An Alternative to DK Iteration for Two-Block µ-synthesis: UQIT

Y. Duan, B. Boulet, and H. Michalska (Canada)


µ synthesis, optimal controller, DK iteration. Q parameter, UQ iteration


A new approach for synthesizing robust µ controllers is proposed for stable plants with a single stable perturbation, which can avoid the difficulties of D -scale fitting in the DK iteration. The optimal controller K is parameterized using a Q-parameter which is obtained in the frequency domain as a FIR filter. An algorithm called UQ iteration is proposed to approximate the optimal frequency response of the Q-parameter. The optimization problem is formulated from the properties of the structured singular value by setting up the robust performance problem as a ‘two-block µ ’ problem. Numerical examples show significant improvement over the standard DK iteration in certain cases.

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