Rotating Machinery Natural Frequency Detection Using FFT Sensors

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Solution Overview

Problem

Existing methods for determining natural frequencies of rotating machinery are inaccurate for actual manufactured systems due to manufacturing inaccuracies and complexities, leading to increased wear and tear and premature failure, and require extensive testing or additional sensors.

Innovation Solution

Utilizing a Discrete Fourier Transform, specifically Fast Fourier Transform, with rotational speed sensors already integrated into the machinery to detect torsional natural frequencies without additional hardware, enabling real-time control algorithms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If computer modeling is used to determine natural frequencies, then the analysis can be performed efficiently, but the results are only valid for idealized systems and do not precisely represent actual manufactured systems

Engineering Contradiction:

Improveanalysis efficiencyVSAvoidnatural frequency accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The system uses sensors already integrated into the manufactured system for their original purposes to simultaneously detect natural frequencies, eliminating the need for separate testing equipment and enabling the system to self-diagnose its dynamic characteristics

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system transforms operational vibration data into natural frequency information through signal processing algorithms, changing the parameter representation from time-domain vibration signals to frequency-domain characteristics that reveal system natural frequencies

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If extensive testing is performed on a physical system to determine natural frequencies, then precise accuracy is achieved for that specific system, but the results serve only as an approximation for other systems with manufacturing variations

Engineering Contradiction:

Improvenatural frequency accuracyVSAvoidapplicability to other systems

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The system continuously monitors vibration signals and uses feedback algorithms to identify natural frequencies in real-time, allowing dynamic adjustment and continuous verification of system characteristics during actual operation

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces extensive physical testing procedures with computational signal processing of operational data, substituting mechanical testing methods with algorithmic analysis that can be applied across different system instances

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If additional sensors are added to detect natural frequencies, then measurement capability is improved, but system complexity and cost increase

Engineering Contradiction:

Improvenatural frequency detection capabilityVSAvoidsensor quantity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system makes existing sensors serve multiple functions - their original measurement purpose plus natural frequency detection - allowing one sensor to perform multiple measurement tasks and eliminating the need for dedicated frequency sensing equipment

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The manufactured system uses its own existing sensors to detect its natural frequencies, enabling self-diagnosis without requiring external testing equipment or additional sensing infrastructure

Inventive Principle:

Principle #25Self-service

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

Accurately detects natural frequencies, reducing wear and tear by allowing for real-time control of rotating systems, enhancing reliability and reducing downtime.

Implementation Method 1

Embodiments of the algorithm utilize a Discrete Fourier Transform (in this case, a Fast Fourier Transform (FFT)) with respect to the revolutions of one component of the rotating machinery

Methodology Applied

Scientific EffectDiscrete Fourier Transform:

Data Source

PatentUS20250277719A1Systems and methods for determining natural frequencies of rotating machinery

Publication Date: 2025.09.04 PURDUE RES FOUND

AI summary

Systems and/or methods for determining the natural frequencies of rotating machinery systems, including complex rotating machinery systems such as the powertrains of vehicles powered by internal combustion engines, are disclosed. Embodiments include receiving information from a sensor related to the rotation of a component in the drivetrain (such as a rotating toothed gear), calculating a velocity of the component, calculating a transformed velocity of the component (such as by using a Fast Fourier Transform), selecting one or more shaft orders desired for analysis (such as those based on a predetermined set of likely shaft orders), selecting the amplitudes of the select shaft orders, normalizing the amplitudes, mapping the normalized amplitudes to the Hertz domain, calculating local maxima of the normalized amplitudes, and/or identifying frequencies associated with the calculated local maxima. Additional embodiments include repeating the procedures and identifying clusters of local maxima. Further embodiments include windowing the velocity profile.