自主水面無人船(AUSV)是現在相當熱門的研究主題，自主無人船可以不需要人類操作即能感測環境及導航，適合執行重複性高、枯燥或高危險性的任務，在海洋資源探勘、生態調查、海上運輸及軍事防衛方面，皆有重要的應用。本研究將提出一個非線性H∞控制器於真實世界的自主無人船上的實現及驗證，實作一艘可以追蹤預定軌跡的自主無人船。首先，根據Lab 611於2014年提出的非線性H∞導引律，結合軌跡產生器，設計一個適用於小型AUSV之非線性H∞控制器。接著，介紹IMU和GNSS感測器之實現過程，並整合感測器資料，經由適當的座標轉換輸入到非線性H∞控制器上。再來，由控制器計算出控制力，經由動力分配決定左右推進器需要的推進力道與轉向。另外，實測前會先進行模擬，模擬中包含風、波浪及洋流的環境干擾，確認設計的控制器可以成功追到軌跡。最後在台南公園的燕潭實地測試，驗證此控制器的可行性與實驗的可重複性。實驗結果顯示，本研究開發的AUSV能在有風和浪的湖泊中成功追蹤到直線軌跡、方形軌跡和圓形軌跡，且誤差不大。本論文不僅驗證提出的控制器可行，更創造了一個驗證平台，使得未來在控制理論有新的進展時，能快速地在此平台上進行驗證。

Autonomous Unmanned Surface Vessels (AUSVs) are currently a popular research topic. AUSVs are capable of sensing the environment and navigating without human intervention, making them suitable for executing repetitive, tedious, or high-risk tasks. They have significant applications in areas such as marine resource exploration, ecological surveys, maritime transportation, and military defense. This study will propose the implementation and validation of a nonlinear H∞ controller on a real-world AUSV. The objective is to develop an AUSV that can track predefined trajectories. Firstly, based on the nonlinear H∞ guidance law proposed by Lab 611, NCKU in 2014, a controller suitable for small-scale AUSVs is designed by integrating a trajectory generator. Next, the implementation process of IMU and GNSS sensors is described, and the sensor data is integrated and appropriately transformed into the nonlinear H∞ controller as inputs. Then, the controller calculates the control forces, and through control allocation, determines the required propulsion forces and turning angle for the left and right thrusters. Additionally, simulations will be conducted to evaluate the performance of the designed controller under the environmental disturbances such as wind, waves, and ocean currents. Finally, field experiments will be conducted at Swallow Lake in Tainan Park to validate the feasibility and repeatability of the proposed controller. The experimental results demonstrate that the developed AUSV is capable of successfully tracking straight-line, square, and circle trajectories in lakes with wind and waves, while maintaining low tracking errors.

[1] “It is estimated that 75% to 96% of marine accidents can involve human error” Allianz Global Corporate & Specialty. https://www.agcs.allianz.com/news-and-insights/expert-risk-articles/human-error-shipping-safety.html (accessed June 2019)
[2] “the global autonomous ships market is expected to grow from USD 6.55 billion in 2021 to USD 12.07 billion in 2028 at a CAGR of 9.13%” Fortune Business Insights. https://www.fortunebusinessinsights.com/industry-reports/autonomous-ship-market-101797 (accessed Feb, 2022)
[3] "HD Hyundai’s Avikus Successfully Conducts the World’s First
Transoceanic Voyage of a Large Merchant Ship Relying on Autonomous
Navigation Technologies," ed: HD Hyundai, 2022.
[4] F. A. Papoulias, “Cross track error and proportional turning rate guidance of marine vehicles”, Journal of Ship Research, Vol. 38, No. 2 ,pp. 123–132, 1994.
[5] Z. Vukic, H. Ozbolt and D. Pavlekovic, “Improving fault handling in marine vehicle course-keeping systems”, IEEE Proceedings Robotics and Automation Magazine, Vol.6, No. 2, pp. 39-52, 1999.
[6] H. Ashrafiuon, “Sliding-Mode tracking control of surface vessels”, IEEE Transactions Industrial Electronics, Vol. 55, No. 11, pp. 4004-4012, 2008.
[7] X. Bao, K. Nonami and Z. Yu, “Combined Yaw and Roll Control of an Autonomous Boat”, Proceedings of the IEEE International Conference on Robotics and Automation, pp.188-193, Kobe, May 12-17, 2009.
[8] J. Ghommam, F. Mnif and N. Derbel, “Global stabilisation and tracking control of underactuated surface vessels”, IEEE Control Theory & Applications, Vol. 4, No. 1, pp. 71-88, 2010.
[9] S. Qiaomei and R. Guang, “An online adaptive logic-oriented neural approach for tracking control”, Ocean Engineering, Vol. 58, pp. 106-114, 2013.
[10] T. W. VANECK, C. D. RODRIGUEZ-ORTIZ, M. C. SCHMIDT, and J. E. MANLEY, "Automated Bathymetry Using an Autonomous Surface Craft," NAVIGATION, vol. 43, no. 4, pp. 407-419, 1996.
[11] Z. Jiang, Y. Weisheng, G. Jian, and S. Shuwei, "Design and implement of the control system for unmanned surface vehicle based on the VxWorks," in 2010 2nd International Asia Conference on Informatics in Control, Automation and Robotics (CAR 2010), 2010, vol. 3, pp. 13-16.
[12] W.-M. Hu, " Nonlinear H2 and H∞ Control Law Designs of Autonomous Unmanned Surface Vessels", Master Degree, Systems and Naval Mechatronic Engineering, National Cheng Kung University, Tainan, Taiwan, 2014.
[13] T. I. Fossen, “Guidance and Control of Ocean Vehicles”, John Wiley and Sons, 5-91, 1994.
[14] T. I. Fossen and T. A. Johansen, "A Survey of Control Allocation Methods for Ships and Underwater Vehicles", in 2006 14th Mediterranean Conference on Control and Automation, 2006, pp. 1-6.
[15] T. Fossen, Handbook of Marine Craft Hydrodynamics and Motion Control. John Wiley & Sons, 2021.
[16] Chen, Y.-Y.; Tsao, C.-H.; Liu, K.-H and Huang, Y.-X.;, “CONTROL SYSTEM DESIGN FOR UNDERWATER VEHICLES WITH ACTUATOR CONSTRAINTS”. Journal of Taiwan Society of Naval Architects and Marine Engineers. vol. 41, no. 2, pp. 77-90, 2022.
[17] Chen, Y.-Y.; Lee, C.-Y.; Huang, Y.-X.; Yu, T.-T. “Control Allocation Design for Torpedo-Like Underwater Vehicles with Multiple Actuators”. Actuators 2022, 11, 104.
[18] B.-Y. Wu, "A Real Verification Platform Design for Guidance Law Performances of Unmanned Surface Vehicles," Master Degree, Systems and Naval Mechatronic Engineering, Natianal Cheng Kung University, Tainan, Taiwan, 2020.