Position localization is a necessary and important task for an intelligent robot, which moves and works in place of human workers. Various methods for position localization tasks have been proposed and developed by many researchers; for example, can active method using ultrasonic waves or laser and a passive method using images of bar codes or marks in the workspace of the robot. The passive method, using images of the object in the workspace of the robot, is particularly desirable, as this method does not influence the workspace. Thus, an arrangement of the workspace is not necessary and many robots can work simultaneously.
