R2F: Repurposing Ray Frontiers for LLM-free Object Navigation

Fuente: arXiv
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Main Authors: Argenziano, Francesco, Marcelo, John Mark Alexis, Brienza, Michele, Drid, Abdel Hakim, Musumeci, Emanuele, Nardi, Daniele, Bloisi, Domenico D., Suriani, Vincenzo
Format: Preprint
Published: 2026
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author Argenziano, Francesco
Marcelo, John Mark Alexis
Brienza, Michele
Drid, Abdel Hakim
Musumeci, Emanuele
Nardi, Daniele
Bloisi, Domenico D.
Suriani, Vincenzo
author_facet Argenziano, Francesco
Marcelo, John Mark Alexis
Brienza, Michele
Drid, Abdel Hakim
Musumeci, Emanuele
Nardi, Daniele
Bloisi, Domenico D.
Suriani, Vincenzo
contents Zero-shot open-vocabulary object navigation has progressed rapidly with the emergence of large Vision-Language Models (VLMs) and Large Language Models (LLMs), now widely used as high-level decision-makers instead of end-to-end policies. Although effective, such systems often rely on iterative large-model queries at inference time, introducing latency and computational overhead that limit real-time deployment. To address this problem, we repurpose ray frontiers (R2F), a recently proposed frontier-based exploration paradigm, to develop an LLM-free framework for indoor open-vocabulary object navigation. While ray frontiers were originally used to bias exploration using semantic cues carried along rays, we reinterpret frontier regions as explicit, direction-conditioned semantic hypotheses that serve as navigation goals. Language-aligned features accumulated along out-of-range rays are stored sparsely at frontiers, where each region maintains multiple directional embeddings encoding plausible unseen content. In this way, navigation then reduces to embedding-based frontier scoring and goal tracking within a classical mapping and planning pipeline, eliminating iterative large-model reasoning. We further introduce R2F-VLN, a lightweight extension for free-form language instructions using syntactic parsing and relational verification without additional VLM or LLM components. Experiments in Habitat-sim and on a real robotic platform demonstrate competitive state-of-the-art zero-shot performance with real-time execution, achieving up to 6 times faster runtime than VLM-based alternatives.
format Preprint
id arxiv_https___arxiv_org_abs_2603_08475
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle R2F: Repurposing Ray Frontiers for LLM-free Object Navigation
Argenziano, Francesco
Marcelo, John Mark Alexis
Brienza, Michele
Drid, Abdel Hakim
Musumeci, Emanuele
Nardi, Daniele
Bloisi, Domenico D.
Suriani, Vincenzo
Robotics
Artificial Intelligence
Zero-shot open-vocabulary object navigation has progressed rapidly with the emergence of large Vision-Language Models (VLMs) and Large Language Models (LLMs), now widely used as high-level decision-makers instead of end-to-end policies. Although effective, such systems often rely on iterative large-model queries at inference time, introducing latency and computational overhead that limit real-time deployment. To address this problem, we repurpose ray frontiers (R2F), a recently proposed frontier-based exploration paradigm, to develop an LLM-free framework for indoor open-vocabulary object navigation. While ray frontiers were originally used to bias exploration using semantic cues carried along rays, we reinterpret frontier regions as explicit, direction-conditioned semantic hypotheses that serve as navigation goals. Language-aligned features accumulated along out-of-range rays are stored sparsely at frontiers, where each region maintains multiple directional embeddings encoding plausible unseen content. In this way, navigation then reduces to embedding-based frontier scoring and goal tracking within a classical mapping and planning pipeline, eliminating iterative large-model reasoning. We further introduce R2F-VLN, a lightweight extension for free-form language instructions using syntactic parsing and relational verification without additional VLM or LLM components. Experiments in Habitat-sim and on a real robotic platform demonstrate competitive state-of-the-art zero-shot performance with real-time execution, achieving up to 6 times faster runtime than VLM-based alternatives.
title R2F: Repurposing Ray Frontiers for LLM-free Object Navigation
topic Robotics
Artificial Intelligence
url https://arxiv.org/abs/2603.08475