13.08.2018 Views

[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

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

<strong>Vision</strong> System for Group of Mobile Robots 151<br />

F<strong>in</strong>ally, central moments of <strong>in</strong>ertia can be calculated:<br />

1 2 1 2 4 <br />

(27)<br />

<br />

1 2 1 2 4 <br />

(28)<br />

<br />

Angles of both axes of <strong>in</strong>ertia are calculated from the follow<strong>in</strong>g formulas:<br />

<br />

<br />

(29)<br />

<br />

<br />

<br />

(30)<br />

<br />

To calculate the value of arc tangent it is the best to use 2 function from<br />

standard math library, as it automatically deals with f<strong>in</strong>d<strong>in</strong>g proper sign of result<br />

depend<strong>in</strong>g on the quadrant of coord<strong>in</strong>ate system. For objects symmetrical with<br />

respect to both axes of <strong>in</strong>ertia, the one described by angle is perpendicular to<br />

the axis of longest dimension of the object while the axis described by the angle<br />

is co-l<strong>in</strong>ear with the axis of longest dimension, so the vision algorithm uses<br />

the second axis of <strong>in</strong>ertia <strong>in</strong> further calculations.<br />

2.9 Direction of Ma<strong>in</strong> Axis of Inertia<br />

The algorithm relies on special design of the shape of color marker on top of each<br />

robot described earlier <strong>in</strong> this chapter. The idea of f<strong>in</strong>d<strong>in</strong>g the direction of ma<strong>in</strong><br />

axis of <strong>in</strong>ertia is expla<strong>in</strong>ed on Figure 7 and expla<strong>in</strong>ed below. Steps taken by the<br />

algorithm <strong>in</strong> order to decide whether the directed angle describ<strong>in</strong>g direction of<br />

ma<strong>in</strong> axis of <strong>in</strong>ertia is equal to or can be described as follows:<br />

Fig. 7. Idea of f<strong>in</strong>d<strong>in</strong>g the direction of orientation axis

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!