We present a new fiber assignment algorithm for a robotic fiber positioner system in multi-object spectroscopy. Modern fiber positioner systems typically have overlapping patrol regions, resulting in the number of observable targets being highly dependent on the fiber assignment scheme. To maximize observable targets without fiber collisions, the algorithm proceeds in three steps. First, it assigns the maximum number of targets for a given field of view without considering any collisions between fiber positioners. Then, the fibers in collision are grouped, and the algorithm finds the optimal solution resolving the collision problem within each group. We compare the results from this new algorithm with those from a simple algorithm that assigns targets in descending order of their rank by considering collisions. As a result, we could increase the overall completeness of target assignments by 10% with this new algorithm in comparison with the case using the simple algorithm in a field with 150 fibers. Our new algorithm is designed for the All-sky SPECtroscopic survey of nearby galaxies (A-SPEC) based on the K-SPEC spectrograph system, but can also be applied to similar fiber-based systems with heavily overlapping fiber positioners.

Introduction
    Spectroscopic Surveys with Multi-Object Spectrographs
    A-SPEC and K-SPEC
    Fiber Assignment Algorithm
K-SPEC Focal Plane System Layout
    Robotic Fiber Positioner
    Collision Formulation
Method
    Process 1: Target Selection without Considering Collisions
    Process 2: Group Collided Fiber Positioners
    Process 3: Optimal Target Assignment in Each Group
        Process 3-1: Find Optimal Configuration in Each Group and Its Surrounding Fibers
        Process 3-2: Find Optimal Configuration for Inconsistent or Colliding Fibers
Performance
Conclusions
Acknowledgments
References

• Minseong Kwon(Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea)
• Hyeonguk Bahk(Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea)
• Dongkok Kim(Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea, Institute for Data Innovation in Science, Seoul National University, Seoul 08826, Republic of Korea)
• Ho Seong Hwang(Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea, SNU Astronomy Research Center, Seoul National University, Seoul 08826, Republic of Korea, Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea, Australian Astronomical Optics - Macquarie University, North Ryde, NSW 2113, Australia) Corresponding author
• Jong Chul Lee(Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea)
• Jae-Woo Kim(Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea)
• Moo-Young Chun(Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea)
• Sang-Hyun Chun(Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea)
• Kang-Min Kim(Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea)
• Jongwan Ko(Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea)
• Ho-Gyu Lee(Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea)
• Yongseok Lee(Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea)
• Heeyoung Oh(Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea)
• Sungwook E. Hong(Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea, Astronomy Campus, University of Science and Technology, Daejeon 34055, Republic of Korea)
• Yunjong Kim(Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea, Astronomy Campus, University of Science and Technology, Daejeon 34055, Republic of Korea)
• Mingyeong Yang(Astronomy Campus, University of Science and Technology, Daejeon 34055, Republic of Korea, Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea)
• Minhee Hyun(Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Menlo Park, CA 94305, USA, Korea Astronomy and Space Science Institute, Daejeon 34055, Republic of Korea)
• Young-Man Choi(Department of Mechanical Engineering, Ajou University, Suwon-si, Gyeonggi-do, 16499, Republic of Korea)
• Haeun Chung(University of Arizona, Steward Observatory, Tucson, AZ 85721, USA)
• Donghui Jeong(School of Physics, Korea Institute for Advanced Study (KIAS), Seoul 02455, Republic of Korea, Department of Astronomy and Astrophysics, and Institute for Gravitation and the Cosmos, The Pennsylvania State University, University Park, PA 16802, USA)
• Dachan Kim(Department of Astronomy and Space Science, Chungnam National University, Daejeon 34134, Republic of Korea)
• Hyunho Lim(Department of Mechanical Engineering, Ajou University, Suwon-si, Gyeonggi-do, 16499, Republic of Korea)
• Changbom Park(School of Physics, Korea Institute for Advanced Study (KIAS), Seoul 02455, Republic of Korea)
• Hyunmi Song(Department of Astronomy and Space Science, Chungnam National University, Daejeon 34134, Republic of Korea)
• Yongmin Yoon(Department of Astronomy and Atmospheric Sciences, Kyungpook National University, Daegu 41566, Republic of Korea)