Do Ants Need to Estimate the Geometrical Properties of Trail Bifurcations to Find an Efficient Route? A Swarm Robotics Test Bed

Abstract

Interactions between individuals and the structure of their environment play a crucial role in shaping self-organized collective behaviors. Recent studies have shown that ants crossing asymmetrical bifurcations in a network of galleries tend to follow the branch that deviates the least from their incoming direction. At the collective level, the combination of this tendency and the pheromone-based recruitment results in a greater likelihood of selecting the shortest path between the colony's nest and a food source in a network containing asymmetrical bifurcations. It was not clear however what the origin of this behavioral bias is. Here we propose that it results from a simple interaction between the behavior of the ants and the geometry of the network, and that it does not require the ability to measure the angle of the bifurcation. We tested this hypothesis using groups of ant-like robots whose perceptual and cognitive abilities can be fully specified. We programmed them only to lay down and follow light trails, avoid obstacles and move according to a correlated random walk, but not to use more sophisticated orientation methods. We recorded the behavior of the robots in networks of galleries presenting either only symmetrical bifurcations or a combination of symmetrical and asymmetrical bifurcations. Individual robots displayed the same pattern of branch choice as individual ants when crossing a bifurcation, suggesting that ants do not actually measure the geometry of the bifurcations when travelling along a pheromone trail. Finally at the collective level, the group of robots was more likely to select one of the possible shorter paths between two designated areas when moving in an asymmetrical network, as observed in ants. This study reveals the importance of the shape of trail networks for foraging in ants and emphasizes the underestimated role of the geometrical properties of transportation networks in general.

The Best-of-n Problem in Robot Swarms: Formalization, State of the Art, and Novel Perspectives

“…The study of Garnier et al (2013) provides the only experimental results over a problem with n = 7 options (see Section 4.2), while the study of Scheidler et al (2016) provided a theoretical analysis for the case of n = 3 options (see Section 5.1.1).…”

“…In contrast, the length of each path indirectly biases the collective decision-making process, which takes place at the source area, because robots traveling through the shortest (and fastest) path have higher chances to influence other members of the swarm (i.e., asymmetric option cost). Garnier et al (2013) considered a foraging scenario that takes place in a maze. Similarly to the double-bridge scenario, a swarm of robots is located in an environment composed of corridors that connect a source area with a destination area.…”

“…Similarly to the double-bridge scenario, a swarm of robots is located in an environment composed of corridors that connect a source area with a destination area. In the case of Garnier et al (2013), corridors form a maze that provides the swarm with n = 7 different paths connecting the source area with the destination area (see Figure 4B). The robots in the swarm do not measure explicitly any feature of a foraging path, and the option quality is therefore symmetric.…”

“…The option cost is still represented by the length of each path and is asymmetric due to the existence of a path shorter than all other paths (i.e., best option). In addition to the path length, Garnier et al (2013) also showed that a second environmental factor that can bias the collective decision is the angle of branches in a bifurcation whereby the branch offering the smallest deviation from the current direction of motion has a lower cost.…”

Colias-Φ: An Autonomous Micro Robot for Artificial Pheromone Communication

“…Moreover, utilizing continuous and long-term of the chemical pheromones in the laboratory environment would be harmful. Therefore, artificial media such as RFID [9], audio [10]- [12] and light [5], [13]- [15] could be the safe media to be used as the artificial pheromone and cue. Garnier et al [16] presented an experimental setup for study on pheromone based communication with micro autonomous robots using the projected light.…”