Title: Linear and nonlinear MPC for track following in the design of HDD servo systems

Authors: Manel Taktak-Meziou; Ahmed Chemori; Jawhar Ghommam; Nabil Derbel

Addresses: Department of Electrical Engineering, National School of Engineers of Sfax (ENIS), BP, W 3038 Sfax, Tunisia ' LIRMM, University Montpellier 2, CNRS, UMR5506, CC477, 161 rue Ada, 34095 Montpellier Cedex 5, France ' Department of Electrical Engineering, National School of Engineers of Sfax (ENIS), BP, W 3038 Sfax, Tunisia ' Department of Electrical Engineering, National School of Engineers of Sfax (ENIS), BP, W 3038 Sfax, Tunisia

Abstract: This paper proposes to use the model predictive controllers (MPC) for servo control of hard-disk-drives (HDD). Nonlinear compensation of high-frequency dynamics is achieved using two control algorithms generated from model predictive control (MPC): classical linear MPC, and MPC technique with multiple coincidence points and a reference trajectory to ensure an exponential convergence towards the reference trajectory. At low-frequency, the resonance compensation is realised using nonlinear model predictive control (NMPC). This paper aims at applying the proposed predictive control solutions to resolve the track-following problem of the read/write (R/W) head of a HDD servo-system in different operating conditions. To the best authors' knowledge, these predictive methods and comparative study at low and high frequency regions have never been conducted before on HDDs. Different scenarios are analysed including nominal case, disturbance rejection, and robustness towards parameters change to show the effectiveness of the proposed control solutions in achieving a precise and fast R'W head positioning. Numerical simulation results of the overall scenarios are presented and compared with those of a proportional integral derivative (PID) controller.

Keywords: hard disk drives; HDD servo systems; linear predictive control; nonlinear predictive control; PID controllers; disturbance rejection; track following; control design; model predictive control; MPC; servo control; numerical simulation.

DOI: 10.1504/IJSCC.2014.062799

International Journal of Systems, Control and Communications, 2014 Vol.6 No.1, pp.20 - 47

Received: 18 Jun 2013
Accepted: 05 Oct 2013
Published online: 26 Jul 2014 *

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