Frequency Domain Identification of a Multi-Input Control Equivalent Turbulence Input Model

Abstract

This paper describes a frequency-domain method for the identification of multi-input control equivalent turbulence input models. Such models can be identified from flight data gathered in specific turbulent environments, such as behind a ship or near a rooftop vertiport, and used to accurately simulate an aircraft’s response to turbulence. Identification of control equivalent turbulence input models has previously been done in the frequency domain for single-input/single-output applications or using a two-step time- and frequency-domain approach for multi-input/multi-output applications. In this paper, the frequency-domain approach is extended to account for the possible correlation between the measured control inputs and aircraft states (when flight data are collected closed loop) and to handle multi-input/multi-output applications. Several simulation examples are provided that demonstrate that known turbulence models can be accurately identified, for both open- and closed-loop simulations. The results validate the multi-input control equivalent turbulence input model frequency-domain identification approach proposed in this paper.