In recent years more and more emphasis was placed on the idea of autonomous mobile robots, researches being constantly rising. Mobile robots have a large scale use in industry, military operations, exploration and other applications where human intervention is risky. The accurate estimation of the position is a key component for the successful operation for most of autonomous mobile robots. The localization of an autonomous robot system refers mainly to the precise determination of the coordinates where the system is present at a certain moment of time. In many applications, the orientation and an initial estimation of the robot position are known, being supplied directly or indirectly by the user or the supervisor. During the execution of the tasks, the robot must update this estimation using measurements from its sensors. This is known as local localization. Using only sensors that measure relative movements, the error in the pose estimation increases over time as errors are accumulated. Localization is a fundamental operation for navigating mobile robots
