Jh. Lim et Dw. Cho, Sonar based systematic exploration method for an autonomous mobile robot operating in an unknown environment, ROBOTICA, 16, 1998, pp. 659-667
A new systematic exploration method is addressed that permits a mobile robo
t to effectively acquire the information on an unkown environment without w
asting time. The algorithm is composed of following three modules: the firs
t is the decomposition of a workspace into several sub-nodes by employing t
he concept of Quadtree. These nodes are chosen as sub-goals to be reached s
uccessively. The second is that controls the robot to follow the boundaries
of objects in the environment in order to reach each sub-goal avoiding the
situation of the robot entering a local minima. Here we utilize the imagin
ary distance forces exerted by objects. The third is the node conditions fo
r estimating the map quality for each node, which enables the robot to remo
ve sufficiently informed nodes from the Quadtree. Two conditions are define
d for the estimation of the map quality; entropy and maximum level of Quadt
ree. The proposed approaches were successfully implemented to our mobile ro
bot equipped with sonar sensors for constructing a sonar map of an unknown
environment in a real world.