Evolving a cooperative transport behavior for two simple robots

This paper addresses the problem of cooperative transport of an object by a group of two simple autonomous mobile robots called s-bots. S-bots are able to establish physical connections between each other and with an object called the prey. The environment consists of a flat ground, the prey, and a light-emitting beacon. The task is to move the prey as far as possible in an arbitrary direction by pulling and/or pushing it. The object cannot be moved without cooperation. There is no explicit communication among s-bots; moreover, the s-bots cannot sense each other. All experiments are carried out using a 3D physics simulator. The s-bots are controlled by recurrent neural networks that are created by an evolutionary algorithm. Evolved solutions attained a satisfactory level of performance and some of the exhibit remarkably low fluctuations under different conditions. Many solutions found can be applied to larger group sizes, making it possible to move bigger objects.