A framework for telecontrolled service robots

The present work is a part of the ongoing development of a semi-autonomous remotely controlled IP centric service robot framework. An instance of the framework is a robot for weed extermination in an outdoor environment. Technologies built upon in this thesis include an embedded platform, reconfigurable hardware, a software platform and 802.11 WLAN technology for communication. The hardware includes a DC motor controller subsystem, sensory subsystem and stepper motor controller subsystem, whereas the software handles the communication between the processor and the remote PC, transforms two-dimensional information of the joystick to speed and direction commands using a vector-based control scheme and provides the video feedback stream. The robot is comprised of a heavy duty chassis with four wheels. Two DC motors provide the drive for the back wheels operating from two 12 volts car batteries. Two open source motor control modules (OSMC) implement the high power H-bridge control system for each of the motors. This operator assisted robot includes some degree of machine intelligence in order to deal with uncertainty in an outdoor environment. A collision avoidance subsystem provides local intelligence designed to avoid obstacles that the operator may not be able to respond to quickly enough. This aspect of the framework was based on a fuzzy logic controller and utilizes sonar to estimate distances to obstacles. The semi-autonomous operation also includes suitable APIs to implement weed removal service tasks with the help of a stepper motor controller subsystem.