The authors are in the School of Electrical, Electronic and Information Engineering, Centre for Automated and Robotic NOT, South Bank University, 103 Borough Road, London SEI OAA. The aim of the research project was to develop a robotic system that would perform a raster scan of large horizontal metal plates using an ultrasonic inspection technique. The project involved a number of tasks requiring in-liouse research in automated control and self-navigation of the robot, NOT sensor deployment and ultrasonic data acquisition and analysis. In-house software has been developed to control the scan trajectory of the vehicle and locate and plot position of the ultrasonic sensors and the presence of any defects. The system is readily transportable from one inspection site to another and a graphic display analyses and shows results of the ultrasonic inspection. The cost of the system is several times less than the large gantry X-Y scanning systems that are currently used for steel plate inspection.