Abstract-In order to accurately build a model about external environment of mobile robot, a robot multi-sensor system is designed. Ultrasonic sensor array adopt a distributed archi-tecture, infrared distance sensor use the design of class laser radar type, using multi-sensor information fusion technology, establish a 180 ° scrolling window in front of the robot, though the method of polar coordinates vector to obstacle detection and external environment model, using the "rolling window" obstacle avoidance algorithm, robots achieve autonomous obstacle avoidance and navigation in unknown environment. The experimental results confirmed that the robot system and the validity of the theory mentioned in this paper is valid and optimal.Index Terms-Mobile robot, communication fusion, polar coordinate vector, rolling window.I.