  The versatility of humanoid robots in locomotion, full-body motion,
interaction with unmodified human environments, and intuitive human-robot
interaction led to increased research interest. Multiple smaller platforms are
available for research, but these require a miniaturized environment to
interact with---and often the small scale of the robot diminishes the influence
of factors which would have affected larger robots. Unfortunately, many
research platforms in the larger size range are less affordable, more difficult
to operate, maintain and modify, and very often closed-source. In this work, we
introduce NimbRo-OP2X, an affordable, fully open-source platform in terms of
both hardware and software. Being almost 135cm tall and only 18kg in weight,
the robot is not only capable of interacting in an environment meant for
humans, but also easy and safe to operate and does not require a gantry when
doing so. The exoskeleton of the robot is 3D printed, which produces a
lightweight and visually appealing design. We present all mechanical and
electrical aspects of the robot, as well as some of the software features of
our well-established open-source ROS software. The NimbRo-OP2X performed at
RoboCup 2017 in Nagoya, Japan, where it won the Humanoid League AdultSize
Soccer competition and Technical Challenge.
