Manufacturing plants in all industries require ongoing inspection of their production parts, to monitor consistency and quality of the production process. Typical part features to measure are the diameter and the location of a hole (circle, slot, etc.), the location of an edge, the distance to a surface, the location and length of studs, etc. Historically, off-line measuring systems, such as CMM’s, have been used to measure random part samples removed from the production line, and brought over to a dedicated metrology room. Then came in-line ‘fixed sensor’ stations, offering the possibility to inspect 100% of the production output and ensure prompt reactivity to the production process control.
However, such stations inherently suffer from their lack of flexibility, since any new feature along the part one would want to inspect would generally require the installation or re-installation of a fixed sensor within the station. This is obviously time-consuming and expensive, and therefore limits the ability to change the features to inspect over time as the production process evolves. Hence the more prevalent approach nowadays of using a robot right along the production line, and turning it into a measurement robot – the resulting equipment being referred to as Flexible Measurement System (FMS) or as Automated In-Line Gauging.
By mounting a small-range sensor (such as a 3D laser/camera system, a 1D distance sensor, or a touch probe, etc.) at the end of the robot, one has now access to an, in effect, large-range measurement equipment which can be reprogrammed at any time to inspect new features. However, considering the lack of accuracy of an ‘off-the-shelf’ robot, it is imperative to complement this equipment with a robot calibration solution, in order to ensure high enough measurement accuracy within the entire effective measurement area.
