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This paper addresses temporal logic task planning problems for mobile robots. We consider missions that require accomplishing multiple high-level sub-tasks, expressed in natural language (NL), in a temporal and logical order. To formally define the mission, we treat these sub-tasks as atomic predicates in a Linear Temporal Logic (LTL) formula. We refer to this task specification framework as LTL-NL. Our goal is to design plans, defined as sequences of robot actions, accomplishing LTL-NL tasks. This action planning problem cannot be solved directly by existing LTL planners due to the NL nature of atomic predicates. Therefore, we propose HERACLEs, a hierarchical neuro-symbolic planner that relies on a novel integration of (i) existing symbolic planners generating high-level task plans determining the order at which the NL sub-tasks should be accomplished; (ii) pre-trained Large Language Models (LLMs) to design sequences of robot actions for each sub-task in these task plans; and (iii) conformal prediction acting as a formal interface between (i) and (ii) and managing uncertainties due to LLM imperfections. We show, both theoretically and empirically, that HERACLEs can achieve user-defined mission success rates. We demonstrate the efficiency of HERACLEs through comparative numerical experiments against recent LLM-based planners as well as hardware experiments on mobile manipulation tasks. Finally, we present examples demonstrating that our approach enhances user-friendliness compared to conventional symbolic approaches.
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SafeNet: A Neural-Symbolic Network for Safe Planning in Robotic Systems using Formal Method-Guided LLM Fine-Tuning
Robotic systems present unique safety challenges due to their complex integration of computational and physical processes and direct interaction with humans and environments. Traditional approaches to robot safety planning either rely on conventional methods, which struggle with the complexity of modern robotic systems, or on pure machine learning techniques, which lack formal safety guarantees. While recent advances in Large Language Models (LLMs) offer promising capabilities, pre-trained LLMs alone lack the specific domain expertise required for effective robotic safety planning. This paper introduces SafeNet, a novel neural-symbolic network architecture that enhances LLMs' safety planning capabilities through formal method-guided fine-tuning for robotic applications. Our approach integrates formal logical knowledge and reward machines into pre-trained LLMs by carefully designed fine-tuning, creating a neural-symbolic approach that combines the flexibility of neural networks with the precision of formal methods for robot trajectory generation and task planning. Experimental results demonstrate significant improvements in safe trajectory generation for robotic systems, with planning success rates increasing from 1.17% to 91.60% for the block manipulation task and from 7.23% to 90.63% for the robotic path planning task.
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- PAR ID:
- 10670645
- Publisher / Repository:
- IEEE
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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