  The arrangement of the fiber positioning units in LAMOST focal plane may lead
to the collisions during the fiber allocation. To avoid these collisions, the
soft protection system has to abandon some targets located in the overlapped
field of the adjacent fiber units. In this paper, we firstly analyzed the
probability of the collisions between fibers and inferred their possible
reasons. It is useful to solve the problem of the fiber-positioning units
collisions so as to improve LAMOST efficiency. Based on it, a collision
handling system is designed by using the master-slave control structure between
the micro control unit (MCU) and the microcomputer. The simulated experiments
validate that the system can provide real-time inspection and swap the
information between the fiber unit controllers and the main controller.
