Nanometre-cutting machine using a Stewart-platform parallel mechanism

This paper deals with a nanometre-cutting machine using a parallel mechanism with six degrees of freedom. A movable stage was supported with six links, each of which extends with a lever mechanism to expand the extension of a piezoelectric actuator. The movable range of the prototype was 20 µm in the x- and y-directions and 100 µm in the z-direction. The resonant frequency of the prototype was 94 Hz in the x- and y-directions and 102 Hz in the z-direction. The stage motion was controlled by the feedback of the link length. The motion accuracy of the stage was 0.1 µm after the calibration with fourth-order polynomials. This stage was applied as a positioning device of the nanometre-cutting machine with an atomic force microscope structure. The motion performance was also evaluated by observing diffraction gratings and an optical flat. Pockets with a depth of several tens of nanometres could be machined on acrylic resin. Not only the motion error of the stage but also the anisotropic stiffness of the probe affected the machining error.