A design based on final-state control for residual vibrationless seeking in hard disk drives

Abstract

A new design method -based on a final-state control (FSC) -for short-span seeking in a hard-disk drive (HDD) has been developed. The short-span seeking is performed by two-degree-of-freedom (2-DOF) control, which uses a feedforward (FF) control input along with a reference trajectory. The design method can directly generate the FF control input, whose derivative at a specified order is minimized and whose power spectrum amplitude is reduced at a specified frequency. The residual vibration caused by mechanical resonance can therefore be reduced by the generated FF control input. Test with a 2.5-in form-factor HDD experimentally confirmed that the developed seeking control significantly reduces the residual vibration in a HDD.

State Space Disturbance Compensation for Robust Fast Servo Track Writer Seek Control*

“…Preprints of the 18th IFAC World Congress Milano (Italy) August 28 -September 2, 2011 Okuyama et al [2005], Hirata and Hasegawa [2007]) and for a minimum phase delay (see e.g. Tomizuka [1987]).…”

“…A reference profile can be designed to minimize residual vibration (see e.g. Mizoshita et al [1996], Okuyama et al [2005], Hirata and Hasegawa [2007]). It is also possible to reduce residual vibration by minimizing the rate of control input (see e.g.…”

Design of Seeking Control Based on Two-Degree-of-Freedom Controller Using Frequency Shaped Final-State Control

“…Several methods have been proposed to avoid the residual vibrations: The SMART control (Mizoshita et al, 1996) is proposed for designing a trajectory that minimizes a jerk during seeking. An augmented band reject filter (BRF) with the final-state control (FSC) is also used to reduce the energy in control input at a certain frequency band (Okuyama et al, 2005). Using LMI constraints to limit the energy of the control intput at a certain frequency band and the amplitude of the control command is proposed to avoid resonance mode excitation (Hirata et al, 2002).…”

“…In this paper, an add-on type disturbance observer (DOB) in the form of finite impulse response (FIR) is used with a feedback controller (Suh et al, 2002). This is a kind of mode switching control (MSC) different from the conventional MSC (Yamaguchi et al, 1996) (Okuyama et al, 2005). The conventional MSC uses two controllers and switching between the controllers is made when the objective of the control changes.…”

Design of robust controller for high performance servo track writer

“…There are many approaches: the SMART control method [2] for designing a trajectory that minimizes vibration at the seek control of the HDD, method using band reject filter (BRF) to make sure that control input does not have energy at certain frequency bands [3], and a method using LMI constraint to limit energy of the frequency band that the resonance exists generating control input [4,5].…”