The next generation of large-scale spectroscopic survey experiments such asDESI, will use thousands of fiber positioner robots packed on a focal plate. Inorder to maximize the observing time with this robotic system we need to movein parallel the fiber-ends of all positioners from the previous to the nexttarget coordinates. Direct trajectories are not feasible due to collision risksthat could undeniably damage the robots and impact the survey operation andperformance. We have previously developed a motion planning method based on anovel decentralized navigation function for collision-free coordination offiber positioners. The navigation function takes into account the configurationof positioners as well as their envelope constraints. The motion planningscheme has linear complexity and short motion duration (~2.5 seconds with themaximum speed of 30 rpm for the positioner), which is independent of the numberof positioners. These two key advantages of the decentralization designate themethod as a promising solution for the collision-free motion-planning problemin the next-generation of fiber-fed spectrographs. In a framework where acentralized computer communicates with the positioner robots, communicationoverhead can be reduced significantly by using velocity profiles consisting ofa few bits only. We present here the discretization of velocity profiles toensure the feasibility of a real-time coordination for a large number ofpositioners. The modified motion planning method that generates piecewiselinearized position profiles guarantees collision-free trajectories for all therobots. The velocity profiles fit few bits at the expense of highercomputational costs.
展开▼
