A fiber positioner robot for the Gran Telescopio Canarias

Azzaro, M.; Becerril, S.; Vilar, Cristian; Arrillaga, X.; Sánchez, J.; Morales, Isaac; Carrera, M. A.; Prada, Francisco

doi:10.1117/12.856254

Cited by 5 publications

(4 citation statements)

References 6 publications

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“…For each pointing, the reconfiguration of the fibers at the focal plane is convenient (Jovanovic et al 2020). Thus, the fiber-feed approach is considered more versatile (Azzaro et al 2010).…”

Section: Introductionmentioning

confidence: 99%

“…Theta-phi positioners were first designed and adopted by the Large Sky Area Multi-Object Fiber Spectroscopy Telescope (LAMOST; Xing et al 1998). They have been widely adopted by the Super Ifu Deployable Experiment (SIDE; Prada et al 2008;Azzaro et al 2010), LAMOST second stage (Hu et al 2016(Hu et al , 2018Guo et al 2022), Multi-Object Optical and Nearinfrared Spectrograph (MOONS;Horler et al 2018;Kronig et al 2020a;Gonzalez et al 2022), Prime Focus Spectrograph (PFS; Fisher et al 2014;Wang et al 2022), and Dark Energy Spectroscopic Instrument (DESI;Fahim et al 2015;Martini et al 2018;Silber et al 2023). R-theta positioners have been designed for SIDE (Schlegel & Ghiorso 2008), BigBOSS (Silber et al 2012), 4MOST (Saviauk et al 2014), and VLT-MOONS and VLT-KMOS (Louth et al 2022).…”

Section: Introductionmentioning

confidence: 99%

“…For the RFP introduced above, the fiber ends must be accurately positioned at the focal surface to capture the light from targets (Fahim et al 2015). The positioning accuracy is a common problem in MOS facilities (Azzaro et al 2010). To achieve the desired precision, one focus is on the image-guided closed-loop control (Baltay et al 2019;Gillingham 2020).…”

Section: Introductionmentioning

confidence: 99%

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The Calibration of theta-phi Fiber Positioners Based on the Differential Evolution Algorithm

Zhang,

Huang,

Chen

et al. 2024

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Robotic fiber positioner (RFP) arrays are commonly adopted in multiobject spectroscopic instruments. The positioning accuracy is a common but vital issue for RFP as inaccurate fiber placement may heavily affect the observation performance. The calibration of RFP can effectively improve the positioning accuracy. Least-square is a widely used calibration method. However, it has disadvantages, such as sensitivity to the initial values and calculation complexity. To improve the positioning accuracy and reduce the iteration moves, we propose a new calibration method based on the differential evolution algorithm and verify it by calibrating the RFP of the Large Sky Area Multi-Object Fiber Spectroscopy Telescope. We first build the kinematic models of the RFP based on the Denavit–Hartenberg matrix and geometry relationship. Then, we analyze the error components and present the proposed calibration algorithms. The experiments are done with the digital universal tool microscope 19JC and the errors are calculated using the distance between the positions of achieved and target. Results show that the proposed algorithm can achieve higher accuracy than the least-square method and the average positioning accuracy is improved by 78.94% after calibration. Combined with the “pulse reduction” strategy and close-loop compensation, after two moves, the positioners can place the fiber ends within 40 μm of the intended location. The proposed calibration method is also suitable for other similar theta-phi positioners.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Calibration of theta-phi Fiber Positioners Based on the Differential Evolution Algorithm

Zhang,

Huang,

Chen

et al. 2024

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“…One successful positioning approach is the use of robotic positioners with two axes of rotation such as used for MEGARA, 10 MOONS, 11 PFS, 12,13 DESI, 14,15 and more recently for SDSS-V 16 and also proposed by others. [17][18][19][20][21][22][23][24] These positioners carry out Cartesian (x; y) planar movements using two actuated rigid arms serially linked. They have SCARA-like kinematics with two motorized rotational joints.…”

Section: Introductionmentioning

confidence: 99%

Optical test procedure for characterization and calibration of robotic fiber positioners for multiobject spectrographs

Kronig

Hörler

Caseiro

et al. 2020

J. Astron. Telesc. Instrum. Syst.

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The recent burgeoning interest in massive multiobject spectroscopy has pushed the development of massive optical fiber positioning systems. These systems rely on precise fiber placement to detect the light spectra of many stars and galaxies. One successful approach is the use of robotic fiber positioners, which allow one to automate and scale up observations. However, due to the need for high precision and accuracy, each positioner must be calibrated and verified to comply with the requirements. The calibration measurements are nontrivial, and the large number of the robotic positioners up to thousands can lead to a prohibitively long time for calibration. We describe and validate an optical calibration setup and procedure for robotic fiber positioning systems. Based on the measurements results, we have developed models describing the behavior of the positioners and we introduce new performance metrics that allow one to verify the stringent positioner specifications and furthermore help to identify and analyze design and manufacturing flaws. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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An 8-mm diameter fibre robot positioner for massive spectroscopy surveys

Fahim¹,

Prada²,

Kneib³

et al. 2015

Monthly Notices of the Royal Astronomical Society

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Context. Massive spectroscopic survey are becoming trendy in astrophysics and cosmology, as they can address new fundamental knowledge such as Galactic Archaeology and probe the nature of the mysterious Dark Energy. To enable massive spectroscopic surveys, new technology are being developed to place thousands of optical fibers at a given position on a focal plane. These technology needs to be: 1) accurate, with micrometer positional accuracy; 2) fast to minimize overhead; 3) robust to minimize failure; and 4) low cost. In this paper we present the development of a new 8-mm in diameter fiber positionner robot using two 4mm DC-brushless gearmotors, developed in the context of the Dark Energy Spectroscopic Instrument. This development was conducted by a SpanishSwiss (ES-CH) team led by the Instituto de Física Teórica (UAM-CSIC) and the Laboratoire d'Astrophysique (EPFL), in collaboration with the AVS company in Spain and the Faulhaber group (MPS & FAULHABER-MINIMOTOR) in Switzerland. Aims. The meachanical concept, DC-brushless motor properties, and the final performance of a prototyped unit is presented. Methods. Performance and verification tests were conducted with a fiber view camera-based optical set-up and using an automatic algorithm. Results. The prototype build is mechanically robust and reliable, and its control electronics ensure a very firm system with an xy positional accuracy better than 5µm. Conclusions. In this paper, we validate the concept of our advanced 8-mm fiber robot positioner prototype, as well as demonstrate that it can meet the requirements of the DESI project. Such efficient gearmotor fiber positionner robotic system can be adapted to any future massive fiber-fed spectrograph instrument.

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A fiber positioner robot for the Gran Telescopio Canarias

Cited by 5 publications

References 6 publications

The Calibration of theta-phi Fiber Positioners Based on the Differential Evolution Algorithm

The Calibration of theta-phi Fiber Positioners Based on the Differential Evolution Algorithm

Optical test procedure for characterization and calibration of robotic fiber positioners for multiobject spectrographs

An 8-mm diameter fibre robot positioner for massive spectroscopy surveys

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