  Collective movement occurs in living systems where the simple movements of
individual members of a pop- ulation are combined to generate movement of the
collective as a whole, displaying complex dynamics which cannot be found in the
component parts themselves. The plasmodium stage of slime mould Physarum
polycephalum displays complex amoeboid movement during its foraging and hazard
avoidance and its movement can be influenced by the spatial placement of
attractant and repellent stimuli. Slime mould is attractive to robotics due to
its simple component parts and the distributed nature of its control and
locomotion mechanisms. We investigate methods of automated guidance of a
multi-agent swarm collective along a pre-defined path to a goal location. We
demonstrate a closed-loop feedback mechanism using attractant and repellent
stimuli. We find that guidance by repellent stimuli (a light illumination mask)
provides faster and more accurate guidance than attractant sources, which
exhibit overshooting phenomena at path turns. The method allows traversal of
convoluted arenas with challenging obstacles and provides an insight into how
unconven- tional computing substrates may be hybridised with classical
computing methods to take advantage of the benefits of both approaches.
