抄録
This paper presents a study of calibration method for a 6-degree-of-freedom parallel mechanism. A coordinate measuring machine (CMM) based on 6-degree of freedom parallel mechanism is considered to give higher accuracy, speed and stiffness in measurement. In order to reduce kinematic parameter errors, which is directly cause to measurement errors, a calibration is needed. In this calibration, kinematic parameter errors are identified by the least square method. However, it is difficult to perform a calibration when using a high accuracy angle measuring device with small angle range. In this research, a calibration method is performed by least squares method so that the position error of ballplate measured by CMM and the angular error of the end effector is minimized. The measuring points are increased in the simulation, under the limitation of the small angle range of the end effector. The simulation results shows that by adding measuring points from 66 to 132, the parameter error, the position error of ballplate and the angular error of the end effector are reduced from 1264um_RMS to 37.3um_RMS, from 568.3 um_RMS to 1.8 um_RMS, and 116.2 um_RMS to 0.1 um_RMS, respectively.
