Measurement and compensation of deformations in coordinate measurement arm

Abstract

The paper is dealing with Coordinate Measuring Arm (CMA) accuracy. Error sources contributing to the measurement uncertainty of CMAs are summarized. In sequence, the focus is on elastic deformations as one of the main error sources. A novel system is presented, developed specifically for measuring link deflections. A detailed evaluation of the system was performed. The results confirmed suitability of the system, which was subsequently mounted on a CMA segment for measurements of 1. external force influence on segment deflection, 2. dynamic measurements of link deflection and 3. compensation of CMA deformations. Vertical deformation in the segment was measured at 30 µm, the dynamic deformations were measured at 40 µm, while the improvement with compensation was found in order of 11% to 16%.