Non contact measurement & inspection
individual ampoules are upright or have tipped over and therefore cannot be picked up by the robot. The robot’s gripper is equipped to handle 46 vials at a time. Once a drawer has been completely unloaded, the 3D camera determines the position of the drawer handle so that the robot can close it again. This process is then repeated with the remaining eight drawers until the trolley has been completely unloaded.
MACHINE VISION SOFTWARE HANDLES DIFFERENT TASKS
Implementing this type of solution, in which the robot is largely autonomous, presents a number of challenges. Stephan Trunk from Goldfuß engineering describes it this way: “The development of the robot cell took place under tremendous time pressure. The demand for the vaccine had to be met as quickly as possible, which also served as an intrinsic motivation for our employees.”
The main challenge was to achieve high precision. The position of the vials must be detected with an accuracy of 0.1 millimeters. And with a working area of 800 x 600 mm and a depth of 600 mm, this is no easy task. The extremely valuable contents of the vials make this requirement even more critical. The vials must not be damaged under any circumstances. However, loading and unloading must be done quickly, in part to facilitate the rapid vaccine delivery. “The vision system also faced two special challenges. On the one hand, it was necessary to work with different materials. The glass of the vials and the metal, such as that of the trolleys, have transparent or reflective surfaces and are therefore difficult to detect. On the other hand, the system will only work if the robots can operate autonomously in three-dimensional space. To do this, however, the machine vision software must also include powerful 3D vision technologies. There are not many machine vision software products that achieve the necessary performance and robustness in this regard,” says
Daniel Simon. The companies decided to go with the MVTec HALCON machine vision software. “Based on our many years of experience with HALCON, we knew that the software has an extensive library with many extremely powerful methods,” explains Daniel Simon.
Various machine vision technologies are used in the robot cell that was developed. One of the technological requirements in the system is the so-called hand-eye calibration. This technology is essential for any application in which cameras work in conjunction with robots. During this process, the robot’s coordinate system and the camera’s coordinate system are synchronised. This makes it possible to match the movements of the robot to the images from the camera with the utmost precision. HALCON’s hand-eye calibration delivers extremely high accuracy in determining the relative position between the camera and the robot. This makes
it possible to determine the exact positions and orientations of the vials in relation to the robot. This calibration is the basis for all further machine vision applications with HALCON that are necessary for this application. At the same time, the system additionally utilises the stereo vision 3D vision technology, which is also included in HALCON. This technology is designed for 3D reconstruction and is particularly useful for large or medium-sized structured objects. In addition, this technology facilitates quality control or position detection of three-dimensional objects. The technology also calculates 3D coordinates on object surfaces. This can be done with one or with multiple cameras. Stereo vision is particularly well suited for the precise measurement of elevations. One feature within the technology is multigrid stereo, an advanced method of interpolating the 3D data in homogeneous parts of the image. This method yields greater accuracy for small objects.
NEW ROBOT CELL IN OPERATION SINCE JULY 2021
“We have managed to develop a completely new robot cell and get it up and running with process stability in just six months. We are proud to have contributed to accelerating the production of a vaccine against a dangerous virus,” says Stephan Trunk of Goldfuß engineering. The system was put into operation in July 2021. The strict requirements - in terms of speed and precision, for example - were also met. “This project illustrates all of the potential and possibilities offered by machine vision. Thanks to the successful implementation, we are very motivated to automate other challenging tasks. There are a number of promising projects already underway with Goldfuß engineering,” says Daniel Simon.
MVTec Software
www.mvtec.com
58 March 2025 Instrumentation Monthly
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