Collision-free path planning for LAMOST fiber positioners based on the rapidly-exploring random tree method

Abstract

The key to solving numerous crucial astronomical and astrophysics issues lies in massive spectroscopic surveys mainly conducted at multi-object spectroscopy (MOS) facilities on large-aperture telescopes such as Large Sky Area Multi-Object Fiber Spectroscopy Telescope (LAMOST). The efficiency of these surveys is greatly influenced by the fast and accurate movement of fiber positioners. However, due to the overlapped patrol discs and unexpected mechanical failure, mutual interference and collisions between positioners may occur. One existing solution is based on Markov chains and greedy selection method for navigation, which has high time complexity and results in oscillations of fiber positioners. Through analysis and research on collision types and trajectories, a fast collision-free path planning method for fiber positioners based on the RRT algorithm and B-spline curvefitting is proposed. The proposed algorithm can generate continuous and smooth feasible paths when collisions happen. Simulation experiments show that the proposed method can meet the requirements of fast, safe, and collision-free path planning for fiber positioners, help to improve the efficiency of massive spectroscopic surveys. This method can be adopted by not only LAMOST but also other projects such as Dark Energy Spectroscopic Instrument(DESI) and MOS.