DIV-Nav: Open-Vocabulary Spatial Relationships for Multi-Object Navigation

Abstract-- Advances in open-vocabulary semantic mapping and object navigation have enabled robots to perform an informed search of their environment for an arbitrary object. However, such zero-shot object navigation is typically designed for simple queries with an object name like "television" or "blue rug". Here, we consider more complex free-text queries with spatial relationships, such as "find the remote on the table" while still leveraging robustness of a semantic map. We present DIV-Nav, a real-time navigation system that efficiently addresses this problem through a series of relaxations: i) Decomposing natural language instructions with complex spatial constraints into simpler object-level queries on a semantic map, ii) computing the Intersection of individual semantic belief maps to identify regions where all objects co-exist, and iii) V alidating the discovered objects against the original, complex spatial constrains via a L VLM. We further investigate how to adapt the frontier exploration objectives of online semantic mapping to such spatial search queries to more effectively guide the search process. Robots operating in human environments must interpret natural language commands that go beyond simple object identification. While a command like "find a chair" requires handling simple object classes only, real-world search instructions often specify spatial relationships: "go to the chair next to the desk," "find the towel in the bathroom," or "get the book on the nightstand."