The Robot Formation Language — A formal description of formations for collective robots

In this paper we will present the Robot Formation Language (RFL), a topology description language for the formation of multi robot systems, such as robot swarms or self-reconfigurable modular robot platforms. The RFL supports homogeneous as well as heterogeneous multi robot platforms. This is important especially for modular robots (we also call them robot organisms), as there can also be robots included which have a different kinematic behaviour. Additionally, it supports tools, such as active wheels, grippers or structural elements, which enhance the capabilities of a modular robot platform. As we focus on creating organisms out of a robot swarm (i.e. the swarm robots have capabilities to connect to each other to build a modular robot organism), it is important to have a common language, which describes the swarm as well as the organism. Using the RFL, we will define a distance between two formations and describe how the calculation for this purpose can be distributed among the members of the collective. RFL cannot only be used to describe the formation of a multi robot system, but it can also be used to retrieve the kinematic chain of an organism or as a genome to evolve different organism shapes for example. It is also useful for the swarm robots to identify their position in the swarm.