STRIDER: Navigation via Instruction-Aligned Structural Decision Space Optimization

TL;DR

STRIDER is a novel framework for zero-shot vision-and-language navigation that enhances decision-making by integrating spatial priors and task feedback, leading to significant improvements over state-of-the-art methods.

Contribution

It introduces a structured waypoint generator and a task-alignment regulator to optimize decision space and improve navigation accuracy in unseen environments.

Findings

Achieves a 20.7% relative increase in success rate on benchmarks.

Outperforms previous methods across key navigation metrics.

Demonstrates the effectiveness of spatial and feedback integration in zero-shot VLN-CE.

Abstract

The Zero-shot Vision-and-Language Navigation in Continuous Environments (VLN-CE) task requires agents to navigate previously unseen 3D environments using natural language instructions, without any scene-specific training. A critical challenge in this setting lies in ensuring agents' actions align with both spatial structure and task intent over long-horizon execution. Existing methods often fail to achieve robust navigation due to a lack of structured decision-making and insufficient integration of feedback from previous actions. To address these challenges, we propose STRIDER (Instruction-Aligned Structural Decision Space Optimization), a novel framework that systematically optimizes the agent's decision space by integrating spatial layout priors and dynamic task feedback. Our approach introduces two key innovations: 1) a Structured Waypoint Generator that constrains the action space through spatial structure, and 2) a Task-Alignment Regulator that adjusts behavior based on task progress, ensuring semantic alignment throughout navigation. Extensive experiments on the R2R-CE and RxR-CE benchmarks demonstrate that STRIDER significantly outperforms strong SOTA across key metrics; in particular, it improves Success Rate (SR) from 29% to 35%, a relative gain of 20.7%. Such results highlight the importance of spatially constrained decision-making and feedback-guided execution in improving navigation fidelity for zero-shot VLN-CE.