1037-1047Artificial potential field (APF) is widely used for obstacles avoidance of autonomous surface vessel (ASV). However, its performance is poor for the case that the ASV encounters multiple ships. The collision may happen since the APF method is only taking distance and velocity into account. To solve this problem, a collision risk assessment based approach is proposed. A fuzzy logic system is applied to assess the collision risk with distance of close point of ppproaching (DCPA) and time of close point of approaching (TCPA). The collision risk is used to modify the APF for the ASV to avoid multiple ships. A critical encounter scenario is simulated to test the proposed approach. The simulation results indicate that the proposed method overcomes the problem to help an ASV successfully avoids the ship collision
