4 research outputs found
Emergent velocity agreement in robot networks
In this paper we propose and prove correct a new self-stabilizing velocity
agreement (flocking) algorithm for oblivious and asynchronous robot networks.
Our algorithm allows a flock of uniform robots to follow a flock head emergent
during the computation whatever its direction in plane. Robots are
asynchronous, oblivious and do not share a common coordinate system. Our
solution includes three modules architectured as follows: creation of a common
coordinate system that also allows the emergence of a flock-head, setting up
the flock pattern and moving the flock. The novelty of our approach steams in
identifying the necessary conditions on the flock pattern placement and the
velocity of the flock-head (rotation, translation or speed) that allow the
flock to both follow the exact same head and to preserve the flock pattern.
Additionally, our system is self-healing and self-stabilizing. In the event of
the head leave (the leading robot disappears or is damaged and cannot be
recognized by the other robots) the flock agrees on another head and follows
the trajectory of the new head. Also, robots are oblivious (they do not recall
the result of their previous computations) and we make no assumption on their
initial position. The step complexity of our solution is O(n)
On Asynchrony, Memory, and Communication: Separations and Landscapes
Research on distributed computing by a team of identical mobile computational
entities, called robots, operating in a Euclidean space in
-- () cycles, has
recently focused on better understanding how the computational power of robots
depends on the interplay between their internal capabilities (i.e., persistent
memory, communication), captured by the four standard computational models
(OBLOT, LUMI, FSTA, and FCOM) and the conditions imposed by the external
environment, controlling the activation of the robots and their synchronization
of their activities, perceived and modeled as an adversarial scheduler.
We consider a set of adversarial asynchronous schedulers ranging from the
classical semi-synchronous (SSYNCH) and fully asynchronous (ASYNCH) settings,
including schedulers (emerging when studying the atomicity of the combination
of operations in the cycles) whose adversarial power is in
between those two. We ask the question: what is the computational relationship
between a model under adversarial scheduler () and a
model under scheduler ()? For example, are the robots in
more powerful (i.e., they can solve more problems) than those in
?
We answer all these questions by providing, through cross-model analysis, a
complete characterization of the computational relationship between the power
of the four models of robots under the considered asynchronous schedulers. In
this process, we also provide qualified answers to several open questions,
including the outstanding one on the proper dominance of SSYNCH over ASYNCH in
the case of unrestricted visibility