Range extension for large-scale robotic precision 3-D measurements in vibration-prone environments

Abstract

This paper presents a range extension concept for a high-precision robotic inline 3D measurement system. A scanning confocal chromatic sensor (SCCS) is integrated with a magnetically levitated and actuated measurement platform for the acquisition of 3D images with sub-micrometer resolution, enabled by means of active sample-tracking to compensate for relative motion between the SCCS and the sample. Based on an intermediate range extension approach, the lateral scan area is pre-extended to enable a robotic repositioning of the 3D measurement module, ensuring sufficient overlap regions between the individual 3D image frames. Experimental results show that the proposed concept extends the 3D measurement modules’ measurement range by about 80% of the lateral scan area within an acquisition time of about 90 s. Range-extended 3D measurements directly in a vibration-prone environment reveal that 97% of disturbing relative motion between the SCCS and the sample are compensated by the active sample-tracking approach. In this way, lab-like conditions for the SCCS are established directly in an industrial production line and, improving the measurement error by three orders of magnitude down to several tens of nanometers.