Micro corrdinate measuring machine for micro mechanism using parallel kinematics

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This study proposed a new coordinate measuring machine (CMM) based on a parallel mechanism instead of XYZ mechanism. Because the conventional CMM using XYZ mechanism consisting of three mutually orthogonal slide mechanism is not suitable for measurement with nano-order accuracy. This CMM is suited for precision measurement of the geometrical deviations of the micro parts with three dimensional profile because the parallel mechanism has a number of advantages as follows. The motion error of the moving platform has little effect on the measured value, because the measuring point is in sensitive directions of the scale units. The truss structure has a high stiffness because its members are subjected to very few bending force. The systematic error produced by each of the scales is averaged with the other two. The small inertial mass enables high moving speed. First, we performed the link configuration design using the error analysis by singular value decomposition. Obtained link configuration improves the moving accuracy and the measuring resolution. Moreover, we have designed the strut consisting of the prismatic joint, linear scale unit and the actuator. The inch-worm mechanism using piezoelectric actuators has been employed as the actuator of the strut. The strut has been expanded and contracted by the inch-worm mechanism under the load of 4 N.In addition, full-close-controlled positioning using the scale unit has been performed. The settling time for 10 micrometer positioning was less than 0.1 second.