Automation of the matting process for improved accuracy in optical coordinate measurements

Abstract

Optical coordinate measurements provide numerous benefits, such as high speed and non-contact operation; however, they are highly sensitive to the surface properties of the object being measured. Surfaces that are highly reflective or transparent, in particular, present significant challenges for optical measurement systems. In such cases, specialized matting sprays are commonly employed to ensure reliable data acquisition. As indicated by previous studies, manually applying these sprays can result in uneven coating thickness and streak formation, which are especially problematic for high-precision coordinate measurements and may negatively affect the accuracy of the results. This research tackles this challenge by aiming to improve the precision of optical coordinate measurements for applications requiring surface matting. A concept for an automated matting process is proposed, implemented using a robot designed and manufactured through 3D printing technology. The system enables controlled and repeatable application of spray, with a regulated force applied to the atomizer. The study details the mechanical design of the robot, the control components integrated into the system, and the methods used to regulate both the atomizer’s position and the applied force. To assess the effectiveness of the approach, comparative experiments were conducted. These experiments analyzed changes in the measured diameter of a reference sphere after applying the spray manually and via the robotic system. Measurements were performed using a Hexagon Absolute Arm RA-7320 in combination with PolyWorks software, and the force exerted on the atomizer was recorded in both cases. The findings demonstrate that automation allows the matting agent to be applied more evenly and in thinner layers, significantly enhancing measurement repeatability compared to manual application. Overall, the study confirms the advantages of automating surface preparation and highlights potential avenues for further development.