Rotor unbalance diagnosis method using vision based orbit and phase analyses

Eunjin Jo; Sung-Hwan Shin

doi:10.7776/ASK.2026.45.3.305

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2026 Vol.45, Issue 3 Preview Page Next Page

Rotor unbalance diagnosis method using vision based orbit and phase analyses 비전 기반 궤도 및 위상 분석을 이용한 회전체 불균형 진단

31 May 2026. pp. 305-312

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Abstract

This paper proposes a practical non-contact unbalance diagnosis method for rotating machinery using a single camera to overcome the limitations of conventional multi-sensor systems. An unbalance diagnosis algorithm was developed to extract two-dimensional shaft orbits at a sub-pixel level through autonomous Region of Interest (ROI) tracking and centroid calculation. Principal Component Analysis (PCA) and Fast Fourier Transform (FFT) were utilized to identify the principal vibration axis and frequency characteristics. The magnitude of the unbalance mass was inversely estimated by correlating the Root Mean Square (RMS) of the displacement response with the static stiffness model of the system. Furthermore, the physical radial direction of the unbalance mass on a shaft was identified without additional sensors by synchronizing the major axis direction of the orbit with the image phase information. Experimental results at 240 r/min demonstrated that the system could capture a minute displacement increase of 0.11 mm, estimating a micro-unbalance mass, which represents only 0.84 % of the total rotor assembly mass, with an error of less than 9 %. This study demonstrates that the magnitude and direction of unbalance can be accurately estimated without complex multi-sensor systems, providing a practical alternative for efficient on-site balancing and predictive maintenance through vision-based measurement.

Keywords

Non-contact diagnosis

Rotor unbalance

Vision based measurement

Orbit analysis

Phase synchronization

본 논문은 기존 멀티 센서 시스템의 제약을 극복하기 위해, 단일 카메라를 활용한 실용적인 비접촉식 회전체 불균형 진단 기법을 제안한다. 불균형 진단 알고리즘을 개발하여 관심영역(Region of Interest, ROI) 자동 추적 및 무게중심 산출법으로 2차원 축심 궤도를 서브 픽셀 단위로 추출하고, 주성분 분석(Principal Component Analysis, PCA)과 고속 푸리에 변환(Fast Fourier Transform, FFT) 분석을 통해 진동의 주축 방향과 주파수 특성을 규명하였다. 변위 응답의 실효치(Root Mean Square, RMS)를 시스템의 정적 강성 모델과 연계하여 불균형 질량의 크기를 역산하였으며, 궤도의 장축 방향과 이미지 위상 정보를 동기화하여 별도의 추가 센서 없이 불균형 질량의 물리적 방향을 식별하였다. 240 r/min 조건의 실험 결과, 0.11 mm의 미세 변위 증가를 포착하여 전체 회전부 질량 대비 단 0.84 %에 불과한 미소 불균형 질량을 9 % 이내의 오차로 추정하고, 그 방향을 정확히 식별하였다. 본 연구는 별도의 멀티 센서 시스템 없이도 불균형 질량의 크기와 방향 추정이 가능함을 입증하였으며, 비전 기반 계측을 활용한 효율적인 현장 밸런싱 및 예지 보전의 실용적 대안을 제시하였다.

키워드

비접촉 진단

회전체 불균형

비전 기반 계측

궤도 분석

위상 동기화

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Information

Publisher :The Acoustical Society of Korea
Publisher(Ko) :한국음향학회
Journal Title :The Journal of the Acoustical Society of Korea
Journal Title(Ko) :한국음향학회지
Volume : 45
No :3
Pages :305-312
Received Date : 2026-03-12
Accepted Date : 2026-04-16
DOI :https://doi.org/10.7776/ASK.2026.45.3.305

The Journal of the Acoustical Society of KoreaISSN:1225-4428(Print) 2287-3775(Online)한국음향학회

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