was tested in a laboratory environment and results show that the UAV is capable of recreating a 3D point cloud of its surrounding environment. Future work includes testing in a more representative underground environment and further processing of the collected point cloud to determine the volume of an underground cavity.
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