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: "legged robot state estimation through combined forward kinematic and preintegrated contact factors"
  Abstract: State-of-the-art robotic perception systems have achieved sufficiently good performance using Inertial Measurement Units (IMUs), cameras, and nonlinear optimization techniques, that they are now being deployed as technologies. However, many of these methods rely significantly on vision and fail when visual tracking is lost due to lighting or scarcity of features. In addition, such systems are formulated such that the system is independent of the operating platform. This paper presents state-estimation technique for legged robots that takes into account the robot's kinematic model as well as its contact with the environment. This is achieved by introducing forward kinematic factors and preintegrated contact factors into a factor graph framework that can incrementally solved in real-time. The forward kinematics factor relates the robot's base pose to a contact frame through noisy encoder measurements. The preintegrated contact factor provides odometry measurements of this contact frame, while accounting for possible foot slippage. Taken together, the two factors constrain the graph optimization problem allowing the robot's trajectory to be estimated. The paper evaluates the method using simulated and real sensory IMU and kinematic data from experiments with a Cassie-series robot designed by Agility Robotics. These experiments show that using the proposed method in addition to IMU significantly decreases drift and improves localization accuracy, suggesting that its use can enable successful recovery from loss of visual tracking.

Connected through hyperedge HE-1 (induced by source paper "feedback control for autonomous riding of hovershoes by a cassie bipedal robot"):
  with members:
    - "feedback control of a cassie bipedal robot walking standing and riding a segway"
    - "keep rollin whole body motion control and planning for wheeled quadrupedal robots"
    - "vins mono a robust and versatile monocular visual inertial state estimator"
    - "orb slam2 an open source slam system for monocular stereo and rgb d cameras"
    - "sampling based algorithms for optimal motion planning"

Connected through hyperedge HE-2 (induced by source paper "characterizing the uncertainty of jointly distributed poses in the lie algebra"):
  with members:
    - "on manifold preintegration for real time visual inertial odometry"
    - "estimating uncertain spatial relationships in robotics"

Connected through hyperedge HE-3 (induced by source paper "hybrid contact preintegration for visual inertial contact state estimation using factor graphs"):
  with members:
    - "contact aided invariant extended kalman filtering for legged robot state estimation"
    - "on manifold preintegration for real time visual inertial odometry"
    - "state estimation for a humanoid robot"

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)