Towards fixtureless robotic in-line measurement assisted assembly, a case study

In the realm of Industry 4.0, measurement systems play an important role in adapting industrial robots to dynamic environments. Real-time control techniques such as Measurement Assisted Assembly (MAA) can exploit the digital measurements for operation process corrections. Likewise, the propagation of defects can be avoided with in-line measurement conditions. The purpose of this paper is to first understand the capability of robotic in-line measurement assisted assembly in the industrial case of peg-in-hole assembly and second, record the encountered challenges and their enablers. A proof of concept-formed by two 6DoF industrial robots, an in-line Linear Laser (LL), and an on-machine force sensor-have been designed and tested in a lab environment. The experimental results show that robotic in-line measurement assisted assembly can be performed within the tight tolerances of (i) 0,071 ° to 0,154° angular deviation between X and Y axes, (ii) applying minimum (near 0) Newton forces in X and Y axes when performing the peg-in-hole robotic assembly of two parts with only 50μm clearance, and (iii) within the company's cycle time. Further, for the effectiveness and practicality of robotic measurement assisted assembly systems, we recorded the encountered challenges and key enablers.