Track-Following Control With Active Vibration Damping of a PZT-Actuated Suspension Dual-Stage Servo System

Abstract

In this paper we discuss the controller design of a PZT-actuated suspension dual-stage servo system in hard disk drives. The proposed control structure includes an active vibration damping control loop and a track-following control loop. The vibration damping control loop, which runs at a faster rate than the track-following control loop, utilizes a PZT element on a PZT-actuated suspension as a vibration sensor to damp the resonance modes of the voice coil motor (VCM) and the PZT actuator. The vibration damping controller is designed using Kalman filter based state feedback control techniques. A simple dual-stage track-following controller is designed, based on the damped actuator model, using the sensitivity function decoupling design method. Simulation and experimental results are presented to demonstrate the benefits of this control scheme in expanding servo control bandwidth and suppressing airflow excited structural vibrations.

Track-following control with active vibration damping and compensation of a dual-stage servo system

“…The idea of utilizing additional sensors to further increase the servo bandwidth has been explored by several researchers (Pannu and Horowitz 1999;Oboe 2000;Li and Horowitz 2001a;Li et al 2003). In (Pannu and Horowitz 1999;Oboe 2000), it was proposed to attach an acceleration sensor at a proper location in the HDD to provide a vibration signal for feedforward control.…”

“…The detected vibration signal is fed back to the VCM and fed forward to the MA simultaneously for vibration attenuation. The suspension model used in this simulation study is based on a newly redesigned suspension from an original one that had been used in our previous simulation and experimental study (Li et al 2003). The frequency response of the redesigned suspension is shown in Fig.…”

“…Thus the servo bandwidth cannot be significantly extended due to its single-stage property. In Li et al (2003), active vibration damping of a dual-stage servo system with a PZT-actuated suspension was proposed and experimentally tested. The main disadvantage of this configuration is that the PZT actuators are located between the E-block arm and the suspension, and thus may still excite the structural resonance modes, which may limit its achievable bandwidth.…”

Active Vibration Control of a Microactuator for the Hard Disk Drive Using Self-Sensing Actuation

“…The desire to more effectively suppress the effect of disturbances has led many researchers to propose the addition of more sensors and actuators. One example which has been proposed is to use a piezoelectric actuator on the suspension in a dual-stage system with one of the two strips as the sensor and the other as the actuator [1,2]. This, however, reduces the effectiveness of the actuator by half and is not efficient.…”

Modeling and Control of a Dual Stage Actuator Hard Disk Drive

“…Some of these micro-actuators are MEMS-type devices (microelectromechanical systems) based on electrostatic or electromagnetic effects (3) - (10) . Other micro-actuators are based on piezoelectric principles (11) - (13) . The actuators are either mounted on the suspension or on the slider.…”