Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Rolling in the Deep -- Hybrid Locomotion for Wheeled-Legged Robots using
  Online Trajectory Optimization   Wheeled-legged robots have the potential for highly agile and versatile
locomotion. The combination of legs and wheels might be a solution for any
real-world application requiring rapid, and long-distance mobility skills on
challenging terrain. In this paper, we present an online trajectory
optimization framework for wheeled quadrupedal robots capable of executing
hybrid walking-driving locomotion strategies. By breaking down the optimization
problem into a wheel and base trajectory planning, locomotion planning for high
dimensional wheeled-legged robots becomes more tractable, can be solved in
real-time on-board in a model predictive control fashion, and becomes robust
against unpredicted disturbances. The reference motions are tracked by a
hierarchical whole-body controller that sends torque commands to the robot. Our
approach is verified on a quadrupedal robot with non-steerable wheels attached
to its legs. The robot performs hybrid locomotion with a great variety of gait
sequences on rough terrain. Besides, we validated the robotic platform at the
Defense Advanced Research Projects Agency (DARPA) Subterranean Challenge, where
the robot rapidly mapped, navigated and explored dynamic underground
environments.

18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
6
The categories of this paper are: astro-ph
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an