A number of growing fields, such as nanotechnology, MEMS development, and optical metrology, demand increasing performance from devices capable of nanometer scale positioning resolution. Piezoelectric actuators provide sub-nanometer resolution, but a very limited total range that necessitates motion amplification. Current mechanisms for motion amplification produce limited output motion for their size and contain trajectory errors. The work presented here is the synthesis of a single-degree-of-freedom motion stage with a large output motion relative to the device size and with no design induced trajectory errors. Topology optimization is used as a means of identifying an optimal configuration for a compliant mechanism. A parametric study of this mechanism configuration guides development of an initial solid model, which is refined using geometrically non-linear structural finite element analysis. It is demonstrated computationally that amplifications up to ten times the input motion can be produced with linear output motion. This represents a 2% displacement relative to the device height, which is significant when compared to the 0.1% motion of the input piezoelectric actuator. Methodology and software were developed for experimentally characterizing motion of piezoelectrically driven actuators using a laser interferometric microscope. Results for the measured motion of a commercially available motion stage are presented.
Worcester Polytechnic Institute
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