155. ROBUST CONTROLLER TUNING FOR DISTURBANCE REJECTION

Department: Mechanical & Aerospace Engineering
Research Institute Affiliation: Center for Control Systems and Dynamics (CCSD)
Faculty Advisor(s): Raymond de Callafon

Primary Student
Name: Charles E. Kinney
Email: cekinney@ucsd.edu
Phone: 858-822-1763
Grad Year: 2009

Abstract
Incomplete knowledge of either plant or disturbance dynamics complicates the design of a feedback control system. Uncertainty in plant dynamics can cause feedback instabilities and should at least be considered in the context of stability robustness. Inaccurate controller design due to uncertainty in disturbance dynamics will not destabilize the system but may deteriorate feedback performance. In the presence of uncertainty in system and disturbance dynamics, the so-called Youla parameterization can be used to alleviate the tuning process of a feedback controller. In this poster, we show that this parameterization can be used to recast the tuning of a feedback controller as a robust estimation problem. The formulation as an estimation problem allows tuning of the controller in real-time on the basis of closed loop system data. Furthermore, robust estimation is obtained by constraining the parameter estimates so that feedback stability will be maintained during controller tuning in the presence of plant uncertainty. The combination of real-time tuning and guaranteed stability robustness opens the possibility to perform robust controller tuning for disturbance rejection. The procedure is illustrated via the application of a narrow-band disturbance rejection in the active noise cancellation of a cooling fan. In the application, the output variance is reduced by 80% by removing harmonic disturbances.

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