More precisely, to control the motion of a mobile robot, it is required to establish kinematic and dynamic modelling of the mobile robot. But due to the friction with the ground, it is not easy to model the equation of motion. When the slip happens, this difficulty becomes more complex. Even though it is not easy to model the slip, after considering some conditions based on the dynamic modelling of the mobile robot, the slip effect on path error is simulated. When the slip happens the mobile robot looses its own position and gose astray. To prevent this lost, some absolute position sensing system is needed. In this thesis a new optical absolute position sensor is presented to detect the absolute position, velocity and heading angle. This sensor is comprised of an infrared laser as an emitter, an array of photo transister as a receiver and the interface boards for communication with main controller. This optical sensor was pretested on the reference conveyor in details for various conditions, and experimented on the AGV motion.