Only passive sensors (cameras) are used on ARGO to sense the
surrounding environment, since they offer the possibility
to acquire data in a non-invasive way, namely without altering
the environment. Because of the large number of vehicles that
could be moving simultaneously, this is a prominent advantage
with respect to invasive ways of perceiving the environment,
which could lead to an unacceptable pollution of the environment.
Figure 1: The left and right cameras
The ARGO vehicle is equipped with a stereoscopic vision system
consisting of two synchronized cameras able to acquire
pairs of grey level images.
The installed devices are small
(3.2cm X 3.2cm)
low cost cameras featuring a 6.0 mm focal length
and a 360 lines resolution which can receive the synchronism
from an external signal.
The cameras lie inside the car at the top corners of the
windscreen, so that the longitudinal distance between the two cameras is
The optical axes are parallel and, in order to handle also non flat roads,
part of the scene over the horizon is captured, even if the framing
of a portion of the sky can be critical for the image brightness:
in case of high contrast the sensor may acquire oversaturated images.
Images are acquired by a PCI Matrox board, which is able to grab
three 768 X 288
pixel images simultaneously.
The images are directly stored into the main memory of the
host computer thanks to the use of DMA.
The acquisition can be performed in real time, at a 25Hz rate in case of
full frames or at a 50Hz rate in case of single field acquisition.