Control >> Aggregation >> Chains

Chain Pattern Formation

Chaining requires the creation of linear connections and can be considered as one of the basic patterns of self-assembly. An interesting example of chain formation is observed in chemistry. Polymerisation is a chemical process that creates long chains of polymers through interactions of basic elements, called monomers. After an initiating reaction with a catalyst reactant, free monomers connect to each other to form chains. These chains attract other free monomers to form longer chains. The process terminates when another reactant molecule connect to the chain, completing the electron octet of the last element. Thus, the individual behaviour of a single monomer is a probabilistic connection to other monomers or chains.

The behaviours for the formation of chains in the swarm-bot system are inspired from the polymerisation process. Initially, the s-bots are distributed uniformly in the environment and are attracted to each other. When an s-bot connects to a chain, it turns on its speaker, signalling the presence of a chain. As a consequence of this, free s-bots, attracted by sound, become more likely to connect to existing chains, rather than creating new ones.

In particular, the s-bots explore the arena searching for a chain. The s-bot located at the end of a already formed chain emits sound in order to attract other s-bots. If an s-bot sees a close connection point (the rear of an s-bot/chain), it is attracted by it for creating a connection. On the contrary, if an s-bot is very close to another one, but cannot see any connection point, it will be repelled in order to find a proper position for connection. Disconnection from chains is possible only for s-bots connected at the end of a chain: it is controlled by a fixed probability. If it is zero, the s-bots does not disconnect after joining a chain, leading to the formation of many small chains. For some values of the disconnection probability it is possible to observe that small chain quickly dissolves in favour of longer ones. Finally, a too high disconnection probability does not lead to the formation of any stable chain.

initial positions	final positions

See the movie (MPEG, 8.6Mb)

Control >> Aggregation >> Chains