Comparison of three obstacle avoidance methods for an autonomous guided vehicle

Obstacle avoidance is one of the most critical factors in the design of autonomous vehicles such as mobile robots. One of the major challenges in designing intelligent vehicles capable of autonomous travel on highways is reliable obstacle avoidance. Obstacle avoidance may be divided into two parts, obstacle detection and avoidance control. Numerous methods for obstacle avoidance have been suggested and research in this area of robotics is done extensively. Three different methods for obstacle detection and avoidance are available on the BEARCAT III. These include fixed mounting of sonar sensors, a rotating sonar sensor and a laser scanner. The fixed mounting system uses two sonar sensors which are mounted at the outer front edges of the vehicle. The rotating sonar system consists of a Polaroid ultrasound transducer element mounted on a micro motor with an encoder feedback. The motion of this motor is controlled using a Galil DMC 1000 motion control board. It is possible to obtain range readings at known angles with respect to the center of the robot. The laser range scanner system consists of a SICK Optics laser scanner which returns a two dimensional profile of the horizontal region in front of the vehicle. The data from these systems can be used to detect and avoid obstacles. The systems were tested in July 2002 at the International Ground Robotics Competition. The BEARCAT III placed third in the autonomous challenge contest. This test bed system provides experimental evaluation of the tradeoffs among the systems in terms of resolution, range and computation speed as well as mounting arrangements. The significance of this work is in the increased understanding of obstacle avoidance for robot control and the applications of autonomous guided vehicle technology for industry, defense and medicine.