Machine Vision Guidance System for a Modular Climbing Robot used in Shipbuilding

Abstract

During naval construction, vessels are divided into various blocks or subunits that are manufactured in different workshops and then carried to a building dock or shipway where they are welded together. This paper describes a versatile lightweight climbing robot that is capable of moving on the hull and a compact machine vision guidance system that allows it to follow grooves on the surface of the hull. This capability is useful for tasks such as inspecting welding seams, reducing the need for scaffolds. The robot is designed as a three wheeled Synchro-Drive vehicle. That allows it to perform movements in any direction without changing its orientation. The force of attraction necessary to stick the robot to the ship’s hull is provided by three permanent magnets that are placed at the bottom of the robot. To guide this robot when it operates in automatic mode, a real time machine vision system has been developed. This system is prepared to detect and track the groove that is formed between two blocks of a ship when they are joined for welding. This groove is detected by the vision system using a multiline laser beam and a camera with an appropriate filter. The camera used for this application is a compact vision system that includes image capturing, image processing and communications capacities in a single unit.