Fuzzy gain-tuning approach for active control system adaptable to physical constraints

Abstract

This paper presents a fuzzy gain-tuning approach of optimally pre-designed active controller in order to guarantee its stable adaptability against the limitations on control force and device stroke. The pre-designed optimal controller can be obtained by using conventional control theory, and it is typically designed for nominal control system which is an ideal system with no limitations on force and stroke. However, the actual control system has the maximum capacity of control force and its movement is also restricted due to the limited space, which can deteriorate the control performance when the maximum control force or stroke are exceeded. To minimize such performance deterioration, the proposed approach introduces a fuzzy-tuned scaling factor, which converts the static control gain into the time-varying control gain. For its realization, fuzzy logic is used to identify whether or not the real-time force and stroke of the control system exceeds its allowable limits and to quantify the scale up and down of the control gain. The numerical simulation results demonstrate that the proposed approach successfully guarantees the improved robustness of the control system under the control limitations on control force and stroke.