Abstract
Route planning for small ships involves unique considerations, as these ships often operate in restricted and dynamic maritime environments such as marinas and shallow depth areas. Due to the complexity and limited depth of such areas, ensuring safe and reliable routes is critical. Conventional optimization-based methods for route planning tend to focus on economic factors such as travel distance, fuel consumption, and ETA (Estimated Time of Arrival). However, they frequently fail to incorporate real-world ship behavior and the empirical knowledge of ship operators. As a result, the planned routes may significantly differ from historical navigation trajectories, potentially increasing navigational risk. To address these limitations, this study proposed a novel route planning method that integrates AIS (Automatic Identification System) data with a quadtree-based navigational chart to reflect actual navigation information and safety considerations. The method first extracts maritime obstacles from ENC (Electronic Navigational Charts). It incorporates the unnavigable terrain based on a draft of the ship into the navigational chart to improve the accuracy of depth-related constraints. From the AIS data, frequency and directional information were extracted to design the HFDA∗ (Historical Frequency and Directional A∗) algorithm, which plans routes based on historically preferred trajectories and directions. Additionally, we applied the Douglas-Peucker (DP) algorithm to simplify route geometry and incorporated dredged areas to enhance safety and practical applicability.
