Non contact measurement & inspection
work autonomously. Employees manually position the trolleys on the system, which means that the exact position always varies. In addition, the weight of the trolleys and therefore the position of the drawers is constantly changing during loading and unloading. In order to maintain the required positional accuracy so that the vials are always grasped correctly, it is necessary to constantly recalculate the exact position for each row. In an almost fully automated production process, this task can only be accomplished by a 3D vision system based on machine vision. Other technologies would not have been able to meet the requirements. The use of sensors requires several scanning positions, which would extend the robot cycle considerably, making it impossible to achieve the desired number of cycles. The use of a 2D camera on the gripper would also be problematic because in addition to the extra weight, it would also be necessary to lay sensitive cables in such a way that they can withstand the robot’s movements over the long term. “The 3D cameras with a working distance of
Instrumentation Monthly March 2025
approximately 120 cm to the top drawer and 180 cm to the bottom drawer are extremely precise and still offer the robot a sufficient working range for collision-free handling. In combination with powerful machine vision software, however, it has been possible to meet all the requirements for this application,” explains Daniel Simon, authorised representative and responsible for technical sales at SIMON IBV.
3D VISION SYSTEM FACILITATES A FULLY AUTOMATED PROCESS
In addition to the robot, the hardware components of the robot cell include high-resolution 3D cameras using the stereometric method with pattern projection and industrial computer technology with fast processors for PC-based evaluation. MVTec HALCON was selected for the machine vision system. HALCON is the comprehensive standard machine vision software. On the one hand, the software offers a wide range of powerful machine vision methods. On the other hand, because the software is hardware-independent, it can be
used flexibly with different cameras, for example. SIMAVIS from SIMON IBV is utilised as the user interface for visualisation and for the simple operation of the system. Here is how the process works: First, an employee pushes a trolley with the vials into one of two possible positions. A 3D camera within the robot cell pinpoints the trolley and checks the status of the drawers, i.e. whether they are open or closed. The programmable logic controller (PLC) contains information on whether the trolley currently being processed is to be loaded or unloaded, which drawer is to be opened, and how many vials are already there and where. To begin with, the 3D camera always takes a picture of the drawer to be opened. The MVTec HALCON machine vision software uses this image to create a coordinate system and shares it with the robot. This enables the robot to open the drawer. In the next step, the 3D camera takes a picture of the contents of the drawer. This is used to determine how many vials are stored there and where exactly they are located. In addition to the number, the system also checks for errors, such as whether
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