[3B3] Process to part inspection: using hybrid robotics to enable flexible manufacturing NDT
S G Pierce¹, H Gover¹, R Vithanage¹, E Mohseni¹, M Vasilev¹, C Loukas¹, C MacLeod¹, G Dobie¹, J O’Brien-O’Reilly², S Paton², G Munro², T O’Hare³, M Grosser⁴ and A Oakley⁵
¹University of Strathclyde, UK
²Spirit AeroSystems, Aerospace Innovation Centre, Glasgow, UK
³Spirit AeroSystems Belfast, UK
⁴Spirit AeroSystems, USA
⁵KUKA Robotics UK Ltd, UK
Automated NDT inspection of large components currently involves precision positioning of the part with respect to the NDT scanning equipment to allow predetermined inspection scan paths to be executed. Historically, for ultrasonic scanning a full immersion tank scanner would be employed, with a predetermined taught path for the scanning probe. As technology has evolved, a number of non-immersion systems have emerged for ultrasonic NDT, using industrial robots as flexible positioners to allow inspection using contact-based probes (wheel probes or conformable wedges) or squirter-based systems. The same technology can, of course, be used to deliver other NDT modalities more suited to surface or near-surface inspection such as vision-based or eddy current inspection.
As automation technology has progressed, new hybrid robotic systems have emerged, particularly combining industrial robotic arms with mobile robotic platforms. This hybrid combination presents unique opportunities to revolutionise NDT inspection of large components at the manufacturing stage. Now, instead of a part being fixtured and brought into an NDT cell for inspection, it is possible to bring the NDT process to the part. With current collaborative robotic technology involving safe-space human-machine collaboration and obstacle avoidance based on sensor feedback (force-torque, optical, etc), a wheeled base unit can be employed to bring an inspection robot to a part for inspection (whether ultrasonic, visual or electromagnetic). The scientific challenges for this hybrid approach lie in the increased degrees of freedom in the robot system and the coupling of kinematics between the base and robot arm, with the different positional accuracy and repeatability associated with the traditionally separate robot technologies. The emergence in the supply chain of these hybrid robot systems (such as the KUKA KMR) provides new opportunities for NDT inspection. Here, we report on studies of the positional accuracy and repeatability of such a hybrid robot system (KUKA KMR) using precision 3D volumetric metrology to show the opportunities and limitations of the current hybrid robotic technology for such ‘process to part’ NDT inspections. The study will examine the decoupled error of the robot base and arm, before analysing the compounding effect that the base error may have on the error experienced at the tool centrepoint (TCP). To reduce this error inherent to the robot hardware, the implementation of vision-based feedback from an RGBD camera is also examined.
As automation technology has progressed, new hybrid robotic systems have emerged, particularly combining industrial robotic arms with mobile robotic platforms. This hybrid combination presents unique opportunities to revolutionise NDT inspection of large components at the manufacturing stage. Now, instead of a part being fixtured and brought into an NDT cell for inspection, it is possible to bring the NDT process to the part. With current collaborative robotic technology involving safe-space human-machine collaboration and obstacle avoidance based on sensor feedback (force-torque, optical, etc), a wheeled base unit can be employed to bring an inspection robot to a part for inspection (whether ultrasonic, visual or electromagnetic). The scientific challenges for this hybrid approach lie in the increased degrees of freedom in the robot system and the coupling of kinematics between the base and robot arm, with the different positional accuracy and repeatability associated with the traditionally separate robot technologies. The emergence in the supply chain of these hybrid robot systems (such as the KUKA KMR) provides new opportunities for NDT inspection. Here, we report on studies of the positional accuracy and repeatability of such a hybrid robot system (KUKA KMR) using precision 3D volumetric metrology to show the opportunities and limitations of the current hybrid robotic technology for such ‘process to part’ NDT inspections. The study will examine the decoupled error of the robot base and arm, before analysing the compounding effect that the base error may have on the error experienced at the tool centrepoint (TCP). To reduce this error inherent to the robot hardware, the implementation of vision-based feedback from an RGBD camera is also examined.
