Presently, there is increasing interest in autonomous ships to reduce human errors and support intelligent navigation, where automatic collision avoidance and path planning is a key problem, especially in restricted waters. To solve this problem, a path-guided hybrid artificial potential field (PGHAPF) method is first proposed in this paper. It is essentially a reactive path-planning algorithm that provides fast feedback in a changeable environment, including dynamic target ships (TSs) and static obstacles, for steering an autonomous ship safely. The proposed strategy, which is a fusion of the potential field and gradient methods, consists of potential-based path planning for arbitrary static obstacles, gradient-based decision-making for dynamic TSs, and their combination with consideration of the prior path and waypoint selection optimization. A three-degree-of-freedom dynamic model of a Mariner class vessel and a low-level controller have been incorporated together in this method to ensure that the vessel’s positions are updated at each time step in order to acquire a more applicable and reliable trajectory. Simulations show that the PGHAPF method has the potential to rapidly generate adaptive, collision-free and International Regulations for Preventing Collisions at Sea (COLREGS)-constrained trajectories in restricted waters by deterministic calculations. Furthermore, this method has the potential to perform path planning on an electronic chart platform and to overcome some drawbacks of traditional artificial potential field (APF) methods.

In marine simulator, trainee controls the position of own ship. The precision of own ship's hydrodynamic mathematical model is relatively high. Usually, there isn't a hydrodynamic model corresponding to the target ships planned by instructor. These target ships navigation along the planned sea route with speed and course set by instructor. The course of ship will change suddenly to another when ship passes a waypoint, so ship's image in visual system will change suddenly. This phenomenon will greatly decrease the fidelity of visual system. This paper introduces a simplified mathematical model of these target ships and how to calculate the beginning position, the instantaneous position, the course and the end position of ships in details. The model has been applied in marine simulation system successfully.