Browsing by Subject "Linear time invariant systems"

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    Robust LQ control for harmonic reference/disturbance signals
    (IEEE, 2000) Köroğlu, Hakan; Morgül, Ömer
    Linear Quadratic (LQ) controller design is considered for continuous-time systems with harmonic signals of known frequencies and it is shown that the design is reducible to an interpolation problem. All LQ optimal loops are parametrized by a particular solution of this interpolation problem and a (free) stable/proper transfer function. The appropriate choice of this free parameter for optimal stability robustness is formulated as a multiobjective design problem and reduced to a Nevanlinna-Pick interpolation problem with some interpolation points on the boundary of the stability domain. Using a related result from the literature, it is finally shown that, if there is sufficient penalization on the power of the control input, the level of optimum stability robustness achievable with LQ optimal controllers is the same as the level of optimum stability robustness achievable by arbitrary stabilizing controllers.
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    Time-varying repetitive control for better transient response and stochastic behaviour
    (IET, 2001) Köroğlu, H.; Morgül, Ö.
    A stability proof is given for a time-varying repetitive control strategy. It is illustrated by a simulation example that this time varying strategy can be used to improve the transient response and stochastic behaviour of the repetitive control system simultaneously.