Master Thesis - Hochschule Bonn-Rhein-Sieg

5. Algorithms Master Thesis Björn Ostermann page 98 of 126
a) b)
current
Dynamic objects
Robot
goal
current
c) d)
current
current
Dynamic objects
Robot
goal
e) f)
current
Dynamic objects
goal
current
Robot
Robot
Dynamic objects
Dynamic objects
Dynamic objects
Robot
Robot
Figure 71: Graphical explanation of the calculation of the shortest evasion path
The calculations that lead to the results depicted by the images are:
- A straight line is drawn from the first to the last point (Figure 71a)
- The next point is checked, whether it is “below” the first line (closer to the robot) and if so it is
set as the start-pixel for the current line. (Figure 71b)
- Step one and two are repeated, until no more pixels are below the current line (Figure 71c).
- The current line is stored and a new line is begun.
- The new line is drawn from the fist pixel to the start of the recently stored line (Figure 71d).
- Step one and two are repeated, until no more pixels are below the new line (Figure 71e).
- Again, a new line is drawn from the first pixel to the start of the recently stored line (Figure 71f).
The algorithm is finished, if the stored line begins in the first pixel.
A flowchart, showing the complete algorithm, is shown in Figure 72.
goal
goal
goal