碩士 / 國立臺灣大學 / 電機工程學研究所 / 106 / In this thesis, a system structure for Unmanned Aerial Vehicle (UAV) quadrotor navigation and exploration is proposed. The system is composed of five nodes running in parallel, each responsible for different tasks. First of all, a pose controller continuously sends control commands to the quadrotor. This enables the quadrotor to continue in pose controlling even when other nodes are waiting for their computations to complete.
The Large Scale Direct SLAM (LSD-SLAM) provides self-localization of the quadrotor and semi-dense depth map estimation. The collected depth maps are then integrated into a three-dimensional occupancy map with the Octomap, and the occupancy information of the currently built map is utilized by the Navigation node, dealing with the navigation of the quadrotor and the exploration of the environment. For the scale recovery of monocular vision-based systems, such as the LSD-SLAM system, the Scale Estimation node provides an estimate of the scale with the aid of an ultrasound sensor.
Given the estimated scale, the quadrotor can then be navigated with the re-scaled pose provided by the LSD-SLAM system. The pose controller for both the simulated quadrotor and the real-world quadrotor are designed and verified. Also with the estimated scale, the proposed system avoids collision of the quadrotor body with any obstacle, allowing the quadrotor to only approach to those areas that are free of collision.
An exploration strategy is also proposed in this thesis, which is essentially a frontier-based Next-Best-View (NBV) exploration strategy. The next point to approach to during each step of exploration is selected by taking the extracted frontier points as NBV candidates. The expected visibility-gain as well as the expected trackability are calculated for each NBV candidate and the most qualified among all is selected, moving towards the highest information gain in the meanwhile ensuring the trackability while moving.
Experiments in both simulation and the real world are provided to verify the proposed system and the proposed exploration strategy.
| Identifer | oai:union.ndltd.org:TW/106NTU05442029 |
| Date | January 2018 |
| Creators | Jyun-Sheng Fu, 傅鈞笙 |
| Contributors | Feng-Li Lian, 連豊力 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | en_US |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 185 |
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