Rotational Speed Determination via Vibration Signal Analysis
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Solution Overview
Problem
Modern aircraft systems often lack tachometers or other rotational speed sensors, making it costly and impractical to directly measure the rotational speed of components, which is essential for vibration diagnostic techniques used in prognostics and health management systems.
Innovation Solution
A method and system that utilize vibration signal analysis to determine rotational speed by sensing vibrational data, converting it to frequency domain data, identifying the frequency bin index corresponding to maximum vibration, fitting the data to a model curve, and interpolating to accurately estimate the rotational speed without the need for additional speed sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated rotational speed sensors (tachometers) are added to directly measure rotational speed, then measurement precision is improved, but device complexity and system cost increase
Solution Approach 1:
The system uses the rotating component's own vibration signals to determine its rotational speed, eliminating the need for external tachometers. The vibration diagnostic system serves dual purposes: both diagnosing component health and measuring rotational speed, thereby reducing system complexity and cost while maintaining measurement capability.
Solution Approach 2:
Vibration signals serve as an intermediary between the rotating component and the measurement system. Instead of directly measuring rotational speed with a tachometer, the system measures vibration signals and derives rotational speed information from them, using vibration as a mediating parameter that contains speed information.
2Device complexity
If vibration signal analysis is used to determine rotational speed without tachometers, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The invention directly utilizes mechanical vibration signals from the rotating component to determine rotational speed. By analyzing the frequency content of vibration signals, particularly identifying peaks corresponding to rotational frequencies and their harmonics, the system extracts speed information inherently contained in the mechanical vibration without requiring additional sensing equipment.
Solution Approach 2:
The system transforms the vibration signal from time domain to frequency domain through spectral analysis, changing the parameter representation to reveal rotational speed information. By identifying frequency peaks and their relationship to known component geometries and operating conditions, the system converts vibration data into rotational speed measurements with improved precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for accurate determination of rotational speed without additional sensors, enhancing the accuracy of prognostics and health management systems by leveraging model curve fitting and interpolation techniques, thus reducing system costs and complexity.
Implementation Method 1
The processor converts the time sequence of vibrational data to frequency domain vibrational data using a Fast Fourier Transform
Data Source
AI summary
Rotational speed of a rotating component is determined using frequency domain vibrational data. A time sequence of vibrational data of the rotating component is sensed and converted to the frequency domain vibrational data. A portion of the frequency domain vibrational data corresponding to an expected rotational speed of the rotating component is identified. A frequency bin index of the frequency domain vibrational data corresponding to a maximum vibration within the portion of the frequency domain vibrational data is identified. The maximum vibration at the identified frequency bin index and vibrations associated with adjacent frequency bin indices are fitted to a model curve. A floating point frequency bin index corresponding to a maximum of the model curve is identified, and the rotational speed of the rotating component is determined based on the frequency bin index corresponding to the maximum of the model curve.