A Low Order Equivalent Matching Method for Mixing Time-Domain and Frequency-Domain Parameter Identification

The low order equivalent matching method is one of the important means to study the flight quality of complex high-order aircraft models. Low order equivalent matching methods are usually divided into frequency domain matching method and time domain matching method. The frequency domain matching method requires obtaining the model or frequency domain response of higher order systems and cannot process aircraft data. The time domain matching method requires processing a large amount of data and has low operational efficiency. By combining frequency-domain matching and time-domain matching methods, a low-order equivalent matching method based on parameter identification mixing time-domain and frequency-domain is proposed. The one-step least squares finished algorithm is used to extract the transitional lower order model from aircraft operation data in the time domain, and then the frequency-domain matching method is applied to identify the parameters of the lower order equivalent model from the transitional lower order model. Simulation shows that this method does not rely on the setting of initial values and parameter ranges, and can improve the simulation efficiency of the time-domain equivalent matching method by nearly ten times without losing accuracy. The results indicate that the low order equivalent matching method based on parameter identification mixing time-domain and frequency-domain is effective when applied to parameter identification of low order models.