The map building method for mobile robot

A map building method for a mobile robot is provided to sense accurate shape of an obstacle and to obtain position and information on the obstacle by swinging a body of the robot having a plurality of ultrasonic sensors. A map building method for a mobile robot comprises the steps of moving the mobile robot to a position apart from a wall by a predetermined distance, adjusting a steering angle of the mobile robot to let the mobile robot travel along the wall, and inputting the position of the mobile robot as a reference point, swinging a body of the stopped mobile robot to the right and left to sense obstacles within a swing range with a plurality of ultrasonic sensors, recognizing the sensed obstacles, and moving the mobile robot along the wall by a predetermined distance and stopping the robot, repeating the obstacle sensing step and the moving step several times to make a map.