仿生型自主式水下載具使用立體視覺在水流中之動態定位控制器設計

Abstract

仿生型自主式水下載具(BAUV)在紊流場下達到動態定位之目的為本研究團隊發展水下雷射通訊系統最不可或缺的技術。為了提高資料傳送的準確性和完整性，本文致力於發展仿生型自主式水下載具在紊流場下達到動態定位，由於仿生型水下載具系統之非線性及所在環境的不確定性，增加了自主式水下載具在控制上之困難度，所以希望載具在水中達到穩定精確定位的前提下，本文提出以立體視覺作為回授輔助並發展一控制器，使系統動態誤差達到全域性的穩定狀態。本文首先使用拉格朗日方程推導仿生型自主式水下載具的動力平面數學模型，求得尾鰭和胸鰭運動參數與仿生型水下載具的運動關係，並依據此關係所計算出的追踪誤差及其隨時間的變化量提出滑模控制器設計之方法，再利用立體視覺觀測目標物(三球)之測量值，透過幾何方法計算出載具與目標物之間的相對關係，結合載具系統之數學模型經由實驗取得適當的權重作為控制器回授，並利用雷射掃描測量其路徑找出實際值與立體視覺之測量值之間的誤差。實驗包括放置仿生型自主式水下載具於有波浪干擾及定速流干擾之流場，觀察其運動及使用雷射掃描測量其路徑，透過上述實驗驗証本文所使用的控制器能有效令仿生型水下載具系統達到動態定位之目的。

Biomimetic Autonomous Underwater Vehicle (BAUV) achieve the purpose of dynamic positioning in turbulent flow environment is the essential technology for our research team of Underwater Laser Communication System. In order to improve the accuracy and completeness of the information transmitted, this thesis is committed to development of a stable dynamic positioning for the BAUV in the turbulent water field. Nonlinearity of the dynamic systems and the uncertain environment are challenges of the controller design. This work presents a controller which adopts the stereo visual feedback as aids to the BAUV for the dynamic positioning in water currents. Firstly, a planar mathematical model of the BAUV is derived based on the Euler-Lagrange equation. The relationship between parameters of caudal, pectoral fins and movement of the BAUV are determined and design method based on sliding mode control theory is presented. Measured positions of the landmark by stereo vision were used to calculate relative relationship between the landmark and the BAUV in global coordinate. They combined with the motion model of the BAUV as the controller feedback. It is shown that the system error dynamics achieves stable state. This is verified by experimental data by showing that the vehicle under control reached stable hovering in water of constant and periodic disturbances flow.