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Various methods for controlling mobile robot systems have been developed which are generally classified into two categories: global planning and local control. Many works, based on the complete knowledge of the robot and the environment, use a global planning method such as artificial potential fields [11], connectivity graph, cell decomposition [12], etc. These methods build some paths (set of sub-goals) which are free of obstacles | ELSEVIER Robotics and Autonomous Systems 38 2002 1-18 Robotics and Autonomous Systems www.elsevier.com locate robot Sensor-based navigation of a mobile robot in an indoor environment H. Maaref C. Barret CEMIF Complex Systems Group University ofEvry CE 1455 Courcouronnes 40 rue du Pelvoux 91020 Evry Cedex France Received 14 December 1998 received in revised form 23 May 2001 Communicated by T.C. Henderson Abstract The work presented in this paper deals with the problem of the navigation of a mobile robot either in unknown indoor environment or in a partially known one. A navigation method in an unknown environment based on the combination of elementary behaviors has been developed. Most of these behaviors are achieved by means of fuzzy inference systems. The proposed navigator combines two types of obstacle avoidance behaviors one for the convex obstacles and one for the concave ones. The use of zero-order Takagi-Sugeno fuzzy inference systems to generate the elementary behaviors such as reaching the middle of the collision-free space and wall-following is quite simple and natural. However one can always fear that the rules deduced from a simple human expertise are more or less sub-optimal. This is why we have tried to obtain these rules automatically. A technique based on a back-propagation-like algorithm is used which permits the on-line optimization of the parameters of a fuzzy inference system through the minimization of a cost function. This last point is particularly important in order to extract a set of rules from the experimental data without having recourse to any empirical approach. In the case of a partially known environment a hybrid method is used in order to exploit the advantages of global and local navigation strategies. The coordination of these strategies is based on a fuzzy inference system by an on-line comparison between the real scene and a memorized one. The planning of the itinerary is done by visibility graph and A algorithm. Fuzzy .
