Fiber assignment in wide-field multiobject fiber-fed spectrographs

Zhang, Feifan; Wang, Jianping; Zhai, Chao; Jin, Yi; Liu, Zhigang; Chu, Jiaru; Zhou, Zengxiang

doi:10.1117/1.jatis.6.4.047001

Cited by 6 publications

(3 citation statements)

References 33 publications

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“…Considering the disadvantages of LSM, we treated the calibration problem as an optimization problem. DE is one of the simplest and most effective global optimization algorithms with few parameters and high identification accuracy and optimal rate (Das & Suganthan 2011;Zhang et al 2020b). Thus, we adopted the DE algorithm to calibrate the positioner parameters.…”

Section: De Algorithmmentioning

confidence: 99%

“…They have considerably revolutionized our understanding of the formation and evolution of the universe (Dong et al 2018). Their success has motivated the proposal and construction of new large-scale multiplexed spectroscopic instruments (Miszalski et al 2006;Zhang et al 2020aZhang et al , 2020b. Currently, they are primarily conducted at multiobject spectroscopy (MOS) facilities on large-aperture telescopes (Morales et al 2012;Makarem et al 2014).…”

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

Self Cite

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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: De Algorithmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Zhang,

Huang,

Chen

et al. 2024

Self Cite

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“…Massive observation surveys are powerful tools for collecting spectral data on celestial objects (Yan et al 2022). These surveys are primarily conducted using multiobject spectroscopy (MOS) instruments on large telescopes (Zhang et al 2020a(Zhang et al , 2020b. Among these instruments, the Large Sky Area Multi-Object Fiber Spectroscopy Telescope (LAMOST) has one of the highest spectral acquisition rates.…”

Section: Introductionmentioning

confidence: 99%

Motion Planning for the Robotic Fiber Positioners of the Large Sky Area Multiobject Fiber Spectrocopy Telescope

Zhang,

Chen,

Wang

et al. 2024

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The Large Sky Area Multi-Object Fiber Spectroscopy Telescope (LAMOST) is one of the most effective multiobject spectroscopic instruments. Its survey efficiency is guaranteed by simultaneously positioning multiple fibers via 4000 robotic fiber positioners (RFPs). With the further updates to LAMOST, the new-generation RFPs will be smaller, and the number of RFPs will increase to 5000. The RFPs are densely packed with shared working space. Thus, they may collide with each other, leading to them damaged and reducing the survey speed. In this study, we propose a new motion planning algorithm that prevents the collision of RFPs. To simplify the collision avoidance problem, we transform the motion planning process from a dynamic one into a static one by selecting one of the RFPs in each collision pair as the waiting robot. Accordingly, we design a method for choosing the waiting robot, and use a rapidly exploring random tree to plan a collision-free path for the waiting robot. However, there may be blocks between the waiting robots and their neighbors. Therefore, we also design methods to resolve these blocks. Simulations suggest that the proposed algorithm can prevent 98.4% of the collisions. About 99.9% of the positioners can reach their targets without collisions. Although developed for LAMOST, we believe that our algorithm can also be used for other instruments with equal-arm theta-phi positioners, such as the Dark Energy Spectroscopic Instrument.

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Precision control and performance of new-generation integrated fiber positioners for LAMOST

Zhang

Chen²,

Zhu³

et al. 2023

Advanced Optical Manufacturing Technologies and Applications 2022; And 2nd International Forum of Young Scientists on Advanced

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An improvement project of LAMOST will be implemented soon. To improve the observation accuracy and spectral acquisition rate, a new integrated fiber positioner was designed for the new robotic Focal Plane System. This paper designs the drive system for the integrated fiber positioner, and introduces the mechanical, electronic and software design in detail. We also built a vision measurement platform with a telecentric lenses to test the position performance. The fiber positioner positions the fiber to target by first blind positioning and multiple position corrections. After the positioner completes the first blind move, the camera takes the fiber image and calculates the offset between the actual position of the fiber from its target position. Then, the drive system controls the fiber positioner move according the offset value to correct the fiber position. We achieve the final accuracy through iterative position corrections. Experimental results show that both the drive system and the fiber positioner have reliable performance and high efficiency. With a first blind move inside of its workspace, the positioner can position the fibers with a planar precision better than 100um, the position error is less than 10um after the second correction and the RMS error is less than 3um.

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Fiber assignment in wide-field multiobject fiber-fed spectrographs

Cited by 6 publications

References 33 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

Motion Planning for the Robotic Fiber Positioners of the Large Sky Area Multiobject Fiber Spectrocopy Telescope

Precision control and performance of new-generation integrated fiber positioners for LAMOST

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