577 research outputs found
BigDipper: A hyperscale BFT system with short term censorship resistance
Byzantine-fault-tolerant (BFT) protocols underlie a variety of decentralized
applications including payments, auctions, data feed oracles, and decentralized
social networks. In most leader-based BFT protocols, an important property that
has been missing is the censorship resistance of transaction in the short term.
The protocol should provide inclusion guarantees in the next block height even
if the current and future leaders have the intent of censoring. In this paper,
we present a BFT system, BigDipper, that achieves censorship resistance while
providing fast confirmation for clients and hyperscale throughput. The core
idea is to decentralize inclusion of transactions by allowing every BFT replica
to create their own mini-block, and then enforcing the leader on their
inclusions. To achieve this, BigDipper creates a modular system made of three
components. First, we provide a transaction broadcast protocol used by clients
as an interface to achieve a spectrum of probabilistic inclusion guarantees.
Afterwards, a distribution of BFT replicas will receive the client's
transactions and prepare mini-blocks to send to the data availability (DA)
component. The DA component characterizes the censorship resistant properties
of the whole system. We design three censorship resistant DA (DA-CR) protocols
with distinct properties captured by three parameters and demonstrate their
trade-offs. The third component interleaves the DA-CR protocols into the
consensus path of leader based BFT protocols, it enforces the leader to include
all the data from the DA-CR into the BFT block. We demonstrate an integration
with a two-phase Hotstuff-2 BFT protocol with minimal changes. BigDipper is a
modular system that can switch the consensus to other leader based BFT protocol
including Tendermint
Efficient Global Navigational Planning in 3D Structures based on Point Cloud Tomography
Navigation in complex 3D scenarios requires appropriate environment
representation for efficient scene understanding and trajectory generation. We
propose a highly efficient and extensible global navigation framework based on
a tomographic understanding of the environment to navigate ground robots in
multi-layer structures. Our approach generates tomogram slices using the point
cloud map to encode the geometric structure as ground and ceiling elevations.
Then it evaluates the scene traversability considering the robot's motion
capabilities. Both the tomogram construction and the scene evaluation are
accelerated through parallel computation. Our approach further alleviates the
trajectory generation complexity compared with planning in 3D spaces directly.
It generates 3D trajectories by searching through multiple tomogram slices and
separately adjusts the robot height to avoid overhangs. We evaluate our
framework in various simulation scenarios and further test it in the real world
on a quadrupedal robot. Our approach reduces the scene evaluation time by 3
orders of magnitude and improves the path planning speed by 3 times compared
with existing approaches, demonstrating highly efficient global navigation in
various complex 3D environments. The code is available at:
https://github.com/byangw/PCT_planner.Comment: 11 pages, 9 figures, submitted to IEEE/ASME Transactions on
Mechatronic
Patched Line Segment Learning for Vector Road Mapping
This paper presents a novel approach to computing vector road maps from
satellite remotely sensed images, building upon a well-defined Patched Line
Segment (PaLiS) representation for road graphs that holds geometric
significance. Unlike prevailing methods that derive road vector representations
from satellite images using binary masks or keypoints, our method employs line
segments. These segments not only convey road locations but also capture their
orientations, making them a robust choice for representation. More precisely,
given an input image, we divide it into non-overlapping patches and predict a
suitable line segment within each patch. This strategy enables us to capture
spatial and structural cues from these patch-based line segments, simplifying
the process of constructing the road network graph without the necessity of
additional neural networks for connectivity. In our experiments, we demonstrate
how an effective representation of a road graph significantly enhances the
performance of vector road mapping on established benchmarks, without requiring
extensive modifications to the neural network architecture. Furthermore, our
method achieves state-of-the-art performance with just 6 GPU hours of training,
leading to a substantial 32-fold reduction in training costs in terms of GPU
hours
Wireless Monitoring of Small Strains in Intelligent Robots via a Joule Heating Effect in Stretchable Graphene–Polymer Nanocomposites
Flexible strain sensors are an important component for future intelligent robotics. However, the majority of current strain sensors must be electrically connected to a corresponding monitoring system via conducting wires, which increases system complexity and restricts the working environment for monitoring strains. Here, stretchable graphene–polymer nanocomposites that act as strain sensors using a Joule heating effect are reported. When the resistance of the sensor changes in response to a strain, the resulting change in temperature is wirelessly detected in an intelligent robot. By engineering and optimizing the surface structure of graphene–polymer nanocomposites, the fabricated strain sensors exhibit excellent stability when subjected to periodic temperature signals over 400 cycles while being periodically strained and deliver a high strain sensitivity of 7.03 × 10−4 °C−1 %−1 for strain levels of 0% to 30%. As a wearable electronic device, the approach provides the capability to wirelessly monitor small strains for intelligent robots at a high strain resolution of ≈0.1%. Moreover, when the strain sensing system operates as a multichannel structure, it allows precise strain detection simultaneously, or in sequence, for each finger of an intelligent robot.</p
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