[Studies in Computational Intelligence 481] Artur Babiarz, Robert Bieda, Karol Jędrasiak, Aleksander Nawrat (auth.), Aleksander Nawrat, Zygmunt Kuś (eds.) - Vision Based Systemsfor UAV Applications (2013, Sprin

116 D. Bereska et al.
Presented in this article opto-electronic gimbal is the result of the first stage of
the work carried out over a gyro-stabilized platform for autonomous vehicles. It
was designed to enable the installation of optical sensors allowing simultaneous
acquisition of images in the visible and infrared bands. At this stage the priority
was to create a gyro-stabilized platform for selected optical sensors. The platform
enables rotation around two axes.
2 Optical Sensors
Paradoxically, the selection of appropriate optical sensors is not a simple task.
Great variety of available solutions and their types requires an analysis of several
technical documentations. It is useful to predefine basic criteria such as the availability
of equipment, price, native resolution, weight, size, power consumption or
operating temperature. In case of a dedicated platform for unmanned ground vehicles
(UGVs) a criterion based on dimension of weight is not critical. Important
are however image resolution, operating temperature and of course price. During
selection of equipment a special attention was paid to the availability of dedicated
optical systems, which in case of infrared cameras significantly increase the
weight of the device and its price.
As a result of the analysis it was decided to purchase two cameras. The visible
light camera was chosen as block camera Sony FCB-EX980 with integrated optics
and motorized 26x zoom. The camera is characterized by an extensive automation.
As the infrared sensors the Miracle Thermoteknix Systems Ltd. was chosen. It is
characterized by a very good price to cost ratio. Technical parameters of both
cameras are shown in the tab. 1. It is also sufficient for object detection [7].
3 Camera Calibration
As noted in the introduction the resulting opto-electronic gimbal is ought to allow
the installation of optical sensors in such a way that simultaneous acquisition of
images from both visible and infrared band are possible.
For many image processing algorithms it is important that both cameras are
mutually fit. The desired installation outcome is when both cameras provide consistent
output image in terms of size and content of the scene. Such effect can be
achieved by adjusting the optical axes of the cameras, their mutual appropriate
location and suitable setting of their lenses.
In order to achieve the desired parameters (tab.1) a dedicated test platform was
developed and created. A tripod used to enable the measurement of the convergence
of optical axes is presented in fig. 1.