Closed-Loop Supervised Fine-Tuning of Tokenized Traffic Models

Fuente: arXiv
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Main Authors: Zhang, Zhejun, Karkus, Peter, Igl, Maximilian, Ding, Wenhao, Chen, Yuxiao, Ivanovic, Boris, Pavone, Marco
Format: Preprint
Published: 2024
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_version_ 1866916652151472128
author Zhang, Zhejun
Karkus, Peter
Igl, Maximilian
Ding, Wenhao
Chen, Yuxiao
Ivanovic, Boris
Pavone, Marco
author_facet Zhang, Zhejun
Karkus, Peter
Igl, Maximilian
Ding, Wenhao
Chen, Yuxiao
Ivanovic, Boris
Pavone, Marco
contents Traffic simulation aims to learn a policy for traffic agents that, when unrolled in closed-loop, faithfully recovers the joint distribution of trajectories observed in the real world. Inspired by large language models, tokenized multi-agent policies have recently become the state-of-the-art in traffic simulation. However, they are typically trained through open-loop behavior cloning, and thus suffer from covariate shift when executed in closed-loop during simulation. In this work, we present Closest Among Top-K (CAT-K) rollouts, a simple yet effective closed-loop fine-tuning strategy to mitigate covariate shift. CAT-K fine-tuning only requires existing trajectory data, without reinforcement learning or generative adversarial imitation. Concretely, CAT-K fine-tuning enables a small 7M-parameter tokenized traffic simulation policy to outperform a 102M-parameter model from the same model family, achieving the top spot on the Waymo Sim Agent Challenge leaderboard at the time of submission. The code is available at https://github.com/NVlabs/catk.
format Preprint
id arxiv_https___arxiv_org_abs_2412_05334
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Closed-Loop Supervised Fine-Tuning of Tokenized Traffic Models
Zhang, Zhejun
Karkus, Peter
Igl, Maximilian
Ding, Wenhao
Chen, Yuxiao
Ivanovic, Boris
Pavone, Marco
Machine Learning
Traffic simulation aims to learn a policy for traffic agents that, when unrolled in closed-loop, faithfully recovers the joint distribution of trajectories observed in the real world. Inspired by large language models, tokenized multi-agent policies have recently become the state-of-the-art in traffic simulation. However, they are typically trained through open-loop behavior cloning, and thus suffer from covariate shift when executed in closed-loop during simulation. In this work, we present Closest Among Top-K (CAT-K) rollouts, a simple yet effective closed-loop fine-tuning strategy to mitigate covariate shift. CAT-K fine-tuning only requires existing trajectory data, without reinforcement learning or generative adversarial imitation. Concretely, CAT-K fine-tuning enables a small 7M-parameter tokenized traffic simulation policy to outperform a 102M-parameter model from the same model family, achieving the top spot on the Waymo Sim Agent Challenge leaderboard at the time of submission. The code is available at https://github.com/NVlabs/catk.
title Closed-Loop Supervised Fine-Tuning of Tokenized Traffic Models
topic Machine Learning
url https://arxiv.org/abs/2412.05334