Brave new weld

With a worldwide shortage of skilled welders creating problems for manufacturers,
engineers have developed the world’s first autonomous welding robot. Jon Excell reports.

The once widely-held notion that robots are stealing our jobs is now little more than technophobia. The reality, of course, is that industrial robots are increasingly being used to carry out the dirty, unpleasant and often dangerous jobs that we no longer want to do.

While many of the tasks performed by industrial robots are therefore relatively unskilled jobs, improvements in both hardware and software have led to the increasing use of robots in operations that require a fair degree of skill. For instance, in response to a worrying global shortage of trained welders, participants in the EU’s Nomad project, which aims to develop an autonomous robot for welding, recently demonstrated a prototype.

Keith Herman, Nomad’s technical co-ordinator and a senior R&D engineer at Caterpillar, explained that companies like his rely on skilled welders to work on customised products. And while robots are perfect for the accuracy and speed required by large production runs, typical robotic welding techniques become far too expensive when used to weld custom products.

By the time a robot has been re-programmed to cope with new component dimensions, and the components due to be welded have been precisely positioned, a skilled welder could have completed the job, losing the advantages of automation. Unfortunately, finding and maintaining skilled welders is, said Herman, a problem.

Thus, the project has set about developing the robot equivalent of a skilled manual welder – an adaptable, intelligent individual that’s able to cope with the unexpected.’With the Nomad system you just put a part in the area, the vision system finds it, and the autonomous robot welds it,’ said Herman, adding that the biggest technical strides taken by the project are in the development of the software and algorithms used to locate the part. He contrasted this with a traditional robot welding system where fixturing would be used to find the part.

The prototype system, recently demonstrated at Germany’s Fraunhofer Institute, consists of a robot arm from German robotics specialist Reis, mounted on an autonomous vehicle developed by French company Robosoft. Equipped with a navigation and vision system developed at the institute, the system also relies heavily on IGRIP, a 3D software simulation tool from Delmia Corporation,to design and evaluate robot operations.

During the Fraunhofer demonstration, the system recognised a test component – part of a bridge – and by matching the real image of this component with 3D CAD data, was able to locate the part and identify its precise position and orientation. IGRIP then created the offline program and path data for both the robot arm and the vehicle. The vehicle then approached the bridge component and carried out robot arm movements as if performing a weld.

Herman claimed that the project’s findings demonstrate that it should be possible to fabricate customised products as quickly and easily as large multiples, opening up new customisation opportunities for manufacturers.

He added that while the demonstration system has worked with fairly small parts, there is no reason that it couldn’t be scaled up to cope with large-scale fabrications like earth-moving equipment and pedestrian bridges.

The project is due to run until next August. After that Herman said it is difficult to predict how long it will take the technology to appear on the factory floor. But he is confident that the techniques are accurate enough to ultimately make robot welders as good as experienced humans.