SafePath: Conformal Prediction for Safe LLM-Based Autonomous Navigation

TL;DR

SafePath enhances LLM-based autonomous navigation by integrating conformal prediction to provide formal safety guarantees, reducing collision risks and planning uncertainty in complex traffic scenarios.

Contribution

This paper introduces SafePath, a novel modular framework that combines LLMs with conformal prediction to ensure safety in autonomous path planning.

Findings

Reduces planning uncertainty by 77%

Decreases collision rates by up to 70%

Guarantees safe trajectories with user-defined probability

Abstract

Large Language Models (LLMs) show growing promise in autonomous driving by reasoning over complex traffic scenarios to generate path plans. However, their tendencies toward overconfidence, and hallucinations raise critical safety concerns. We introduce SafePath, a modular framework that augments LLM-based path planning with formal safety guarantees using conformal prediction. SafePath operates in three stages. In the first stage, we use an LLM that generates a set of diverse candidate paths, exploring possible trajectories based on agent behaviors and environmental cues. In the second stage, SafePath filters out high-risk trajectories while guaranteeing that at least one safe option is included with a user-defined probability, through a multiple-choice question-answering formulation that integrates conformal prediction. In the final stage, our approach selects the path with the lowest expected collision risk when uncertainty is low or delegates control to a human when uncertainty is high. We theoretically prove that SafePath guarantees a safe trajectory with a user-defined probability, and we show how its human delegation rate can be tuned to balance autonomy and safety. Extensive experiments on nuScenes and Highway-env show that SafePath reduces planning uncertainty by 77\% and collision rates by up to 70\%, demonstrating effectiveness in making LLM-driven path planning more safer.