Task Allocation for Multi-Robot Task and Motion Planning: a case for Object Picking in Cluttered Workspaces

TL;DR

This paper introduces an integrated multi-robot task and motion planning method using AND/OR graphs, capable of handling unknown object re-arrangements in cluttered environments, demonstrated with two robotic arms.

Contribution

It presents a novel approach combining task allocation and motion planning that manages unknown re-arrangements in cluttered workspaces using utility maximization.

Findings

Effective task allocation in cluttered environments.

Robust handling of unknown re-arrangement steps.

Successful simulation with two robotic manipulators.

Abstract

We present an AND/OR graph-based, integrated multi-robot task and motion planning approach which (i) performs task allocation coordinating the activity of a given number of robots, and (ii) is capable of handling tasks which involve an a priori unknown number of object re-arrangements, such as those involved in retrieving objects from cluttered workspaces. Such situations may arise, for example, in search and rescue scenarios, while locating/picking a cluttered object of interest. The corresponding problem falls under the category of planning in clutter. One of the challenges while planning in clutter is that the number of object re-arrangements required to pick the target object is not known beforehand, in general. Moreover, such tasks can be decomposed in a variety of ways, since different cluttering object re-arrangements are possible to reach the target object. In our approach, task allocation and decomposition is achieved by maximizing a combined utility function. The allocated tasks are performed by an integrated task and motion planner, which is robust to the requirement of an unknown number of re-arrangement tasks. We demonstrate our results with experiments in simulation on two Franka Emika manipulators.