Insights | Berghof Testing

Testing with 3D scanners

December 9, 2019

With the "Smart Component Tester (SCoT)” from Berghof Testing, for the first time components at the end of the assembly line can be tested for the correct assembly and position, regardless of the light, contrast, reflection and position. SCoT also no longer requires any complex conveyor technology based on workpiece carriers – and is therefore very flexible to use.

Many provides currently use industrial image processing systems with cameras for their testing systems to be able to quickly and reliably test components after production and assembly in all relevant quality parameters.

This method has its pitfalls: “The industrial image processing systems used to date are now no longer the first choice of equipment, especially for different painted surfaces and very different components,” explains Dipl.-Ing. Klaus Maichle, project manager at Berghof Testing.

The reason: These systems rely on a corresponding contrast of the components and a light adapted to those components. To be able to achieve convincing results, a large number of aligned cameras is therefore required in the case of different painted surface finishes and large component variance. And this is very complex and therefore very expensive to do. It is also inflexible for future variants. In practice, interfering light or changing ambient light also frequently falsifies the results.

Klaus Maichle with a team of specialists from various Berghof Testing divisions developed a whole new testing system for a renowned automotive supplier, which put an end to these difficulties once and for all. No cameras are used, but rather special 3D scanners. The optical check occurs here using 3D images and is absolutely independent of light, contrast, reflection and position.

However, these devices have another advantage that Berghof Testing purposefully took advantage of with its new testing system: They can use triangulation to determine the exact position of the supplied component. In this way, Berghof is now able for the first time to do without the normally used specific workpiece carriers and therefore do without expensive conveyor technology.

 

A short linear conveyor belt transports the components – without a fixed orientation and without determining a variant to the first station where a 3D scanner records the respective 3D model. This 3D model uses the robot gripper to precisely calculate the removal coordinates.

The robot is therefore able to quickly and reliably record the respective component - and it does this regardless of where and at what angle it is positioned on the conveyor belt. “Thanks to this completely new approach to inspecting components, the system of course saves a tremendous amount of time and money, because the old system with numerous individual workpiece carriers and corresponding set-up times is no longer required,” explains Maichle.

 

The robot then picks up the component and positions it in the suitable inspection position. The second 3D scanner shows the 3D data for the virtual camera developed by Berghof, which performs the optical inspection similar to the conventional vision inspections – however unlike the conventional inspections, it is completely unaffected by the current lighting situation, the contrast between the component and its environment or interfering reflections.

 

It sounds simple, but it is quite complex – especially when it comes to the software, which project engineer Benjamin Ulrich explains: “We developed a special software solution for this new type of testing system based on ‘LabVIEW,’ which we also use to control the robot. We also used this as a basis to program the virtual camera and our unique solution to correct the position tolerances resulting from this type of localization. The system is also designed so that we can very easily and quickly add new test specimens via the user interface." To optimize the cycle time, the software also controls the three stations of feed, test and discharge at the same time. In this way, three components can be in the system at the same time.

Other important advantages of SCoT: The system concept not only saves a lot of production space, but it also costs a lot less: “Roughly estimated, our new system is around 50 percent cheaper than conventional systems with industrial image processing systems and specific workpiece carriers,” summarizes Maichle.