Disturbance rejection in hard disk drives with multi-rate estimated state feedback

Federico Marcassa, Roberto Oboe

Research output: Contribution to journalArticlepeer-review


Multi-rate control has been proposed as a solution to improve the performance of Hard Disk Drives (HDDs) head servo positioning. Some authors report unexpected decrease in performance when using this approach. This paper presents an analytical method to obtain the closed-loop sensitivity function of a multi-rate control system, with estimated state feedback. By using this tool, it is shown why disturbance rejection in multi-rate control may be worse than in single-rate. The paper reports both simulation and experimental results, confirming the possible decrease in performance, when using a standard design for the multi-rate control, even when a first-order hold is used. The paper also presents a novel design procedure for the multi-rate estimator, which takes into account the spectral distribution of disturbances and yields to a better performance, compared to both single-rate and standard multi-rate control.

Original languageEnglish
Pages (from-to)1409-1421
Number of pages13
JournalControl Engineering Practice
Issue number11
Publication statusPublished - Nov 2004


  • Multi-rate
  • Position control
  • Sensitivity function
  • State estimation
  • State feedback

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Industrial and Manufacturing Engineering


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