Dynamic modelling and open-loop control of a two-degree-of-freedom twin-rotor multi-input multi-output system

S. M. Ahmad, A. J. Chipperfield, M. O. Tokhi*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

A dynamic model for the characterization of a two-degree-of-freedom (2DOF) twin-rotor multi-input multi-output system (TRMS) in hover is extracted using a black box system identification technique. Its behaviour in certain aspects resembles that of a helicopter, with a significant cross-coupling between longitudinal and lateral directional motions. Hence, it is an interesting identification and control problem. The extracted model is employed for designing and implementing a feedforward/open-loop control. Open-loop control is often the preliminary step for development of more complex feedback control laws. Hence, this paper also investigates open-loop control strategies using shaped command inputs for resonance suppression in the TRMS. Digital low-pass and band-stop shaped inputs are used on the TRMS test bed, based on the identified vibrational modes. A comparative performance study is carried out and the results presented. The low-pass filter is shown to exhibit better vibration reduction. When modal coupling exists, decoupled feedback controllers are incapable of eliminating vibration. In such cases, generating motion by shaped reference inputs is clearly advantageous.

Original languageEnglish
Pages (from-to)451-463
Number of pages13
JournalProceedings of the Institution of Mechanical Engineers. Part I: Journal of Systems and Control Engineering
Volume218
Issue number6
DOIs
StatePublished - Sep 2004
Externally publishedYes

Keywords

  • Discrete-time systems
  • Helicopter
  • Linear identification
  • Open-loop control
  • Twin-rotor multi-input multi-output (MIMO) system
  • Vibration suppression

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Mechanical Engineering

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