3.4.1. Environments

The three systems discussed in this paper were tested in two environments. The first is a square environment measuring 15 × 15 m. The first 2 meters of the environment were assigned as the nest area, highlighted in grey as illustrated in Figure 4. This environment provided an arena for simple operation, identifying whether the system, under only the pressure of the specified demand could operate effectively.

**Figure 4.** Screenshot of first simulated environment used. Food items are shown as black circles in the white environment, puck robots can be seen waiting in the nest area (light grey).

The second environment (illustrated in Figure 5) instead measured 20 × 10 m though retained a similar nest layout to the first. Four funnelled corridors were included in this environment to act as obstacles. These increase swarm density during exploration and provides additional difficulty to the tested systems, akin to that of a group of robots attempting to complete tasks in industrial settings such as mines, power plants or drainage systems, where space could be limited. This congestion will not only limit the success of the robots by slowing them down, but short range collision sensors will be triggered more frequently, meaning that the return hormone will potentially instruct robots to return home too early. This will heavily test the adaptability of the system, giving the combination of hormone systems a greater challenge, making the probability of one system disrupting the other in a negative fashion more likely.

**Figure 5.** Screenshot of second simulated environment used. Food items are shown as black circles in the white environment, puck robots can be seen waiting in the nest area (light grey). Obstacles creating corridors are illustrated in dark grey.
