BMW tests robot-assisted CT for non-destructive material testing
The use of RoboCT in the production environment offers the advantage over conventional CT systems of achieving inspection positions on complexly shaped objects, such as a vehicle body. Researchers at Fraunhofer development center X-Ray technology EZRT in Erlangen (Germany) have developed RoboCT technology for this purpose.
The CT system was installed in close cooperation with engineers from BMW’s Research and Innovation Centre (FIZ) in Munich at the interface between development and production and went into operation in July 2018.
In this setup, four cooperating robots, which move the imaging components such as the X-ray source and detector accordingly, drive around the vehicle. This allows RoboCT to reach all positions of the vehicle. Thus, the system can generate three-dimensional CT with the detail recognizability of the size of a human hair. With this technology, the object can be examined in detail with the highest precision without damaging it. Previously, the corresponding components had to be dismantled or even sawn out for such an analysis and examined in a separate CT system. By shortening the development cycles from idea to market launch, users are able to bring products to market faster.
X-ray CT systems commonly used in industrial applications are capable of tomographing objects with a diameter of around 30 centimetres and thus of capturing 3D information about all external as well as concealed internal structures. The CT images can be virtually split and analyzed on the computer into any number of stacks of sectional images. To achieve resolutions of less than one micrometer, extremely precise hardware components are required. Large industrial robots – here with ranges of three meters and more – can be used to achieve “regions of interest (ROI)” on much larger and more complex objects. The special challenge is to correct geometrical inaccuracies of the robots algorithmically directly from the recorded measurement data.
The most precise industrial robots of this size only achieve accuracies of ½ to ¼ millimeters over their entire working space – while for the CT, depending on the application, at least 1/20 millimeters are required. The solution to this problem is the basis for using this technology productively today.
However, this robot-supported CT is only the beginning of a larger idea: The long-term goal is not simply to acquire material data randomly, but only to record the relevant data. This so-called cognitive sensor system will decide for itself which data are relevant. Customers are supplied with a kind of highly flexible black box. They do not have to have any expertise in the field of non-destructive testing. Part of this box are robots, for example, which have access to different, self-adapting sensor systems and then decide for themselves in the broadest sense which methods they use and how. The robot then uses an X-ray system, an air ultrasound system or even a thermography system to solve a very specific defined task. Through the use of artificial intelligence, RoboCT can support people in various tasks by suggesting optimal parameters for accessibility and recording parameters as a black box, depending on the task at hand.
More information: https://www.iis.fraunhofer.de/en/profil/jb/2017/roboct.html
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