August 5, 2026 HAM-VLN: Harnessing Hierarchical Agentic Memory for Zero-Shot Vision-and-Language Navigation HAM-VLN 为 zero-shot VLN agent 提供决策耦合的层次化记忆系统，通过世界图存储导航历史，结合动态门控检索，在无需训练的情况下超越现有方法 vision-language-navigation vln embodied-ai multimodal-llm agentic-memory zero-shot robotics world-graph