TWI Technology Centre (Wales) has been using industrial robots for automated non-destructive testing (NDT) since 2012, and is continually working towards improving the existing setup. While research until now has focused on integrating NDT into the manufacturing process, TWI is also developing a more flexible automated inspection solution for smaller component inspection that can be used alongside a human operator.
A cooperative robot (also referred to as a cobot) has been purchased as part of the AEMRI initiative. These robots are specifically designed to work alongside humans in a shared workspace by monitoring the forces applied to each joint to avoid injury during collision. Furthermore, cobots are easily programmable, can interface with external equipment and can position NDT sensors with six degrees of freedom. The cobot has a high-resolution force-torque sensor, which allows it to “feel” and follow a surface while exerting a controlled force onto the surface. This is especially relevant for ultrasonic and potentially eddy-current inspections. A cobot is also useful from an R&D perspective; when developing a new NDT technique employing a robot, there is inevitably a lot of initial physical interaction required between robot and operator. With a cobot, this can be done safely and more efficiently compared with a traditional robot cell setup
TWI has been working alongside a consortium of project partners on an Innovate UK-funded project called CFLUX to develop an inspection system utilising the cobot for inspection sensor probe deployment. The project partners, M Wright & Sons, ETherNDE, Advanced Hall Sensors, Far UK and TWI are developing two non-contact, dry NDT techniques for carbon fibre. These techniques will allow thorough quality assurance of raw composite materials, using automation and advanced eddy current technologies to identify subsurface defects in larger manufactured components.
The project reached a milestone recently, with a 3D dummy part designed by FAR and printed by Wright & Sons being tested in an integrated system for the first time. A plastic dummy part, enhanced with metal washers, was used to produce positive signals that could be used to tune the eddy current response. This offline path planning was performed by TWI using RoboDK software before the system signals were integrated into TWI developed software. The amplitude signals from the bespoke EtherNDE eddy current probes were successfully translated and plotted on a 3D mesh to create a CAD type model C-Scan result on the operator screen.
This first breakthrough is a large step in creating a final system that will allow for the fast inspection of composite parts for the aerospace industry.
