Abstract: In order to improve the calibration precision of 6DOF parallel mechanism, a calibration method based on external coordinate measurement is presented. The position and attitude informations of the par- allel mechanism are acquired using common measuring devices and the residual equations with uniform measure are constructed. These equations can ensure the identifiability of each geometry parameter's , so no special auxiliary calibration equipments or redundant sensors are required. From the residual equa- tions, the estimated values of geometry parameters are obtained by optimization method, and the ideal pa- rameters are replaced by them for the parallel mechanism inverse kinematics calculation of to realize the error compensation. The simulation results show that this method can decrease the effect of measure noise, and the kinematics accuracy after calibration can reach the same order of magnitude as measurement noise since the errors of parallel mechanism's are not usually cumulated. The calibration accuracy is improved more than 5 times after error compensation by using the method.

Key words: mechanics, kinematics calibration, 6DOF, parallel mechanism, error compensation