Autonomous measuring robots independently find their way to the target object for inspection and measurement
With funding from the German Federal Ministry of Education and Research (BMBF), metrology company ZEISS has researched and developed the concept of an autonomous measurement robot (AuMeRo) in co-operation with partners including BMW and the Institute for Metrology, Control and Microtechnology (MRM) at the University of Ulm in Germany.
Now, a fully functional prototype has proven the AuMeRo can handle tasks such as the inspection of gap dimensions and flushness on unpainted or painted car body parts. The need for autonomous metrology arose from the increasing demands of industry for the need for modularisation in their production. Industries particularly affected by this, such as the automotive industry, are therefore planning in the long term to dissolve sequential manufacturing processes with highly specialised stations and replace them with flexibly deployable manufacturing islands.
Intelligence and autonomy
The AuMeRo is a rectangular platform with wheels at the bottom and a robotic arm with an optical measurement sensor at the top. “Of course, this hardware aspect is not revolutionary in itself,” explains Dr. Matthias Karl from Corporate Research at the ZEISS Group. “The key task was to create the necessary intelligence on the software side for autonomous movement to the object, its measurement and data processing.”
The Institute for Metrology, Control and Microtechnology at the University of Ulm has a focus on autonomous driving in collaboration with several car manufacturers. It therefore developed and implemented the navigation system for the mobile measurement platform, which enables it to move autonomously to the target object while safely avoiding obstacles. The Institute for Laser Technologies in Medical and Metrology researched suitable optical measurement techniques for the special application, focusing on multi-wavelength holography. ZEISS, as the group coordinator, contributed the application-specific optical metrology and handled the movement of the robotic arm, object recognition and measurement pose control using optical image recognition in conjunction with machine learning.
According to Manuel Schmid, Product Manager at ZEISS, the user selects an object via software, for example a vehicle door, its rough location and then the intended measurement plan. From this point on, AuMeRo acts fully autonomously. Object recognition happens via camera and is based on a digital twin of the object. For the actual measurement, the mobile platform is equipped with additional optical sensors: For this purpose, ILM developed a special measurement sensor with advantages for short measurement times and robust environmental influences, which uses multi-wavelength digital holography.
In this way, topographic data of an entire area for diffuse and/or specular reflective surfaces can be obtained within one snapshot. After the platform has found and approached the object, the robotic arm moves the measuring head according to the requirements from the measuring program, taking into account the current spatial conditions.
“With its ability for autonomous mobility and object recognition, AuMeRo is ready for a future in which mobile,modular manufacturing islands are the norm, and allows measurement to take place wherever and whenever it is needed,” Schmid says.
According to Jan-Klaus Dziergwa, Project Manager Car Body Engineering, Quality Management BMW Group, the car manufacturer is enthusiastic about the result of the project.
“At BMW, we are highly interested in fulfilling individual customer wishes and at the same time continuously increasing the efficiency of our production and quality assurance. This requires innovative methods and technologies, and AuMeRo is an excellent example of this,” he concludes.