Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Self-synchronization and Self-stabilization of 3D Bipedal Walking Gaits   This paper seeks insight into stabilization mechanisms for periodic walking
gaits in 3D bipedal robots. Based on this insight, a control strategy based on
virtual constraints, which imposes coordination between joints rather than a
temporal evolution, will be proposed for achieving asymptotic convergence
toward a periodic motion. For planar bipeds with one degree of underactuation,
it is known that a vertical displacement of the center of mass---with downward
velocity at the step transition---induces stability of a walking gait. This
paper concerns the qualitative extension of this type of property to 3D walking
with two degrees of underactuation. It is shown that a condition on the
position of the center of mass in the horizontal plane at the transition
between steps induces synchronization between the motions in the sagittal and
frontal planes. A combination of the conditions for self-synchronization and
vertical oscillations leads to stable gaits. The algorithm for
self-stabilization of 3D walking gaits is first developed for a simplified
model of a walking robot (an inverted pendulum with variable length legs), and
then it is extended to a complex model of the humanoid robot Romeo using the
notion of Hybrid Zero Dynamics. Simulations of the model of the robot
illustrate the efficacy of the method and its robustness.

29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
0
The categories of this paper are: hep-ph
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph