
while avoiding collisions with neighboring vehicles.
No specific formation of followers is required.
During the experiments, the results of which are
presented in the paper, the vehicles were unable to
distinguish obstacles from other vehicles in the swarm
using the only long-range sensor which was sonar. In
consequence, it was decided that avoiding collisions
with obstacles external to the swarm is the responsi-
bility of the leader which detects obstacles and, in the
event of a threat, decides to change the depth for the
entire swarm. However, for the leader to be able to
detect obstacles and not confuse them with followers,
none of the followers must be in the field of vision
of the leader sonar. Such a limitation was a serious
challenge for the neural control system, especially on
bends.
If we assume that the leader is able to quickly de-
tect obstacles and change the immersion depth of the
swarm, then we can conclude that the followers are
not at risk of colliding with external objects. How-
ever, if followers move near obstacles, they are still
visible to them, which makes it difficult to follow the
leader because it is not known whether the detected
object is another vehicle or an obstacle. The impos-
sibility of correctly interpreting information from the
sonar is another problem that the neural control sys-
tem had to face.
An additional difficulty for the system was also the
limited information available for decision-making.
To follow the leader, the followers were supplied with
information about the distance to it. However, this
information was provided rarely, one by one to each
follower. Directional information was not available to
the followers. In addition, the followers used limited-
range sensors such as sonar and cameras to avoid col-
lisions.
Despite all the challenges that the neural control
system had to face, the simulations, the results of
which are presented in the paper, showed that the use
of recurrent neural networks as a high-level control
system of the followers, i.e. the system determining
the direction of movement and speed of vehicles, al-
lows for collective movement of vehicles along the
route designated by the leader. As it turned out, ve-
hicles equipped with a neural network can follow the
leader both in an ideal, obstacle-free marine environ-
ment where every nearby object is a threat - it is just
another vehicle in a swarm that can lead to a collision
and in an environment containing obstacles in which
followers have to deal with both other vehicles that
may pose a threat and with underwater objects that do
not pose a threat because they are at a different depth
away from the swarm.
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WSEAS TRANSACTIONS on SYSTEMS and CONTROL
DOI: 10.37394/23203.2023.18.30
Tomasz Praczyk, Piotr Szymak