Vibration RMS Error Function for Machine Monitoring
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Solution Overview
Problem
The reliable determination of root mean square values of vibration variables in machine state monitoring is hindered by the influence of measurement duration, particularly in the presence of beats, leading to oscillating results and inconsistencies, as there is no strict guideline for measurement duration and existing methods fail to suppress these oscillations.
Innovation Solution
A method involving a test measurement to estimate the influence of signal length on the root mean square value, using a root mean square value error function to determine the optimal measurement duration and quality indicator, allowing for the choice of best-suited measurement duration based on predetermined error tolerance and updating quality indicators during actual measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If measurement duration is shortened to improve productivity, then measurement time is reduced, but measurement precision deteriorates due to oscillating root mean square values caused by beats
Solution Approach 1:
The patent performs a preliminary test measurement with a long measurement duration to capture the complete vibration signal including beats. Based on this test measurement, it determines the actual measurement duration required for accurate root mean square value calculation. This preliminary action allows subsequent measurements to use the optimized duration, achieving both speed and accuracy.
Solution Approach 2:
The patent dynamically adjusts the measurement duration parameter based on the characteristics of the vibration signal detected in a test measurement. By analyzing the signal content and determining the appropriate measurement duration from the test results, the system adapts the measurement parameters to achieve accurate root mean square values while minimizing measurement time.
2Measurement precision
If measurement duration is extended to improve measurement precision, then root mean square value accuracy improves, but measurement time increases reducing productivity
Solution Approach 1:
The system performs a preliminary test measurement to analyze the vibration signal characteristics and determine the minimum required measurement duration for accurate root mean square value calculation. This preliminary analysis eliminates the need for consistently using excessive measurement durations, optimizing the balance between precision and productivity for subsequent measurements.
Solution Approach 2:
Instead of always using a fixed long measurement duration, the patent applies partial action by using only the necessary measurement duration determined from test measurements. This avoids the excessive measurement time that would reduce productivity while ensuring sufficient duration for accurate measurements in each specific case.
3Ease of operation
If a fixed measurement duration is used to simplify operation, then ease of operation improves, but reliability deteriorates due to oscillating results in the presence of beats
Solution Approach 1:
The system performs self-diagnosis through test measurements to automatically determine the appropriate measurement duration for the specific vibration signal being measured. This self-service approach eliminates the need for manual configuration by operators, maintaining ease of operation while ensuring reliable and consistent measurements by adapting to each signal's characteristics.
Solution Approach 2:
The patent uses feedback from test measurements to determine the optimal measurement duration. The results of the test measurement feed into the determination of subsequent measurement parameters, creating a closed-loop system that ensures reliable root mean square value calculations while maintaining simple operation through automated parameter selection.
Data Source
AI summary
The invention relates to a method for determining the root mean square value of a vibration variable that is measured on a machine. A test measurement is carried out in order to obtain a test signal of the vibration variable with a test signal length; the influence of shortening the signal length of the test signal on the associated root mean square value is estimated and the relative deviation of the root mean square value emerging for a shortened signal length from the root mean square value emerging for the full test signal length is estimated therefrom as a function of the signal length to obtain a root mean square value error function; and a measurement of the vibration variable is carried out for determining the root mean square value. The measurement duration of this measurement is selected on the basis of the root mean square value error function.