Abstract: The gain crossover frequency band and phase crossover frequency bands of a set of frequency response curves in the whole flight envelope for a fly-by-wire system have been stud-ied in this paper.Eight characteristic formulas for lag-lead correctiVe network with any two pairs poles and zeros distributions have been derived.The compensative relationships between the gain and phase crossover frequency bands of the frequency curves and the corner frequencies of the corrective network were established. A compensation method for a set of open-loop fre-quency characteristic curves has been proposed. Four fixed parameters of two-order corrective network which covers all conditions in the whole enveIope are. designed at a time by using this method,so that alI the gain and phase margins of the FBW system completely satisfy the mili-tary specification requirements, and the handling quality has been also improved.The equiva-lent time delay has been reduced by 0.05 second on an average.The phase compensation method proposed in this paper has been demonstrated by the ground tests and the flight tests.

Key words: fly-by-wire control, frequency response method of characteristics, amplitudes-phase-frequency ranges, freguency control