Rotating Machine Diagnosis Using Undersampled Frequency Correction

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Solution Overview

Problem

Existing diagnostic devices for rotating machines struggle with accurately diagnosing equipment under varying operating conditions using undersampled measurement signals, as they require complex hardware and pre-information, making it difficult to differentiate between closely arranged frequency peaks and increasing hardware requirements.

Innovation Solution

A diagnostic device that processes undersampled measurement signals by converting them into the frequency domain, determining a relation parameter based on operational parameters, and performing a frequency component multiplying process to generate a corrected frequency spectrum, which suppresses false peaks and reduces computational burden, allowing for accurate diagnosis without complex hardware.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If high-speed sampling is used to fulfill the Nyquist criterion, then measurement precision is improved, but device complexity and computational burden increase

Engineering Contradiction:

Improvediagnosis accuracyVSAvoidhardware requirements

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent changes the sampling rate parameter from high-speed (fulfilling Nyquist criterion) to low-speed (below Nyquist criterion), and compensates through signal processing parameter adjustments in the frequency domain to maintain diagnosis accuracy while reducing hardware complexity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical/sampling-based solution (high-speed sampling hardware) with a signal processing-based solution (frequency domain analysis and peak correction algorithms), substituting hardware complexity with computational methods

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If band pass sampling approach is used with pre-information, then measurement precision is improved, but device complexity increases due to required pre-information

Engineering Contradiction:

Improvefrequency peak accuracyVSAvoidpre-information requirements

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes the diagnostic system self-sufficient by extracting all necessary information directly from the undersampled measurement signal itself, eliminating the need for external pre-information about operating conditions or frequency characteristics

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent performs preliminary frequency domain transformation and peak detection directly on the undersampled signal, preparing the data in advance for correction without requiring pre-acquired information about the system's operating parameters

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If detailed pre-information is provided for peak correction, then measurement precision is improved, but ease of operation deteriorates due to reduced general usability

Engineering Contradiction:

Improvefrequency spectrum accuracyVSAvoidgeneral usability

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent creates a universal diagnostic method that can handle various operating conditions and machine types without requiring condition-specific pre-information, making the system broadly applicable across different scenarios while maintaining accuracy

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Device complexity

If undersampled signals are used, then device complexity is reduced, but measurement precision deteriorates due to false frequency peaks

Engineering Contradiction:

Improvehardware requirementsVSAvoidfrequency spectrum accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent extracts and identifies false frequency peaks (aliases) from the frequency spectrum obtained through undersampling, and removes or corrects them to recover the true frequency characteristics of the measurement signal

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the harmful effect of undersampling (which creates false peaks) into a beneficial diagnostic tool by developing correction methods that specifically target and eliminate these false peaks, ultimately improving the robustness of low-speed sampling approaches

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentEP4053660B1Diagnostic device and method for a rotating machine

Publication Date: 2025.01.08 HITACHI LTD

Figure 1(a)~1(d)
Figure 2(a)~2(d)
Figure 3(a)~3(c)

AI summary

The present disclosure relates to a diagnostic device 200 for analyzing measurement signals of a rotating machine and for diagnosing a state of a rotating machine. The diagnostic device 200 at least comprises a measurement signal input unit 201 that is configured to receive at least two measurement signals, a control parameter input unit 202 that is configured to receive a second operational parameter of the rotating machine for each of the received measurement signals, and an analyzing unit 203.