  For several years, high development and production costs of humanoid robots
restricted researchers interested in working in the field. To overcome this
problem, several research groups have opted to work with simulated or smaller
robots, whose acquisition costs are significantly lower. However, due to scale
differences and imperfect simulation replicability, results may not be directly
reproducible on real, adult-sized robots. In this paper, we present the
NimbRo-OP2X, a capable and affordable adult-sized humanoid platform aiming to
significantly lower the entry barrier for humanoid robot research. With a
height of 135 cm and weight of only 19 kg, the robot can interact in an
unmodified, human environment without special safety equipment. Modularity in
hardware and software allow this platform enough flexibility to operate in
different scenarios and applications with minimal effort. The robot is equipped
with an on-board computer with GPU, which enables the implementation of
state-of-the-art approaches for object detection and human perception demanded
by areas such as manipulation and human-robot interaction. Finally, the
capabilities of the NimbRo-OP2X, especially in terms of locomotion stability
and visual perception, are evaluated. This includes the performance at RoboCup
2018, where NimbRo-OP2X won all possible awards in the AdultSize class.
