Sonar-based obstacle avoidance, mapping, and graphical user interfaces for integrated teleautonomous systems

This thesis describes a project whose goal is to move a robot in teleautonomous mode in an unknown environment and find pipes to decommission. The project is divided into several modules to allow for porting to other platforms with a minimum of effort. While the robot moves through the environment, a low-level map, in the form of an occupancy grid, along with detailed location of pipes in the environment are obtained. This thesis deals with the low-level "reflex" of obstacle avoidance that is performed while the robot moves along its path. Also, it is concerned with some of the higher-level tasks involved in path planning and robot motion in order to negotiate through a hazardous environment. Pipe modeling is performed and verification made by overlaying the 3-D models onto actual images of the pipes. These 3-D models are easily edited and passed to previewers so that the operator can use the same controllers to manipulate both real and virtual platforms. The operators interactions with the system is made simple, user- friendly, and efficient using a graphical interface to control high-level tasks, keeping all low-level communications and sensor processing transparent.

The experimental testbed utilizes a wheeled mobile robot with ultrasonic range sen- sors. A fast and efficient obstacle avoidance algorithm has been created using sixteen ultrasonic range sensors. sensor using weighted sums of the sensor readings. This al- lows the robot to negotiate around obstacles quickly. This robot may not be capable of precise mapping due to its inaccuracy, but does serve as a very good testbed. Extensive experimentation has been performed with the modeling modules and the mobile plat- form. The integration has been performed and a testbed of pipes developed to show the operation and capabilities of the initial system. The results show robust operation in a variety of situations within the limits imposed upon it by positional inaccuracy.