IEEE Robotics & Automation Magazine - December 2019 - 109

further facilitates the seamless integration and interchange
of third-party contributions. To showcase the robot's
capabilities, we present its performance in a challenging
industrial maintenance scenario that requires human-robot
collaboration, where the robot autonomously recognizes the
human's need of help and offers said help in a proactive way.
Background and Related Work
Humanoid robots have existed for decades in research labs all
around the world. Although there is a wealth of possible
applications in practical use cases, the inherent complexity of
humanoid robots as well the intricate nature of the tasks they
are expected to perform has hindered their transition from
research labs to real-world use. One of these difficult tasks is
the need to work closely with humans in a safe, predictable,
intuitive, and productive manner. An important step toward
the transition of humanoids into real-world applications is
therefore the proliferation of technologies that permit robots
to work cooperatively and safely with humans, which has led
to the development of collaborative robots.
On the design side, these technologies include lightweight
robot design [1]; anthropomorphic kinematics (e.g., [2] and
[3]); force and torque sensing [4]; high-speed, real-time bus
systems [e.g., Ethernet for control automation technology
(EtherCAT)]; and an extremely high level of system integration, which is required to fit the functionalities into the
desired form factor.
These technologies have found their way into commercial
products in the form of individual arms (e.g., by Kuka, Universal Robots, and Franka Emika), dual-arm systems (e.g., by
ABB and Kawada Industries), and even complete humanoid
robots such as PAL Robotics' REEM-C [39] and TALOS [5].
The design, however, is only one aspect of truly collaborative robots. Other crucial aspects are the cognitive abilities of
the robot, which are needed to correctly interpret situations
and understand how to work together with humans, even in
environments that are not completely known beforehand. A
hardware platform that supports cognitive, bimanual mobile
manipulation capabilities must be equipped with various
exteroceptive sensors and sufficient on-board computing
resources, in addition to the body, arms, and end effectors.
Mobility is another important requirement for such a robot
because it drastically expands the working radius, thereby
enabling a vast number of additional applications.
Several complete humanoid systems that integrate these
capabilities for real-world use have recently been introduced.
The list of such systems is long; therefore, we limit the scope
of this article to systems designed for dual-arm mobile
manipulation. These include the HRP (Humanoid Robotics
Project) robots, used for aircraft assembly tasks [6] and construction work [7]; DLR's Rollin' Justin [8]; the fully torquecontrolled TORO [9]; and robots such as the WALK-MAN
[10] and E2-DR [11].
With ARMAR-6, we set out to advance the state of the art
in mobile collaborative robots in terms of its system design,
i.e., regarding its physical capabilities and overall technologi-

cal readiness for real-world applications, as well as in all aspects of the cognitive capabilities necessary to accomplish
challenging tasks beyond laboratory environments. The presented robot advances the state of the art with respect to kinematics, workspace, and workload. To the best of our
knowledge, no other humanoid system currently exists that
combines an arm reach of more than 1 m with a carrying capacity of more than 10 kg at full arm extension to go along
with its limitless joints. ARMAR-6 is not only physically capable of demanding tasks; it is also equipped with a comprehensive suite of sensors as well as the cognitive abilities necessary
to facilitate natural, safe collaboration with humans.
Depicted in Figure 1 is ARMAR-6, the latest generation in
the ARMAR humanoid robot family [15]. It was developed as
a robotic research platform within the SecondHands project
[40], the vision of which is to develop and enable a robot to
literally provide a human worker with a second pair of hands
to support, increase safety, and enhance efficiency. Its development is driven by an ambitious use case, in which the robot
autonomously and proactively assists a maintenance technician with repair tasks on a material handling system in an
online retailer's highly automated customer fulfillment center.
This particular scenario poses many requirements of the
robotic system, which challenged us to "push the envelope" of
what is currently possible in collaborative robotics.
Its deployment in an actual warehouse environment
requires ARMAR-6 to be extraordinarily robust and reliable. The robot therefore incorporates all of the experiences
from the construction and deployment of its predecessors
regarding the choice of components, material selection,
cable routing, and software modules on all levels to realize a

Figure 1. ARMAR-6: a collaborative humanoid robot.

DECEMBER 2019

IEEE ROBOTICS & AUTOMATION MAGAZINE

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IEEE Robotics & Automation Magazine - December 2019

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