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: "passive whole body control for quadruped robots experimental validation over challenging terrain"
  Abstract: We present experimental results using a passive whole-body control approach for quadruped robots that achieves dynamic locomotion while compliantly balancing the robot's trunk. We formulate the motion tracking as a Quadratic Program (QP) that takes into account the full robot rigid body dynamics, the actuation limits, the joint limits and the contact interaction. We analyze the controller's robustness against inaccurate friction coefficient estimates and unstable footholds, as well as its capability to redistribute the load as a consequence of enforcing actuation limits. Additionally, we present practical implementation details gained from the experience with the real platform. Extensive experimental trials on the 90 kg Hydraulically actuated Quadruped (HyQ) robot validate the capabilities of this controller under various terrain conditions and gaits. The proposed approach is superior for accurate execution of highly dynamic motions with respect to the current state of the art.

Connected through hyperedge HE-1 (induced by source paper "learning how to walk warm starting optimal control solver with memory of motion"):
  with members:
    - "memory of motion for warm starting trajectory optimization"
    - "crocoddyl an efficient and versatile framework for multi contact optimal control"
    - "differential dynamic programming for multi phase rigid contact dynamics"
    - "simultaneous contact gait and motion planning for robust multi legged locomotion via mixed integer convex optimization"
    - "trajectory optimization through contacts and automatic gait discovery for quadrupeds"
    - "planning and execution of dynamic whole body locomotion for a hydraulic quadruped on challenging terrain"

Connected through hyperedge HE-2 (induced by source paper "stance locomotion adaptation over soft terrain"):
  with members:
    - "heuristic planning for rough terrain locomotion in presence of external disturbances and variable perception quality"
    - "frequency aware model predictive control"
    - "dynamic locomotion for passive ankle biped robots and humanoids using whole body locomotion control"
    - "contact implicit optimization of locomotion trajectories for a quadrupedal microrobot"
    - "whole body nonlinear model predictive control through contacts for quadrupeds"
    - "robust whole body motion control of legged robots"
    - "robot impedance control and passivity analysis with inner torque and velocity feedback loops"
    - "momentum control with hierarchical inverse dynamics on a torque controlled humanoid"

Connected through hyperedge HE-3 (induced by source paper "on the hardware feasibility of nonlinear trajectory optimization for legged locomotion based on a simplified dynamics"):
  with members:
    - "feasible region an actuation aware extension of the support region"
    - "efficient humanoid contact planning using learned centroidal dynamics prediction"
    - "application of wrench based feasibility analysis to the online trajectory optimization of legged robots"
    - "real time motion planning of legged robots a model predictive control approach"
    - "structured contact force optimization for kino dynamic motion generation"

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)