This paper describes the sensor suite and the sensor fusion algorithms used for external environment sensing in the Ohio State University Desert Buckeyes 2005 DARPA Grand Challenge autonomous off-road vehicle entry. The external environment sensor suite included laser range£nders, a stereo vision system, a radar system, and ultrasonic range£nders. The positioning and orientation sensor suite included a precision GPS receiver, a vertical gyroscope, a digital compass, and dead reckoning wheel speed sensors. Sensor fusion was accomplished on a cell-based map using multiple con£dence measures and estimated object height. Issues arising from terrain and the estimation of a ground pro£le ahead of the vehicle are also discussed.