Mode-shape magnification in high-speed camera measurements

Čufar, Krištof (avtor), Slavič, Janko (avtor), Boltežar, Miha (avtor)

If motion, identified using image-based methods, is too small to be seen with the naked eye, motion magnification can be used to help with the visualization. Established motion-magnification methods magnify (typically up to 1000 times) the band-passed content of the image data. Especially at higher frequencies, the amplitudes of measured displacements are often below the noise floor. In this research, a novel method for amplifying vibrations, based on experimental modal analysis (EMA), is introduced. The response of the examined structure to dynamic excitation is measured with a simplified, gradient-based, optical flow method and used to perform a hybrid modal analysis in conjunction with a reference accelerometer response measurement. Such a hybrid approach can: (a) identify structural dynamics significantly in the sub-pixel range, and (b) significantly below the image noise floor. The image of the vibrating structure is subdivided using a planar triangle mesh, which is then warped in accordance with the identified mode shape. A mesh-element-wise affine transformation is performed to obtain an image of the magnified mode shape. In the experimental part, the proposed method achieved magnification factors of approximately 40 thousand times, which is an order of magnitude deeper into noise than available before; additionally, the proposed approach is numerically significantly less demanding. The introduced mode-shape magnification presents an alternative to existing motion-magnification methods for applications where the harmonic displacement information is hidden by image noise.

• Jezik: Angleški jezik
• Ključne besede: image-based structural identification, mode-shape magnification, motion magnification, DIC, optical flow
• Vrsta gradiva: Članek v reviji
• Tipologija: 1.01 - Izvirni znanstveni članek
• Organizacija: FS - Fakulteta za strojništvo
• Status publikacije: Objavljeno
• Različica publikacije: Objavljena publikacija
• Leto izida: 2024
• Št. strani: 15 str.
• Številčenje: Vol. 213, art. 111336
• PID: 20.500.12556/RUL-158171
• UDK: 519.677:681.7
• ISSN pri članku: 1096-1216
• DOI: 10.1016/j.ymssp.2024.111336
• COBISS.SI-ID: 196821507
• Datum objave v RUL: 27.05.2024

Gradivo je del revije

• Naslov: Mechanical systems and signal processing
• Skrajšan naslov: Mech. syst. signal process.
• Založnik: Elsevier
• ISSN: 1096-1216
• COBISS.SI-ID: 15296283

Licence

• Licenca: CC BY 4.0, Creative Commons Priznanje avtorstva 4.0 Mednarodna
• Povezava: http://creativecommons.org/licenses/by/4.0/deed.sl
• Opis: To je standardna licenca Creative Commons, ki daje uporabnikom največ možnosti za nadaljnjo uporabo dela, pri čemer morajo navesti avtorja.

Sekundarni jezik

• Jezik: Slovenski jezik
• Ključne besede: identifikacija struktur na podlagi slikovnega gradiva, povečanje nihanja na podlagi modalnih oblik, DIC, optični tok

Projekti

• Financer: ARRS - Agencija za raziskovalno dejavnost Republike Slovenije
• Številka projekta: P2-0263
• Naslov: Mehanika v tehniki

• Financer: ARRS - Agencija za raziskovalno dejavnost Republike Slovenije
• Številka projekta: N2-0144
• Naslov: Optična metoda za obratovalno identifikacijo reduciranega nelinearnega modela