For this PoC, the Universal Robot cobot was suggested because of convenient safety and collaboration features and previously proven suitability for similar applications. While these robots provide a capable and intuitive programming interface natively, it is difficult to program scalable and complex interactions. For example, using the CAD geometry of the reactor as reference to localize and calibrate the screw holes, and subsequently plan the handling motions in the new reference frames, would be difficult to achieve using the native programming on the robot directly. Similarly, generating and parameterizing the various dynamic behaviors for searching for the alignment of the screw and screw hole, or the screwdriver and nut, and executing those behaviors in a force-compliant control mode, would require a lot of complicated and specific scripts on the robot. Not only does this need specialized knowledge of the proprietary robot language, but also makes it difficult to switch to another brand without needing to reprogram everything (for example, because payload or IP rating requirements change, or because a 7th joint is needed for the robot to be flexible and dextrous enough to reach the difficult locations).

Overall, the use of an external controller not only allows for more advanced sensor-driven control, but also makes the software development process more agile, scalable and reusable. Any custom functionality for the project is written in C++ or Python modules that can then be reused in other applications and even with different robots.