| Summary: | 碩士 === 淡江大學 === 航空太空工程學系碩士班 === 102 === In this research, three flight data of Boeing747-400 including two normal and one abnormal are analyzed, which derived from Flight Operations Quality Assurance (FOQA), by using Wavelet Transform and Hilbert-Huang Transform methods. Considering the tremendous amount of relevant parameters involved, such as true airspeed, vertical speed, thrust, angle of attack, wind speed, wind direction, etc., we need to first decompose these engineering data to different frequencies inside the signals, observe their changes, and acquire valuable and meaningful flight interpretations. The main purpose for this work is to figure out unusual warning by contrasting with the analyses via two theoretical methods.
In this study, we re-establish two-dimensional horizontal wind fields by data taken from Flight Data Recorder (FDR) via the equations of flight mechanics and the system of dead-reckoning. Then we could analyze parameters of wind speed and wind direction into HHT and Wavelet Transform formats. HHT is a modern tool for non-linear and non-stationary time series interpretation, and has a high-resolution spectrum compared to traditional methods for understanding background physical meaning. In the cases studied, HHT gave results much sharper than those from any of the traditional analytical methods in the time-frequency-energy representations. Moreover, traditional methods such as Fourier transform (FT) and short-time fast Fourier (STFT), utilizing fixed window to analyze frequencies in signal, but Wavelet Transform applying a dilation window function to fit the length of the data, and it really work out on decomposing from high-frequency to low-frequency oscillation in signals. Therefore, Wavelet Transform obtains more prominent results in the frequency domain.
Data generated consequences of HHT and Wavelet method, compared with each other, in order to see clearly the results which were demonstrated. Comprehensive the interpretations of two methods combined with the report of Aviation Safety Council give us more precise analytical results in landing profile and physical phenomena. Moreover, our expectation is to obtain the "prediction warning message" which would pose a serious threat to flight safety before the occurrence of accident/incident from observing the abnormal parameters data set.
|
|---|
