A Method for Selecting Initial Value of Aircraft Dutch Roll Equivalent Fitting

Abstract

The invention discloses a method for selecting an initial value of an aircraft Dutch roll equivalent quasi-equipment, and belongs to the technical field of aircraft control system design. The method includes the following steps: Step 1. Obtain the amplitude and phase data of the high-order system of sideslip angle versus pedal force in the range of 0.1 to 10 rad / s; Step 2. Obtain the high-order transfer function based on the typical second-order system and Step 1. Equivalent second-order system; Step 3: Determine the initial value of the Dutch Roll damping ratio according to the maximum value of the amplitude curve and the amplitude at ω=0.1; Step 4: Calculate the initial value of the Dutch Roll frequency ω d Step 5, using the amplitude and frequency initial value at ω=0.1 to calculate the initial value of gain K; Step 6, determining the time delay value τ; the present invention obtains the equivalent fitting according to the amplitude and phase data of the high-order system The initial value, which is close to the exact solution, can ensure that the equivalent fitting requirements are met in subsequent solutions. This method avoids the work of repeatedly debugging the initial value, improves work efficiency, and simplifies calculation difficulty.

Description

technical field [0001] The invention belongs to the technical field of aircraft control system design, and in particular relates to a method for selecting an initial value of an aircraft Dutch roll equivalent fitting. Background technique [0002] Most current aircraft are designed with a control stability augmentation system. There are far more aircraft modes after control stabilization than those without stabilization, so it is difficult to directly apply mature flight quality specifications. At present, the typical method is equivalent matching, that is, to find an equivalent low-order system for a certain high-order system, and the difference of the corresponding output of the two systems in a certain frequency domain range satisfies certain index conditions. Equivalent low-level systems can use quality specifications for modal analysis, flight quality assessment, etc. [0003] The equivalent matching principle is that the index function of the amplitude and phase diff...

AI Technical Summary

Problems solved by technology

The expression of the mismatch degree function is complex. When using algorithms such as least squares and Newton iteration, the calculation of the initial value will affect the accuracy of the equivalent fitting. Improper selection of the initial value will result in unreasonable results, which cannot reflect the characteristics of high-order systems.

[0009] Initial value selection is a key task in equivalent fitting. At present, there is no unified method for initial value selection, which mainly depends on the experience of engineers.

Images