In this paper, a simple method of plotting logarithmic phase frequency response curve for open-loop systems is advanced.

Then the fuzzy controller based on the improved fuzzy table-rotating optimization is designed and applied to the open-loop systems with pure time delay.

Due to the inherent hysteretic nonlinearity, the giant magnetostrictive actuator (GMA) can cause position error in the open-loop systems, and cause instability in the closed-loop systems.