Dynamic modelling and linear quadratic Gaussian 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

41 Scopus citations


This paper presents an investigation into the modelling and control of a one-degree-of-freedom (1 DOF) twin-rotor multi-input multi-output (MIMO) system (TRMS). The behaviour of the TRMS in certain aspects resembles that of a helicopter. Hence, it is an interesting identification and control problem. A dynamic model characterizing the TRMS in hover is extracted using a black-box system identification technique. The extracted model is employed in the design of a feedback linear quadratic Gaussian compensator, namely the stability augmentation system (SAS). This has a good tracking capability but requires high control effort and has inadequate authority over residual vibration of the system. These problems are resolved by further augmenting the system with a command path prefilter, resulting in the command and stability augmentation system (CSAS). The combined feedforward and feedback compensator satisfies the performance objectives and obeys the actuator constraint. The control law is implemented in realtime on the TRMS platform.

Original languageEnglish
Pages (from-to)203-227
Number of pages25
JournalProceedings of the Institution of Mechanical Engineers. Part I: Journal of Systems and Control Engineering
Issue number3
StatePublished - 2003
Externally publishedYes


  • Command and stability augmentation
  • Feedforward control
  • Helicopter
  • Linear identification
  • Linear quadratic Gaussian
  • Stability augmentation
  • Twin-rotor multi-input multi-output system

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Mechanical Engineering


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