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: "when to make a step tackling the timing problem in multi contact locomotion by topp mpc"
  Abstract: We present a model predictive controller (MPC) for multi-contact locomotion where predictive optimizations are realized by time-optimal path parameterization (TOPP). A key feature of this solution is that, contrary to existing planners where step timings are provided as inputs, here the timing between contact switches is computed as output of a fast nonlinear optimization. This is particularly appealing to multi-contact locomotion, where proper timings depend on terrain topology and suitable heuristics are unknown. We show how to formulate legged locomotion as a TOPP problem and demonstrate the behavior of the resulting TOPP-MPC controller in simulations with a model of the HRP-4 humanoid robot.

Connected through hyperedge HE-1 (induced by source paper "whole body walking generation using contact parametrization a non linear trajectory optimization approach"):
  with members:
    - "a control architecture with online predictive planning for position and torque controlled walking of humanoid robots"
    - "a benchmarking of dcm based architectures for position and velocity controlled walking of humanoid robots"
    - "whole body nonlinear model predictive control through contacts for quadrupeds"
    - "simultaneous contact gait and motion planning for robust multi legged locomotion via mixed integer convex optimization"
    - "real time motion planning of legged robots a model predictive control approach"
    - "straight leg walking through underconstrained whole body control"
    - "a receding horizon push recovery strategy for balancing the icub humanoid robot"
    - "trajectory generation for multi contact momentum control"

Connected through hyperedge HE-2 (induced by source paper "feasible region an actuation aware extension of the support region"):
  with members:
    - "heuristic planning for rough terrain locomotion in presence of external disturbances and variable perception quality"
    - "application of wrench based feasibility analysis to the online trajectory optimization of legged robots"
    - "dynamic walking over rough terrains by nonlinear predictive control of the floating base inverted pendulum"
    - "structured contact force optimization for kino dynamic motion generation"
    - "minkowski sum of polytopes defined by their vertices"
    - "minkowski sum of hv polytopes in rn"

Connected through hyperedge HE-3 (induced by source paper "a robust walking controller based on online step location and duration optimization for bipedal locomotion"):
  with members:
    - "walking stabilization using step timing and location adjustment on the humanoid robot atlas"
    - "online adaptation for humanoids walking on uncertain surfaces"
    - "dynamic walking over rough terrains by nonlinear predictive control of the floating base inverted pendulum"
    - "momentum control with hierarchical inverse dynamics on a torque controlled humanoid"
    - "structured contact force optimization for kino dynamic motion generation"
    - "step timing adjustment a step toward generating robust gaits"
    - "a convex model of momentum dynamics for multi contact motion generation"
    - "stepping stabilization using a combination of dcm tracking and step adjustment"

Connected through hyperedge HE-4 (induced by source paper "walking control based on step timing adaptation"):
  with members:
    - "whole body nonlinear model predictive control through contacts for quadrupeds"
    - "walking stabilization using step timing and location adjustment on the humanoid robot atlas"
    - "online adaptation for humanoids walking on uncertain surfaces"
    - "dynamic walking over rough terrains by nonlinear predictive control of the floating base inverted pendulum"
    - "momentum control with hierarchical inverse dynamics on a torque controlled humanoid"
    - "structured contact force optimization for kino dynamic motion generation"
    - "step timing adjustment a step toward generating robust gaits"
    - "stepping stabilization using a combination of dcm tracking and step adjustment"

Connected through hyperedge HE-5 (induced by source paper "on time optimisation of centroidal momentum dynamics"):
  with members:
    - "simultaneous contact gait and motion planning for robust multi legged locomotion via mixed integer convex optimization"
    - "an efficient optimal planning and control framework for quadrupedal locomotion"
    - "momentum control with hierarchical inverse dynamics on a torque controlled humanoid"
    - "structured contact force optimization for kino dynamic motion generation"
    - "multi contact walking pattern generation based on model preview control of 3d com accelerations"
    - "stability of surface contacts for humanoid robots closed form formulae of the contact wrench cone for rectangular support areas"
    - "trajectory generation for multi contact momentum control"

Connected through hyperedge HE-6 (induced by source paper "dynamic walking over rough terrains by nonlinear predictive control of the floating base inverted pendulum"):
  with members:
    - "step timing adjustment a step toward generating robust gaits"
    - "multi contact walking pattern generation based on model preview control of 3d com accelerations"
    - "stability of surface contacts for humanoid robots closed form formulae of the contact wrench cone for rectangular support areas"
    - "zmp support areas for multi contact mobility under frictional constraints"
    - "a general fast and robust implementation of the time optimal path parameterization algorithm"

Connected through hyperedge HE-7 (induced by source paper "a mpc walking framework with external contact forces"):
  with members:
    - "momentum control with hierarchical inverse dynamics on a torque controlled humanoid"
    - "structured contact force optimization for kino dynamic motion generation"
    - "step timing adjustment a step toward generating robust gaits"
    - "humanoid momentum estimation using sensed contact wrenches"

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)