Cooperative multi-target hunting by unmanned surface vehicles based on multi-agent reinforcement learning

To solve the problem of multi-target hunting by an unmanned surface vehicle (USV) fleet, a hunting algorithm based on multi-agent reinforcement learning is proposed. Firstly, the hunting environment and kinematic model without boundary constraints are built, and the criteria for successful target capture are given. Then, the cooperative hunting problem of a USV fleet is modeled as a decentralized partially observable Markov decision process (Dec-POMDP), and a distributed partially observable multi-target hunting Proximal Policy Optimization (DPOMH-PPO) algorithm applicable to USVs is proposed. In addition, an observation model, a reward function and the action space applicable to multi-target hunting tasks are designed. To deal with the dynamic change of observational feature dimension input by partially observable systems, a feature embedding block is proposed. By combining the two feature compression methods of column-wise max pooling (CMP) and column-wise average-pooling (CAP), observational feature encoding is established. Finally, the centralized training and decentralized execution framework is adopted to complete the training of hunting strategy. Each USV in the fleet shares the same policy and perform actions independently. Simulation experiments have verified the effectiveness of the DPOMH-PPO algorithm in the test scenarios with different numbers of USVs. Moreover, the advantages of the proposed model are comprehensively analyzed from the aspects of algorithm performance, migration effect in task scenarios and self-organization capability after being damaged, the potential deployment and application of DPOMH-PPO in the real environment is verified.