Calibration of a Translational 3-DOF Parallel Kinematic Machine using Full Pose Measurements and Mechanical Adjustments

This paper presents a complete calibration method for a translational Parallel Kinematic Machine (PKM) with three degrees of freedom (DOF). The method takes advantage of the geometric specificities of this type of machine to easily compute the kinematic parameters from full pose measurements. The work presented here also includes a process to mechanically adjust the machine in order to reduce the rotational error, unlike other calibration methods where the results are only used in software to compensate for the positional errors. The inaccuracies of the linear actuators are also measured and included into the kinematic model of the machine to allow for a better compensation of the errors. The effectiveness of the procedure has been verified by experiments on a specific PKM prototype, but the method may also be applied to other configurations of translational 3-DOF PKMs.