Master Thesis - Hochschule Bonn-Rhein-Sieg

4. Overall evading concept Master Thesis Björn Ostermann page 45 of 126
a) b)
Figure 26: Detected intrusion a) before targeting and
b) after targeting the robot base
virtual
robot
base
The calculation of the reachable space results in the flexible fence as displayed in Figure 27b. The
computations start with the data of the intrusion detection (Figure 24) including the virtual robot base.
Upon this data a region growing algorithm is executed (see chapter 5.2.4.1). The remaining noise is
eliminated by a size filter (see chapter 5.2.4.2). Then the flexible fence, depicted as a blue line, is
computed (see chapter 5.5.3). The resulting vectors of the blue line are transmitted to the data
exchange object (see chapter 4.6) to be later used in the path planning control thread (see chapter 4.4).
The next subpart is the calculation of distance between the robot and intruding objects, for the
implemented approach control. It can be activated by button 10, which automatically deactivates the
reachable space calculation. The resulting image of this subpart is displayed as shown in Figure 27c.
The green area shows the robot, surrounded by (green) distance lines which automatically extend
around the robot’s area, until they touch the nearest (red) intruding object. To achieve this image,
again the data of the intrusion detection (Figure 24) containing the virtual robot base is used. As
before, regions are grown, identified and filtered. The region identified as the robot is taken by the
algorithm described in chapter 5.4, which creates the distance lines by uniformly enlarging the taken
area, until one intruding region is touched. The steps of this algorithm are counted and transmitted to
the data exchange object (see chapter 4.6) to be later used in the path planning control thread (see
chapter 4.4), which controls the robot’s speed according to the distance.