Master Thesis - Hochschule Bonn-Rhein-Sieg

5. Algorithms Master Thesis Björn Ostermann page 59 of 126
5 Algorithms for robotic evasion
Chapter 4 gives an overview on the flow of the data and the internal connection of the subparts and
algorithms, which control the robot by analysis of the 3D images of the camera and the position
information of the robot. To understand this project in total, a deeper view on the algorithms is
necessary. Therefore the used algorithms are explained in this chapter in detail. Some algorithms have
been developed in previous work [78], but only the depiction of the acquired information (see chapter
5.1) could be reused without further improvement.
5.1 Depicting the acquired information
As described in chapter 4.3.1 it is necessary, to show the images and information acquired from the
camera, in order to set up the workplace and explain the camera’s function during demonstrations.
These algorithms are not necessary in the object avoidance process of the robot. The algorithms
controlling the robot are designed to work with the unmodified data, delivered by the camera.
Figure 37 shows two sample images, taken during operations.
a) b)
Figure 37: Sample images, taken in the workplace
a) reflection image and b) distance image (see also Figure 21)
The image data are acquired from the camera with the help of the C++ library supplied by the
camera’s manufacturer (see chapter 3.4). The library’s function, responsible for the data acquisition,
fills a prepared buffer variable in the developed program with an array of float numbers followed by
an array of unsigned integer numbers. This process is described in detail in previous work [78].
The float numbers represent the spherical distance data in meter, the integer values indicate the
quantity of reflected light per pixel.
To translate the spherical distance data into carthesian coordinates, the vectors of the respective pixels
have to be used. This step is also achieved by a function supplied by the camera’s manufacturer. For
demonstrative purposes it is sufficient to only display the carthesian value of the z-axis, the one