Multi-Agent Reinforcement Learning with Transformer-based Spatio-temporal Fusion for Autonomous Driving in Mixed Traffic

Abstract

Driving decision-making in mixed traffic, characterized by high-dynamic interactions and stochastic behaviors of human-driven vehicles, poses significant challenges for autonomous driving systems. To address these issues, we propose a novel Transformer-based Spatial Temporal Fusion (TSTF) module integrated with an auxiliary contrastive learning task within a multi-agent reinforcement learning (MARL) framework. The TSTF module captures interaction-aware behaviors and long-term temporal dependencies that tackle mixed cooperative driving scenarios, while the auxiliary contrastive learning task refines feature representations to enhance exploration efficiency and decision stability. Experimental evaluations on the MetaDrive platform demonstrate that the proposed approach outperforms baseline algorithms in safety, adaptability and robustness to dynamic traffic scenarios. The results highlight the effectiveness of the TSTF module in enabling robust and context-aware collaborative driving behaviors, offering a scalable solution for real-world mixed traffic. This work advances MARL by addressing key challenges in interaction modeling and driving decision-making under uncertainty, with significant implications for the development of intelligent transportation systems.