Rotational Speed Estimation via Vibration Harmonic Analysis
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Solution Overview
Problem
Existing methods for determining the rotational speed of machines without a tachometer are inaccurate due to reliance on assumptions or manual data entry, leading to incorrect rotational speed measurements, especially when the load on the machine varies.
Innovation Solution
An apparatus comprising a vibration sensor, analog-to-digital converter, and processor that processes vibration data to determine the rotational speed by analyzing harmonic peaks and their relative amplitudes, considering a broader range of initial candidate speeds and iterative error calculations to improve reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If rotational speed is determined using assumption or manual data entry, then the process is simple and quick, but the accuracy and reliability of rotational speed measurement deteriorates
Solution Approach 1:
The vibration analyzer automatically determines rotational speed by analyzing vibration spectra and identifying harmonic relationships, eliminating the need for manual tachometer measurements or subjective assumptions. The system self-calibrates by detecting the fundamental frequency and its harmonics directly from the vibration data
Solution Approach 2:
The patent replaces mechanical tachometer measurement systems with an electronic vibration analysis system that uses spectral analysis algorithms to determine rotational speed, providing both automation and improved accuracy through objective mathematical analysis of vibration harmonics
2Measurement precision
If a broader range of candidate speeds is analyzed with iterative error calculations, then the accuracy of rotational speed determination is improved, but the complexity of the analysis process increases
Solution Approach 1:
The system performs preliminary analysis by identifying potential candidate speeds based on the vibration spectrum before conducting detailed harmonic analysis. This preliminary filtering reduces the search space and allows systematic evaluation of candidates in order of likelihood
Solution Approach 2:
The patent employs iterative feedback mechanisms where each candidate speed is evaluated based on how well its predicted harmonics match the observed vibration spectrum. The error calculation provides feedback that guides the selection process, systematically eliminating unlikely candidates and converging on the correct rotational speed
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 significantly enhances the accuracy of rotational speed determination, enabling precise diagnosis of machine issues such as unbalance, misalignment, and bearing damage, even in the absence of a tachometer signal.
Implementation Method 1
a vibration sensor that generates an analog vibration signal
Data Source
AI summary
An apparatus is described that determines an estimated rotational speed of a rotating component of a machine in the absence of a reliable tachometer signal to indicate an actual rotational speed. The apparatus includes a processor that determines a range of rotational speeds for the machine based on historical data, generates a vibration spectrum based on measured digital vibration data, identifies vibration peaks in the spectrum, determines a maximum peak amplitude of the vibration peaks, determines candidate frequency values within the range of rotational speeds, for multiple harmonics identifies a nearest peak within a spectral peak frequency tolerance of each harmonic, determines an error value based on a difference between the candidate frequency value and the nearest peak frequency value, determines an error sum value for each candidate frequency value, which is an iterative sum of the error values determined for the harmonics, determines the estimated rotational speed of the machine based on the candidate frequency value having a largest error sum value, and analyzes the digital vibration data using the estimated rotational speed of the machine to determine an operational characteristic of the machine.