Copyright IQ IF AC Intelligent Autonomous Vehicles, Madrid, Spain, 1998 INTELLIGENT NAVIGATION ON A AUTONOMOUS VEHICLE Nelson Costat§, Manuel Crisostomot§, Paulo Coimbrat§, Anibal T. de Almeidat§ t Assistant at the Polytechnic Institute of Leiria Morro do Lena, Alto Vieiro - 2400 Leiria - PORTUGAL t Professor at the Electrical Engineering Department - University ofCoimbra § Researcher at the Institute for Systems and Robotics - University ofCoimbra Pinhal de Marrocos - 3030 Coimbra - PORTUGAL E-mail: ncosta@estg.iplei. pt.mcris @isr.ucpt.acoimbra@ucpt.adealmeida@isr.uc. pt tTel. +351.44.820349 nel. +351.39.7006286 Fax. +351.39.7006247 Abstract: The work presented in this paper describes a low cost implementation of mobile vehicles, capable of moving in semi-structured environments, using an ultrasonic sensor based approach for navigation. The first robot developed knows a working map which contains permanent obstacles. The use of external sensing mechanisms allows the vehicle to interact with its environment in a flexible manner, in order to move autonomously in the test area, detecting unknown obstacles and avoid them. The movement is ensured by two stepping motors without feedback. A radio communication system was also developed allowing the transfer of live video pictures and data between the robot and a remote station. The user interface is performed by a portable computer placed onto the robot. In this way it is possible to endow the robot with new capacities, increasing its flexibility. In order to give a greater degree of intelligence, reliability, usability, and safety a second prototype is being developed. To ensure this a more efficient and robust navigation, composed by map acquisition, planning and steering algorithms together with the use of additional sensors such as electronic compass and infrared proximity sensors is being developed. Copyright © 19981 FAC Keywords: Vehicle, sensors, navigation, path planning, control. I. INTRODUCTION The study and development of robot mechanisms began after Il World War. Soon after the Automated Guided Vehicles appeared, in 1950 ' s, and their evolution were notable, due to the development of the microprocessor technology in the 1980's and the integration of intelligent sensors. The interest and intensive research in mobile robots widespread with different approaches for design of mechanical and electrical components to sensors technology, computer systems and artificial intelligence algorithms being proposed in the past few decades. Mobile robots are a type of autonomous vehicle with a wide range of characteristics and potentialities, namely 247 they have the capability of self-driving. They have advantages operating in hostile environments to the human being, such as : in toxic environments, maintaining nuclear plants, inspecting and repairing underwater structures, in high or low temperature environments, in factories , offices and hospitals, and in the automation of residences. Summarising, they can operate in a wide range of domestic, humanity, industrial, military and scientific applications. In this communication it is described a conventional approaches for space representation, path planning and a steering control method implemented on a vehicle, capable of moving in either structured or semi- structured environments. The first vehicle is a low cost