Mobile robots are used in many industries for performing various tasks. For navigation of mobile robots, their self - position need to be known. The methods used for estimating the self - position of mobile robots is rapidly growing. A convenient method is to use GPS. Although GPS provides self - position in outdoor environments but GPS alone is not sufficient to provide an accuracy of the centimetre scale. Therefore, the need arises to combine the GPS information with other techniques for accurate localization. Several techniques viz. odometry, environmental range sensors, time of flight range sensors, vision based methods etc. are being employed along with GPS for accurately localizing an autonomous vehicle. This paper discusses various techniques which are used for estimating the self - position of mobile robots used in industries