## 1 Introduction  
Global shipping, accounting for over 80 percent of world merchandise trade by volume, has been rapidly embracing technological advancements, particularly in the realm of maritime autonomous surface ships (MASS) [1]. This shift has been driven by the recognition of vulnerabilities in global supply chains, as highlighted during the 2019 COVID-19 pandemic, when labor shortages and widespread lockdowns disrupted international trade. The autonomous ships market, already a billion-collar industry, is poised for substantial growth in the coming years [2]. The deployment of MASS is anticipated to bring about cost reductions and enhance the resilience of global supply chains against labor shortages and external shocks. Additionally, the implementation of autonomous ships could contribute to offshore safety by mitigating accidents attributed to human error and negating the need for human operators in challenging sea conditions [3], though some argue the extent of this impact is uncertain [4; 5]. Furthermore, proponents believe that the introduction of MASS has the potential to decrease greenhouse gas emissions and enhance port efficiency through practices such as slow-steaming and improved route planning. Maritime autonomous surface ships, one of the innovative advances in the field of maritime transport, have attracted considerable attention and are under development in many countries. For example, the EU has evaluated the economic, technological, and legal validity of MASS via the Maritime Unmanned Navigation through Intelligence in Networks project [6]. In Finland, Rolls-Royce developed an MASS able to can operate in coastal waters via the Advanced Autonomous Waterborne Application (AAWA) project. The AAWA project played an important role in accelerating the development and commercialization of MASS technologies and has contributed to shaping the future of the maritime transport industry [7]. In Norway, Kongsberg Gruppen ASA, a marine technology company, and YARA International, a fertilizer manufacturer, cooperated to develop the world's first electric battery-powered autonomous container ship [8]. In South Korea, the Korean Autonomous Surface Ship project led by the government aims to improve the safety of MASS as well as to develop and verify related technologies [9]. Efforts to enhance automation in maritime shipping have been ongoing for several years, with the International Maritime Organization (IMO) playing a pivotal role in guiding the development of MASS in collaboration with regulators, industry stakeholders, and researchers [10]. Several essential advancements are required for MASS to reach full autonomy. The key technologies used in MASS include sensing the surrounding environment using various sensors (e.g., radar, sonar, light detection and ranging, GPS, and cameras) [11; 12; 13; 14; 15], artificial intelligence (AI) and machine learning technologies that are used to direct the navigation by analyzing the sensor data [16; 17], and navigation automation systems that set the course of a ship, adjust its speed, and automatically perform navigation tasks (e.g., collision avoidance) [18; 19; 20; 21]. One crucial challenge involves the development of robust path planning and collision avoidance systems capable of navigating waters safely, considering the presence of other autonomous and traditional vessels, and adhering to the rules of the road at sea as defined by the Convention on the International Regulations for Preventing Collisions at Sea (COLREG). [PERSON] et al. [22] introduced a control system for autonomous surface vessels featuring a path-planning algorithm based on the angle-guidance fast marching square method and a path-following algorithm utilizing the line-of-sight tracking approach. [PERSON] et al. [23] proposed a modified vector field path-following control system for underactuated autonomous surface ships that simultaneously addressed both path following and obstacle avoidance.