POrTAL: Plan-Orchestrated Tree Assembly for Lookahead

TL;DR

POrTAL is a lightweight probabilistic planning algorithm that combines existing methods to efficiently generate better plans for robots operating under uncertainty within limited computational resources.

Contribution

The paper introduces POrTAL, a novel hybrid planning algorithm that outperforms baseline methods in bounded time scenarios for partially observable robotic tasks.

Findings

POrTAL generally produces shorter plans than baseline algorithms.

POrTAL performs well under moderate uncertainty levels.

It is an anytime algorithm adaptable to computational constraints.

Abstract

When tasking robots in partially observable environments, these robots must efficiently and robustly plan to achieve task goals under uncertainty. Although many probabilistic planning algorithms exist for this purpose, these algorithms can be inefficient if executed with the robot's limited computational resources, or may produce policies that take more steps than expected to achieve the goal. We therefore created a new, lightweight, probabilistic planning algorithm, Plan-Orchestrated Tree Assembly for Lookahead (POrTAL), that combines the strengths of two baseline planning algorithms, FF-Replan and POMCP. We demonstrate that POrTAL is an anytime algorithm that generally outperforms these baselines in terms of the final executed plan length given bounded computation time, especially for problems with only moderate levels of uncertainty.