Increasing the milling accuracy for industrial robots using a piezo-actuated high-dynamic micro manipulator

The strong process forces arising during highspeed machining operations, combined with the limited stiffness of industrial robots, have hampered the usage of industrial robots in high-end milling tasks. However, since such manipulators may offer flexible and cost-effective machining solutions, a three-dimensional piezo-actuated compensation mechanism, which aims to compensate for the positioning errors of the robot, has earlier been developed. A prototype model-based control scheme for position control of the mechanism, utilizing LQG control, has been proposed. The main contribution of this paper is an experimental verification of the benefit of utilizing the online compensation scheme. We show that the milling accuracy achieved with the proposed compensation mechanism is increased up to three times compared to the uncompensated case.