On the optimization of HDD arms with piezoelectric actuation

Abstract

As storage data density in hard-disk drives (HDDs) increases, precision positioning of HDD heads becomes a more relevant issue to ensure enormous amounts of data to be properly written and read. Since the traditional single-stage voice coil motor cannot satisfy the positioning requirement of high-density tracks per inch HDDs, dual-stage servo systems have been proposed to overcome this matter, by using voice coil motors to coarsely move the HDD head while piezoelectric actuators provide fine and fast positioning. Thus, the aim of this work is to apply topology optimization to design HDD arms, by finding optimal placement of base-plate and piezoelectric material for high precision positioning HDD heads. Topology optimization is a structural optimization technique that combines the finite element method with optimization algorithms, and it uses a rational approximation of material properties to vary the material properties between “void” and “filled” portions. The design problem consists in generating optimized structures that provide maximized displacements, appropriate structural stiffness, and resonance phenomena avoidance. The requirements are achieved by applying formulations to maximize displacement, first resonance frequency, and structural stiffness. The implementation of the algorithm and results that confirm the feasibility of the approach in obtaining improved conceptual designs are presented.