UBC Theses and Dissertations

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UBC Theses and Dissertations

Terrain tracking motion planning and control of unmanned aerial vehicles AlQahtani, Nasser Ayidh


In a modern society, autonomous quadrotors can be used to perform tasks and collect data in dangerous and inaccessible environments where human involvement would traditionally be necessary. Unmanned Aerial Vehicles (UAVs), and especially the quadrotor, are still facing obstacles in terms of following a trajectory and flying autonomously in enclosed, complex or GPS denied areas. This work presents a novel framework for navigating a quadrotor over undulated terrains, so it can be of great importance for the use of UAVs in civilian applications such as monitoring of pipes, bridges and buildings. The proposed approach involves the use of a single-beam LiDAR to estimate the terrain profile under uncertainty. The LiDAR is installed at the base of a quadrotor and can be set at different angles to send information to the quadrotor about undulations of the terrain ahead. This strategy helps the quadrotor to build a smooth trajectory for the UAV and allows the controller to follow it closely. In turn, maneuverability of UAV over and around ground obstacles is improved in comparison to default autopilot controllers programmed to maintain a UAV at a given altitude. Through simulation, the result shows how this alternative technique with motion planning algorithms improves the performance of the quadrotor. In this thesis, the method used in the simulation was tested using a single-beam LiDAR reading the undulations of the terrain beneath and ahead of the quadrotor at a desired altitude. Then, motion planning algorithms, such as Gaussian filter and cubic spline, plan a smooth trajectory so that the quadrotor can avoid having to make any sudden turn or recoveries. Finally, this planned trajectory is provided to an appropriate controller, such as the model predictive control, linear quadratic regulator, proportional integral derivative control which help the quadrotor to not only follow the terrain exactly, but also to minimize energy wasted on sudden recoveries.

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Attribution-NonCommercial-NoDerivatives 4.0 International