Zugl.: München, Techn. Univ., Diss., 2009

Erlangen-Nürnberg, Univ., Diss., 2009.

Zugl.: Diss.

This master’s thesis describes a sensorial subsystem of a mobile robot. The thesis mentions the structure and a basis of the satellite navigation. There are also described each systems and visualization techniques as e. g. WGS 84, including also other systems for specification of more accurate position on the Earth (EGNOS, WAAS and others). This thesis describes closely also a differential GPS and the corrections. For the purposes of the thesis there has been assembled GPS software for a fundamental and a remote station. There have been chosen and used modules for receiving a GPS signal and wireless modules for their communication. There are also used outcomes from the project of the Open Street Map in the thesis. Results of this project are described in details, decoded, adjusted and converted into RNDF file. At the end of this thesis there has been composed a function of the program for portable camera which works on principle time of flight. This portable camera is dedicated to look for immediate barrier and also for 3D space view in front of the robot. This thesis also including the process how the power source has been built up for this portable scanner.

Thesis deals with automatic guided mobile robot focused on obstacle avoidance during ride on planned route. There are summaries of usually used obstacle detecting sensors and algorithms used for path finding. Based on this, own solution is designed. It uses waypoints changes to pass obstacle. MATLAB simulation is created for tests of new designed method. This method is implemented to real robot for real world testing. Reached goals and upgrade possibilities are summarized in bottom of thesis.

Time-of-Flight (ToF)-Kameras erzeugen Tiefenbilder (3D-Bilder), indem sie Infrarotlicht aussenden und die Zeit messen, bis die Reflexion des Lichtes wieder empfangen wird. Durch den Einsatz mehrerer ToF-Kameras können ihre vergleichsweise geringere Auflösungen überwunden, das Sichtfeld vergrößert und Verdeckungen reduziert werden. Der gleichzeitige Betrieb birgt jedoch die Möglichkeit von Störungen, die zu fehlerhaften Tiefenmessungen führen. Das Problem der gegenseitigen Störungen tritt nicht nur bei Mehrkamerasystemen auf, sondern auch wenn mehrere unabhängige ToF-Kameras eingesetzt werden. In dieser Arbeit wird eine neue optische Synchronisation vorgestellt, die keine zusätzliche Hardware oder Infrastruktur erfordert, um ein Zeitmultiplexverfahren (engl. Time-Division Multiple Access, TDMA) für die Anwendung mit ToF-Kameras zu nutzen, um so die Störungen zu vermeiden. Dies ermöglicht es einer Kamera, den Aufnahmeprozess anderer ToF-Kameras zu erkennen und ihre Aufnahmezeiten schnell zu synchronisieren, um störungsfrei zu arbeiten. Anstatt Kabel zur Synchronisation zu benötigen, wird nur die vorhandene Hardware genutzt, um eine optische Synchronisation zu erreichen. Dazu wird die Firmware der Kamera um das Synchronisationsverfahren erweitert. Die optische Synchronisation wurde konzipiert, implementiert und in einem Versuchsaufbau mit drei ToF-Kameras verifiziert. Die Messungen zeigen die Wirksamkeit der vorgeschlagenen optischen Synchronisation. Während der Experimente wurde die Bildrate durch das zusätzliche Synchronisationsverfahren lediglich um etwa 1 Prozent reduziert. / Time-of-Flight (ToF) cameras produce depth images (three-dimensional images) by measuring the time between the emission of infrared light and the reception of its reflection. A setup of multiple ToF cameras may be used to overcome their comparatively low resolution, increase the field of view, and reduce occlusion. However, the simultaneous operation of multiple ToF cameras introduces the possibility of interference resulting in erroneous depth measurements. The problem of interference is not only related to a collaborative multicamera setup but also to multiple ToF cameras operating independently. In this work, a new optical synchronization for ToF cameras is presented, requiring no additional hardware or infrastructure to utilize a time-division multiple access (TDMA) scheme to mitigate interference. It effectively enables a camera to sense the acquisition process of other ToF cameras and rapidly synchronizes its acquisition times to operate without interference. Instead of requiring cables to synchronize, only the existing hardware is utilized to enable an optical synchronization. To achieve this, the camera’s firmware is extended with the synchronization procedure. The optical synchronization has been conceptualized, implemented, and verified with an experimental setup deploying three ToF cameras. The measurements show the efficacy of the proposed optical synchronization. During the experiments, the frame rate was reduced by only about 1% due to the synchronization procedure.