The applicability of vision systems to positional control of hot wire TIG welding

TWI Industrial Member Report Summary  433/1991

C J Foster

Scope

Modern vision sensing systems offer a route to the development of controlled welding automation. Such systems are able to accommodate changes (often large and abrupt) in workpiece presentation standards (fit, finish and position) encountered in many welding applications.

A precursor to the successful application of vision sensing systems is a full understanding of the means by which they are able to acquire and analyse images of the workpiece. Using the hot wire tungsten inert gas (TIG) process applied to multipass welding as a vehicle to explore such systems, work has been directed towards developing image acquisition and image analysis techniques capable of working in the harsh and real time, world of the welding process.

Hardware and software have been developed to provide welding head guidance (joint tracking) with information derived from a vision sensor system. With this facility it has been possible to demonstrate controlled arc welding.

As the underlying analysis and control principles are likely to outlast the specific equipment involved, this report stresses these principles (illumination, noise, image enhancement and joint location) rather than the hardware details.