郭振華臺灣大學:工程科學及海洋工程學研究所王偉翰Wang, Wei-HanWei-HanWang2010-07-142018-06-282010-07-142018-06-282009U0001-1508200916214700http://ntur.lib.ntu.edu.tw//handle/246246/188993無人水下載具常用來執行水下測繪、水下監控等任務。由於缺乏預設的地標，因此無人水下載具在未知環境下的導航仍是一大挑戰，發展海床即時特徵偵測能力對水下無人載具的導航有相當大的助益。本文提出一套利用側掃聲納掃描線即時偵測水下目標物的方法，此方法可以使無人水下載具在無特定結構的環境下建置海底地圖來做自身定位。此方法主要包含二部分：第一，訊號前處理，以增強資料訊號並降低資料量和運算時間; 第二，特徵偵測，以辨識出有包含目標物的掃描線並用適應性閥值突顯出目標物。在偵測過程之後，為了得到整體環境的地圖，使用了佔格格網圖的方法來融合每ㄧ條掃描線上的偵測值，最後，無人水下載具使用運動感測器來表達移動路徑，並整合導航測器的量測值與側掃聲納所偵測到的目標物，建構具有較高信任度的移動路徑以及水底地圖。利用此方法實作在無人載具上即時偵測水下目標物，實驗說明水下載具所建立之沙床上的水泥目標物特徵與水底格網圖，可以用來做為無人水下載具的導航依據。Navigation of UUV in unstructured environments with accurate positioning capabilities still is a challenging problem due to the lack of predefined landmarks on the sea floor. The aim of this work is the development of a method for target detection by the processing of side-scan sonar scanlines. The detection method developed in this work enables UUVs to build seafloor map for the self localization in an unstructured environment. The detection procedure has two steps. Firstly, a pre-processing step is used to filter the data and to reduce computation time. Then a detector is designed to detect the target position in a scanline. After detection procedure, for the purpose to obtain the whole map of the environment, the occupancy grid mapping method was applied to combine the detect result and the acoustic wave of side-scan sonar in sea water. Finally, trajectory of the UUV could be estimated by motion of the vehicle. This procedure was implemented on an UUV to verify its landmark detection capability. Experimental results conducted on sandy seabed with concrete targets are demonstrated with their signal contents and the final grid maps that are useful for UUV navigation purpose.誌 謝.... I 要.... IIbstract..IIIable of Contents..IVist of Figures... VIist of Tables.... XIIist of Symbol.... XIIIhapter 1 Introduction..... 1.1Motivation.............. 1.2Literature Review....... 2.3Thesis Organization..... 5hapter 2 Observation Model of Side-scan Sonar Scanlines......... 7.1 Side-scan sonar system...........7.2 Side-Scan Sonar Geometry.........10.3 Sound Velocity in the Ocean......11.4 Side-scan Sonar Scanlines........13.5 Target detection.................18.6 The footprint of Side-scan sonar scanline..23.6.1 Across-track resolution..................23.6.1 Along-track resolution...................28hapter 3 Mapping Using Side-scan Sonar Scanlines......30.1 Observation Uncertainty of Side-scan Sonar.........30.2 Occupancy grid mapping.............................31.4 The Inverse Measurement Model......................35hapter 4 Localization Using Side-scan Sonar...........45.1 Monte Carlo Localization...........................45.2 Motion Model.......................................46.3 Importance Factor..................................48.4 Resampling.........................................50hapter 5 Mapping using Side-scan Sonar Scanlines......51.1 System overview....................................51.2 Occupancy Grid Mapping with Known UUV Position.....53.3 Monte Carlo Localization with A Known Map..........70hapter 6 Conclusion...................................74eference ..............................................751248313 bytesapplication/pdfen-US無人水下載具水下導航側掃聲納佔格格網圖建立地圖UUVunderwater navigationsidescanoccupancy gridmappingthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/188993/1/ntu-98-R96525064-1.pdf