Closed-Loop Identification and Control of Multivariable Chemical Processes: a Case Study

  • G. Marchetti
  • F. Tognini
  • C. Scali
Conference paper


Closed-loop identification methods based on relay techniques have been analyzed and compared with open loop methods for an application to a multivariable nonlinear chemical process (a distillation unit: C 3C 4 splitter). Classical relay techniques and a recently proposed method for identification and control design (ATV+) are applied in a sequential procedure which leads to the design of decentralised controllers.

Several disadvantages of open-loop identification techniques have been put into evidence, mainly the inconsistency of the obtained results in the case of a non linear process (model parameters depend on the amplitude of the perturbations used during the identification). Also, longer times are necessary for the experimental tests and a more complex controller tuning technique is required. Closed loop relay techniques are faster, identify the real dynamics of the system and allow a more direct design of the control system. The ATV+ technique can be successfully applied to the process under study, after some modifications made necessary by the nonlinear nature of the system.


Distillation Column Manipulate Variable Process Gain Transfer Function Model Closed Loop Performance 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Italia, Milan 2002

Authors and Affiliations

  • G. Marchetti
    • 1
    • 2
  • F. Tognini
    • 1
    • 2
  • C. Scali
    • 1
    • 2
  1. 1.Laboratorio di Controllo dei Processi Chimici(CPCLab)Università di PisaPisaItaly
  2. 2.Dipartimento di Ingegneria Chimica(DICCISM)Università di PisaPisaItaly

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