mono.net

Build your own responsive website!

Free Trial
Vehicle Tracking
  • Home
    • the rotation of stepper motors
    • Levy search based mobile
    • Levy Flight Controllers

We have tested our Levy search based mobile target fol-
lowing algorithm within the Webots 6.1 simulator. The
main objective of our experimental results is to deter-
mine how the locating time of targets is affected for
different parameters of the Levy search, The two pa-
rameters that control the behavior of the Levy search
are the scale parameter c and the shift parameter μ.
For all our settings we use five robots to locate and
track targets and one target that can be either station-
ary or mobile. The robots are situated with a 10 × 10
m2 square environment. Each robot is simulated as
a mini-robot that has the following sensors: (1) Cam-
era: a color VGA camera with a maximal resolution of
640 × 480 . (2) Eight infra-red distance sensors mea-
suring ambient light and proximity of obstacles in a
range of 4 cm. (3) Two wheels controlling speed and
direction by the rotation of stepper motors, and, (4)
A Bluetooth-enabled transmitter and receiver for send-
ing and receiving messages between robots. To localize
each robot, we have added a GPS node on each simu-
lated robot. (In a system with real robots, localization
can be realized using an overhead camera-based local-
ization system.) Mobile targets are simulated as colored
cylindrical robots, which can either remain stationary
or move in the environment at a certain speed. The
robots simulating the mobile targets have two forward
looking IR distance sensors to avoid obstacles. When
the tracking robot’s camera encounters a colored ob-
ject of interest1, it informs other robots that converge
on the last observed location of the target and perform
a Levy search to locate it.

For our first set of experiments we considered a tar-
get that moves from an initial location to a final loca-
tion and remains stationary after that. The distance
between the initial and final locations of the target has
an average value of 4.5m. The robots are only aware of
the initial location of the target and have to discover the
final location of the target using a Levy search starting
from the target’s initial location. Figure 5 shows the
effect of different values of the shift and scale param-
eters on the time required to locate the target at its
final location. The scale parameterc was set at either
0.5 or 1, while the shift parameter, μ, was varied from
0.5 to 1, 2, and 4. With the Levy looped search, we
observe that as the length of a leg of the Levy search,

Figure 4: Average time required locate a target that moves from an initial location to a final location and remains
stationary thereafter using Levy looped search (left) and Levy timed search (right).
0.5 1 2 4
3
3.5
4
4.5
5
5.5
6
6.5
7
μ
Average Time (min)
c= 1.0
c= 0.5
Locating Mobile Target:
Levy Looped Search
0 0.5 1 2 4
2
3
4
5
6
7
μ
Average Time (min)
c = 0.5
c = 1.0
Locating Mobile Target:
Levy Timed Search
Figure 5: Average time required to locate a mobile target that moves at half the speed of the tracking robots,
using Levy looped search (left) and Levy timed search (right).

FacebookTwitterGoogle+LinkedIn
mono.net

Build your own responsive website!

Free Trial