变系数飞行器系统气动系数辨识计算与应用

本文研究了变系数飞行器系统气动系数的辨识算法。变系数系统的辨识计算通常是非常困难的。本文依据飞行试验中实际测量,通过对飞行器变系数微分方程组中系数变化趋势的分析,转方程中变系数为一个变化规律已知的函数与未知常数的乘积,把这些未知常数当作待定系数,然后推广Newton-Ra-phson法到变系数微分方程组中,通过迭代法求这些待定系数,这样就使得复杂的变系数飞行器系统的辨识计算得以实现。为了证明这种算法的有效性,本文从飞行器的一次不稳定飞行的测量数据,计算了该飞行器的气动系数,并讨论了辨识计算所得气动系数的可信度,计算结果与实际符合较好,在改进飞行器的飞行试验中起了一定作用。

AERODYNAMIC COEFFICIENT IDENTIFICATION OF TIME-VARYING AIRCRAFT SYSTEM AND ITS APPLICATION

Aerodynamic coefficient identification for time-varying aircraft system has been studied. Usually, the time-varying system identification is quite difficult. On the basis of practical measurement in flight tests and by analyzing trend of the coefficients in aircraft time-varying differential equations, it is possible to transform the individual time-varying coefficient into a known function multi- plied by an unknown constant. These unknown constants are referred to as undefined coefficients. With the aid of the Newton-Raphson method extended to the time-varying coefficient differential equations the undefined coefficients can be evaluated by iteration calculation. In this way the complicated time-varying aircraft identification can be carried out.In order to verify this calculation the aerodynamic coefficients of an aircraft have been evaluated by the data taken from one of its unsteady flight, and the reliability of aerodynamic coefficients obtained from this identification has been discussed. The calculation results matched very well the test data and made a contribution to the improvement of aircraft fight tests.