The estimation method of uncertainty of articulated coordinate measuring machine

The articulated coordinate measuring machine (A-CMM) is a measuring machine, the traceability of which should be kept. However, it is difficult to keep the traceability because the calibration of A-CMM is performed by the manufacturer´s own method. We planed to use a 3D artifact which consists of 9 balls for the calibration and testing of the A-CMM. The kinematical model of A-CMM was described in the D-H notation. In A-CMM measurement, a cone-shaped stylus was used. We measured the artifact in five different locations and orientations. Each ball was measured five times in different postures of A-CMM. Totally, 45 points were measured in each location and orientation of the artifact. After that, five sets of the kinematic parameters were estimated. One set of kinematic parameters was applied to the measured points in five different locations and orientation of the artifact one after the other. Then the root mean squares are calculated in 25 different combinations to estimate the correctness of the kinematical parameters. As a result, the calibration achieved a better result than the specified accuracy of A-CMM.