Abstract: To improve flexible coordinate measuring machine(FCMM) measurement precision, the design method of spatial error model is put forward based on functional networks owing to the error model limitations from the D-H method. The measurement model and the error model commonly used at home and abroad presently are introduced. The design process of functional network topology structure is presented detailedly. How to choose primary function is discussed. The approximate algorithm is researched, and the calibration experiment is performed by using 800 mm criterion gauges. The precision measurement results show that 800 mm gauge length measuring error from the model based on the functional network is far lower than those from the D-H method. It validates the new error model and the approximate algorithm.

Key words: Calibration, Flexible coordinate measuring machine(FCMM), Functional networks, Spatial error