Browsing by Subject "Linear quadratic control"

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Open Access
LQ optimal design at finitely many frequencies
(Institute of Electrical and Electronics Engineers, 1998) Köroğlu, H.; Morgül, Ö.
The notion of Linear Quadratic (LQ) optimality at a single frequency is developed in single-input single-output (SISO) linear time-invariant (LTI) system/quasi-stationary signal framework and the optimality condition is given. LQ optimal design at finitely many frequencies is then shown to be reducible to an interpolation problem.
Open Access
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.