Delay-dependent feedforward control of time-delay systems with parametric uncertainties via dynamic IQCs

Levent Ucun*, Ibrahim B. Kucukdemiral

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


This paper studies the design problem of a robust delay-dependent H ∞ feedforward controller design for a class of linear uncertain time-delay system having state and control delays when the system is subject to L2-type disturbances. The proposed controller scheme involves two main controllers, which are static state-feedback and dynamic feedforward controllers. The state-feedback controller is used for stabilizing the delay and uncertainty-free system, whereas the feedforward controller performs disturbance attenuation. Dynamic type integral quadratic constraints (IQCs), which consist of frequency-dependent multipliers, have been introduced to represent the delays and parametric uncertainties in the system where the degree of the multiplier used in IQC representation is in an adjustable nature. This scheme allows the designer to obtain less conservative controllers with increasing precision. Sufficient delay-dependent criteria in terms of linear matrix inequalities are obtained such that the uncertain linear time-delay system is guaranteed to be globally, uniformly, asymptotically stable with a minimum disturbance attenuation level. Several numerical examples together with the simulation studies provided at the end illustrate the usefulness of the proposed design. © 2013 John Wiley & Sons, Ltd.
Original languageEnglish
Pages (from-to)127-144
Number of pages18
JournalOptimal Control Applications and Methods
Issue number2
Early online date5 Nov 2012
Publication statusPublished - Apr 2014


  • time delay systems
  • feed forward control
  • dynamic integral quadratic
  • controller synthesis
  • dynamic integral quadratic constraints
  • time-delay systems
  • feedforward control


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