Fuzzy Tracking Methods for Mobile Robots

This chapter deals with the application of fuzzy logic to autonomous navigation of mobile robots. Two different tracking problems are considered: tracking of previously computed explicit paths, and tracking of walls and other nat- ural features in the robot environment. Fuzzy logic allows the management of heuristic rule base knowledge, impre- cise information from sensors, and the uncertainties in the knowledge about the environment. The Chapter includes the application of the tracking methods to the mobile robots RAM-1 and AURORA. A. Ollero*, A. García-Cerezo**, J.

L. Martínez** and A. Mandow**. * Departamento de Ingeniería de Sistemas y Automática. Escuela Superior de Ingenieros. Universidad de Sevilla. Avenida Reina Mercedes s/n, 41012 Sevilla (Spain). Fax: (+34) 5 455-68-49; Tel: (+34) 5 455-68-71; E-mail: aollero@cartuja.us.es ** Departamento de Ingeniería de Sistemas y Automática. Universidad de Málaga. Plaza el Ejido s/n, 29013 Málaga (Spain). Fax: (+34) 5 213-14-13; Tel: (+34) 5 213-14-18; E-mail: gcerezo@tecma1.ctima.uma.es Key Words . fuzzy control, autonomous vehicles, path tracking, navigation behaviors. 25.1 INTRODUCTION The number of applications of fuzzy logic to mobile robot and autonomous vehicle control has increased significantly in the last years. The most well known arguments supporting fuzzy control are the ability to cope with imprecise information in heuristic rule based knowledge and sensor measurements, the interpolative nature of the fuzzy control- lers, and the flexibility in the definition of non linear control laws. Motion planning and control of autonomous vehicles involves several problems related with environment perception and representation, path planning, path tracking, velocity control and low level motion control. This paper deals with the applications to the mobile robot tracking of references, which include: This document was created with FrameMaker 4.0.4 a) tracking of explicit previously defined paths, using dead reckoning and navigation sensors. b) tracking of walls and other natural features in the environment using external sensors. In a) the tracking objective is to generate the control commands for the vehicle to follow the previously defined path by taking into account the actual position and the constraints imposed by the vehicle and its lower level motion con- trollers. Fuzzy logic can be used both to supervise conventional path trackers, as proposed in [1], and for direct fuzzy control. This Chapter considers the second case. That is, the fuzzy controller directly generates the steering command from the sensor inputs [2]. The approach b) is related with fuzzy reactive approaches for mobile robot navigation. In this case the controller inputs are provided by the external sensors. The chapter is organized as follows. The following section is devoted to fuzzy direct explicit path tracking. The sec- tion includes the description of the method and the application to the mobile robot RAM-1. The next section is related to reactive navigation. Fuzzy tracking is considered in the framework of a behavior based architecture for mobile robot control. The application of this method to the AURORA mobile robot is considered in the next section. The...

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