human: Given a node-centered hypergraph: <hypergraph>, where nodes represent papers and hyperedges represent sets of papers co-cited by a source paper.

Details of the hypergraph:
Center node: "nimbro op2 grown up 3d printed open humanoid platform for research"
  Abstract: 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.

Connected through hyperedge HE-1 (induced by source paper "nimbro robots winning robocup 2018 humanoid adultsize soccer competitions"):
  with members:
    - "grown up nimbro robots winning robocup 2017 humanoid adultsize soccer competitions"
    - "hierarchical and state based architectures for robot behavior planning and control"
    - "fused angles a representation of body orientation for balance"
    - "omnidirectional bipedal walking with direct fused angle feedback mechanisms"
    - "robocup 2016 humanoid teensize winner nimbro robust visual perception and soccer behaviors"
    - "a monocular vision system for playing soccer in low color information environments"
    - "nimbro op2x adult sized open source 3d printed humanoid robot"
    - "combining simulations and real robot experiments for bayesian optimization of bipedal gait stabilization"

Connected through hyperedge HE-2 (induced by source paper "robocup 2019 adultsize winner nimbro deep learning perception in walk kick push recovery and team play capabilities"):
  with members:
    - "nimbro robots winning robocup 2018 humanoid adultsize soccer competitions"
    - "grown up nimbro robots winning robocup 2017 humanoid adultsize soccer competitions"
    - "location dependency in video prediction"
    - "omnidirectional bipedal walking with direct fused angle feedback mechanisms"
    - "a monocular vision system for playing soccer in low color information environments"
    - "online balanced motion generation for humanoid robots"
    - "real time visual tracking and identification for a team of homogeneous humanoid robots"
    - "nimbro op2x adult sized open source 3d printed humanoid robot"

Connected through hyperedge HE-3 (induced by source paper "nimbro op2x adult sized open source 3d printed humanoid robot"):
  with members:
    - "on the convergence of adam and beyond"
    - "grown up nimbro robots winning robocup 2017 humanoid adultsize soccer competitions"
    - "fused angles a representation of body orientation for balance"
    - "omnidirectional bipedal walking with direct fused angle feedback mechanisms"
    - "a ros based software framework for the nimbro op humanoid open platform"
    - "a monocular vision system for playing soccer in low color information environments"
    - "child sized 3d printed igus humanoid open platform"
    - "combining simulations and real robot experiments for bayesian optimization of bipedal gait stabilization"

Connected through hyperedge HE-4 (induced by source paper "grown up nimbro robots winning robocup 2017 humanoid adultsize soccer competitions"):
  with members:
    - "learning to improve capture steps for disturbance rejection in humanoid soccer"
    - "omnidirectional bipedal walking with direct fused angle feedback mechanisms"
    - "robocup 2016 humanoid teensize winner nimbro robust visual perception and soccer behaviors"
    - "a monocular vision system for playing soccer in low color information environments"
    - "child sized 3d printed igus humanoid open platform"

Question: Please tell me which class the center node belongs to. The 40 classes are: cs.NA(Numerical Analysis), cs.MM(Multimedia), cs.LO(Logic in Computer Science), cs.CY(Computers and Society), cs.CR(Cryptography and Security), cs.DC(Distributed, Parallel, and Cluster Computing), cs.HC(Human-Computer Interaction), cs.CE(Computational Engineering, Finance, and Science), cs.NI(Networking and Internet Architecture), cs.CC(Computational Complexity), cs.AI(Artificial Intelligence), cs.MA(Multiagent Systems), cs.GL(General Literature), cs.NE(Neural and Evolutionary Computing), cs.SC(Symbolic Computation), cs.AR(Hardware Architecture), cs.CV(Computer Vision and Pattern Recognition), cs.GR(Graphics), cs.ET(Emerging Technologies), cs.SY(Systems and Control), cs.CG(Computational Geometry), cs.OH(Other Computer Science), cs.PL(Programming Languages), cs.SE(Software Engineering), cs.LG(Machine Learning), cs.SD(Sound), cs.SI(Social and Information Networks), cs.RO(Robotics), cs.IT(Information Theory), cs.PF(Performance), cs.CL(Computation and Language), cs.IR(Information Retrieval), cs.MS(Mathematical Software), cs.FL(Formal Languages and Automata Theory), cs.DS(Data Structures and Algorithms), cs.OS(Operating Systems), cs.GT(Computer Science and Game Theory), cs.DB(Databases), cs.DL(Digital Libraries), cs.DM(Discrete Mathematics). Directly output the class name.

gpt: cs.RO(Robotics)