Obstacle avoidance is one of the most critical factors in the design of autonomous vehicles such as mobile robots. The purpose of this paper is to compare and contrast three different methods for obstacle detection and avoidance. These include fixed mounting of sonar sensors, a rotating sonar sensor and a laser scanner. The three systems have been installed on the BEARCAT mobile robot. Current work is on going and was tested in June 2001 at the International Ground Robotics Competition. 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.