237 research outputs found
Learning Programmatically Structured Representations with Perceptor Gradients
We present the perceptor gradients algorithm -- a novel approach to learning
symbolic representations based on the idea of decomposing an agent's policy
into i) a perceptor network extracting symbols from raw observation data and
ii) a task encoding program which maps the input symbols to output actions. We
show that the proposed algorithm is able to learn representations that can be
directly fed into a Linear-Quadratic Regulator (LQR) or a general purpose A*
planner. Our experimental results confirm that the perceptor gradients
algorithm is able to efficiently learn transferable symbolic representations as
well as generate new observations according to a semantically meaningful
specification.Comment: Published as a conference paper at ICLR 201
A Novel Design and Evaluation of a Dactylus-Equipped Quadruped Robot for Mobile Manipulation
Quadruped robots are usually equipped with additional arms for manipulation,
negatively impacting price and weight. On the other hand, the requirements of
legged locomotion mean that the legs of such robots often possess the needed
torque and precision to perform manipulation. In this paper, we present a novel
design for a small-scale quadruped robot equipped with two leg-mounted
manipulators inspired by crustacean chelipeds and knuckle-walker forelimbs. By
making use of the actuators already present in the legs, we can achieve
manipulation using only 3 additional motors per limb. The design enables the
use of small and inexpensive actuators relative to the leg motors, further
reducing cost and weight. The moment of inertia impact on the leg is small
thanks to an integrated cable/pulley system. As we show in a suite of
tele-operation experiments, the robot is capable of performing single- and
dual-limb manipulation, as well as transitioning between manipulation modes.
The proposed design performs similarly to an additional arm while weighing and
costing 5 times less per manipulator and enabling the completion of tasks
requiring 2 manipulators.Comment: 6 pages, 10 figures, updated layout to fit in margins and corrected
typos, accepted to the 2022 IEEE/RSJ International Conference on Intelligent
Robots and Systems (IROS 2022
Learning from Demonstration with Weakly Supervised Disentanglement
Robotic manipulation tasks, such as wiping with a soft sponge, require
control from multiple rich sensory modalities. Human-robot interaction, aimed
at teaching robots, is difficult in this setting as there is potential for
mismatch between human and machine comprehension of the rich data streams. We
treat the task of interpretable learning from demonstration as an optimisation
problem over a probabilistic generative model. To account for the
high-dimensionality of the data, a high-capacity neural network is chosen to
represent the model. The latent variables in this model are explicitly aligned
with high-level notions and concepts that are manifested in a set of
demonstrations. We show that such alignment is best achieved through the use of
labels from the end user, in an appropriately restricted vocabulary, in
contrast to the conventional approach of the designer picking a prior over the
latent variables. Our approach is evaluated in the context of two table-top
robot manipulation tasks performed by a PR2 robot -- that of dabbing liquids
with a sponge (forcefully pressing a sponge and moving it along a surface) and
pouring between different containers. The robot provides visual information,
arm joint positions and arm joint efforts. We have made videos of the tasks and
data available - see supplementary materials at:
https://sites.google.com/view/weak-label-lfd.Comment: 18 pages, 16 figures, accepted at the International Conference on
Learning Representations (ICLR) 2021, supplementary website at
https://sites.google.com/view/weak-label-lf
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