Vision-based sensing of the welding process: a survey

A substantially successful technology that has emerged is the use of electro-optics, which has been expanded into the realm of ‘machine vision’ with the rapid advance in optical sensor technology and computer processing power. The basic principle of the optical sensor has remained unchanged over the years. Charge-Coupled Devices (CCDs), laser diodes and microprocessors form the basis of this type of sensing technique. CCDs have found their use in the observation of weld pool. It is known that the surface of the weld pool contains information that can be used to control the welding process. Researchers have used cameras to observe the weld pool and study the shape of the weld pool. Optical sensors have also been used to measure the arc light to determine the state of the weld pool. This paper summarises limited research done in the field of sensing the weld pool visually or optically and is intended to give the reader a brief overview of what optical technologies and techniques have been used to sense the weld pool state.