$H{\infty}$ optimal controller robustness and performance improvement by frequency domain analysis of open loop transfer function

개루프 전달함수 주파수영역 해석에 의한 $H{\infty}$ 최적 제어기의 견실성 및 성능 개선

When the controller designed by the $H{\infty}$ control technique is applied to the object system, sometimes the controller does not satisfy the robust stability and robust performance but only satisfy the nominal performance. In this paper, we derive the region on the frequency response curve of the open-loop transfer function which satisfy the robustness and robust performance of the designed controller. We also derive the region for the suitableness of the weighting function on the frequency response curve of the weighting function. We showed that the robust stability and the robust performance of the $H{\infty}$ optimal control)or by applying the designed controller on an electromechanical actuator system could be improved by determining parameter ${\gamma}$ and weighting function gain ${\alpha}$ using the derived region.