Multi-Target Coordinated Search Algorithm for Swarm Robotics Considering Practical Constraints

In order to deal with the multi-target search problems for swarm robots in unknown complex environments, a multi-target coordinated search algorithm for swarm robots considering practical constraints is proposed in this paper. Firstly, according to the target detection situation of swarm robots, an ideal search algorithm framework combining the strategy of roaming search and coordinated search is established. Secondly, based on the framework of the multi-target search algorithm, a simplified virtual force model is combined, which effectively overcomes the real-time obstacle avoidance problem in the target search of swarm robots. Finally, in order to solve the distributed communication problem in the multi-target search of swarm robots, a distributed neighborhood communication mechanism based on a time-varying characteristic swarm with a restricted random line of sight is proposed, and which is combined with the multi-target search framework. For the swarm robot kinematics, obstacle avoidance, and communication constraints of swarm robots, the proposed multi-target search strategy is more stable, efficient, and practical than the previous methods. The effectiveness of this proposed method is verified by numerical simulations.

A Random-Line-Graph Approach to Overlapping Line Segments

We study graphs that are formed by independently positioned needles (i.e. line segments) in the unit square. To mathematically characterize the graph structure, we derive the probability that two line segments intersect and determine related quantities such as the distribution of intersections, given a certain number of line segments $N$. We interpret intersections between line segments as nodes and connections between them as edges in a spatial network that we refer to as random-line graph (RLG). Using methods from the study of random-geometric graphs, we show that the probability of RLGs to be connected undergoes a sharp transition if the number of lines exceeds a threshold $N^*$.

Comparison of microhabitat use in young regrowth and unlogged forest by the eastern pygmy-possum (Cercartetus nanus)

We describe microhabitat use and response to disturbance by the eastern pygmy-possum (Cercartetus nanus) in heathy dry sclerophyll forest using spool-and-line-tracking. We compared unlogged forest with forest regenerating four years after selective logging. Structural and floristic attributes were scored along spool lines and compared with a random line for each possum. We found that possums (n = 23) selected areas based on both structural and floristic attributes. Possums selected dense understorey, especially that comprising flowering hairpin banksia (Banksia spinulosa) and Gymea lily (Doryanthes excelsa). Fallen logs were not selected by nocturnally active possums. Spool lines in regrowth forest had less eucalypt cover and more understorey cover (e.g. D. excelsa and B. spinulosa) than unlogged forest. Conversely, cover of Banksia serrata was less in regrowth than unlogged forest. Spool lines were commonly found both at ground level (mean = 52–57% of lengths) and above the ground (43–48% of lengths). There was no difference in the mean spool height between the logging treatments (regrowth: 0.47 ± 0.14 m; unlogged: 0.49 ± 0.10 m; ± s.e.). Overall, our results suggest that the dense, flowering understorey that regenerates after selective logging is suitable for use and is the primary attribute selected by active pygmy-possums.