Your browser does not support JavaScript!

Nonlinear least-squares optimisation of sensitivity function for disturbance attenuation on hard disk drives

Nonlinear least-squares optimisation of sensitivity function for disturbance attenuation on hard disk drives

For access to this article, please select a purchase option:

Buy article PDF
(plus tax if applicable)
Buy Knowledge Pack
10 articles for $120.00
(plus taxes if applicable)

IET members benefit from discounts to all IET publications and free access to E&T Magazine. If you are an IET member, log in to your account and the discounts will automatically be applied.

Learn more about IET membership 

Recommend Title Publication to library

You must fill out fields marked with: *

Librarian details
Your details
Why are you recommending this title?
Select reason:
IET Control Theory & Applications — Recommend this title to your library

Thank you

Your recommendation has been sent to your librarian.

Sensitivity function or error rejection function is crucial to determine the disturbance attenuation capability of a closed-loop control system. A nonlinear least-squares optimisation method is applied in sensitivity function shaping to design a feedback controller for a micro-actuator such that its sensitivity function fulfills desired specifications in order to attenuate disturbances at specific frequencies. The micro-actuator is used as a secondary actuator to enhance the positioning accuracy of a servo track writer for hard disk drives. The disturbance attenuation capability of the designed control system is also evaluated for disturbances with varying frequencies. Simulation and experimental results show the effectiveness of this method in designing a controller so that specific conditions imposed on the sensitivity function are satisfied.


    1. 1)
    2. 2)
      • Kim, Y.H., Kang, C.I., Tomizuka, M.: `Adaptive and optimal rejection of non-repeatable disturbance in hard disk drives', IEEE/ASME Conf. on Advanced Intelligent Mechatronics Proc., July 2005, Monterey, CA, USA, p. 1–6.
    3. 3)
    4. 4)
    5. 5)
      • Beghi, A., Oboe, R., Capretta, P., Soldavini, F.C.: `Loop shaping issues in hard disk drive servo system design', IEEE/ASME Conf. on Advanced Intelligent Mechatronics Proc., July 2001, Como, Italy, p. 828–832.
    6. 6)
      • Fujimoto, H., Kawakami, F., Kondo, S.: `Multirate repetitive control and applications', Proc. American Control, June 2003, Denver, Colorado, USA, p. 2875–2880.
    7. 7)
      • Kawafuku, M., Iwasaki, M., Hirai, H., Kobayashi, M., Okuyama, A.: `Rejection of repeatable runout for HDDs using adaptive filter', The 8th IEEE Intl. Workshop on Advanced Motion Control, March 2004, Kawasaki, Japan, p. 305–310.
    8. 8)
      • MicroE PA100 Positioner-Installation Guide and User's Manual, MicroEColorado.
    9. 9)
    10. 10)
      • Du, C., Xie, L., Guo, G.: `A generalized KYP lemma based control design and application for 425 kTPI servo track writing', Proc. American Control Conf., June 2006, Minneapolis, Minnesota, USA, p. 1303–1308.
    11. 11)
      • Nagamune, R., Blomqvist, A.: `Sensitivity shaping with degree constraint by nonlinear least-squares optimization', Technical Report, Optimization and Systems Theory, , Royal Institute of Technology. Available at
    12. 12)
    13. 13)
      • A. Blomqvist , R. Nagamune . Matlab interface ‘Sshaper’.
    14. 14)
      • R. Ehrlich , D. Curran . Major HDD TMR sources and projected scaling with TPI. IEEE Trans. Magn. , 885 - 891

Related content

This is a required field
Please enter a valid email address