**Siyu Guo, Xiuguo Zhang \*, Yisong Zheng and Yiquan Du**

School of Information Science and Technology, Dalian Maritime University, Dalian 116026, China; guosy@dlmu.edu.cn (S.G.); zhengyisong@dlmu.edu.cn (Y.Z.); duyiquan@dlmu.edu.cn (Y.D.)

**\*** Correspondence: zhangxg@dlmu.edu.cn; Tel.: +86-185-5305-9562

Received: 27 November 2019; Accepted: 2 January 2020; Published: 11 January 2020

**Abstract:** Deep reinforcement learning (DRL) has excellent performance in continuous control problems and it is widely used in path planning and other fields. An autonomous path planning model based on DRL is proposed to realize the intelligent path planning of unmanned ships in the unknown environment. The model utilizes the deep deterministic policy gradient (DDPG) algorithm, through the continuous interaction with the environment and the use of historical experience data; the agent learns the optimal action strategy in a simulation environment. The navigation rules and the ship's encounter situation are transformed into a navigation restricted area, so as to achieve the purpose of planned path safety in order to ensure the validity and accuracy of the model. Ship data provided by ship automatic identification system (AIS) are used to train this path planning model. Subsequently, the improved DRL is obtained by combining DDPG with the artificial potential field. Finally, the path planning model is integrated into the electronic chart platform for experiments. Through the establishment of comparative experiments, the results show that the improved model can achieve autonomous path planning, and it has good convergence speed and stability.

**Keywords:** unmanned ships; deep reinforcement learning; DDPG; autonomous path planning; end-to-end; collision avoidance
