5 DISCUSSION & FUTURE
WORK
This paper presents a strategy to model realistic flood-
ing scenarios in a robotic simulator in order to eval-
uate rescue USVs on harsh environments safely and
cheaply when compared to an actual field test in a
disaster site. Initial experiments show the importance
of proper disturbance modeling and simulation in the
control of USVs, which may even prevent the USV
from achieving its goal or cause collisions — unac-
ceptable for disaster response missions.
Beyond the presented flooding scenario, we plan
to simulate several other types of disasters, such as,
the effects of tsunamis or dam breaches. This would
allow new GNC algorithms to be evaluated even in
such harsh environment conditions.
However, there is much to be done to improve
simulations in maritime environments. Current open-
source simulators for USVs still lack many features.
Proper simulation of sensors and communications
problems with USVs in simulations are often limited
to Gaussian noise. Instead, intermittent and unreliable
services should be considered to validate the robust-
ness of the whole system. These could be achieved
by considering factors such as the simulation of wire-
less transmissions’ shadows and GPS errors close to
buildings and trees, as well as the effect of water dis-
turbances & weather on sensors and communications.
For instance, radio waves can be reflected by the water
surface and waves, sporadicly interrupting wireless
communications. The same is true for weather con-
ditions and heavy rain, which affects cameras and the
range of communications. Finally, underwater data
transmission, should also consider physically correct
signal attenuation and multi-path simulations. By do-
ing that, the validation of unmanned systems in simu-
lation environments will be more similar to that which
UAV, UGV and USVs facing actual disaster missions.
In order to improve the realism of disaster loca-
tions, debris could be added to scene, so they could
become floating obstacles which could even be car-
ried by the water flow, colliding with USV and UUV.
If needed, users could combine those objects together
(by adding joints) and defining a limit force that
would break their joints. This way, when the grouped
object collides with another one with considerable
strength, many parts or pieces can be detached gener-
ating even more debris deposited all over the city and
into water channels, ports and bays. Then, the result-
ing scenario can be used to emulate post disaster as-
sessment missions, where the amount and location of
debris must be estimated by an heterogeneous team of
unmanned systems. As a result, new strategies could
be designed and properly tested & compared for area
coverage, debris detection rate and their removal from
affected areas in realistic simulation environments.
Future works may also include the integration of
UAVs (affected by winds) and USVs (affected by
winds, waves and water currents) collaborating in the
same scenario where they look for strained people.
We also plan to model landslides, bigger turbulent
waves (tsunami like), bridge and oil platform col-
lapses to assess, in simulations, heterogeneous teams
of unmanned systems in such marine disaster environ-
ments.
ACKNOWLEDGEMENTS
This paper was partially funded by CAPES/Brazil,
under project 88887.115590/2015-01, Pro-Alertas
program.
The MDT and MDS maps belong to the munici-
pality of Porto Alegre, Brazil. The maps were pro-
vided by the Secretary of Municipal Urbanism (Sec-
retaria Municipal de Urbanismo - SMURB) to profes-
sor Regis Lahm.
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