Advanced control design for HDD in mobile consumer devices
Date of Issue2011
School of Electrical and Electronic Engineering
As the HDD finds more applications in various mobile consumer devices, HDD servo control needs to improve the performance in the seeking acoustics and vibration rejection. This research provides feasible solutions to these two problems. The work described in this thesis is summarized as follows: A new seeking controller for minimizing the acoustics is proposed. A systematic way of designing the seek controller with acoustics into consideration is given. The Two-Degree-Of-Freedom (TDOF) model reference controller is employed. The sinusoidal wave is used as the model reference input to produce the smooth current profile. The voltage saturation is taken into account in the control design so that the single seeking controller can be applied to full span of seek length. An acoustics factor is used as a controller input to easily tune the acoustics performance. Both simulation and experimental results are presented. To handle various external vibrations, two kinds of vibration rejection schemes are proposed in this research: 1. An add-on loop gain booster algorithm is used to deal with the pink noise and the linear/rotational vibrations with relatively low amplitude. The add-on feature will be turned on only in the specific vibration environment.The scheme comprises two parts: the vibration detection through analysis of the vibration sensor output or PES and the vibration compensation through the add-on feature. The transient response in switching on/off the add-on feature is successfully shortened by the reset control. Reset Integral-Derivative Element (RIDE) is adopted to form the reset controller. The scheme is implemented in real HDD and produces the satisfactory experimental results under various vibrations. 2. Two adaptive filltering based algorithms are developed to reject the pure tone disturbance and the linear/rotational vibrations with high amplitude: Least Mean Square (LMS) and Recursive Least Square (RLS).
DRNTU::Engineering::Electrical and electronic engineering::Control and instrumentation