On-Policy Distillation of Language Models for Autonomous Vehicle Motion Planning

Fuente: arXiv
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Autori principali: Afsharrad, Amirhossein, Abedsoltan, Amirhesam, Moradipari, Ahmadreza, Lall, Sanjay
Natura: Preprint
Pubblicazione: 2026
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author Afsharrad, Amirhossein
Abedsoltan, Amirhesam
Moradipari, Ahmadreza
Lall, Sanjay
author_facet Afsharrad, Amirhossein
Abedsoltan, Amirhesam
Moradipari, Ahmadreza
Lall, Sanjay
contents Large language models (LLMs) have recently demonstrated strong potential for autonomous vehicle motion planning by reformulating trajectory prediction as a language generation problem. However, deploying capable LLMs in resource-constrained onboard systems remains a fundamental challenge. In this paper, we study how to effectively transfer motion planning knowledge from a large teacher LLM to a smaller, more deployable student model. We build on the GPT-Driver framework, which represents driving scenes as language prompts and generates waypoint trajectories with chain-of-thought reasoning, and investigate two student training paradigms: (i) on-policy generalized knowledge distillation (GKD), which trains the student on its own self-generated outputs using dense token-level feedback from the teacher, and (ii) a dense-feedback reinforcement learning (RL) baseline that uses the teacher's log-probabilities as per-token reward signals in a policy gradient framework. Experiments on the nuScenes benchmark show that GKD substantially outperforms the RL baseline and closely approaches teacher-level performance despite a 5$\times$ reduction in model size. These results highlight the practical value of on-policy distillation as a principled and effective approach to deploying LLM-based planners in autonomous driving systems.
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id arxiv_https___arxiv_org_abs_2604_07944
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publishDate 2026
record_format arxiv
spellingShingle On-Policy Distillation of Language Models for Autonomous Vehicle Motion Planning
Afsharrad, Amirhossein
Abedsoltan, Amirhesam
Moradipari, Ahmadreza
Lall, Sanjay
Robotics
Artificial Intelligence
Systems and Control
Large language models (LLMs) have recently demonstrated strong potential for autonomous vehicle motion planning by reformulating trajectory prediction as a language generation problem. However, deploying capable LLMs in resource-constrained onboard systems remains a fundamental challenge. In this paper, we study how to effectively transfer motion planning knowledge from a large teacher LLM to a smaller, more deployable student model. We build on the GPT-Driver framework, which represents driving scenes as language prompts and generates waypoint trajectories with chain-of-thought reasoning, and investigate two student training paradigms: (i) on-policy generalized knowledge distillation (GKD), which trains the student on its own self-generated outputs using dense token-level feedback from the teacher, and (ii) a dense-feedback reinforcement learning (RL) baseline that uses the teacher's log-probabilities as per-token reward signals in a policy gradient framework. Experiments on the nuScenes benchmark show that GKD substantially outperforms the RL baseline and closely approaches teacher-level performance despite a 5$\times$ reduction in model size. These results highlight the practical value of on-policy distillation as a principled and effective approach to deploying LLM-based planners in autonomous driving systems.
title On-Policy Distillation of Language Models for Autonomous Vehicle Motion Planning
topic Robotics
Artificial Intelligence
Systems and Control
url https://arxiv.org/abs/2604.07944