4 - Approaches to Exploration

Summary

Published work shows a variety of approaches to exploration for mobile robots, ranging from disregarding the issue completely through to detailed mathematical analysis of exploration algorithms. This chapter reviews this work in the context of the recent debate between ‘reactive’ and ‘model-based’ robotics (as discussed in Section 2.1).

Many of the published papers on the map-building and navigation of mobile robots do not consider the question of exploration at all. This is, of course, often just a choice of research focus; effort is expended on the mechanics of map construction from sensor data without worrying about how the sensing positions were selected. On the other hand there are theoretical reasons why some researchers have chosen not to study exploration. A robot will not need to explore if its application is such that it does not need a map (Brooks 1990, pages 8–9) or if the map is to be supplied by the operator (Crowley 1985; Drumheller 1987). Neither of these arguments apply in the context of this thesis. Section 2.1 argued that a map was needed for the proposed delivery application and Section 3.4 explained the reasons for allowing ARNE to build its own maps.

Some researchers (Engelson (1992), for example) have adopted a strategy of ‘passive’ mapping, in which the map is built while the robot carries out its normal activities. In contrast, the current research proposes an initial exploration period during which the robot' objective is simply to learn about its environment.