An Extended Convergence Result for Behaviour Tree Controllers

TL;DR

This paper extends the theoretical understanding of behavior tree controllers by providing a generalized convergence result that encompasses cyclic switching and broader classes of BTs, enhancing their reliability in robotic control.

Contribution

It offers a generalized convergence theorem for behavior trees, including new cyclic switching cases, broadening the applicability of BTs in robotics.

Findings

Generalized convergence conditions for behavior trees.

Inclusion of cyclic switching cases in convergence analysis.

Enhanced theoretical foundation for BT-based control in robotics.

Abstract

Behavior trees (BTs) are an optimally modular framework to assemble hierarchical hybrid control policies from a set of low-level control policies using a tree structure. Many robotic tasks are naturally decomposed into a hierarchy of control tasks, and modularity is a well-known tool for handling complexity, therefor behavior trees have garnered widespread usage in the robotics community. In this paper, we study the convergence of BTs, in the sense of reaching a desired part of the state space. Earlier results on BT convergence were often tailored to specific families of BTs, created using different design principles. The results of this paper generalize the earlier results and also include new cases of cyclic switching not covered in the literature.