Parameterized Analysis of Aeroservoelastic Stability for Closed-Loop Aircraft

The closed-loop flight control system of fly by wire is generally adopted in modern aircraft. Based on the frequency-domain stability analysis, the aeroservoelastic model of closed-loop aircraft is established, and aeroservoelastic stability parameterized calculation of design improvement is conducted after the preliminary analysis. The design variables are mounted location of integrated sensors and damping coefficients ζ_1, ζ₂ of notch filter, with stability margin of the system as design objective. Results indicate that aeroservoelastic margin of the aircraft in certain states is insufficient. While the mounted location of integrated sensors is adjusted, the system stability can be improved to certain extent. It’s more appropriate to mount the integrated sensors in the overlapping field between the nodal lines of vertical and lateral bending for the fuselage. The system stability is also significantly improved by adding notch filter, both gain margin and phase margin increase when the real number pair ζ₁-ζ₂ is located in the zone above the 45° diagonal of ζ_1, ζ₂ construction plane, and the farther the ζ₁-ζ₂ is from the 45° diagonal, the stronger the system stability. Also the decrease in the gain peak of frequency response and the enhancement of relative stability of the system are achieved by the appropriate ζ₁-ζ₂ of notch filter.