3,622 research outputs found
TZC: Efficient Inter-Process Communication for Robotics Middleware with Partial Serialization
Inter-process communication (IPC) is one of the core functions of modern
robotics middleware. We propose an efficient IPC technique called TZC (Towards
Zero-Copy). As a core component of TZC, we design a novel algorithm called
partial serialization. Our formulation can generate messages that can be
divided into two parts. During message transmission, one part is transmitted
through a socket and the other part uses shared memory. The part within shared
memory is never copied or serialized during its lifetime. We have integrated
TZC with ROS and ROS2 and find that TZC can be easily combined with current
open-source platforms. By using TZC, the overhead of IPC remains constant when
the message size grows. In particular, when the message size is 4MB (less than
the size of a full HD image), TZC can reduce the overhead of ROS IPC from tens
of milliseconds to hundreds of microseconds and can reduce the overhead of ROS2
IPC from hundreds of milliseconds to less than 1 millisecond. We also
demonstrate the benefits of TZC by integrating with TurtleBot2 that are used in
autonomous driving scenarios. We show that by using TZC, the braking distance
can be shortened by 16% than ROS
Breakdown of Ergodicity and Self-Averaging in Polar Flocks with Quenched Disorder
We show that spatial quenched disorder affects polar active matter in ways
more complex and far-reaching than believed heretofore. Using simulations of
the 2D Vicsek model subjected to random couplings or a disordered scattering
field, we find in particular that ergodicity is lost in the ordered phase, the
nature of which we show to depend qualitatively on the type of quenched
disorder: for random couplings, it remains long-range ordered, but
qualitatively different from the pure (disorderless) case. For random
scatterers, polar order varies with system size but we find strong
non-self-averaging, with sample-to-sample fluctuations dominating
asymptotically, which prevents us from elucidating the asymptotic status of
order.Comment: 6 pages, 5 figures, comments are welcom
- …