RRT$^\eta$: Sampling-based Motion Planning and Control from STL Specifications using Arithmetic-Geometric Mean Robustness

TL;DR

This paper introduces RRT$^ eta$, a novel sampling-based motion planning framework that uses AGM robustness for STL specifications, enabling more efficient and robust planning in complex robotic tasks.

Contribution

It proposes AGM robustness interval semantics, an incremental monitoring algorithm, and enhanced satisfaction vectors, improving planning efficiency and robustness over traditional methods.

Findings

Outperforms traditional STL robustness planners in complex scenarios

Successfully applied to robots with varying complexity, including a 7-DOF arm

Maintains probabilistic completeness and asymptotic optimality

Abstract

Sampling-based motion planning has emerged as a powerful approach for robotics, enabling exploration of complex, high-dimensional configuration spaces. When combined with Signal Temporal Logic (STL), a temporal logic widely used for formalizing interpretable robotic tasks, these methods can address complex spatiotemporal constraints. However, traditional approaches rely on min-max robustness measures that focus only on critical time points and subformulae, creating non-smooth optimization landscapes with sharp decision boundaries that hinder efficient tree exploration. We propose RRT$^\eta$, a sampling-based planning framework that integrates the Arithmetic-Geometric Mean (AGM) robustness measure to evaluate satisfaction across all time points and subformulae. Our key contributions include: (1) AGM robustness interval semantics for reasoning about partial trajectories during tree construction, (2) an efficient incremental monitoring algorithm computing these intervals, and (3) enhanced Direction of Increasing Satisfaction vectors leveraging Fulfillment Priority Logic (FPL) for principled objective composition. Our framework synthesizes dynamically feasible control sequences satisfying STL specifications with high robustness while maintaining the probabilistic completeness and asymptotic optimality of RRT$^\ast$. We validate our approach on three robotic systems. A double integrator point robot, a unicycle mobile robot, and a 7-DOF robot arm, demonstrating superior performance over traditional STL robustness-based planners in multi-constraint scenarios with limited guidance signals.