On identifying natural frequencies in the JAST80 telescope and validation with a simplified 3-d Model

Arranz, Fernando ; Abad, Javier (Universidad de Zaragoza) ; Ramos, Pedro (Universidad de Zaragoza) ; Bielsa, Samuel ; Yanes-Díaz, Axel ; Palacios-Navarro, Guillermo (Universidad de Zaragoza)

Resumen: The instrumentation of professional telescopes is very sensitive to vibrations. These vibrations, caused by wind, terrain, or its actuators, affect the quality of the images taken. If vibrations present frequency components coinciding with the natural frequencies associated with the proper modes of the telescope mount, the vibratory response is amplified and cause a decrease in image quality below the required standards. The goal of our study is to identify the natural frequencies of the German equatorial mount of the JAST80 telescope of the Observatorio Astrofísico de Javalambre (OAJ) and to validate a simplified finite element model (FEM). In addition, the interaction of the vibrations produced by the actuators in a right ascension (RA) movement with the natural frequencies obtained by means of a finite element analysis (FEA) is analyzed. To excite the structure of the telescope, its response in free vibration after an unexpected emergency stop of an RA movement was used. A setup of three accelerometers allowed us to compare the excitation frequencies of the structure with those obtained with the FEA. Natural frequency values obtained through the FEM showed deviations below 12% with respect to the experimental values, thus validating the simplified 3-D numerical model of the telescope mount for further analysis of its dynamic behavior. On the other hand, the analysis of the measured vibratory indicated that the natural frequencies of the mount for an RA movement in normal operation were not excited by the actions produced by the actuator, and therefore, the quality of the images taken is not compromised. Finally, the possibility of using the measurement of the vibrational response of the mount in emergency stop conditions to monitor its structural integrity is pointed out.

Idioma: Inglés

DOI: 10.1109/TIM.2023.3246530

Año: 2023

Publicado en: IEEE Transactions on Instrumentation and Measurement 72 (2023), 6501213 [13 pp.]
ISSN: 0018-9456

Factor impacto JCR: 5.6 (2023)

Categ. JCR: INSTRUMENTS & INSTRUMENTATION rank: 9 / 76 = 0.118 (2023) - Q1 - T1
Categ. JCR: ENGINEERING, ELECTRICAL & ELECTRONIC rank: 53 / 353 = 0.15 (2023) - Q1 - T1

Factor impacto CITESCORE: 9.0 - Electrical and Electronic Engineering (Q1) - Instrumentation (Q1)

Factor impacto SCIMAGO: 1.536 - Instrumentation (Q1) - Electrical and Electronic Engineering (Q1)

Financiación: info:eu-repo/grantAgreement/ES/UZ/Cátedra Devoture de Tecnología para el Ser Humano

Tipo y forma: Article (PostPrint)

Área (Departamento): Área Tecnología Electrónica (Dpto. Ingeniería Electrón.Com.)
Área (Departamento): Área Ingeniería Mecánica (Dpto. Ingeniería Mecánica)
Área (Departamento): Área Teoría Señal y Comunicac. (Dpto. Ingeniería Electrón.Com.)