Flight test robust determination method for equivalent stability margin of statically unstable aircraft

Abstract

The invention discloses a flight test robust determination method for the equivalent stability margin of a statically unstable aircraft, which is used for solving the technical problem of large errors of the conventional flight stability margin determination method. The technical scheme is that: a closed loop transfer function frequency characteristic matrix of a multi-loop system of the statically unstable aircraft can be obtained through a sweep frequency flight test; a relational expression between a closed loop transfer function and the stability margin of the system is established according to a corresponding relation between the closed loop transfer function and an open loop transfer function; and the closed loop transfer function frequency characteristic matrix of the system is subjected to characteristic decomposition, and a multi-loop stability margin analysis scalar equation is obtained according to the critical stability condition of the system, so that the phase margin andmagnitude margin of the whole loop is calculated, and problem difficulty is greatly simplified.

Description

technical field [0001] The invention relates to a flight test determination method of flight quality, in particular to a flight test robust determination method of an equivalent stability margin of a statically unstable aircraft. Background technique [0002] Stability margin is an important performance index to evaluate a flight control system, indicating the reliability of system stability. The stability margin of the system includes two aspects: gain stability margin and phase stability margin. The research on the stability margin of SISO system is relatively mature, and it is easy to obtain it from the classic methods such as Bode or Nyquist diagram. For the stability margin of the aircraft, a series of sweep flight tests are required, and then it is determined whether the stability margin index is satisfied or not. Nowadays, many aircraft have canards, and the longitudinal and lateral headings can be expressed as two-input-two-output systems. The stability margin cann...

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Problems solved by technology

[0007] In order to overcome the shortcomings of the existing flight stability margin determination method with large errors, the present invention provides a flight test robust determination method for the equivalent stability margin of a statically unstable aircraft. The method obtains statically unstable The frequency characteristic matrix of the closed-loop transfer function of the aircraft multi-loop system, according to the corresponding relationship between the closed-loop transfer function and the open-loop transfer function, establishes the relationship between the closed-loop transfer function and the system stability margin, and the frequency characteristic of the system closed-loop transfer function The eigendecomposition of the matrix is ​​carried out, and the multi-loop stability margin analysis scalar equation is obtained according to the critical stability conditions of the system, so as to calculate the phase margin and amplitude margin of the overall loop;

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