A COLREGs-Based Dynamic Navigation Safety Domain for Unmanned Surface Vehicles: A Case Study of Dolphin-I

Abstract

Unmanned Surface Vehicles (USVs) are intelligent machines that have been widely studied in recent years. The safety of USVs’ activities is a priority issue in their applications; one effective method is to delimit an exclusive safety domain around the USV. Besides considering collision avoidance, the safety domain should satisfy the requirements of encounter situations in the COLREGs (International Regulations for Preventing Collisions at Sea) as well. Whereas the model providing the safety domain for the USVs is defined through the experience of the manned ships, a specific model for USVs has been rarely studied. A dynamic navigation safety domain (DNSD) for USVs was proposed in this paper. To construct the model, the essential factors that could affect the navigation safety of the USVs were extracted via a rough set, and the extension functions of these factors were carried out. The DNSD was employed in various situations and compared with the ship domain models of common ships. It was found that the domain boundary can be automatically corrected according to the change in the working conditions when the DNSD is in use. Compared with the Fujii and Coldwell models, the DNSD can provide a larger safety area for a USV’s action of collision avoidance.

Maritime Autonomous Vessels

“…As can be observed, the proposed method can control the ship to avoid the obstacles, meanwhile, the path-following task is also an important factor. The traditional obstacle avoidance system usually only emphasizes how to minimize the collision risk [56,57]. Therefore, the collision avoidance methods will take the ship to travel away from obstacles and neglect the path-following task.…”

Electronic Navigational Charts for Visualization, Simulation, and Autonomous Ship Control

“…Recent example applications include traffic monitoring with respect to collision detection and risk assessment [39], obstacle tracking and reactive collision avoidance based on sensor fusion [40], and the development of adaptive safety domains for identification of grounding risks [41] and collision avoidance during vessel interactions (COLREG) [42]. Thus, it is clear that the demand for open and accessible ENC software and resources for real-time simultaneous visualization and efficient computation of hydrographic data is evermore increasing.…”

COLREGs: Compliant Dynamic Obstacle Avoidance of USVs Based on the Dynamic Navigation Ship Domain

“…Factors such as maneuverability, speed, and course were taken into consideration. On this basis, Zhou et al [19] proposed the basic navigation safety domain (BNSD) by putting the encounter situation coefficients carried out by Kijima and Furukawa [35] into the DQSD formula. However, since there are four radii that need to be determined, this type of ship domain is somewhat complicated when applied to path planning.…”

“…Otherwise, nonstandard avoidance maneuvers may lead to confusion and potentially collision risk [4]. Thus, ship domains considering COLREGs have been proposed subsequently [17][18][19]. Referring to Szlapczynski and Szlapczynska [13], ship domains can be implemented in an encounter situation with four safety criteria (see Figure 1).…”