A swarm of autonomous rovers for cooperative planetary exploration

The improvements in computational power, miniaturization processes, sensors and robotics technology allow today to realize low cost, small and multi-tasking mobile robotic platforms with high level of artificial intelligence. In addition, the increasing capabilities of the computer vision in the field of 3D scene reconstruction and obstacles localization allow to integrate an efficient and robust multi-vision based navigation system thus supplying learning capacity. This architecture is typical of an autonomous rover, i.e. a mobile platform which is able to navigate, to plan and follow a safe path without human remote control. These skills are obviously mandatory requirements for space missions like planetary or asteroid exploration. Till now, typical missions has been characterized by non-cooperative autonomous rovers working in different and quite far areas. Increased availability of performing autonomous platforms now suggests to plan missions involving a swarm of cooperative rovers exploring a predefined area of a planet, an asteroid or a comet, with a common target. Coordination leads to versatility and lower cost in terms of data return. The logic of cooperation is based on the fact that each member of the swarm shares a set of information that might help the others in achieving their tasks. The paper describes a possible system architecture of a swarm of two small rovers designed, built and tested at the Guidance and Navigation Lab of Università di Roma “La Sapienza". The goal of the mission is to reach a common and pre-assigned target position - a hypothetic scientific post on the surface of a planet - while exploring and analysing the surrounding environment. The coordinates of a localised obstacles are shared with the other member in order to build a common and continuously upgradable map of the environment and a database of available safe paths. The whole architecture of the designed autonomous guidance and vision-based navigation system together with the communication system are presented in detail.