IIR Filter Tachometer Signal Jitter Reduction
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Solution Overview
Problem
Inaccurate tachometer signals due to jitter lead to spectral smearing, reducing the effectiveness of vibration analysis in detecting component faults, especially for higher frequency signatures and harmonics, in rotating equipment condition monitoring systems.
Innovation Solution
A tachometer signal jitter reduction system that includes a tachometer sensor coupled with a controller using an Infinite Impulse Response (IIR) filter to remove jitter from the tachometer signal, ensuring zero phase lag and enabling accurate shaft speed monitoring, thereby improving fault discrimination and separability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a tachometer sensor is used to monitor shaft speed, then shaft speed monitoring is enabled, but jitter in the tachometer signal causes spectral smearing that reduces measurement precision
Solution Approach 1:
An Infinite Impulse Response (IIR) filter is introduced as an intermediary component between the tachometer sensor and the vibration analysis system. The filter processes the tachometer signal to remove jitter while preserving the essential speed information, thereby eliminating spectral smearing and improving fault detection accuracy without losing reliability
Solution Approach 2:
The patent applies parameter changes by modifying the tachometer signal through filtering operations. The IIR filter changes the signal parameters by attenuating high-frequency jitter components while maintaining the lower-frequency speed variation information, thus improving measurement precision without compromising the fundamental signal characteristics
2Measurement precision
If jitter is removed from the tachometer signal, then fault separability increases by 26%, but phase information may be altered
Solution Approach 1:
The IIR filter is designed with specific parameters that allow it to selectively remove jitter frequencies while preserving phase information at the frequencies of interest. By carefully selecting the filter cutoff frequency and order, the system achieves 26% improved fault separability while maintaining phase integrity for vibration analysis
Solution Approach 2:
The filter design incorporates feedback mechanisms that monitor the output signal quality and adjust filtering parameters to maintain phase information integrity. This feedback approach ensures that while jitter is removed to improve fault separability, the phase information required for accurate vibration analysis is preserved
Data Source
AI summary
Assessing and removing jitter from tachometer signals enhances the performance of condition monitoring systems where accurate tachometer signals are needed. A system as disclosed herein can be designed and configured to have a low order of operations, so as to allow for implementation on low cost microcontrollers, which can be important for bused, distributed monitoring systems in which the tachometer zero crossing data is collected at a tachometer sensor and then broadcast to other remote sensors needing that information for vibration or other advanced analysis. Moreover, for monolithic architecture systems (e.g., a centralized processing and control architecture), the low order of operation and small software code base allows the system to be a simple/low cost addition to existing monitoring systems.