Chunling Du; Cheng Peng Tan; Jiaping Yang, "Three-Stage Control for High Servo Bandwidth and Small Skew Actuation," in Magnetics, IEEE Transactions on , vol.51, no.1, pp.1-7, Jan. 2015 doi: 10.1109/TMAG.2014.2339192
A three-stage actuation control system is proposed to enable high servo bandwidth track-following and possibly for small skew angle actuation system of hard disk drives. It involves a VCM actuator as a primary actuator, a PZT actuated milliactuator as a secondary actuator. Both of them have the 1st dominant resonance mode at 5kHz, and the milliactuator has 200nm stroke. A thermal microactuator having 50nm stroke is used as a third actuator for a high servo bandwidth. A control strategy with controller design method is proposed to meet the performance requirement of each actuator’s control loop and the overall control system. More than 6kHz servo bandwidth is achieved and 430nm external vibration can be covered by the three-stage actuation system. Simulation and experiment results demonstrate the control performance of the three-stage closed-loop system.
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