20,405 research outputs found
Multi-Robot Transfer Learning: A Dynamical System Perspective
Multi-robot transfer learning allows a robot to use data generated by a
second, similar robot to improve its own behavior. The potential advantages are
reducing the time of training and the unavoidable risks that exist during the
training phase. Transfer learning algorithms aim to find an optimal transfer
map between different robots. In this paper, we investigate, through a
theoretical study of single-input single-output (SISO) systems, the properties
of such optimal transfer maps. We first show that the optimal transfer learning
map is, in general, a dynamic system. The main contribution of the paper is to
provide an algorithm for determining the properties of this optimal dynamic map
including its order and regressors (i.e., the variables it depends on). The
proposed algorithm does not require detailed knowledge of the robots' dynamics,
but relies on basic system properties easily obtainable through simple
experimental tests. We validate the proposed algorithm experimentally through
an example of transfer learning between two different quadrotor platforms.
Experimental results show that an optimal dynamic map, with correct properties
obtained from our proposed algorithm, achieves 60-70% reduction of transfer
learning error compared to the cases when the data is directly transferred or
transferred using an optimal static map.Comment: 7 pages, 6 figures, accepted at the 2017 IEEE/RSJ International
Conference on Intelligent Robots and System
On the Construction of Safe Controllable Regions for Affine Systems with Applications to Robotics
This paper studies the problem of constructing in-block controllable (IBC)
regions for affine systems. That is, we are concerned with constructing regions
in the state space of affine systems such that all the states in the interior
of the region are mutually accessible through the region's interior by applying
uniformly bounded inputs. We first show that existing results for checking
in-block controllability on given polytopic regions cannot be easily extended
to address the question of constructing IBC regions. We then explore the
geometry of the problem to provide a computationally efficient algorithm for
constructing IBC regions. We also prove the soundness of the algorithm. We then
use the proposed algorithm to construct safe speed profiles for different
robotic systems, including fully-actuated robots, ground robots modeled as
unicycles with acceleration limits, and unmanned aerial vehicles (UAVs).
Finally, we present several experimental results on UAVs to verify the
effectiveness of the proposed algorithm. For instance, we use the proposed
algorithm for real-time collision avoidance for UAVs.Comment: 17 pages, 18 figures, under review for publication in Automatic
The effect of hydrogen on the magnetic properties of FeV superlattice
The electronic and magnetic structures of a hydrogenated and hydrogen free
superlattice of 3 iron monolayers and 9 vanadium monolayers are studied using
the first principle full-potential augmented-plane-wave method as implemented
in WIEN2k package. The volume, the total energy and the magnetic moments of the
system are studied versus the hydrogen positions at the octahedral sites within
the superlattice and also versus the filling of the vanadium octahedral
location by hydrogen atoms. It is found that the hydrogen locations at the
interior of vanadium layer are energetically more favourable. The local Fe
magnetic moment and the average magnetic moment per supercell are found to
increase as the H position moves towards the Fe-V interface. On the other hand,
the average magnetic moment per supercell is found to initially decrease up to
filling by 3 H atoms and then increases afterwards. To our knowledge, this is
the first reporting on the increase in the computed magnetic moment with
hydrogenation. These trends of magnetic moments are attributed to the volume
changes resulting from hydrogenation and not to electronic hydrogen-metal
interaction.Comment: 13 pages, 5 figures and 2 table
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