Tree-Planner: Efficient Close-loop Task Planning with Large Language Models

1The University of Hong Kong, 2Harbin Institute of Technology 3Noah’s Ark Laboratory, 4Shanghai AI Laboratory

An overview of Tree-Planner of three stages:
Plan Sampling prompts the LLM to sample potential task plans with its inherent commonsense.
Action Tree Construction aggregates the sampled plans. Grounded Deciding instructs the LLM again in closed loops to reason on the action tree with the environmental observation.

Abstract

This paper studies close-loop task planning, which refers to the process of generating a sequence of skills (a plan) to accomplish a specific goal while adapting the plan based on real-time observations.

Recently, prompting Large Language Models (LLMs) to generate actions iteratively has become a prevalent paradigm due to its superior performance and user-friendliness. However, this paradigm is plagued by two inefficiencies: high token consumption and redundant error correction, both of which hinder its scalability for large-scale testing and applications.

To address these issues, we propose Tree-Planner, which reframes task planning with LLMs into three distinct phases: plan sampling, action tree construction, and grounded deciding.

Tree-Planner starts by using an LLM to sample a set of potential plans before execution, followed by the aggregation of them to form an action tree. Finally, the LLM performs a top-down decision-making process on the tree, taking into account real-time environmental information.

Experiments show that Tree-Planner achieves state-of-the-art performance while maintaining high efficiency. By decomposing LLM queries into a single plan-sampling call and multiple grounded-deciding calls, a considerable part of the prompt are less likely to be repeatedly consumed. As a result, token consumption is reduced by 92.2% compared to the previously best-performing model. Additionally, by enabling backtracking on the action tree as needed, the correction process becomes more flexible, leading to a 40.5% decrease in error corrections.

BibTeX


@article{hu2023tree,
  title={Tree-Planner: Efficient Close-loop Task Planning with Large Language Models},
  author={Hu, Mengkang and Mu, Yao and Yu, Xinmiao and Ding, Mingyu and Wu, Shiguang and Shao, Wenqi and Chen, Qiguang and Wang, Bin and Qiao, Yu and Luo, Ping},
  journal={arXiv preprint arXiv:2310.08582},
  year={2023}
}