Dynamic modelling and open-loop control of a 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

46 Scopus citations


A dynamic model for a one-degree-of-freedom (DOF) twin rotor multi-input multi-output (MIMO) system (TRMS) in hover is obtained using a black-box system identification technique. The behaviour of the TRMS in certain aspects resembles that of a helicopter; hence, it is an interesting identification and control problem. This paper investigates modelling and open-loop control of the longitudinal axis alone, while the lateral axis movement is physically constrained. It is argued that some aspects of the modelling approach presented are suitable for a class of new generation or innovative air vehicles with complex dynamics. 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. Open-loop control strategies using shaped command inputs are accordingly investigated for resonance suppression in the TRMS. Digital low-pass and band-stop filter shaped inputs are used on the TRMS testbed, based on the identified vibrational modes. A comparative performance study is carried out and the corresponding results presented. The low-pass filter is shown to result in better vibration reduction.

Original languageEnglish
Pages (from-to)477-496
Number of pages20
JournalProceedings of the Institution of Mechanical Engineers. Part I: Journal of Systems and Control Engineering
Issue number6
StatePublished - 2002


  • Helicopter
  • Open-loop control
  • System identification
  • Twin rotor MIMO system
  • Vibration suppression

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Mechanical Engineering


Dive into the research topics of 'Dynamic modelling and open-loop control of a twin rotor multi-input multi-output system'. Together they form a unique fingerprint.

Cite this