Anti-shock controller design for optical drives

A Survey of Control Issues in Optical Data Storage Systems

“…Surface defects distort tracking error signals reflected by the disk surface, and cause it to obtain false information and deteriorate the track-following performance. The robust controllers introduced in the previous subsections have shown good performance during periodic disturbances caused by eccentricity, but have been unable to effectively eliminate nonperiodic disturbances such as surface defects and external shock (Miyazaki et al [2004], Zhou et al [2004]).…”

“…Although the systems in these studies (Zhou et al [2002], Miyazaki et al [2004]) enhance anti-shock performance, the control structures are complicated. In a recent study of anti-shock controllers (Zhou et al [2004]), a nonlinear anti-shock controller with a simple control structure (a dead zone in this case) was developed. The dead zone was simply added parallel to the original linear servo control loop in order to improve the anti-shock performance by virtually boosting low-frequency gain.…”

Adaptive control for focusing of optical drive read/write heads

“…Vibration-induced jitter typically consists of multiple narrow and broad bandwidths produced by such excitations as device rotating motion, manipulation, and transportation compounded with vibration modes of the structure supporting the optical system. In this paper, we consider focusing control using a digital video recording read/write head (pickup head), which has lightly damped elastic modes [1], [4]- [8], [13], [25], [27], [28]. This complex combination of disturbances, which often change with time, necessitates the use of adaptive controllers capable of rejecting disturbances with broadband and varying spectra.…”

Robustness Enhanced Adaptive Control And Optical Head Focusing Experiment

“…[1994], Imagawa et al [2001], Cohen et al [1984], Baek et al [2006], Liu [2006, 2007], Choi and Kim [2008], Zhou et al [2004]. This complex combination of disturbances, which often change with time, calls for use of adaptive controllers capable of rejecting disturbances with broadband and varying spectra.…”