Multirobot Cooperative Model Applied to Coverage of Unknown Regions

Abstract

This chapter describes the problems of robotic exploration and coverage, and also presents the main characteristics that must include a multirobot platform in order fulfill such task in terms of general architecture, goals and cooperativeness. It is described a validated model for multirobot exploration called Backtracking Spiral Algorithm – Cooperative Multirobot, BSA-CM. Exploration and coverage of unknown regions are tasks that have been developed by human beings throughout history. Nevertheless, tasks that imply lands under hazardous or hostile circumstances such as planetary exploration (Menzel, 2000), humanitarian demining (Freese et al., 2007), environmental cleaning (Tilden, 1996) of dangerous materials as radioactive or military remainders leads to delegating such exercise to robots. The main issue is to protect human life at all cost. In this particular case, by unloading the people of tasks in daily routine that implies covering of regions. Exploration of unknown areas and lands, and also execution of complex tasks in unknown or partially structured regions, is an extremely complex job for an independent robot, given the nature of the algorithms and intelligence and reasoning levels whereupon are equipped the robots (Murphy, 2000). Nevertheless, the possibility of having robotic platforms able to explore these spaces is becoming more and more a fundamental necessity in the development of autonomous mobile robots. The subject of covering and exploration with robotic entities has been boarded from different optical but in case of multi-robot systems, the challenge just begins. Systems that involve several robots can present advantages over those that include a single robot of great power, processing capacity and cost. First of all, a robot team can cover an area more quickly than a single robot. On the other hand, the exploration performed by a set of robots is robust due to the added redundancies and allows to have a notion of the best next point of view to gain information of the area where a single system would fail (Balch & Parker, 2002). After a review of different approaches to the coverage problem with robots, it is possible to conclude that such solutions are subscribed in one of two main groups depending on the movement strategy chosen to solve the problem of coverage: those that use Non-Structured trajectories, where the navigation of the robots depends on the search of the best next point of view that derives in the elimination of borders of the unknown world, or, by means of