We develop the kinematic model of portable coordinate measuring arm (PCMA) based on the research on its mechanical characteristics and working principle, and present a comprehensive thermally-induced error correction model for PCMA. Based on the model and nominal data provided by a highly accurate coordinate measuring machine, the technique for thermally-induced error compensation of PCMA is presented along with measuring a standard artifact at the corresponding temperature field. Experimental results demonstrate that the deviation of PCMA at different temperatures is controlled in the range of ±10 μm using this technique to calibrate the PCMA.

A technique to calibrate faro retro probe using laser tracker system (LTS) is presented. The deep-access retro probe enables LTS to perform three-dimensional (3D) measurements of surface hidden features. It has been shown that misalignment errors are the key contributor to measuring errors of retro probe. A device for measuring misalignment errors of retro probe is invented. Theoretical analysis and experiment show that using this technique to calibrate retro probe, the misalignment errors of retro probe can be eliminated effectively and quickly.