Localization Based on Visibility Sectors using Range Sensors

This paper presents a rapid localization method for mobile robots. Localization, i.e., absolute position measurement, is an important issue since odometer errors render it impossible for any robot to precisely follow a speci ed trajectory, resulting in a growing di erence between the actual con guration and the calculated con guration as the robot travels. Periodic localization is required to correct these errors. In this paper, we propose a new localization method using range sensor data which is based on simple geometric properties of the environment. In many common situations, information regarding the environment is provided a priori for path planning. During processing, the method proposed here utilizes this information to partition the workspace into sectors using simple visibility computations, and a small identifying label is computed for each sector. The localizer analyzes range sensor readings (distances) and extracts characteristic points, which are compared with the pre-computed sector labels to localize the robot, rst to a sector, and then to a particular con guration within that sector. Advantages of this two step process are that it is computationally very simple, and that it allows precise localization without any landmarks from any con guration in the environment. This localization method also provides opportunities for the global navigation procedure to analyze and select trajectories in terms of their tolerance to localization errors.