Application And Research Of Matching Techniques Of Circular Indexing Error On Optimal Measurement Areas Of FCMM

The flexible coordinate measuring machine (FCMM) is mainly composed ofcircle optical grating encoder, high-precision mechanical structure andmultifunction software. However, because the FCMM is a kind of multistep,tandem type and polar coordinate measurement system. Its error will be passed stepby step, accumulated and magnified, resulting in its accuracy can not meet therequirements of some practical applications, Therefore, we must continue toimprove its measurement accuracy.Because circle optical grating encoder have circular indexing error in practicalmeasurement, so different combinations of encoders make flexible coordinatemeasuring machine produce different measurement errors. If we can find arelatively small area of the measurement error of the flexible coordinate measuringmachine-the optimal working area, when the measured piece is placed in theoptimum working area, we can use the low-precision FCMM to achieve highprecision measurement.The main research contents of this paper include following aspects:(1) Obtaining angle measurement error,also called circular indexing error in thispaper, caused by circle optical grating encoder installation eccentric, giving themathematical expressions and the fitting graphics;(2) Doing experiments and analysis the effect on measurement precision caused bya single circle optical grating encoder which contains circular indexing error, theeffects of combination and matching between two, three, the six circular gratingencoder, measurement error distribution in working area, giving the optimalworking area;(3) Validating the optimal working area by actual measurement experiment.