This work concerns the development of a localization system for the navigation of an autonomous vehicle designed for transportation of heavy loads in an hospital environment. An overview of the physical configuration of the vehicle is presented as well as a description of its locomotion and of its sensing systems. The paper is focused on methods developed for the 2D robot’s localization with respect to a local coordinate frame, and for the topological identification of this local frame. Results on the localization system performances have been evaluated with the real prototype moving in a structured office environment. They indicate that the system can provide data to ensure a reliable, accurate and safe navigation.