[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

162 A. Babiarz, R. Bieda, and K. Jaskot
Acquired images are the only input for vision system, which implements an algorithm,
which main goal is to provide precise estimation of position and orientation
of objects on field (robots and ball) in different lighting conditions. Vision
system not only gives coordinates of objects on the playground, but also field’s
and robot’s dimensions. It was constructed in such a way in order to make vision
system more adjustable to changing real environments. Main characteristics of the
algorithms are [11]:
• The estimation of orientation has 2° standard deviation and 10° in worst case.
• The estimation of position has 2 standard deviation.
• The speed of processing is 30 frames per second (one frame per 30 ).
• Small differences in lightning of playground does not influence work of the
system.
• Algorithm has no problem in recovery from a temporary situation of an object
"lost".
We can say that the above features are satisfactory. As it can be seen on Figure 5,
the values of orientation and position are very accurate.
Fig. 5. View from the camera with orientation and position marks sketched on
The application implementing the vision algorithm is a stand-alone server and
communicates with clients using the TCP/IP network with use of special Extensible
Markup Language (XML) based protocol [12].This XML based communication
is implemented in a C++ communication library called libqteam providing
interface for programming control algorithms. From the view of control algorithms
the vision system works as the feedback loop, providing measurements of
values being inputs to the controller. The general way of signal in the vision system
is shown on Figure 6.