A Holistic Approach to Reactive Mobile Manipulation

TL;DR

This paper introduces a reactive, holistic control system for mobile manipulators that improves motion fluidity and speed by integrating arm and base movements without planning delays, demonstrated through a pick-and-place task.

Contribution

The paper presents a novel, reactive motion controller that treats arm and base as a unified system, enabling more fluid and faster mobile manipulation without planning delays.

Findings

Enhanced motion fluidity and speed in mobile manipulation

Successful implementation of pick-and-place task using behavior trees

Open-source controller available for various mobile platforms

Abstract

We present the design and implementation of a taskable reactive mobile manipulation system. In contrary to related work, we treat the arm and base degrees of freedom as a holistic structure which greatly improves the speed and fluidity of the resulting motion. At the core of this approach is a robust and reactive motion controller which can achieve a desired end-effector pose, while avoiding joint position and velocity limits, and ensuring the mobile manipulator is manoeuvrable throughout the trajectory. This can support sensor-based behaviours such as closed-loop visual grasping. As no planning is involved in our approach, the robot is never stationary thinking about what to do next. We show the versatility of our holistic motion controller by implementing a pick and place system using behaviour trees and demonstrate this task on a 9-degree-of-freedom mobile manipulator. Additionally, we provide an open-source implementation of our motion controller for both non-holonomic and omnidirectional mobile manipulators available at jhavl.github.io/holistic.