Playground for ants - what is this?

It is an ant simulation aimed at investigating their foraging behavior. When ants - small red discs with a line heading marker - swarm out of their nest they appear to wander randomly at first, but soon they form a well-pronounced trail between the nest - blue disc - and the food source - a bunch of green dots in a neighbourhood. Surprisingly, the trail found is typically fairly close to the shortest possible path. When there are multiple food sources, the ant colony usually exploits them in the order of their distance.

Individual ants wander out of the nest in random directions, leaving a trail of ‘homing pheromone’ (a volatile chemical substance) - blue cloud - behind. When an ant finds food, it sets out for the nest, this time dropping ‘food pheromone’ - green cloud - as it goes. Food-seeking ants follow the gradient of ‘food pheromone’ in their local neighborhood, while homing ants seek places with high amounts of ‘homing pheromone’. Below a certain threshold pheromone level and also with a constant probability, the ants move randomly. This latter component controls the balance between ‘exploitation’ and ‘exploration’, the essence of optimizing behavior.

During their walk, ants follow a simple probabilistic rule: they move to the neighboring cell with the highest pheromone level (depending on their destination, they either seek ‘homing pheromone’ or ‘food pheromone’ locations). Below a certain threshold, and with a given probability, they move randomly. However, the ants prefer not to turn, i.e., their selection of new location is biased by their direction.

The simulation has some parameters that can be altered by you:

• Seed: randomization value. The same seed with other parameters unchanged always shows the same colony behavior.
• Food sources: the number of location around which food particles are scattered with a Gaussan distribution.
• Food: Number of food particles in all food sources.
• Ants: Number of foraging ants.

• Step: Elapsed time since the start of the simulation in discrete units.
• Ants carrying: Number of ants possessing a food particle and carrying it to the hive.
• Ants searching: Number of ants without food searching for a particle.
• Food collected: Number of food particles collected so far.
• Step cycle: current speed of the simulation in milliseconds. Be careful and do not use too large parameters to keep the simulation responsive.

If you click on an ant then it becomes the selected ant - highlighted in yellow - and you will see its actual state in the table on the Selected ant tab.

Entropy tab shows the development of the ant and the food entropy over time.

You can watch the on-going simulation by clicking on Run or follow it step by step clicking on Step.

For details of our research you can read this article: Measuring Stigmergy: the Case of Foraging Ants.