Rotorcraft Drive System Anomaly Detection via Sub-Synchronous Spectrum Analysis
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Solution Overview
Problem
Current diagnostic systems for aircraft drive systems, such as rotorcraft, have limited effectiveness in monitoring and identifying anomalies due to the sinusoidal or oscillatory vibratory forces produced during operation, which are not adequately addressed by existing methods like cepstrum analysis and wavelet techniques.
Innovation Solution
A method and system that involves obtaining vibration and tachometer signals, generating a time synchronous average vibration signal, processing it to produce a frequency-domain spectrum, selecting a sub-synchronous band, and determining a condition indicator to diagnose anomalies in drive train components, which includes using discrete Fourier transform and accelerometers for real-time monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cepstrum analysis and wavelet techniques are used for vibration monitoring, then diagnostic capability is provided, but the method has limited use and cannot adequately address sinusoidal or oscillatory vibratory forces in rotorcraft drive systems
Solution Approach 1:
The patent transforms the vibration signal from time domain to frequency domain using Fast Fourier Transform (FFT), and then to a different representation using the Hilbert transform. This parameter transformation allows the system to effectively analyze sinusoidal and oscillatory vibratory forces that were not adequately addressed by conventional cepstrum analysis and wavelet techniques, thereby improving both diagnostic effectiveness and adaptability to rotorcraft drive systems
2Measurement precision
If traditional vibration monitoring methods are implemented, then some diagnostic information is obtained, but early identification of unhealthy components is not achieved
Solution Approach 1:
The patent applies envelope analysis and Hilbert transform to extract modulating frequencies from the vibration signal, which reveals early signs of component degradation before they develop into critical failures. This preliminary detection capability allows maintenance to be scheduled proactively, preventing catastrophic failures and reducing unplanned downtime in rotorcraft operations
3Loss of information
If comprehensive vibration analysis is performed on rotorcraft drive systems, then diagnostic information is obtained, but the complexity of processing oscillatory signals increases
Solution Approach 1:
The patent extracts the envelope signal from the complex vibration data using Hilbert transform, isolating the modulating frequencies that contain the diagnostic information. This extraction process simplifies the signal representation while retaining the essential information about component health, making the data more manageable for analysis without losing critical diagnostic content
Data Source
AI summary
There is a method, system, and device for diagnosing an anomaly of a monitored component in a drive train, the method including obtaining original data based on samples of a vibration signal and a tachometer signal; generating a time synchronous average vibration signal; processing the time synchronous average vibration signal to produce a frequency-domain spectrum; determining the complex magnitudes of the frequency-domain spectrum; selecting a sub-synchronous band of the complex magnitudes of the frequency-domain spectrum to generate a sub-synchronous spectrum; and determining the mean of the sub-synchronous spectrum to generate a condition indicator.