Dynamic Absorber Design for Actuator Arm of Hard Disk Drives to Improve Impact Resistance^#

Abstract

Because the current actuator assemblies in hard disk drives (HDDs) are flexible systems, the resonant modes of the system inevitably limit its servo control bandwidth, which in turn limits the aerial density growth of HDDs, and also its shock robustness especially when HDDs are being increasingly deployed for consumer applications. The design and analysis method of a dynamic absorber to improve dynamic properties and shock resistance of HDDs is presented in this article. The HDD and the attached absorber were established and modeled as a 2 degrees-of-freedom (2DOF) system. The design parameters and structural configuration of the damping device, which is suitable for HDDs under base excitation, have been specified. Theoretical studies on the dynamic characteristics and shock resistance of the actuator assembly of the HDDs with attached dynamic absorbers have been described. The effectiveness of the dynamic absorber and the adopted design procedure are illustrated from the point of view of both bandwidth improvement and shock protection capacities. It has been clearly demonstrated that the introduction of a dynamic absorber into the actuator arm system, if properly designed, can greatly improve the capabilities of shock handling and residual vibration suppression in either operating or nonoperating conditions of HDDs.